NOAA Technical Memorandum NMFS

This TM series is used for documentation and timely communication of preliminary results, interim reports,. or special

purpose information. The TMs have not received complete formal review. editorial control. or detailed editing.

JULY 1995

U.S. PACIFIC

MARINE MAMMAL STOCK ASSESSMENTS

Jay Barlow, Robert L. Brownell, Jr., Douglas P. DeMaster,

Karin A. Forney, Mark S. Lowry, Steven Osmek,

Timothy J. Ragen, Randall R. Reeves, and Robert J. Small

with contributions from

John Calambokidis, Joseph G. Cordaro, Robert L. DeLong

Meghan A. Donahue, Patrick J. Gearin, Doyle A. Hanan,

Harriet R. Huber, Thomas A. Jefferson, Eugene T. Nitta

and Joe Scordino

La Jolla Laboratory, SWFSC

National Marine Fisheries Service, NOAA

P.O. Box 271

La Jolla, California 92038-0271

NOAA-TM-NMFS-SWFSC-219

U.S. DEPARTMENT OF COMMERCE

Ronald H. Brown, Secretary

National Oceanic and Atmospheric Administration

D. James Baker, Under Secretary for Oceans and Atmosphere

National Marine Fisheries Service

Rolland A. Schmitten, Assistant Administrator for Fisheries
NOAA Technical Memorandum NMFS

The National Oceanic and Atmospheric Administration (NOAA). organized in

1970, has evolved into an agency which establishes national policies and

manages and conserves our oceanic, coastal, and atmospheric resources. An

organizational element within NOAA, the Office of Fisheries is responsible for

fisheries policy and the direction of the National Marine Fisheries Service

(NMFS).

In addition to its formal publications, the NMFS uses the NOAA Technical

Memorandum series to issue informal scientific and technical publications when

complete formal review and editorial processing are not appropriate or feasible.

Documents within this series, however, reflect sound professional work and may

be referenced in the formal scientific and technical literature.
TABLE OF CONTENTS

PREFACE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . iii

PINNIPEDS

CALIFORNIA SEA LION (Zalophus californianus californianus): U.S. Stock .........

HARBOR SEAL (Phoca vitulina richardsi): California Stock ......................

HARBOR SEAL (Phoca vitulina richardsi): Oregon & Washington Coastal Waters Stock

HARBOR SEAL (Phoca vitulinu richardsi): Washington Inland Waters Stock .........

NORTHERN ELEPHANT SEAL (Miroungu angustirostris): California Breeding Stock

GUADALUPE FUR SEAL (Arctocephalus townsendi) ............................

NORTHERN FUR SEAL (Callorhinus ursinus): San Miguel Island Stock .............

HAWAIIAN MONK SEAL (Monachus schauinslandi) ............................

CETACEANS - U.S. WEST COAST

1

6

1 0

1 2

1 4

1 8

2 1

23

HARBOR PORPOISE (Phocoena phocoena): Central California Stock ................................ 28

HARBOR PORPOISE (Phocoena phocoena): Northern California Stock ............................... 32

HARBOR PORPOISE (Phocoena phocoena): Oregon/Washington Coast Stock ......................... 35

HARBOR PORPOISE (Phocoena phocoena): Inland Washington Stock ............................... 39

DALL’S PORPOISE (Phocoenoides dalli): California/Oregon/Washington Stock ........................ 43

PACIFIC WHITE-SIDED DOLPHIN (Lagenorhynchus obliquidens):

California/Oregon/Washington, Northern and Southern Stocks ................................ 46

RISSO’S DOLPHIN (Grampus griseus): Califomia/Oregon/Washington Stock .......................... 50

BOTTLENOSE DOLPHIN (Tursiops truncatus): California Coastal Stock ............................. 53

BOTTLENOSE DOLPHIN (Tursiops truncatus): California/Oregon/Washington Offshore Stock .......... . 56

STRIPED DOLPHIN (Stenella coeruleoalba): California/Oregon/Washington Stock ..................... 59

SHORT-BEAKED COMMON DOLPHIN (Delphinus delphis): California/Oregon/Washington Stock ....... . 62

LONG-BEAKED COMMON DOLPHIN (Delphinus capensis): California Stock ........................ 66

NORTHERN RIGHT WHALE DOLPHN (Lissodelphis borealis): California/Oregon/Washington Stock .... . 70

KILLER WHALE (Orcinus orca):.................... 73

SHORT-FINNED PILOT WHALE (Globicephala macrorhynchus): California/Oregon/Washington Stock ... . 77

BAIRD’S BEAKED WHALE (Berardius buirdii): California/Oregon/Washington Stock ................. . 81

MESOPLODONT BEAKED WHALES (Mesoplodon spp.): California/Oregon/Washington Stocks. ........ . 84

CUVIER’S BEAKED WHALE (Ziphizts cavirostris): California/Oregon/Washington Stock ............... . 87

PYGMY SPERM WHALE (Kogiu breviceps): California/Oregon/Washington Stock 90

DWARF SPERM WHALE (Kogia simus): California/Oregon/Washington Stock ........................ 93

SPERM WHALE (Physeter macrocephalus): California/Oregon/Washington Stock ...................... 96

HUMPBACK WHALE (Megapteru novaeungliae): California/Oregon/Washington - Mexico Stock ........ . 99

BLUE WHALE (Balaenoptera musculus): California/Mexico Stock ................................. 103

FIN WHALE (Balaenoptera physalus): California/Oregon/Washington Stock .......................... 107

BRYDE’S WHALE (Baluenoptera edeni): Eastern Tropical Pacific Stock 111

SEI WHALE (Balaenoptera borealis): Eastern North Pacific Stock .................................. 114

MINKE WHALE (Balaenoptera acutorostruta): California/Oregon/Washington Stock ................... 117

CETACEANS - HAWAII

ROUGH-TOOTHED DOLPHIN (Steno bredunensis): Hawaiian Stock ................................ 120

RISSO’S DOLPHIN (Grampus griseus): Hawaiian Stock ........................................... 122

i
BOTTLENOSE DOLPHIN (Tursiops truncatus): Hawaiian Stock .................

PANTROPICAL SPOTTED DOLPHIN (Stenella attenuatu): Hawaiian Stock

SPINNER DOLPHIN (Stenella longirostris): Hawaiian Stock ....................

STRIPED DOLPHIN (Stenella coeruleoalba): Hawaiian Stock ...................

MELON-HEADED WHALE (Peponocephala electra): Hawaiian Stock

PYGMY KILLER WHALE (Feresa attenuata): Hawaiian Stock ..................

FALSE KILLER WHALE (Pseudorca crassidens): Hawaiian Stock ...............

KILLER WHALE (Orcinus orca): Hawaiian Stock

SHORT-FINNED PILOT WHALE (Globicephala macrorhynchus): Hawaiian Stock

BLAINVILLE’S BEAKED WHALE (Mesoplodon densirostris): Hawaiian Stock ....

CUVIER’S BEAKED WHALE (Ziphim cavirostris): Hawaiian Stock

PYGMY SPERM WHALE (Kogia breviceps): Hawaiian Stock ...................

DWARF SPERM WHALE (Kogia simus): Hawaiian Stock ......................

SPERM WHALE (Physeter macrocephalus): Hawaiian Stock

BLUE WHALE (Balaenoptera musculus): Hawaiian Stock ......................

FIN WHALE (Balaenoptera physalus): Hawaiian Stock ........................

BRYDE’S WHALE (Balaenoptera edeni): Hawaiian Stock ......................

124

127

130

133

135

. 137

139

141

143

145

147

149

. 151

153

156

158

160
PREFACE

Under the 1994 amendments to the Marine Mammal Protection Act, the National Marine Fisheries

Service (NMFS) and the U.S. Fish and Wildlife Service (USFWS) were required to produce stock

assessment reports for all marine mammal stocks in waters within the U.S. Exclusive Economic

Zone. This document contains the stock assessment reports for the U.S. Pacific marine mammal

stocks under NMFS jurisdiction. Marine mammal species which are under the management

jurisdiction of the USFWS are not included in this report. A separate report containing background,

guidelines for preparation, and .a summary of all stock assessment reports is available from the

NMFS Office of Protected Resources.

This report was prepared by staff of the Southwest Fisheries Science Center, NMFS and the Alaska

Fisheries Science Center, NMFS. The information presented here was compiled primarily from

published sources, but additional unpublished information was included where it contributed to the

assessments.

The authors wish to thanks the members of the Pacific Scientific Review Group for their valuable

contributions and constructive criticism: Hannah Bernard, Robin Brown, Mark Fraker, Doyle

Hanan, John Heyning, Steve Jeffries, Katherine Ralls, Michael Scott, and Terry Wright. Their

comments greatly improved the quality of these reports, We also thanks the Marine Mammal

Commission, The Humane Society of the United States, The Marine Mammal Center, The Center

for Marine Conservation, and Friends of the Sea Otter for their careful reviews and thoughtful

comments. Special thanks to Paul Wade of the Office of Protected Resources for his exhaustive

review and comments, which greatly enhanced the consistency and technical quality of the reports.

Any ommissions or errors are the sole responsibility of the authors.

This is a working document and individual stock assessment reports will be updated as new

information becomes available and as changes to marine mammal stocks and fisheries occur;

therefore, each stock assessment report is intended to be a stand alone document. The authors solicit

any new information or comments which would improve future stock assessment reports.

This is Southwest Fisheries Science Center Technical Memorandum NOAA-TM-NMFS-SWFSC219, July 1995.

111
CALIFORNIA SEA LION (Zalophus californianus californianus): U.S. Stock

STOCK DEFINITION AND GEOGRAPHIC RANGE

The California sea lion Zulophus californianus includes three subspecies: Z. c. wollebaeki (found on the

Galapagos Islands), Z. c. juponicus (found in Japan, but is thought to be extinct), and Z. c. californianus (found from

southern Mexico to southwestern Canada; herewith referred to as the California sea lion). The breeding areas of the

California sea lion are on islands located in southern California, western Baja California, and the Gulf of California.

These three geographic regions are used to separate this subspecies into three stocks: (1) the United States stock begins

at the U.S./Mexico border and extends northward into Canada; (2) the Western Baja California stock extends from the

U.S./Mexico border to the southern tip of the Baja California Peninsula; and (3) the Gulf of California stock which

includes the Gulf of California from the southern tip of the Baja California Peninsula and across to the mainland and

extends to southern Mexico (Lowry et al. 1992). Some movement has been documented between these geographic

stocks, but rookeries in the United States are widely separateed from the major rookeries of western Baja California,

Mexico. Large genetic differences have been found between the U.S. stock and the Gulf of California Stock

(Maldonado et al. 1995). There are no international agreements for joint management of California sea lions between

the U.S., Mexico, and Canada.

POPULATION SIZE

The entire population cannot be counted because all

age and sex classes are never ashore at the same time. In

lieu of counting all sea lions, pups are counted during the

breeding season because this is the only age class that is

ashore in its entirety. The census is made after all pups are

born, near the end of the breeding season. An estimate of

the mortality that occurs prior to the census is added to the

count of pups to estimate the total number of births for that

year. The size of the population is then estimated from the

number of births and the proportion of pups in the

population.

Because the age structure of California sea lions is

unknown, the proportion of pups in the population is

computed from a life table derived for the northern fur seal

(Callorhinus ursinus) (Boveng 1988, Lowry et al. 1992).

The number of births is estimated from pup counts using an

estimated 15% pre-census mortality rate (Boveng 1988, Lowry et al. 1992). An estimate of 161,066 to 181,355

California sea lions was derived for the U.S. stock based on (1) counts of 36,184 pups made in 1994, (2) a pre-census

mortality rate of 15%, and (3) for growth rates of 8.2% and 5.2%, respectively (see below). The two estimates are

equivalent to multiplying the estimate of births for 1994 by 3.871 or 4.358.

Minimum Population Size

The minimum population size was determined from counts of all age and sex classes that were ashore at all

the major rookeries and haulout sites during the 1994 breeding season. The minimum population size of the U.S. stock

is 84,195 (NMFS unpubl. data). It includes all California sea lions counted during the July 1994 census at the four

rookeries in southern California and at the haulout sites located at Año Nuevo Island and Richardson Rock. An

additional unknown number of California sea lions are at sea or hauled out at locations that were not censused.

Current Population Trend

Records of pup counts from 1975 to 1994 (Figure 1) were compiled from the literature, NMFS reports, and

unpublished NMFS data (the literature is listed in Lowry et al. 1992). Pup counts from 1975 through 1994 were

examined for four rookeries in southern California. Log-linear interpolation between adjacent counts was used to

estimate counts for rookeries when they were not censused in a given year: (1) 1980 at Santa Barbara Is.; (2) 1978-1980

1
at San Clemente Is.; (3) 1978, 1979, 1988, and 1989 at San Nicolas Is. The mean was used when more than one count

was available for a given rookery. Also, an index was used for San Miguel Island because some years lacked data for

certain areas. Two major declines in the number of pups counted occurred during El Niño events in 1983 and 1992

(Figure 1). The natural logarithm of the pup counts, against year, indicate that the counts of pups increased at an annual

rate of 5.2% between 1975 and 1994. The counts of pups between El Niño events increased at 8.8% between 1976 and

1982 and at 8.2% between 1983 and 1994.

CURRENT AND MAXIMUM NET PRODUCTIVITY RATES

The current rate of net production is greater than the observed growth rate because fishery mortality takes a

large fraction of the net production. Net productivity was, therefore, calculated for 1980- 1994 as the realized rate of

population growth (increase in pup counts from year i to year i+l, divided by pup count in year i) plus the harvest rate

(fishery mortality in year i divided by population size in year i). For California sea lions, the total fishery mortalities

estimated from NMFS, California Dept. of Fish and Game, and Columbia River Area observer programs were 1,967,

1,967, 1,967,4,344, 2,476,2,364,4,417, 2,847,3,753,2,315,2,753, 1,915, 3,351,2,073 for 1980 to 1993, respectively

(Miller et al. 1983; Hanan et al. 1988; Hanan and Diamond 1989; Perkins et al. 1992, 1994; Brown and Jeffries 1993;

Julian 1993, 1994; Barlow et al. 1994). The total mortality estimate for 1994 (through the third quarter) was 113 (Julian,

pers. comm. Jan. 1995).

Between 1980 and 1994 the net productivity rate

averaged 11.7% (Figure 2). A regression shows a slight

increase in net production rates, but the regression is

strongly influenced by the El Niño years (1983 and 1992)

and the net production rate for 1994. Maximum net

productivity rates cannot be estimated from available data.

POTENTIAL BIOLOGICAL REMOVAL

The Potential Biological Removal (PBR) for the

United States stock of California sea lions is 5,052. This

PBR value was derived from a minimum population

estimate of 84,195, a default Rmax, value of 12%, and a

recovery factor of 1.0 (unknown status, increasing

significantly).

ANNUAL HUMAN-CAUSED MORTALITY AND

SERIOUS INJURY

Fishery Information

California sea lions are killed incidentally in set 

and drift gillnet fisheries (Hanan et al. 1993; Barlow et al. Figure 2. Net productivity rates and regression line

1994). Through the first three quarters of 1994, the estimated from pup counts with corrections for incidental

estimated mortality in the California gillnet fishery was harvest in commercial fisheries.

113 California sea lions. In 1993, the estimated mortality in the California gillnet fishery was 2,093. The combined

estimated mortality for California and the Columbia River gillnet fisheries in 1992 was 3,351 (Table 1; Brown and

Jeffries 1993, Barlow et al. 1994). Between 1983 and 1989, mortality estimates have ranged between 1,908 and 4,417

California sea lions. Logbook data indicate that mortality of California sea lions occurs also in the following non-gillnet

fisheries: (1) California, Oregon, and Washington salmon troll fisheries; (2) Oregon and Washington non-salmon troll

fisheries; (3) California herring purse seine fishery; (4) California anchovy?;, mackerel, and tuna purse seine fishery; and

(5) California sardine purse seine fishery.

During 1993, in California there were 134 vessels in the set gillnet fishery (J. Cordaro, Southwest Region,

NMFS, pers. comm.) for angel shark, California halibut, white seabass, white croaker, and other species. The number

of vessels are expected to decrease in 1994 because the Marine Resources Protection Act (passed by the state of

California) prohibits gillnet fishing within three nautical miles of the mainland in southern California. During 1993,

in California there were 149 vessels in the drift-gillnet fishery (J. Cordaro, Southwest Region, NMFS, pers. comm.) for

shark and swordfish. During 1992, in the Columbia River there were 750 vessels permitted to fish with gillnets for

2
salmon, but a significantly lower number of vessels actually fished (Brown and Jeffries 1993). Similar drift gillnet

fisheries for swordfish and sharks exist along the entire Pacific coast of Baja California, Mexico and may probably take

animals from the same population. Quantitative data are available only for the Mexican swordfish drift gillnet fishery,

which has increased from two vessels in 1986 to 29 vessels in 1992 (Sosa-Nishizaki et al. 1993). The total number of

sets in this fishery in 1992 can be estimated from data provided by these authors to be approximately 2,700, with an

observed rate of marine mammal bycatch of 0.13 animals per set (10 marine mammals in 77 observed sets; SosaNishizaki et al. 1993). This overall mortality rate is similar to that observed in California driftnet fisheries during 1990-

93 (0.15 marine mammals per set), but species-specific information is not available for the Mexican fisheries.

Fishery Mortality Rates

The total number of California

sea lions killed in U.S. gillnet fisheries

averaged 2,446 from 1991 to 1993. This

total fishery mortality rate is not less than

10% of the calculated PBR and,

therefore, cannot be considered to be

insignificant and approaching zero

mortality and serious injury rate.

However, preliminary mortality

estimates for the first three quarters of

1994 (Table 1) indicate that a large

reduction in the mortality rate has taken

place and that it may be less than 10% of

the calculated PBR for 1994. This

determination cannot be made for

individual fisheries until the

implementing regulations for Section 118

of the Marine Mammal Protection Act

(MMPA) have been reviewed by the

public and finalized.

Other Mortality

California sea lions that were

injured by entanglement in man-made

debris have been observed at rookeries

and haulouts (Stewart and Yochem 1987,

Oliver 1991). The proportion of those

entangled ranged from 0.08% to 0.35%

of those present on land, with the

majority (52%) of those being entangled

with monofilament gillnet material. A

marine mammal rehabilitation center

found that 73% of the marine mammals it

rescued were California sea lions

entangled, and subsequently injured, by

monofilament gillnetting (P. Howorth

Table I. Estimates of incidental mortality for California sea lions in gillnet

fisheries and estimates of fishing effort for each fishery (Julian 1993, 1994,

pers. comm. Jan. 1995, Brown and Jeffries 1993).

pers. comm.). The occurrence of California sea lions injured by monofilament gillnetting indicates that some are

escaping from gillnets after being caught by them. The rate of escape from gillnets, as well as the mortality rate of these

injured animals, is unknown.

Live strandings and dead beach-cast California sea lions have also been observed with gunshot wounds in

California (Lowry and Folk 1987, Deiter 1991, Barocchi et al. 1993, T. Goff pers. comm.). There are currently no

estimates of the number of California sea lions being killed or injured by guns.

3
STATUS OF STOCK

The last analysis of the dynamics of the California sea lion population in the United States concluded that there

was no evidence of a density dependent signal in the series of counts collected between 1983 and 1990, and that it was

not possible to determine the status of this stock relative to OSP (Lowry et al. 1992). They are not listed as

“endangered” or “threatened” under the Endangered Species Act or as “depleted” under the MMPA. They would not

be listed as a “strategic” stock under the MMPA because human-caused mortality is now less than the PBR. The

population has been growing recently at 8.2% per year, and the fishery mortality is declining.

REFERENCES

Barlow, J., R. W. Baird, J. E. Heyning, K. Wynne, A. M. Manville H. L. F. Lowry, D. Hanan, J. Sease, and V. N.

Burkanov. 1994. A review of cetacean and pinniped mortality in coastal fisheries along the west coast of the

USA and Canada and the east coast of the Russian Federation. Rept. Int. Whaling Comm., Special Issue

15:405-425.

Barocchi, M., L. E. Morgan, and K. D. Hanni. 1993. Frequency offishery interactions among live stranded pinnipeds

in central and northern California. (abstract). Tenth Biennial Conference on the Biology of Marine Mammals,

Galveston TX, November 11- 15: 1993.

Boveng, P. 1988. Status of the California sea lion population on the U.S. west coast. Administrative Rept. LJ-88-07,

Southwest Fisheries Science Center, La Jolla, CA. 26 p.

Brown, R. F. and S. J. Jeffries. 1993. Preliminary report on estimated marine mammal mortality in Columbia River

fall and winter salmon gillnet fisheries, 1991-l992. Columbia River Area Marine Mammal Observer Program,

53 Portway St., Astoria, OR. 13 p.

Deiter, R. L. 1991. Recovery and necropsy of marine mammal carcasses in and near the Point Reyes national Seashore.

May 1982-March 1987. In J. E. Reynolds III and D. K. Odell (editors), Marine mammal strandings in the

United States, Proceedings of the second marine mammal stranding workshop, Miami, Florida, December 3-5-

1987. p. 123-141. NOAA Technical Rept. NMFS 98.

Hanan, D. A., and S. L. Diamond. 1989. Estimates of sea lion? harbor seal, and harbor porpoise mortalities in California

set net fisheries for the 1986-87 fishing year. Final Report. Cooperative agreement No. NA-86-ABH-00018.

NOAA/NMFS SWR, January 1989. 10 pages.

Hanan, D. A., D. B. Holts, and A. L. Coan, Jr. 1993. The California drift gill net fishery for sharks and swordfish,

1981-82 through 1990-91. Calif. Dept. Fish and Game Fish. Bull. No. 175. 95 p.

Hanan, D. A., J. P. Scholl, and S. L. Diamond. 1988. Estimates of sea lion and harbor seal mortalities in California set

net fisheries for 1983, 1984, and 1985. Final Report. Cooperative agreement No. NA-86-ABH-00018.

NOAA/NMFS SWR October 1988. 10 pages.

Julian, F. 1993. Pinniped and cetacean mortality in California gillnet fisheries: Preliminary estimates for 1992. Int.

Whal. Comm. Working Paper SC/45/022. 26 p.

Julian, F. 1994. Pinniped and cetacean mortality in California gillnet fisheries: Preliminary estimates for 1993. Int.

Whal. Comm. Working Paper SC/46/011. 28 p.

Lowry], M. S. and R. L. Folk. 1987. Feeding habits of California sea lions from stranded carcasses collected at San

Diego County and Santa Catalina Island, California. Administrative Rept. LJ-87-15, Southwest Fisheries

Science Center, La Jolla, CA. 33 p.

Lowry, M. S., P. Boveng, R. J. DeLong, C. W. Oliver, B. S. Stewart, H. DeAnda, and J. Barlow. 1992. Status of the

California sea lion (Zalophus californianus californianus) population in 1992. Administrative Rept. LJ-92-32:

Southwest Fisheries Science Center, La Jolla, CA. 34 p.

Maldonado, J. E., F. 0. Davila, B. S. Stewart, E. Greffen, and R. K Wayne. 1995. Intraspecific genetic differentiation

in California sea lions (Zulophus californianus) from southern California and the Gulf of California. Mar.

Mamm. Sci. 11(1):46-58.

Miller, D. J., M. J. Herder, and J. P. Scholl. 1983. California marine mammal-fishery interaction study, 1979-1981.

Administrative Rept. LJ-83-13C, Southwest Fisheries Science Center, La Jolla, CA. 233 p.

Oliver, C. W. 1991. 1988- 1991 field studies on pinnipeds at San Clemente Island. Administrative Rept. LJ-91-27,

Southwest Fisheries Science Center, La Jolla, CA. 33 p.

Perkins, P., J. Barlow, and M. Beeson. 1992. Pinniped and cetacean mortality in California gillnet fisheries: 1991.

Working Paper SC/44/SM14 presented to the International Whaling Commission, May 1992 (unpublished).

4
32p.

Perkins, P., J. Barlow, and M. Beeson. 1994. Report on pinniped and cetacean mortality in California gillnet fisheries:

1988-90. Administrative Report LJ-94- 11 available from Southwest Fisheries Science Center, P. 0. Box 271,

La Jolla, California, 92038. 16 p.

Sosa-Nishizaki, O., R. De la Rosa Pacheco, R. Castro Longoria, M. Grijalva Chon, and J. De la Rosa Velez. 1993.

Estudio biologico pesquero del pez (Xiphias gludius) y otras especies de picudos (marlins y pez vela). Rep.

lnt. CICESE, CTECT9306.

Stewart, B. S. and P. K. Yochem. 1987. Entanglement of pinnipeds in synthetic debris and fishing net and line

fragments at San Nicolas and San Miguel Islands, California, 1978-1986. Marine Pollution Bulletin 18:336-

339.

5
HARBOR SEAL (Phoca vitulina richadsi): California Stock

STOCK DEFINITION AND GEOGRAPHIC RANGE

Harbor seals are widely distributed in the North Atlantic and North Pacific. Two subspecies exist in the Pacific:

P. v. stejnegeri in the western North Pacific. near Japan, and P. v. richardsi in the eastern North Pacific, The latter

subspecies inhabits near-shore coastal and estuarine areas from Baja California, Mexico, to the Pribilof Islands in

Alaska. These seals do not make extensive pelagic migrations, but do travel 300-500 km on occasion to find food or

suitable breeding areas (Herder 1986: D. Hanan unpublished data). In California: harbor seal haulout sites are widely

distributed on mainland and offshore islands, including intertidal sandbars, rocky shores and beaches. Because harbor

seal movement is usually limited to less than 500km from their pupping sites, because strong habitat gradients exist

along the U.S. west coast. and because coastal gillnet fisheries along the west coast are largely confined to California,

the harbor seals of California will be treated as a separate stock in this report. Other Marine Mammal Protection Act

(MMPA) stock assessment reports cover the three other stocks that are recognized along the U.S. west coast: 1)

Oregon/Washington outer coastal waters, 2) Washington inland waters. and 3) Alaska coastal and inland waters.

POPULATION SIZE

A complete count of all harbor seals in

California is impossible because some are always

away from the haulout sites. A complete pup count

(as is done for other pinnipeds in California) is also

not possible because harbor seals are precocious,

and pups can enter the water almost immediately

after birth. Population size is therefore estimated by

counting the number of seals ashore during the peak

haul-out period (the May/June molt) and by

multiplying this count by the inverse of the

estimated faction of seals on land. Boveng (1988)

reviewed studies estimating the proportion of seals

hauled out to those in the water and concluded that

a correction factor for harbor seals in California is

likely to be between 1.4 and 2.0. Huber et al.( 1993)

estimate a mean correction factor of 1.61 (CV=O.O62) for harbor seals in Oregon and Washington. Hanan and Beeson

(1994) reported 21.462 seals counted on the mainland coast and islands of California during May and June, 1994. Using

that count and the correction factor 1.61 gives a best population estimate (1.61 times the count) of 34:554 harbor seals.

Minimum Population Estimate

The minimum population size is taken as the lower 20th percentile of a log-normal population estimate based

on the corrected abundance estimate and the CV of the correction factor or approximately 32,798.

Current Population Trend

Harbor seal counts have continued to increase each year except during El Niño events of 1983 and 1993 (Fig.

1). The rate of increase appears, however, to be slowing (Fig. 2).

CURRENT AND MAXIMUM NET PRODUCTIVITY RATES

A realized rate of increase was calculated for the 1982-1994 period by linear regression of the natural logarithm

of total count versus year. The slope this regression line was 0.041 (s.e.=0.009) which gives an annualized growth rate

estimate of 4.1%. The current rate of net production is greater than this observed growth rate because fishery mortality

takes a large fraction of the net production. Net productivity was therefore calculated for 1980-1993 as the realized rate

of population growth (increase in pup counts from year i to year i+l, divided by pup count in year i) plus the harvest

rate (fishery mortality in year i divided by population size in year i). For harbor seals, the total fishery mortalities

estimated from NMFS and California Dept. of Fish and Game (CDF&G) observer programs were 834, 1,138, 2,044,

6
2,118,963, 1,115,746, 890, 559, 1,136, and 480 for 1983 to 1993, respectively (Miller et al. 1983; Hanan et al. 1988;

Hanan and Diamond 1989; Perkins et al. 1992, 1994; Julian 1993, 1994; Julian 1993, 1994).

Between 1983 and 1993, the net

productivity rate for the California stock averaged

9.7% (Figure 2). A regression shows a decrease in

net production rates, but the regression is strongly

influenced by the El Niño years. Maximum net

productivity rates cannot be estimated because

measurements were not made when the stock size

was very small.

POTENTIAL BIOLOGICAL REMOVAL

The potential biological removal (PBR)

level for this stock is calculated as the minimum

population size (32,798) times one half the default

maximum net productivity rate for pinnipeds (l/2 of

12%) times a recovery factor of 1 .O (for a stock of

unknown status that is growing), resulting in a PBR

of 1,968.

Figure 2. Net productivity rates and regression line estimated

from haulout counts, with corrections for incidental harvest in

commercial fisheries.

ANNUAL HUMAN-CAUSED MORTALITY

Historical Takes

Prior to state and federal protection and especially during the nineteenth century, harbor seals along the west

coast of North America were greatly reduced by commercial hunting (Bonnot 1928, 1951; Bartholomew and Boolootian

1960). Only a few hundred individuals survived in a few isolated areas along the California coast (Bonnot 1928). In

the last half of this century, the population has increased dramatically.

Fishery Information

In California, harbor seals are killed incidentally in several gillnet fisheries (Hanan and Diamond 1989). Set

gillnets are used by approximately 134 vessels (J. Cordaro, Southwest Region, NMFS, pers. comm.) to catch halibut,

flounder, angel shark, yellowtail, white seabass, and white croaker in California coastal waters, and marine mammal

mortality has been noted in all these fisheries (Barlow et al. 1994). As a result of area closures, fishing effort has

decreased from approximately 40,000 sets per year in the mid-1980s to 16,000 in 1993 (Barlow et al. 1994) and

decreased again in 1994 because of a new ban on fishing within 3 nmi of shore in southern California. Based on a

California Department of Fish and Game (CDFG) observer program, it was estimated that between 800 and 2,000 harbor

seals were killed annually during the 1980-88 period (Hanan and Diamond 1989, Hanan et al. 1988, Konno pers. corn.).

A National Marine Fisheries Service (NMFS) observation program has monitored 5-16% of all sets in the halibut and

angel shark fisheries from 1990-93. Harbor seal mortality in these fisheries was estimated as 1,085, 717, 865, 571,

1,136, and 480, respectively for 1988-93 (Perkins et al. 1992, 1994; Julian 1993, 1994). The 1990-93 mortality rates

for these vessels were 0.52 total marine mammals and 0.12 harbor seals per fishing day (Barlow et al. 1994).

Drift gillnets are used by approximately 149 vessels (J. Cordaro, Southwest Region, NMFS, pers. comm.) to

catch swordfish, thresher shark, and mako shark in California offshore waters (Hanan et al. 1993). Fishing effort has

decreased from approximately 10,000 sets per year in the mid-1980s to 6,600 in 1993 (Hanan et al. 1993; Barlow et al.

1994). CDFG observers monitored <1 % of sets from 1980-86, and NMFS observers monitored 4- 13% of all sets in this

fishery from 1990-93. Only 2 harbor seals have been observed taken by this fishery during this time period (Perkins

et al. 1992, 1994; Julian 1993, 1994; Hanan et al. 1993). The 1990-93 mortality rates for these vessels were 0.10 total

marine mammals and 0.0005 harbor seals per fishing day (Barlow et al. 1994). Given current levels of fishing effort,

this would result in approximately 3 harbor seal deaths per year.

Fishery Mortality Rates

Annual gillnet mortality may have been as high as 5-10% of the California harbor seal population. A kill this

large would have strong influences on population growth rates and would depress them appreciably below the growth
rate that would be observed in the absence of fishery mortality. Most of the kill was in the southern half of the State

(Hanan et al. 1988; Hanan and Diamond 1989) and most of the mainland seals are in the northern half of California

(Hanan 1993). This differential kill rate by geographic areas has not been investigated but may be an important factor

in harbor seal dynamics in California.

The average rate of incidental fishery mortality for this stock over the last 3 years was 729 animals per year,

which is greater than 10% of the calculated PBR. Therefore, fishery mortality cannot be considered insignificant and

approaching zero mortality and serious injury rate. This determination cannot be made for individual fisheries until the

implementing regulations for Section 118 of the MMPA have been reviewed by the public and finalized.

STATUS OF STOCK

A review of harbor seal dynamics through 1991 concluded that their status relative to OSP could not be

determined with certainty (Hanan 1993). They are not listed as “endangered” or “threatened” under the Endangered

Species Act nor as “depleted” under the MMPA. Because their annual mortality rate is less than the calculated PBR for

this stock, they would not be considered a “strategic” stock under the MMPA. The population appears to be growing

and the fishery mortality is declining.

REFERENCES

Barlow, J., R. W. Baird: J. E. Heyning, K. Wynne, A. M. Manville, II, L. F. Lowry: D. Hanan, J. Sease, and V. N.

Burkanov. 1994. A review of cetacean and pinniped mortality in coastal fisheries along the west coast of the

U.S. and Canada and the east coast of the Russian Federation. Rep. Int. Whal. Commn, Special Issue 15:405-

425.

Bartholomew, G. A., R. A. Boolootian. 1960. Numbers and population structure of the pinnipeds on the California

Channel Islands. Journal of Mammalogy 41:366-375.

Bonnot, P. 1928. Report on the seals and sea lions of California. Fish Bulletin Number 14. California Division of Fish

and Game.

Bonnot, P. 1951. The sea lions, seals and sea otter of the California coast. California Fish and Game 37(4):37 l-389.

Boveng, P. 1988. Status of the Pacific harbor seal population on the U.S. west coast. NOAA/NMFS SWFC Admin.

Rep. LJ-88-06,43 pages.

Hanan, D. A. 1993. Status of the Pacific harbor seal population on the coast of California in 1992. Final Report to the

National Marine Fisheries Service, Southwest Region. 27pp.

Hanan. D. A. and M. J. Beeson. 1994. Harbor seal, Phoca vitulina richardsi census in California. May-June, 1993.

Final Report to the National Marine Fisheries Service. 6lpp.

Hanan, D. A., and S. L. Diamond. 1989. Estimates of sea lion, harbor seal, and harbor porpoise mortalities in California

set net fisheries for the 1986-87 fishing year. Final Report. Cooperative agreement No. NA-86-ABH-00018.

NOAA/NMFS SWR: January 1989. 10 pages.

Hanan, D. A., D. B. Holts, and A. L. Coan, Jr. 1993. The California drift gill net fishery for sharks and swordfish,

198l-82 through 1990-91. Calif. Dept. Fish and Game Fish. Bull. No. 175. 95pp.

Hanan, D. A., J. P. Scholl, and S. L. Diamond. 1988. Estimates of sea lion and harbor seal mortalities in California set

net fisheries for 1983, 1984, and 1985. Final Report. Cooperative agreement No. NA-86-ABH-00018.

NOAA/NMFS SWR October 1988. 10 pages.

Herder, M. J. 1986. Seasonal movements and hauling site fidelity of harbor seals, Phoca vitulina richardsi, tagged at

the Russian River, California. MS Thesis. Humbolt State Univ. 52 pages.

Huber, H., S. Jeffries, R. Brown, and R. DeLong. 1993. Abundance of harbor seals (Phoca vitulina richardsi) in

Washington and Oregon, 1992. Annual report to the MMPA Assessment Program, Office of Protected

Resources, NMFS, NOAA, 1335 East-West Highway, Silver Springs, MD 20910.

Julian, F. 1993. Pinniped and cetacean mortality in California gillnet fisheries: Preliminary estimates for 1992. lnt.

Whal. Comm. Working Paper SC/45/022. 26pp.

Julian. F. 1994. Pinniped and cetacean mortality in California gillnet fisheries: Preliminary estimates for 1993. lnt.

Whal. Comm. Working Paper SC/46011. 28pp.

Miller, D. J., M. J. Herder, and J. P. Scholl. 1983. California marine mammal-fishery interaction study, 1979- 1981.

Administrative Rept. LJ-83-13C, Southwest Fisheries Science Center, La Jolla, CA. 233pp.

Perkins, P., J. Barlow, and M. Beeson. 1992. Pinniped and cetacean mortality in California gillnet fisheries: 1991.

8
Int. Whal. Commn. Working Paper SC/44/SM14. 32pp.

Perkins, P., J. Barlow, and M. Beeson. 1994. Report on pinniped and cetacean mortality in California gillnet fisheries:

1988-90. Administrative Report LJ-94-11 available from Southwest Fisheries Science Center, P. 0. Box 271,

La Jolla, California, 92038. 16pp.

9
HARBOR SEAL (Phoca vitulina richardsi):

Oregon & Washington Coastal Waters Stock

STOCK DEFINITION AND GEOGRAPHIC RANGE

Harbor seals inhabit coastal and estuarine waters off Baja California north to California, Oregon, Washington,

and Prince William Sound, west through the Gulf of Alaska and Aleutian Islands, and in the Bering Sea north to Cape

Newenham and the Pribilof Islands. They haul out on rocks. reefs, beaches, and drifting glacial ice, and feed in marine?

estuarine, and occasionally fresh waters. Along the west coast of the continental U.S., 3 separate stocks have been

defined based on harbor seal biology, in addition to management implications (Boveng 1988): (1) inland waters of

Washington (Hood Canal, Puget Sound, and Strait of Juan de Fuca out to Cape Flattery). (2) outer coast of Oregon and

Washington. and (3) California. These stock definitions are based on differences in mean pupping date (Temte 1986),

movement patterns (Jeffries 1985, Brown 1988), and preliminary genetic analyses (Huber et al. 1994). This report

considers only the second of these stocks.

POPULATION SIZE

Aerial surveys of harbor seals in Oregon and Washington were conducted during the pupping season in 1991

and 1992, when both the total number of seals (including pups) and number of pups were counted. A correction factor

for the proportion of the population that was in the water during surveys was determined from radiomarked animals that

were surveyed simultaneously during count surveys. Population estimates based on the total number of seals were

considered more accurate than estimates based on pup counts because pup counts had a greater variance (Huber et al.

in prep.). Coefficients of variation were determined for multiple surveys and found to be <0.15 in all cases. The total

count for the Oregon and Washington coastal waters stock was 18,596 (CV=O.O2) in 1992, resulting in an estimated

population size of 29,939 (CV=O.O66; 95% CI 26,320 - 34.056) animals using a mean correction factor of 1.61

(CV=O.O62) (Huber et al. 1993).

Minimum Population Estimate

The minimum population estimate for this stock is calculated from equation I from the PBR Guidelines

(this volume): NMIN = N/exp(0,842*[ln(l-[CV(N)]2

)]1/2). Using the population estimate (N) of 29,939 and its associated

CV of 0.066, NMIN for this stock is 28,322.

Current Population Trend

Historical levels of harbor seal abundance are unknown, but the population apparently decreased during the

1940s and 1950s due to mortality from bounty hunting; approximately 17.133 harbor seals were killed in Washington

State by bounty hunters between 1943 and 1960 (Newby 1973). More than 3,800 harbor seals were killed in Oregon

between 1925 and 1972 by a state-hired seal hunter and bounty hunters (Pearson 1969). The population remained

relatively low during the 1960.5, but counts have increased from 6,389 in 1977 to 18,596 in 1992 (Huber et al. in prep.).

CURRENT AND MAXIMUM NET PRODUCTIVITY RATES

The Oregon and Washington coastal waters stock of harbor seals increased at an annual rate of 11% from 1977-

82, and then at 5.5% from 1983- 1992 (Huber et al. in prep.). However: until additional estimates of net productivity

are available, it is recommended that the default pinniped maximum theoretical net productivity rate (RMAX) of 12%

(PBR Guidelines, this volume) be employed for this stock of harbor seals.

POTENTIAL BIOLOGICAL REMOVAL

Under the 1994 re-authorized Marine Mammal Protection Act (MMPA): the potential biological removal (PBR)

is defined as the product of the minimum population estimate, one-half the maximum theoretical net productivity rate,

and a recovery factor: PBR = NMIN x 0.5RMAX x FR The recovery factor (FR for this stock is 1.O, the value for unknown

stocks that are increasing with no evidence of changes in the level of incidental mortality. Thus, for the Oregon and

Washington coastal waters stock of harbor seals, PBR = (28,322 x 0.06 x 1 .O), or 1,699 animals.

10
ANNUAL HUMAN-CAUSED MORTALITY AND SERIOUS INJURY

Fisheries Information

Observers under the direction of the Oregon and Washington Departments of Fish and Wildlife (ODFW &

WDFW) recorded 9 harbor seal mortalities incidental to the Washington and Oregon Lower Columbia River drift gillnet

fishery in 1991, resulting in an extrapolated estimated total kill of 233 seals (CV=O.37) (Brown and Jeffries 1993). The

observed effort was 2,582 drifts with an observer coverage of 4.7%. During 1992, ODFW & WDFW observers recorded

15 harbor seal mortalities incidental to the Washington and Oregon Lower Columbia River drift gillnet fishery, resulting

in an extrapolated estimated total kill of 192 seals (CV=O.32) (Brown and Jeffries 1993). The observed effort was 1,545

drifts with an observer coverage of 27.2%. The average estimated annual kill for this fishery for 1991 and 1992 is

therefore 213 ([233+192]/2) animals per year. Also during 1992, ODFW & WDFW observers recorded 1 harbor seal

mortality incidental to the Washington Grays Harbor salmonid set and drift gillnet fishery, resulting in an extrapolated

estimated total kill of 10 seals (CV=1 .O). The observed effort was 307 drifts with an observer coverage of 4.2%. NMFS

observers recorded 39 harbor seal mortalities incidental to the Washington marine set gillnet fishery during 1989-1992,

which resulting in an extrapolated annual mean kill of 10 animals per year. The mean estimated annual kill based on

the above 3 fisheries is 233 (2l3+ 10+l0) seals per year.

The total fishery mortality and serious injury for this stock (233) is not less than 10% of the calculated PBR

(170) and, therefore, cannot be considered to be insignificant and approaching a zero mortality and serious injury rate.

STATUS OF STOCK

The level of human-caused mortality and serious injury (233) does not exceed the PBR (1,699), thus the

Oregon and Washington coastal waters stock of harbor seals is not classified as a strategic stock.

REFERENCES

Boveng, P. 1988. Status of the Pacific harbor seal population on the U.S. west coast. Southwest Fisheries Center,

NMFS. Admin. Rept. LJ-88-06. 43p.

Brown, R. F. 1988. Assessment of pinniped populations in Oregon. Processed Report 88-05, National Marine Fisheries

Service, Northwest and Alaska Fisheries Center, Seattle, Washington.

Brown, R. F., and S. J. Jeffries. 1993. Preliminary report on estimated marine mammal mortality in Columbia River

Fall and Winter Salmon Gillnet Fisheries, 1991 - 1992. Unpubl. Rpt., Columbia River Area Gillnet Fishery

Observer Program, 13 pp. Available at Oregon Dept. Fish and Wildl., Newport, OR, 97365.

Huber, H., S. Jeffries, R. Brown, and R. DeLong. 1993. Abundance of Harbor Seals (Phoca vitulina richardsi) in

Washington and Oregon, 1992. Annual report to the MMPA Assessment Program, Office of Protected

Resources, NMFS, NOAA, 1335 East-West Highway, Silver Spring, MD 20910

Huber, H. S. Jeffries, R. Brown, and R. DeLong. 1994. Harbor Seal Stock Assessment in Washington and Oregon

1993. Annual report to the MMPA Assessment Program, Office of Protected Resources, NMFS, NOAA, 1335

East-West Highway, Silver Spring, MD 20910

Huber, H., S. Jeffries, R. Brown, and R. DeLong. In preparation. Status of the Harbor Seal (Phoca vitulina richardsi)

population in Washington and Oregon in 1992. Status report.

Jeffries, S. J. 1985. Occurrence and distribution patterns of marine mammals in the Columbia River and adjacent

coastal waters of northern Oregon and Washington. In: Marine Mammals and Adjacent Waters, 1980- 1982.

Processed Report 85-04, National Marine Fisheries Service, Northwest and Alaska Fisheries Center, Seattle,

Washington.

Newby, T. C. 1973. Changes in Washington state harbor seal population, 1942-1972. Murrelet 54:5-6.

Pearson, J. P. 1969. The abundance and distribution of harbor seals and Steller sea lions in Oregon. Master’s Thesis,

Oregon State Univ., Corvallis, Oregon 97331.

Temte, J. L. 1986. Photoperiod and the timing of pupping in the Pacific harbor seal (Phoca vitulinu richardsi) with

notes on reproduction in northern fur seals and Dali’s porpoises. Master’s Thesis, Oregon State University,

Corvallis, Oregon 97331.

11
HARBOR SEAL (Phoca vitulina richardsi):

Washington Inland Waters Stock

STOCK DEFINITION AND GEOGRAPHIC RANGE

Harbor seals inhabit coastal and estuarine waters off Baja California north to California, Oregon, Washington,

and Prince William Sound, west through the Gulf of Alaska and Aleutian Islands, and in the Bering Sea north to Cape

Newenham and the Pribilof Islands. They haul out on rocks, reefs, beaches, and drifting glacial ice, and feed in marine,

estuarine, and occasionally fresh waters. Along the west coast of the continental U.S.. 3 separate stocks have been

defined based on harbor seal biology, in addition to management implications (Boveng 1988): (1) inland waters of

Washington (Hood Canal? Puget Sound, and Strait of Juan de Fuca out to Cape Flattery), (2) outer coast of Oregon and

Washington, and (3) California. These stock definitions are based on differences in mean pupping date (Temte 1986),

movement patterns (Jeffries 1985, Brown 1988), and preliminary genetic analyses (Huber et al. 1994). This report

considers only the first of these.

POPULATION SIZE

Aerial surveys of harbor seals in Washington and Oregon were conducted during the pupping season in 1991

and 1992, when both the total number of seals (including pups) and number of pups were counted. A correction factor

for the proportion of the population that was in the water during surveys was determined from radiomarked animals that

were surveyed simultaneously during count surveys. Population estimates based on the total number of seals were

considered more accurate than estimates based on pup counts because pup counts had a greater variance (Huber et al.

in prep.). Coefficients of variation were determined for multiple surveys and found to be <0.08 in all cases. The total

count for the Washington inland waters stock was 8,592 (CV = 0.03) in 1992, resulting in an estimated population size

of 13:833 (CV=O.O69; 95% Cl 12,095 - 15,820) animals using a mean correction factor of 1.61 (CV=O.O62) (Huber et

al. 1993).

Minimum Population Estimate

The minimum population estimate (NMIN for this stock is calculated from equation 1 from the PBR Guidelines

Report (this volume): NMIN = N/exp(0,842*[ln(l-[CV(N)]2

)]1/2). Using the population estimate (N) of 13,833 and its

associated CV of 0.069, NMIN for this stock is 13:053.

Current Population Trend

Historical levels of harbor seal abundance are unknown, but the population apparently decreased during the

1940s and 1950s due to mortality from bounty hunting; approximately 17.133 harbor seals were killed in Washington

by bounty hunters between 1943 and 1960 (Newby 1973). The population remained relatively low during the 1970s,

but most recently, counts have increased steadily from 4,824 in 1983 to 8,592 in 1992 (Huber et al. in prep.).

CURRENT AND MAXIMUM NET PRODUCTIVITY RATES

From 1983 to 1992, the Washington inland waters stock of harbor seals increased at an annual rate of 6.1%

(Huber et al. in prep.). However, until additional estimates of net productivity are available, it is recommended that the

default pinniped maximum theoretical net productivity rate (RMAX) of 12% (PBR Guidelines: this volume) be employed

for this stock of harbor seals.

POTENTIAL BIOLOGICAL REMOVAL

Under the 1994 re-authorized Marine Mammal Protection Act (MMPA), the potential biological removal (PBR)

is defined as the product of the minimum population estimate, one-half the maximum theoretical net productivity rate,

and a recovery factor: PBR = The recovery factor (FR) for this stock is 1 .0, the value for unknown

stocks that are increasing with no evidence of changes in the level of incidental mortality. Thus, for the Washington

inland waters stock of harbor seals, PBR = (I 3,053 x 0.06 x 1.0), or 783 animals.

12
ANNUAL HUMAN-CAUSED MORTALITY AND SERIOUS INJURY

Fisheries Information

NMFS observers recorded harbor seal mortality incidental to the Washington marine set gillnet fishery during

1989-1992. Following are the number of observed kills and the extrapolated total kill for each year: 1989, 5

extrapolated to 21 (Kajimura in prep.); 1990, 4 extrapolated to IO (Gearin et al. in press); 1991, 8 extrapolated to 13

(Gearin et al. 1992); and 1992. 10 extrapolated to I3 (Gearin et al. 1993). The observed effort and percentage of

observer coverage were as follows: 1989 - 361 net days, 27% coverage; 1990 - 264 net days, 47% coverage; 1991 -

238 net days, 62% coverage; 1992 - 264 net days, 80% coverage. The mean estimated annual kill for this fishery during

1989-92 is 14 seals per year. An observer program was assigned to the sockeye gill net fishery in 1994, primarily to

estimate the incidental kill of Marbled Mm-relets, not harbor seals. However, results from this new observer program

estimated an extrapolated kill of 15 harbor seals (Pierce et al. 1995). Additional incidental take of harbor seals likely

occurs in other fisheries that have not been observed.

The estimated motility rate incidental to commercial fisheries recently monitored is 29 (14 + 15) animals per

year. At present, mortality levels less than 78 animals per year (i.e., 10% of PBR) are considered insignificant.

STATUS OF STOCK

The level of human-caused mortality and serious injury (29) does not exceed the PBR (783), thus the

Washington Inland waters stock of harbor seal is not classified as a strategic stock.

REFERENCES

Boveng. P. 1988. Status of the Pacific harbor seal population on the U.S. west coast. Southwest Fisheries Center,

NMFS. Admin. Rept. LJ-88-06. 43p.

Brown, R. F. 1988. Assessment of pinniped populations in Oregon. Processed Report 88-05, NMFS, Northwest and

Alaska Fisheries Science Center, Seattle, WA.

Gearin, P., M. Johnson and S. Joner. In press. Harbor porpoise interactions with the Makah chinook salmon set-net

fishery, 1988-89. In: Kajimura (ed.) Harbor porpoise abundance and interactions with the Makah salmon setnet fishery in coastal Washington waters, 1988-89. NMFS/NMML Report. 175 pp.

Gearin, P., J. Cooke, J. Thomason and S. Joner. 1992. Summary report on marine mammal observations in the Makah

chinook salmon set-net fishery in 1991. NMFS/MWR Report. 17 pp.

Gearin, P., L. Cooke, M. Gosho and S. Joner. 1993. Summary report on marine mammal observations in the northern

Washington chinook salmon marine set-net fishery in 1992. NMFS/NWR Report. 16 pp.

Huber, H., S. Jeffries, R. Brown, and R. DeLong. 1993. Abundance of Harbor Seals (Phoca vitulina richardsi) in

Washington and Oregon, 1992. Annual report to the MMPA Assessment Program, Office of Protected

Resources, NMFS, NOAA, 1335 East-West Highway, Silver Spring, MD 20910

Huber, H., S. Jeffries, R. Brown, and R. DeLong. 1994. Harbor Seal Stock Assessment in Washington and Oregon

1993. Annual report to the MMPA Assessment Program, Office of Protected Resources, NMFS, NOAA, 1335

East-West Highway, Silver Spring: MD 20910

Huber, H., S. Jeffries, R. Brown: and R. DeLong. In preparation. Status of the Harbor Seal (Phoca vitulina richardsi)

population in Washington and Oregon in 1992. Status report.

Jeffries, S. J. 1985. Occurrence and distribution patterns of marine mammals in the Columbia River and adjacent

coastal waters of northern Oregon and Washington. In: Marine Mammals and their interactions with fisheries

of the Columbia River and adjacent waters, 1980-l982. Processed report 85-04, NMFS, Northwest and Alaska

Fisheries Center, Seattle, WA.

Kajimura, H. (ed). In prep. Harbor porpoise abundance and interactions with Makah salmon set net fishery in coastal

Washington waters, 1988-89. NMFS, Alaska Fisheries Science Center, 7600 Sand Point Way N.E., Seattle,

WA 98115.

Newby, T. C. 1973. Changes in Washington state harbor seal population, 1942-1972. Mm-relet 54:5-6.

Pierce, J. J., M. Alexandersdottie, S. Jerries, P. Erstad, W. Beattie, and A. Chapman. 1995. Draft report: Interactions

of marbled mm-relets and marine mammals with the 1994 sockeye gill net fishery.

Temte, J. L. 1986. Photoperiod and the timing of pupping in the Pacific harbor seal (Phoca vitulina richardsi) with

notes on reproduction in northern fur seals and Dall’s porpoises. Masters Thesis, Oregon State University,

Corvallis, Oregon 97331.

13
NORTHERN ELEPHANT SEAL (Mirounga angustirostris):

California Breeding Stock

STOCK DEFINITION AND GEOGRAPHIC RANGE

Northern elephant seals breed and give birth in California (U.S.) and Baja California (Mexico), primarily on

offshore islands (Stewart et al. 1994), from December to March (Stewart and Huber 1993). Males feed near the eastern

Aleutian lsands and in the Gulf of Alaska: and females feed further south, south of 45°N (Stewart and Huber 1993 ; Le

Boeuf et al. 1993). Adults return to land between March and August to molt, with males returning later than females.

Adults return to their feeding areas again between their spring/summer molting and their winter breeding seasons.

Populations of northern elephant seals in the U.S. and Mexico were all originally derived from a few tens or

a few hundreds of individuals surviving in Mexico after being nearly hunted to extinction (Stewart et al. 1994). Given

the very recent derivation of most rookeries: no genetic differentiation would be expected. Although movement and

genetic exchange continues between rookeries, most elephant seals return to their natal rookeries when they start

breeding (Huber et al. 1991). Because in situ recruitment is much greater than immigration for large rookeries: they

can be considered demographically distinct. Similarly, the California breeding population is now demographically

rather isolated from the Baja California population. No international agreements exist for the joint management of this

species by the U.S. and Mexico. The U.S. breeding population is considered here to be a separate stock.

POPULATION SIZE

All age classes of elephant seal

are never ashore at the same time to allow

a complete population count. Elephant

seal population size is typically estimated

by counting the number of pups produced

and multiplying by the inverse of the

expected ratio of pups to total animals

(McCann 1985). Stewart et al.( 1994) used

McCann’s multiplier of 4.5 to extrapolate

from 28,164 pups to a population estimate

of 127,000 elephant seals in the U.S. and

Mexico in 1991. The multiplier of 4.5

was based on a non-growing population,

and using it erroniously assumes that a

population is not growing. Boveng (1988)

and Barlow et al.( 1993) argue that a

multiplier of 3.5 is more appropriate for a

rapidly growing population such as the

California stock of elephant seals. Based Figure 1. Elephant seal births in California Multiple independent

on the estimated 21,000 pups born in estimates are presented for the Channel Islands 1988-91.

California (Barlow et al. 1993; Stewart eet

al. 1994) and this 3.5 multiplier, the California stock was approximately 73.500 in 1991. Pup counts since 1991 have

not been published yet, but unpublished NMFS data indicate that populations have continued to increase on California’s

Channel Islands (Figure I).

Minimum Population Estimate

The minimum population size for northern elephant seals can be estimated very conservatively as 42,000, twice

the observed pup count (to account for the pups and their mothers). More sophisticated methods of estimating minimum

population size would be available if a variance were associated with the multiplier used to estimate population size.

Current Population Trend

Based on trends in pup counts from 1965 to 1991, northern elephant seal populations were continuing to grow

1 4
in California but appeared to be stable or slowly decreasing in Mexico (Stewart et al. 1994). More recent data (NMFS,

unpublished) indicate that the Channel Islands rookeries (which account for more than 85% of the births in California)

have continued to grow from 1991 to 1994 (Figure I

CURRENT AND MAXIMUM NET

PRODUCTIVITY RATES

Although growth rates as high as 16% per

year have been documented for elephant seal

rookeries in the U.S. from 1959 to 1981 (Cooper

and Stewart 1983), much of this growth was

supported by immigration from Mexico. The

highest growth rate measured for the whole

U.S./Mexico population was 8.3% between 1965

and 1977 (Cooper and Stewart 1983). A continuous

growth rate of 8.3% is consistent with an increase

from approximately 100 animals in 1900 to the

current population size. The “maximum estimated

net productivity rate” as defined in the Marine

Mammal Protection Act (MMPA) would therefore

be 8.3%. In California: the net productivity rate Figure 2. Net productivity rates estimated from pup counts with

appears to have declined in recent years (perhaps corrections for incidental harvest in commercial fisheries.

with a decline in the relative contribution from Mortality for 1980- 1987 is assumed to be 300, the average of

immigration); however, current net productivity is 1988-90 values.

still near 8% per year [Figure 2: net production rate was calculated as the realized rate of population growth (increase

in pup abundance from year i to year i+I, divided by pup abundance in year i) plus the harvest rate (fishery mortality

in year i divided by population size in year i)].

POTENTIAL BIOLOGICAL REMOVAL

The potential biological removal (PBR) level for this stock is calculated as the minimum population size

(42,000) times one half the observed maximum net growth rate for this stock (l/2 of 8.3%) times a recovery factor of

1 .0 (for a species of unknown status that is increasing) resulting in a PBR of 1,743.

ANNUAL HUMAN-CAUSED MORTALITY

Fisheries Information

Set gillnets are used by approximately 134 vessels (J. Cordaro, Southwest Region, NMFS, pers. comm.) to

catch halibut, flounder, angel shark, yellowtail, white seabass, and white croaker in California coastal waters, and marine

mammal mortality has been noted in all these fisheries (Barlow et al. 1994). As a result of area closures: fishing effort

has decreased from approximately 40,000 sets per year in the mid- 1980s to 16,000 in 1993 (Barlow et al. 1994) and is

expected to decrease again in 1994 because of a new ban on fishing within 3 nmi of shore in southern California. An

observation program has monitored 5-16% of all sets in the halibut and angel shark fisheries from 1990-93. Northern

elephant seal mortality in these fisheries was estimated as 19.5, 188, 182, 26, 51, and 71, respectively for 1988-93

(Perkins et al. 1992, 1994; Julian 1993, 1994). The 1990-93 mortality rates for these vessels were 0.52 total marine

mammals and 0.014 elephant seals per fishing day (Barlow et al. 1994).

Drift gillnets are used by approximately 149 vessels (J. Cordaro, Southwest Region, NMFS, pers. comm.) to

catch swordfish, thresher shark, and mako shark in California offshore waters (Hanan et al. 1993). Fishing effort has

decreased from approximately 10,000 sets per year in the mid-1980s to 6,600 in 1993 (Barlow et al. 1994). An

observation program has monitored 4-13% of all sets in this fishery from 1990-93. Northern elephant seal mortality

was estimated as 120, 11.5, 101, 110, 114, and 103, respectively for 1988-93 (Perkins et al. 1992, 1994; Julian 1993,

1994). The 1990-93 mortality rates for these vessels were 0.10 total marine mammals and 0.021 elephant seals per

fishing day (Barlow et al. 1994).

Although all of the above mortalities occurred in U.S. waters? some may be of seals from Mexico’s breeding

population that are migrating through U.S. waters. Similar drift gillnet fisheries for swordfish and sharks exist along

15
the entire Pacific coast of Baja California, Mexico and may probably take animals from the same population,

Quantitative data are available only for the Mexican swordfish drift gillnet fishery? which has increased from two vessels

in 1986 to 29 vessels in 1992 (Sosa-Nishizaki et al. 1993). The total number of sets in this fishery in 1992 can be

estimated from data provided by these authors to be approximately 2,700. with an observed rate of marine mammal

bycatch of 0.13 animals per set (10 marine mammals in 77 observed sets; Sosa-Nishizaki et al. 1993). This overall

mortality rate is similar to that observed in California driftnet fisheries during 1990-93 (0.15 marine mammals per set),

but species-specific information is not available for the Mexican fisheries. The number of set-gillnet vessels in this part

of Mexico is unknown. The take of northern elephant seals in other North Pacific fisheries that have been monitored

appears to be trivial (Barlow et al. 1993).

Fishery Mortality Rates

The average rate of incidental fishery mortality for this stock over the last 3 years was 166 animals per year,

which is less than 10% of the calculated PBR. Therefore. the total fishery mortality appears to be insignificant and

approaching a zero mortality and serious injury rate. This determination cannot be made for individual fisheries until

the implementing regulations for Section 118 of the MMPA have been reviewed by the public and finalized.

STATUS OF STOCK

A review of elephant seal dynamics through 1991 concluded that their status could not be determined with

certainty: but that they might be within their Optimal Sustainable Population (OSP) range (Barlow et al. 1993). They

are not listed as “endangered” or “threatened” under the Endangered Species Act nor as “depleted” under the MMPA.

Because their annual mortality rate is much less than the calculated PBR for this stock, they would not be considered

a “strategic” stock under the MMPA. The population is continuing to grow rapidly and fishery mortality is relatively

constant.

REFERENCES

Barlow. J., R. W. Baird, J. E. Heynin g. K. Wynne, A. M. Manville, II, L. F. Lowry, D. Hanan, J. Sease, and V. N.

Burkanov. 1994. A review of cetacean and pinniped mortality in coastal fisheries along the west coast of the

U.S. and Canada and the east coast of the Russian Federation. Rep. Int. Whal. Commn, Special Issue 15:405-

425.

Barlow, J., P. Boveng. M. S. Lowry, B. S. Stewart, B. J. Le Boeuf, W. J. Sydeman, R. J. Jameson, S. G. Allen, and C.

W. Oliver. 1993. Status of the northern elephant seal population along the U.S. west coast in 1992. Admin.

Rept. LJ-93-O I available from Southwest Fisheries Science Center. P.O. Box 271. La Jolla, CA. 32pp.

Boveng, P. 1988. Status of the northern elephant seal population on the U.S. West Coast. Admin. Rep. LJ-88-05

available from Southwest Fisheries Science Center, P.O. Box 271, La Jolla, CA. 35pp.

Cooper, C. F. and B. S. Stewart. 1983. Demography of northern elephant seals, 191l- 1982. Science 2 19:969-971.

Hanan, D. A., D. B. Holts, and A. L. Coan, Jr. 1993. The California drift gill net fishery for sharks and swordfish,

1981-82 through 1990-91. Calif. Dept. Fish and Game Fish. Bull. No. 175. 95pp.

Huber, H. R., A. C. Rovetta, L. A. Fry, and S. Johnston. 1991. Age-specific natality of northern elephant seals at the

South Farallon Islands, California. J. Mamm. 72(3):525-534.

Julian, F. 1993. Pinniped and cetacean mortality in California gillnet fisheries: Preliminary estimates for 1992. Int.

Whal. Comm. Working Paper SC/45/022. 26pp.

Julian, F. 1994. Pinniped and cetacean mortality in California gillnet fisheries: Preliminary estimates for 1993. Int.

Whal. Comm. Working Paper SC/46/011. 28pp.

Le Boeuf, B. J., D. Cracker. S. Blackwell. and P. Morris. 1993. Sex differences in diving and foraging behaviour of

northern elephant seals. In: I. Boyd (ed.). Marine Mammal: Advances in Behavioural and Population

Biology. Oxford Univ. Press.

McCann, T. S. 1985. Size, status and demography of southern elephant seal (Mirounga leonina) populations. In J. K.

Ling and M. M. Bryden (eds.), Studies of Sea Mammals in South Latitudes. South Australian Museum. 132

pp.

Perkins, P., J. Barlow, and M. Beeson. 1992. Pinniped and cetacean mortaliry in California gillnet fisheries: 1991.

Int. Whal. Commn. Working Paper SC/44/SM14. 32pp.

Perkins, P., J. Barlow. and M. Beeson. 1994. Report on pinniped and cetacean mortality in California gillnet fisheries:

16
1988-90. Administrative Report LJ-94-l1 available from Southwest Fisheries Science Center, P. 0. Box 271,

La Jolla, California, 92038. 16pp.

Sosa-Nishizaki, O., R. De la Rosa Pacheco, R. Castro Longoria, M. Grijalva Chon, and J. De la Rosa Velez. 1993.

Estudio biologico pesquero de1 pez (Xiphias gladus) y otras especies de picudos (marlins y pez vela). Rep.

Int. CICESE, CTECT9306.

Stewart, B. S., and H. R. Huber. 1993. Mirounga angustirostris. Mammalian Species 449: l-10.

Stewart, B. S., B. J. Le Boeuf, P. K. Yochem, H. R. Huber, R. L. DeLong, R. J. Jameson, W. Sydeman, and S. G. Allen.

1994. History and present status of the northern elephant seal population. In: B. J. Le Boeuf and R. M. Laws

(eds.) Elephant Seals Univ. Calif. Press, Los Angeles.

17
GUADALUPE FUR SEAL (Arctocephalus townsendi)

STOCK DEFlNlTION AND GEOGRAPHIC RANGE

Commercial sealing during the 19th century reduced the once abundant Guadalupe fur seal to near extinction

in 1894 (Townsend 1931). Prior to the harvest it ranged from Point Conception, California (and possibly as far north

as the Farrallon Islands), to the Revillagigedo Islands. Mexico (Fleischer 1987). The capture of two adult males at

Guadalupe Island in 1928 established the species’ return (Townsend 1931); however, they were not seen again until

1954 (Hubbs 1956). At the present time Guadalupe fur seals pup and breed only at Guadalupe Island, Mexico, but

individuals have been sighted in the Channel Islands and central California (Stewart et al. 1987, Gallo 1994) and in the

Gulf of California (Gallo 1994: 0. Maravilla, pers. comm. 1994). The population is considered to be a single stock

because they pup and breed only at Guadalupe Island, Mexico.

POPULATION SIZE

The size of the population prior to the commercial harvests of the 19th century is not known, but estimates

range from 20,000 to 100,000 animals (Wedgeforth 1928. Hubbs 1956. Fleischer 1987). The population was estimated

by Gallo (1994) to be about 7.408 animals in 1993. The population estimate was derived by multiplying the number

of pups (counted and estimated) by a factor of 4.0.

Minimum Population Size

All the individuals of the population cannot be counted because all age and sex classes are never ashore at the

same time and some individuals that are on land are not visible during the census. Sub-sampling portions of the rookery

indicate that only 47-55% of the seals present (i.e.. hauled out) are counted during the census (Gallo 1994). The 1993

count of all age classes plus the estimate of missed animals was 6,443 (Gallo 1994). The minimum size of the

population in Mexico can be estimated as the actual count of 3.028 hauled out seals [The actual count data were not

reported by Gallo (1994); this number is derived by multiplying the estimated number hauled out by 47%, the minimum

estimate of the percent counted]. In the United States, a few Guadalupe fur seals are known to inhabit California sea

lion rookeries in the Channel Islands (Stewart et al. 1987)

Current Population Trend

Counts of Guadalupe fur seals have been made

sporadically since 1954. Records of Guadalupe fur seal

counts through 1984 were compiled by Seagars (I 984).

Fleischer (1987): and Gallo (1994). The count for 1988

was taken from Torres et al. (1990). A few of these

counts were made during the breeding season, but the

majority were made at other times of the year (Figure 1).

Also. the counts that are documented in the literature

generally provide only the total of all Guadalupe fur

seals counted (i.e. the counts are not separated by

age/sex class). The counts that were made during the

breeding season? when the maximum number of animals

are present at the rookery, were used to examine

population growth (Gallo 1994). The natural logarithm

of the counts was regressed against year to calculate the

growth rate of the population. These data indicate that

the population of Guadalupe fur seals is increasing Figure 1. Counts of Guadalupe fur seals at Guadalupe

exponentially at an average annual growth rate of 13.7% Island, Mexico and the estimated population growth curve

(Gallo 1994; Figure I). derived from counts made during the breeding season.

18
CURRENT AND MAXlMUM PRODUCTIVITY RATES

The maximum net productivity rate can be assumed to be equal to the annual growth rate observed over the

last 30 years (13.7%) because the population was at a very low level and should have been growing at nearly its

maximum rate.

POTENTIAL BIOLOGICAL REMOVAL

The Potential Biological Removal (PBR) for the Guadalupe fur seal is 104. This PBR value was derived from

a minimum population estimate of 3,028, an Rmax value of 13.7%, and a recovery factor of 0.5 (for a threatened species).

The vast majority of this PBR would apply towards incidental mortality in Mexico.

ANNUAL HUMAN-CAUSED MORTALITY AND SERIOUS INJURY RATE

Fishery Information

In the United States there have been no reports of gillnet mortalities or injuries for Guadalupe fur seals (Lennert

et al. 1991, Perkins et al. 1992, Julian et al. 1993, 1994, Barlow et al. 1994). No information is available for humancause mortalities or injuries in Mexico.

Drift and set giltnet fisheries may cause incidental mortality of Guadalupe fur seals in Mexico and the United

States. In the United States, during 1993 there were 134 vessels in the set-gillnet fishery for halibut and angel shark and

149 vessels in the drift-gillnet fishery for shark and swordfish. The number of set net vessels is expected to decline in

1994 because the Marine Resources Protection Act of 1990 (passed by the state of California) limits fishing within 3

miles of the coast in southern California. Similar drift gillnet fisheries for swordfish and sharks exist along the entire

Pacific coast of Baja California, Mexico and may probably take animals from the same population. Quantitative data

are available only for the Mexican swordfish drift gillnet fishery, which has increased from two vessels in 1986 to 29

vessels in 1992-(Sosa-Nishizaki et al. 1993). The total number of sets in this fishery in 1992 can be estimated from data

provided by these authors to be approximately 2,700, with an observed rate of marine mammal bycatch of 0.13 animals

per set (10 marine mammals in 77 observed sets; Sosa-Nishizaki et al. 1993). This overall mortality rate is similar to

that observed in California driftnet fisheries during 1990-93 (0.15 marine mammals per set), but species-specific

information is not available for the Mexican fisheries. The number of set gillnets used in Mexico is unknown.

Fishery Mortality Rates

The total fishery mortality and serious injury for this stock is less than 10% of the calculated PBR and,

therefore, can be considered to be insignificant and approaching zero mortality and serious injury rate. This

determination cannot be made for individual fisheries until the implementing regulations for Section 118 of the Marine

Mammal Protection Act (MMPA) have been reviewed by the public and finalized.

STATUS OF STOCK

The state of California lists the Guadalupe fur seal as a fully protected mammal in the Fish and Game Code

of California (Chap. 8, sec. 4700, d), and it is listed also as a threatened species in the Fish and Game Commission

California Code of Regulations (Title 14, sec. 670.5, b, 6, H). The Endangered Species Act lists it as a threatened

species, which automatically qualifies this as a “depleted” and “strategic” stock under the Marine Mammal Protection

Act. There is insufficient information to determine whether the fishery mortality in Mexico exceeds the PBR for this

stock. The population is growing at approximately 13.7% per year.

REFERENCES

Barlow, J., R. W. Baird, J. E. Heyning, K. Wynne, A. M. Manville II, L. F. Lowry, D. Hanan, J. Sease, and V. N.

Burkanov. 1994. A review of cetacean and pinniped mortality in coastal fisheries along the west coast of the

USA and Canada and the east coast of the Russian Federation. Rept. Int. Whaling Comm., Special Issue

15:405-425.

Fleischer, L. A. 1987. Guadalupe fur seal, Arcfocephalus townsendi. In J. P. Croxall and R. L. Gentry (eds.). Status,

biology, and ecology of fur seals. Proceedings of an international symposium and workshop. Cambridge,

England, 23-27 April 1984. p. 43-48. U.S. Dept. of Commerce, NOAA, NMFS, NOAA Tech. Rept. NMFS

51.

Gallo, J. P. 1994. Factors affecting the population status of Guadalupe fur seal, Arctocephalus townsendi (Merriam,

19
1897), at lsla de Guadalupe, Baja California? Mexico. Ph.D. Thesis, University of California? Santa Cruz, 199

p.

Hubbs. C. L. 1956. The Guadalupe fur seal still lives! Zoonooz, S. D. Zool. Soc. 29(12):6-9.

Julian: F. 1993. Pinniped and cetacean mortality in California gillnet fisheries: preliminary estimates for 1992. Rept.

Int. Whaling Commission, Working Paper SC/45/022.

Julian F. 1994. Pinniped and cetacean mortality in California gillnet fisheries: preliminary estimates for 1993. Rept.

Int. Whaling Commission, Working Paper SC/46/011.

Lennert, C., S. Kruse, and M. Beeson. 1991. Preliminary report on incidental mammal bycatch in California gillnet

fisheries. Rept. lnt. Whaling Commission, Working Paper SC/43/003.

Perkins, P., J. Barlow, and M. Beeson. 1992. Pinniped and cetacean mortality in California gillnet fisheries: 1991.

Rept. Int. Whaling Commission, Working Paper SC/44/SM14.

Seagars, D. J. 1984. The Guadalupe fur seal: a status review. National Marine Fisheries Service, Southwest Region,

Administrative Rept. SWR-84-6. 29pp.

Sosa-Nishizaki, O., R. De la Rosa Pacheco, R. Castro Longoria, M. Grijalva Chon, and J. De la Rosa Velez. 1993.

Estudio biologico pesquero de1 pez (Xiphias gladius) y otras especies de picudos (marlins y pez vela). Rep.

Int. CICESE, CTECT9306.

Stewart, B. S., P. K. Yochem, R. L. DeLong, and G.A. Antonelis Jr. 1987. Interactions between Guadalupe fur seals

and California sea lions ant San Nicolas and San Miguel islands, California. In J. P. Croxall and R. L. Gentry

(eds.). Status, biology, and ecology of fur seals. Proceedings of an international symposium and workshop.

Cambridge, England, 23-27 April 1984. p. 103-l06. U.S. Dept. of Commerce, NOAA, NMFS, NOAA Tech.

Rept. NMFS 51.

Torres-G., A., A. Aguayo-L., and N. Valdez-T. 1990. Tamaño y distribution de la poblacion del lobo fino de

Guadalupe, Arctocephalus townsendi (Merriam, 1897), durante el verano de 1988. [Abstracts] XV Reunion

internacional para el estudio de los mamiferos marinos, 18-20 April 1990. La Paz, B. C. S.. Mexico.

Townsend, C. H. 1931. The fur seal of the California islands with new descriptive and historical matter. Zoologica

9:443-457.

Wedgeforth, H. M. 1928. The Guadalupe fur seal (Arctocephalus townsendi). Zoonooz: S. D. Zool. Soc. 3(3):4-9.

20
NORTHERN FUR SEAL (Callorhinus m-sinus): San Miguel Island Stock

STOCK DEFINITION AND GEOGRAPHIC RANGE

Northern fur seals occur from southern California north to the Bering Sea and west to the Okhotsk Sea and

Honshu Island, Japan. During the breeding season, approximately 74% of the worldwide population is found on the

Pribilof Islands in the southern Bering Sea, with the remaining animals spread throughout the North Pacific Ocean

(Lander and Kajimura 1982). Of the seals in U.S. waters outside of the Pribilofs, approximately 1% of the population

is found on Bogoslof Island in the southern Bering Sea and San Miguel Island off southern California (NMFS 1993).

Fur seals may temporarily haul-out on land at other sites in Alaska, British Columbia. and on islets along the coast of

the continental United States, but generally outside of the breeding season (Fiscus 1983).

Adults usually occur onshore during a 5 month period, principally during the breeding-season (May-October),

then migrate south and spend the next 7 months at sea. Adult females and pups from the Pribilof Islands migrate

through the Aleutian Islands into the North Pacific Ocean, often to the Oregon and California offshore waters. Pups

may remain at sea for 22 months before returning to their rookery of birth. Adult males from the Pribilof Islands

generally migrate only as far south as the Gulf of Alaska (Kajimura 1984). There is considerable interchange of

individuals between rookeries, thus the distinction between the North Pacific Stock and the San Miguel stock is based

principally on geographic separation during the breeding season.

POPULATION SIZE

The population estimate for the San Miguel Island stock of fur seals is calculated as the estimated number of

pups at rookeries multiplied by an expansion factor. Based on research conducted on the eastern North Pacific stock

of fur seals, a life table analysis was performed to estimate the number of yearlings, 2 yr olds, 3 yr olds, and animals

at least 4 yrs old (Lander 1981). The resulting population estimate was equal to the pup count multiplied by

approximately 4.475. The expansion factors are based on a sex and age distribution estimated after the harvest of

juvenile males was terminated; currently, CVs are unavailable. A more appropriate expansion factor for the San Miguel

stock is 4.0, based on the increased mortality and possible emigration of adults associated with the El Niño Southern

Oscillation event in 1982-l983 (DeLong, pers. comm.). The 1994 pup count of 2,634 (NMFS, unpubl. data) was the

highest reported at San Miguel since the colony was discovered in 1968. Based on this count and the expansion factor,

the most recent population estimate of this stock is 10,536 (2,634 x 4.0) fur seals.

Minimum Population Estimate

The survey technique utilized for estimating the

abundance of northern fur seals within the San Miguel stock

is a direct count, with no associated CV as sites are surveyed

only once. Additional estimates of the overall population

size (i.e., NBEST) and associated CV are also unavailable.

Therefore NMIN, for this stock can not be estimated using

equation 1 from the PBR Guidelines (this volume). Rather,

NMIN is estimated as twice the maximum number of pups

born in 1994 or 5268 (2,634 x 2) animals. This approach

was recommended by the Pacific Scientific Review Group.

Current Population Trend

The population of fur seals on San Miguel has

increased steadily since the early 1970s, except during the El

Niño Southern Oscillation event in 1982-1983. Specifically,

pup counts increased about 24% annually from 1972 through

1982, an increase due, in part, to immigration of females

from the Bering Sea and the western North Pacific Ocean

(DeLong 1982). In 1983, counts decreased dramatically by

63% (DeLong and Antonelis 1991) and have since steadily

2 1
increased; yet, counts remained below the 1982 level (pre-El Niño) until 1990 (Fig. I).

CURRENT AND MAXIMUM NET PRODUCTIVITY RATES

The northern fur seal population increased steadily during 1912-1940 when the commercial harvest on the

Pribilof Islands excluded pregnant females. During this period, the rate of population growth was 8.6% (SE=1.47%)

per year (York pers. comm.), the maximum recorded for this species.

POTENTIAL BIOLOGICAL REMOVAL

Under the I994 re-authorized Marine Mammal Protection Act (MMPA), the potential biological removal (PBR)

is defined as the product of the minimum population estimate, one-half the maximum theoretical net productivity rate,

and a recovery factor: PBR = NMIN x 0.5RMAX x FR. The recovery factor (FR) for this stock is 1 .O, the value for stocks

of unknown status that are increasing with no evidence of change in the level of incidental mortality (PBR Guidelines,

this volume). Thus, for the San Miguel stock of northern fur seals, PBR = (5,268 x 0.043 x 1.0) or 227 animals.

ANNUAL HUMAN-CAUSED MORTALITY AND SERIOUS INJURY

Fisheries Information

Mortality of northern fur seals incidental to the California gillnet fisheries has not been reported in the last 5

years. However, it is the intention of NMFS to consider any takes of northern fur seals by commercial fisheries in

waters off California, Oregon and Washington as being from the San Miguel Island stock. High-seas gillnetting in the

central North Pacific has been discontinued. The estimated mortality rate incidental to commercial fisheries recently

monitored is zero. At present, mortality levels less than 23 animals per year (i.e., 10% of PBR) are considered

insignificant and approaching a zero mortality and serious injury rate.

Other Mortality

Other than occasional reports of fur seals being found dead from gunshot wounds, no other human-caused

mortality is known for this stock.

STATUS OF STOCK

The estimated annual level of total human-caused mortality and serious injury (0) does not exceed the PBR

(227), thus the San Miguel stock of the northern fur seal is not classified as a strategic stock. The population status of

this stock relative to OSP is unknown, unlike the Eastern Pacific stock which is formally listed as depleted under the

MMPA.

REFERENCES

DeLong, R. L. 1982. Population biology of northern fur seals at San Miguel Island, California. Ph.D. dissertation,

University of California, Berkeley. CA. 185p.

DeLong, R. L., and G. A. Antonelis. 199 I. Impacts of the 1982-1983 El Niño on the northern fur seal population at

San Miguel Island, California. Pp. 75-83, In: F. Trillmich and K. Ono (eds.), Pinnipeds and El Niño:

responses to environmental stress. Springer-Verlag, New York. 293p.

Fiscus, C.F. 1983. Fur seals and island. In Background papers submitted by the United States to the 26th annual

meeting of the Standing Scientific Committee of the North Pacific Fur Seal Commission, Washington, D.C.,

March 28-April 5, 1983. National Marine Mammal Laboratory, AFSC, 7600 Sand Point Way NE, Seattle, WA

98115.

Kajimura, H. 1984. Opportunistic feeding of the northern fur seal, Callorhinus ursinus, in the eastern North Pacific

Ocean and eastern Bering Sea. NOAA Technical Report NMFS SSRF-779,49p.

Lander, R. H. 1981. A life table and biomass estimate for Alaskan fur seals. Fishery Research (Amsterdam) 1:55-70.

National Marine Fisheries Service. 1993. Final Conservation Plan for the northern fur seal (Callorhinus ursinus).

Prepared by the National Marine Mammal Laboratory/Alaska Fisheries Science Center. Seattle, Washington,

and the Office of Protected Resources/NMFS, Silver Spring, Maryland. 80p.

22
HAWAIIAN MONK SEAL (Monachus schauinslandi)

STOCK DEFINITION AND GEOGRAPHIC RANGE

Hawaiian monk seals are distributed throughout the Northwestern Hawaiian Islands (NWHI) in six main

reproductive populations at French Frigate Shoals, Laysan Island, Lisianski Island, Pearl and Hermes Reef, Midway

Atoll, and Kure Atoll. The Midway population has not contributed significantly to pup production since the 1950s.

Additional populations, with limited reproduction and maintained by immigration, are found at Necker Island and Nihoa

Island, and a small number of seals are distributed throughout the main Hawaiian Islands. Study of this species has

focused on their abundance and behavior on land during the reproductive season (spring and early summer). Their

pelagic distribution and behavior (and any seasonal or temporal variation therein) are largely unknown.

In the last two centuries, this species has experienced two major declines which: presumably, have severely

reduced its genetic variation. The tendency for genetic drift may have been (and continue to be) relatively large, due

to the small size of the different island/atoll populations. However, l0- 15% of these seals migrate among the populations

(Johnson and Kridler 1983, NMFS unpubl. data) and, at least to some degree, this movement should counter the

development of separate genetic stocks. Genetic variation among the different island populations is currently under

investigation but. at present, we have no evidence that separate genetic stocks have developed.

Demographically, the different island populations have exhibited considerable independence. For example,

abundance at French Frigate Shoals grew rapidly during the 1950s to the 198Os, while other populations declined

rapidly. However, the variation in past population trends may be partially explained by changes in the level of human

disturbance (Gerrodette and Gilmartin 1990). Current demographic variability among the island populations probably

reflects a combination of different recent histories and varying environmental conditions. While management activities

and research focus on problems of single island/atoll populations, this species is managed as, and considered to be, a

single stock.

POPULATION SIZE

Total abundance of the Hawaiian monk seal was estimated to be 1580 (SE=l47) in 1992 (Ragen, 1993). Mean

beach counts are used as the primary index of abundance, and between 1992 and 1993, the total of mean beach counts

at the main reproductive populations (excluding Midway) declined by 11%. If the decline in mean beach counts

indicates a similar decline in total number of seals, then the best estimate of total abundance for 1993 would be 1406

(SE=131; assuming constant coefficient of variation).

Minimum Population Size

Using 1406 as the most current estimate of

abundance, 131/1406 = 0.093 as the coefficient of variation,

and the formula provided in the Report of the PBR (Potential

Biological Removal) Workshop, June 24-27, 1994, the best

estimate of Nmin is 1300.

Current Population Trend

Between 1958 and 1993. mean beach counts at the

main reproductive populations declined by 60% (Fig. 1).

From 1985 to 1993, counts declined at 5% per year.

CURRENT AND MAXIMUM NET PRODUCTIVITY

RATES

Assuming that mean beach counts are a reliable

index of total abundance, the current net productivity rate for

this species is -0.05 yr-1 (i.e., the species is declining at 5%

per year). Much of this decrease reflects an extensive loss of

Figure 2. Total of mean beach counts of Hawaiian

immature seals at French Frigate Shoals, the largest

monk seals (excluding pups) at five of the six main

population. In addition, populations at Laysan and Lisianski

reproductive populations, 1958-1993.

23
Islands continue to decline slowly.

Contrary to the decline at the above sites, the population at Kure Atoll has grown at ca. 3% since 1981 (due

largely to decreased human disturbance and introduced females): and the population at Pearl and Hermes Reef has

grown at approximately 6% since 1975. This 6% growth rate is the best indicator of the maximum net productivity rate

(R,,) for this species.

POTENTIAL BIOLOGICAL REMOVAL

Using the values of Nmin and Rmax given above (1300 and 0.06 yr-1, respectively) and a recovery factor (FR) of

0.1 (the Hawaiian monk seal was designated as both endangered and depleted in 1976) the potential biological removal

(PBR) for this species is 1300 * (0.06 * (0.5)) * 0. 1 = 3.9. However, the Endangered Species Act takes precedence in

the management of this species and, under the Act, allowable take is zero.

ANNUAL HUMAN-CAUSED MORTALITY AND SERIOUS INJURY

Human-related mortality has caused 2 major declines of the Hawaiian monk seal, and may continue to be an

important factor impeding its recovery. In the 1800s this species was decimated by sealers, crews of wrecked vessels,

and guano and feather hunters (Dill and Bryan 1912, Wetmore 1935, Clapp and Woodward 1972). Several populations

may have been driven extinct; for example, no seals were seen at Midway Atoll during a l4-month period in 1888-89,

and only a single seal was seen during three months of observations at Laysan Island in 1912-l3 (Bailey 1952). A survey

in 1958 indicated at least partial recovery of the species in the first half of this century (Rice 1960). However,

subsequent surveys documented a second major decline beginning in 1958 (or earlier), during which several populations

(Kure Atoll, Midway Atoll, and Pearl and Hermes Reef) decreased by 80-100%. This second decline has not been

explained at Pearl and Hermes Reef, or Lisianski and Laysan Islands. However, trends at Kure Atoll, Midway Atoll,

and French Frigate Shoals appear to have been determined by the pattern of human disturbance which, among other

effects, caused pregnant females to abandon prime pupping habitat and nursing females to abandon their pups (Kenyon

1972: Gerrodette and Gilmartin 1990). The result was a decrease in pup survival, which led to poor reproductive

recruitment, low productivity, and population decline. Since 1979, disturbance from human activities on land has been

limited primarily to Kure and Midway Atolls. The U.S. Coast Guard LORAN station at Kure Atoll was closed in 1992

and vacated in 1993. The U.S. Naval Air Facility at Midway was closed in 1993, and will be vacated following clean-up

and restoration activities. Thereafter, human disturbance on land should not impede the recovery of this species.

Disturbance at sea, however, may impede recovery.

Fishery Information

Since the late 197Os, development and expansion of fisheries in the NWHI has lead to interactions detrimental

to monk seals. The interactions fall into four categories: operations/gear conflict: entanglement in fisheries debris, seal

consumption of potentially toxic discard, and competition for prey. Since 1982, a total of five fishery-related monk seal

deaths have been recorded, including three from entanglement in fisheries debris (Henderson 1990) one from

entanglement in the bridle rope of lobster trap (NMFS, unpubl. data), and one from entanglement in an illegally set gill

net off the western shore of Oahu (NMFS, Unpubl. data). In addition, 12 seals have been observed with embedded fish

hooks and 23 seals have been observed with uncharacteristic wounds attributed to interactions, Importantly, the majority

of these deaths and injuries have been observed incidentally during other research activities; study of monk seal/fisheries

interactions has not been adequate to reliably estimate the rate of fisheries-related injury or mortality for this species.

The Hawaiian monk seal interacts with four fisheries. The NWHI lobster fishery began in the late 1970s.

developed rapidly in the 1980s and then declined in the late 1980s and early 1990s. The fishery had to be dosed in 1993

due to low spawning stock biomass, and was limited to nine weeks in 1994. From 1983 to 1991, catch per unit effort

declined by 80% (Polovina 1993). The number of vessels in the fishery increased from four in 1983 to 16 in 1985-86,

and then declined to 12 in 1992 (Dollar and Landgraf 1992, Dollar 1993). Both effort and landings have been

concentrated at Gardner Pinnacles, Mare Reef. Necker Island, and St. Rogatien Bank (Clarke and Todoki 1988. Polovina

and Moffitt 1989). Seasonal and area differences in fisheries interactions, and total incidental mortality, have not been

evaluated. As just noted, one mortality has been documented; in 1986, a monk seal drowned after becoming entangled

in the bridle rope of an actively fishing lobster trap near Necker Island. However, indirect mortality due to competition

for prey may be a more serious problem than direct interactions. The recent trend in the seal population at French Frigate

Shoals indicates that this population is severely food-limited. Monk seals eat lobsters and forage at all the sites where

24
lobster fishing has been concentrated. Competition probably occurs, but the extent of this competition is not known

because the relative importance of lobsters in the monk seal diet has not been determined, Thus, the degree to which

the lobster fishery has contributed to the high mortality of immature seals at French Frigate Shoals is uncertain.

The NWHI bottomfish fishery occurred at low levels (< 50 t per year) until 1977, steadily increased to 460 t

in 1987, and then dropped to ca. I40 to 190 t per year from 1988 to 1992 (Pooley 1993, Kawamoto 1993). The number

of vessels rose from 19 in 1984 to 28 in 1987, and then varied from IO to 17 in 1988 through 1992 (Kawamoto 1993).

Nitta and Henderson (3993) reported an interaction rate of one event per 34.4 hours of fishing (based on observer data),

but they do not provide a confidence interval for their estimate. Documented interactions include seals damaging and

removing hooked catch, seals being hooked in the process, and seals consuming discarded fish, which may contain high

levels of ciguatoxin or other biotoxins. Of the 12 cases where seals have been observed with embedded hooks, only two

cases were known to involve a bottomfish hook. Consumption of discarded fish may be a more serious problem for

interacting seals. In particular, the seals eat discarded kahala (Seriola dumerili), which is not kept by fishery participants

because it is considered to accumulate high levels of ciguatoxin and other biotoxins. The subsequent effects on the seals

have not been assessed. No monk seal mortalities have been documented by participants or observers in the bottomfish

fishery. The ecological effects of this fishery on monk seals (i.e., competition for prey) are unknown and unstudied.

The third fishery with which monk seals interact is the pelagic longline fishery. This fishery targets swordfish

and tunas, primarily, and does not compete with Hawaiian monk seals for prey. The fishery began in the 1940s and

operated at a relatively low level (< 5000 t per year) until the mid 1980s. In 1987. 37 vessels participated in this fishery,

but by 1992, the number had grown to 166 (Dollar 1993). Entry is currently limited to a maximum of 167 vessels. While

much of the fishery operated outside of the NWHl Exclusive Economic Zone, the rapid expansion raised concerns about

the potential for interactions with protected species, including the monk seal. Evidence of interactions began to

accumulate in 1990, including five hooked seals and 13 unusual seal wounds thought to have resulted from interactions.

After some interim management measures, a permanent Protected Species Zone was established in October 1991, This

zone extends 50 nautical miles around the NWHI and the corridors between the islands. However, monk seals are still

observed with evidence of interactions. In 1994, for example, a parturient female at French Frigate Shoals was observed

with a hook in her mouth; the hook was not removed or recovered. but appeared to be from the longline fishery. The

rate of such interactions and their eventual outcome have not been quantitatively assessed.

Finally, monk seals have interacted with recreational fisheries in the main Hawaiian Islands and at Kure Atoll.

In four of the 12 known hookings, the hook was from recreational fishing. As Kure Atoll was vacated by the U.S. Coast

Guard in 1993, such interactions should no longer occur at this site. All (three) documented interactions within the main

Hawaiian Islands have been near Kauai; one hooking occurred in the recreational fishery for ulua (Caranx spp.), and

the fishery was undetermined in the two other cases. These interactions may become more prevalent with the

translocation of seals from populations in the NWHI to the main Islands. However, twenty-one adult males were

translocated in July/August 1994. and as of February 1995, no interactions have been confirmed. In addition. the

translocated males have virtually no reproductive value to the species, and interactions should not pose a significant

threat to the species.

Fishery Mortality Rate

The total fishery mortality and serious injury for this stock is uncertain and cannot be estimated without more

quantitative assessment. However? as seals are still observed with serious injuries (such as the parturient fernal

mentioned in the previous section), the total fishery mortality and serious injury for this stock is greated than 1) zero

allowable take under the Endangered Species Act and 2) 10% of the calculated PBR (3.9 * 0. IO = 0.39). Therefore, total

fishery mortality and serious injury can not be considered to be insignificant and approaching a rate of zero. In addition,

fishery interactions with this species have not been adequately studied and, therefore, the information above represents

only the minimum level of interactions. not the true level. Without further study, the true level of interaction cannot be

estimated. Finally, the most serious interactions may be indirect (i.e., involving competition for prey with the lobster

fishery or consumption of discard from the bottomfish fishery) and, to date, the extent or consequences of such indirect

interactions have not been evaluated.

Other Mortality

Since 1982,29 Hawaiian monk seals have died in captivity (NMFS, unpubl. data). Twenty of these seals were

collected for rehabilitation, four were being held in permanent captivity, three were subjects of field research, one was

25
being translocated from Laysan Island to Johnston Atoll, and one was being held for translocation to the main Hawaiian

Islands.

Seals have also died after encounters with marine debris from sources other than fisheries. In 1986, a weaned

pup died at East Island, French Frigate Shoals, after becoming entangled in wire left when the U.S. Coast Guard

abandoned the island 3 decades earlier. In 1991, a seal died after becoming trapped behind a decaying seawall on Tern

Island, French Frigate Shoals.

The only documented case of illegal killing of an Hawaiian monk seal occurred when a resident of Kauai killed

an adult female.

Other sources of mortality which may be impeding the recovery of this population include mobbing (attacks

on a female my multiple males), sharks, poisoning by ciguatoxin or other biotoxins, and disease/parasitism. Mobbing

appears to be a major impediment to recovery at Laysan and Lisianski Islands. It has also been documented at French

Frigate Shoals: Kure Atoll (although not recently), and Necker Island. The primary cause of mobbing is thought to be

an imbalance in the adult sex ratio, with males outnumbering females. Mobbed seals include adult females and immature

seals of both sexes. These imbalances are more likely to occur when populations are reduced (Starfield et al. in press).

To the extent that human activity has reduced monk seal populations, such activity may have contributed to the mobbing

problem.

The incidence of shark wounds increased in the late 1980s and early 1990s at French Frigate Shoals. However,

sharks have been ruled out as the primary cause of the recent decline observed at French Frigate Shoals (Ragen 1993).

Poisoning by ciguatoxin or related toxins is suspected as the primary cause of the Laysan die-off in 1978, and may have

contributed to the high mortality ofjuvenile seals translocated to Midway Atoll in 1992 and 1993. In the NWHI. the

danger of ciguatera poisoning is considered to be greatest at Midway Atoll (Hokama, University of Hawaii, pers.

comm.), where nearshore construction and the reshaping of Sand Island may contribute to the probability of

dinoflagellate blooms. While virtually all wild monk seals carry parasites after they begin to forage, the role of

parasitism in monk seal mortality is unknown. The role of disease is also uncertain, although Banish and Gilmartin

(1992) did not find any evidence that infectious disease is impeding the recovery of this species.

STATUS OF STOCK

In 1976. the Hawaiian monk seal was designated depleted under the Marine Mammal Protection Act of 1972

and as endangered under the Endangered Species Act of 1973. The species is assumed to be well below its OSP and,

since 1985, has been declining at 5% per year. Therefore, this species is characterized as a strategic stock.

REFERENCES

Bailey, A. M. 1952. The Hawaiian monk seal. Museum Pictorial, Denver Museum of Natural History 7:1-32.

Banish, L. D., and W. G. Gilmartin. 1992. Pathological findings in Hawaiian monk seals. J. Wildl. Dis. 28:428-434.

Clapp. R. B., and P. W. Woodward. 1972. The natural history of Kure Atoll, Northwestern Hawaiian Islands, Atoll Res.

Bull. 164:303-304

Clarke, R. P., and A. C. Todoki. 1988. Comparison of three calculations of catch rates of the lobster fishery in the

Northwestern Hawaiian Islands. Available Honolulu Lab.. Southwest Fish. Sci. Cent., Natl. Mar. Fish. Serv.,

NOAA, Honolulu, Hl 96822-2396. Southwest Fish. Sci. Cent. Admin. Rep. H-88-6, 30 p.

Dill: H. R., and W. A. Bryan. 1912. Report on an expedition to Laysan Island in 1911. U.S. Dept. of Agric. Surv. Bull.

42: l-30.

Dollar, R. A. 1993. Annual report of the 1992 Western Pacific lobster fishery. Available Honolulu Lab., Southwest Fish.

Sci. Cent.: Natl. Mar. Fish. Serv.. NOAA, Honolulu, HI 96822-2396. Southwest Fish. Sci. Cent. Admin. Rep.

H-93-09,27 p.

Dollar, R. A.. and K. C. Landgraf. 1992. Annual report of the 1991 Western Pacific lobster fishery. Available Honolulu

Lab., Southwest Fish. Sci. Cent., Natl. Mar. Fish. Serv.: NOAA, Honolulu, HI 96822-2396. Southwest Fish.

Sci. Cent, Admin. Rep. H-92-10, 26 p.

Gerrodette, T. M., and W. G. Gilmartin. 1990. Demographic consequences of changed pupping and hauling sites of the

Hawaiian monk seal. Conserv. Biol. 4:423-430.

Henderson. J. R. 1990. Recent entanglements of Hawaiian monk seals in marine debris. In R. S. Shomura and M. L.

Godfrey (eds.): Proceedings of the Second International Conference on Marine Debris, April 2-7, 1989,

Honolulu, Hawaii, p. 540-553. U.S. Dep. Commer., NOAA, Tech. Memo. NMFS-SWFSC-154.

26
Johnson, A. M., and E. Kridler. 3983. lnterisland movement of Hawaiian monk seals. ‘Elepaio 44(5):43-45.

Kawamoto, K. E. 3993. Northwestern Hawaiian Islands bottomfish fishery, 1992. Available Honolulu Lab., Southwest

Fish. Sci. Cent.? Natl. Mar. Fish. Serv., NOAA, Honolulu, HI. 96822-2396. Southwest Fish. Sci. Cent. Admin.

Rep. H-93-14, 19 p.

Kenyon, K. W. 1972. Man versus the monk seal. J. of Mammal. 53(4):687-696.

Nitta: E. T., and J. R. Henderson. 1993. A review of interactions between Hawaii’s fisheries and protected species. Mar.

Fish. Rev. 55(2):83-92.

Polovina, J. J. 1993. The lobster and shrimp fisheries in Hawaii. Mar. Fish. Rev. 55(2):28-33.

Polovina, J. J., and R. B. Moffitt. 1989. Status of lobster stocks in the Northwestern Hawaiian Islands, 1988. Available

Honolulu Lab., Southwest Fish. Sci. Cent., Natl. Mar. Fish. Serv., NOAA, Honolulu, HI 96822-2396.

Southwest Fish. Sci. Cent. Admin. Rep. H-89-3. 10 p.

Pooley, S. G. 1993. Hawaii’s marine fisheries: some history, long-term trends, and recent developments. Mar. Fish. Rev.

55(2):7- 19.

Ragen, T. J. 1993. Status of the Hawaiian monk seal in 1992. Available Honolulu Lab., Southwest Fish. Sci. Cent., Natl.

Mar, Fish. Serv., NOAA, Honolulu, HI 96822-2396. Southwest Fish. Sci. Cent. Admin. Rep. H-93-05, 79 p.

Rice, D. W. 1960. Population dynamics of the Hawaiian monk seal. J. of Mammal. 41:376-385.

Starfield, A. M., J. D. Roth, and K. Ralls. In press. “Mobbing” in Hawaiian monk seals: using simulation modeling to

evaluate management strategies. Conserv. Biol.

Wetmore, A. 1925. Bird life among lava rock and coral sand. The Natl. Geograp. Mag. 48:77-108.

27
HARBOR PORPOISE (Phocoena phocoena): Central California Stock

STOCK DEFINITION AND GEOGRAPHIC RANGE

In the Pacific, harbor porpoise are found in coastal and inland waters from Point Conception, California to

Alaska and across to Kamchatka and Japan (Gaskin 1984). Harbor porpoise appear to have more restricted movements

along the western coast of the continental U.S. than along the eastern coast. Regional differences in pollutant residues

in harbor porpoise indicate that they do not mix freely between California, Oregon, and Washington (Calambokidis and

Barlow 1991). That study also showed some regional differences within California (although the sample size was

small). This pattern stands as a sharp contrast to the eastern coast of the U.S. and Canada where harbor porpoise are

believed to migrate seasonally from as far south as the Carolinas to the Gulf of Maine and Bay of Fundy (Polacheck et

al. 1990). A phylogeographic analysis of genetic data from northeast Pacific harbor porpoise did not show complete

concordance between DNA sequence types and geographic location (Rose1 1992). However, an AMOVA analysis of

the same data with additional samples found significant genetic differences for 4 of the 6 pair-wise comparisons between

the four areas investigated: California. Washington, British Columbia, and Alaska (Rose1 et al, in press). These results

demonstrate that harbor porpoise along the west coast of North America are not pan-mictic or migratory, and movement

is sufficiently restricted that genetic differences have evolved.

In their assessment of harbor porpoise, Barlow and Hanan (in press) recommend that the animals inhabiting

central California (defined to be from Point Conception to the Russian River) be treated as a separate stock. The

justifications given for this were 1) fishery mortality of harbor porpoise is limited to central California, 2) movement

of individual animals appears to be restricted within California. and consequently 3) fishery mortality could cause the

local depletion of harbor porpoise if central California is not managed separately. In addition, recent genetic studies

have confirmed that movement on the west coast is limited (Rose1 et al, in press); therefore, harbor porpoise in central

California are considered a separate stock. Other Pacific coast Marine Mammal Protection Act (MMPA) stock

assessment reports for harbor porpoise include: 1) a northern California stock 2) an Oregon/Washington coastal stock,

3) a Washington inland-waters stock. and 4) an Alaska stock

POPULATION SIZE

Barlow and Forney (1994) reviewed previous estimates of harbor porpoise abundance in central California and

presented a new estimate of 4,120 (CV=O.22) based on a series of aerial surveys from 1988 to 1993. This recent

estimate is not significantly different from the previous estimate of 3,274 (CV=O.31) but is more precise (owing to the

greater number of kilometers surveyed). Both of these estimates only include the region between the coast and the 50-

fathom (91m) isobath. Barlow (1988) found that the vast majority of harbor porpoise in California were within this

depth range; however, Green et al.( 1992) found that 24%

of harbor porpoise seen during aerial surveys of Oregon

and Washington were between the 100m and 200m

isobaths (55 to 109 fathoms). The above abundance

estimates are likely to underestimate the total abundance

of harbor porpoise by a non-trivial amount.

Minimum Population Estimate

The minimum population estimate for harbor

porpoise in central California is taken as the lower 20th

percentile of the log-normal distribution of abundance

estimated from the 1988-93 aerial surveys (Barlow and

Forney 1994) or 3,431.

Current Population Trend

An analysis of a 1986-93 time series of aerial

surveys was conducted to examine trends in harbor

porpoise abundance in central California (Forney et al.

1991; Forney, in press). After controlling for the effects Figure 1: Changes in harbor porpoise abundance from

aerial surveys.

28
of sea state, cloud cover: and area on sighting rates, Forney (in press) found a statistically significant decline in harbor

porpoise abundance in central California (p < 0.1) (Fig. 1). The decline is most evident in the southern part of central

California, between Point Conception and Monterey Bay. She did not find any compensating increase in porpoise

abundance in northern California. The decline is somewhat surprising given that fishery mortality has been declining

during this same time period (Table 1).

CURRENT AND MAXIMUM NET PRODUCTIVITY RATES

Based on what are argued to be biological limits of the species (ie. females give birth first at age 4 and produce

one calf per year until death), the theoretical, maximum-conceivable growth rate of a closed harbor porpoise population

was estimated as 9.4% per year (Barlow and Boveng 1991). [Woodley and Read (199 1) calculate a maximum growth

rate of approximately 5% per year, but their argument for this being a maximum (i.e. that porpoise survival rates cannot

exceed those of Himalayan thar) is weak.] This maximum theoretical rate may not be achievable for any real

population. Population growth rates have not actually been measured for any harbor porpoise population. We therefore

conclude that the current and maximum net productivity rates are unknown for the central California population of

harbor porpoise.

POTENTIAL BIOLOGICAL REMOVAL

The potential biological removal (PBR) level for this stock is

calculated as the minimum population size (3,431) times one half the default

maximum net growth rate for cetaceans (l/2 of 4%) times a recovery factor of

0.5 (for a species of unknown status), resulting in a PBR of 34.

ANNUAL HUMAN-CAUSED MORTALITY

Fishery Information

The incidental capture of harbor porpoise is largely limited to set

gillnet fisheries in central California (coastal setnets are not allowed in not-them

California, and harbor porpoise do not occur in southern California). Set

gillnets are used by approximately 134 vessels (J. Cordaro, Southwest Region,

NMFS, pers. comm.) to catch halibut, flounder. angel shark, yellowtail, white

seabass, and white croaker in California coastal waters (Barlow et al. 1994).

Harbor porpoise have been caught in nets set for halibut, flounder, white

croaker, and (historically) white seabass (Barlow and Forney 1994). Due in

part to area closures, fishing effort in central California has decreased from

approximately 10,000 sets per year in the mid-1980s (Hanan et al. 1986) to

approximately 400 sets per year in 1993 (calculated from 270 days of effort

times 1.6 sets per day, Julian 1994). Harbor porpoise mortality in halibut

gillnets has been estimated for the years 1969 through 1993 (Table I) based on

direct observation of a subset of gillnet hauls from 1983 to 1993 and an

extrapolation to the number of gillnet sets from 1969 to 1982. An increase is

seen during this time period to a maximum annual catch of 200-300 porpoise

in the late 1970s and early 1980s. The decrease in annual mortality since the

mid- 1980s was primarily the result of decreased fishing effort (Perkins et al.

1994). The average 1992 and 1993 mortality rates for these vessels were 0.58

total marine mammals and 0.11 harbor porpoise per fishing day (Julian 1993,

1994). The death of one harbor porpoise was observed during the retrieval of

200 white croaker gillnets in central California in the 1980s which gives a

mortality rate of 0.005 porpoise per net (Barlow and Hanan, in press). Total

harbor porpoise mortality has not been estimated for the white croaker fishery.

Fishery Mortality Rates

Table I. Estimated annual mortality

in central California gillnet fisheries

(Barlow and Forney 1994).

The average gillnet mortality for the last 3 years (31 porpoise per year) is greater than 10% of the calculated

PBR; therefore, the fishery mortality cannot be considered insignificant and approaching zero mortality and serious

29
injury rate. This determination cannot be made for individual fisheries until the implementing regulations for Section

118 of the MMPA have been reviewed by the public and finalized.

STATUS OF STOCK

Harbor porpoise in California are not listed as threatened or endangered under the Endangered Species Act nor

as depleted under the Marine Mammal Protection Act. Barlow and Hanan (in press) calculate the status of harbor

porpoise relative to historic carrying capacity (K) using a technique called back-projection. They calculate that the

central California population could have been reduced to between 30% and 97% of K by incidental fishing mortality,

depending on the choice of input parameters. They conclude that there is no practical way to reduce the range of this

estimate. New information does not change this conclusion, and the status of harbor porpoise relative to their Optimum

Sustainable Population (OSP) levels in central California must be treated as unknown. The average mortality rate over

the last 3 years (3 1) is slightly less than the calculated PBR (34) for central California harbor porpoise; therefore, the

central California harbor porpoise population is not “strategic” under the MMPA. The Pacific Scientific Review Group

(established by the MMPA) recommended that this stock be considered strategic because it is declining and may be

listed as threatened under the Endangered Species Act unless the decline is stopped. Because fishery mortality has

declined over the last 10 years and because the decline in the population is likely to be natural, the NMFS does not

believe that a strategic status is -justified at this time. Research will continue to monitor the population size and to

investigate the possible causes of the decline.

REFERENCES

Barlow, J. 1988. Harbor porpoise (Phocoena phocoena) abundance estimation in California, Oregon and Washington:

I. Ship surveys. Fish. Bull. 86:417-432.

Barlow, J. and P. Boveng. 1991. Modelling age-specific mortality for marine mammal populations. Marine Mammal

Sci. 7(1):84-119.

Barlow? J., R. W. Baird, J. E. Heyning, K. Wynne, A. M. Manville, Il. L. F. Lowry, D. Hanan, J. Sease. and V. N.

Burkanov. 1994. A review of cetacean and pinniped mortality in coastal fisheries along the west coast of the

U.S. and Canada and the east coast of the Russian Federation. Rep. Int. Whal. Commn, Special Issue 15:405-

425.

Barlow. J. and K. A. Fomey. 1994. An assessment of the 1994 status of harbor porpoise in California. NOAA

Technical Memorandum NOAA-TM-NMFS-SWFSC-205. 17pp.

Barlow, J. and D. Hanan. (in press). An assessment of the status of harbor porpoise in central California. Rept. Int.

Whal., Special Issue.

Calambokidis, J. and J. Barlow. 1991. Chlorinated hydrocarbon concentrations and their use for describing population

discreteness in harbor porpoises from Washington, Oregon, and California. pp. 101-110 In: J. E. Reynolds III

and D. K. Ode11 (eds.) Marine mammal strandings in the United States. NOAA Technical Report NMFS 98.

Forney, K. A. (In press). A decline in the abundance of harbor porpoise (Phocoena phocoena) in near-shore waters

off California, 1986-93. Fish. Bull. 93(4).

Forney, K. A., D. A. Hanan, and J. Barlow. 1991. Detectin g trends in harbor porpoise abundance from aerial surveys

using analysis of covariance. Fish. Bull. 89(3):367-377.

Gaskin, D. E. 1984. The harbour porpoise (Phocoena phocoena L.): regional populations, status, and information on

direct and indirect catches. Rep. int. Whal. Commn 34:569-586.

Green, G. A., J. J. Brueggeman, R. A. Grotefendt, C. E. Bowlby, M. L. Bonnell, and K. C. Balcomb, III. 1992.

Cetacean distribution and abundance off Oregon and Washington, 1989-l990. Ch. 1 In: J. J. Brueggeman

(ed.). Oregon and Washington Marine Mammal and Seabird Surveys. Minerals Management Service Contract

Report 14-l2-0001-30426 prepared for the Pacific OCS Region.

Hanan, D. A., S. L. Diamond, and J. P. Scholl. 1986. An estimate of harbor porpoise mortality in California set net

fisheries April 1, 1984 through March 31, 1985. Admin. Rep. SWR-86-16. Avail. from Southwest Region,

300 S. Ferry Street, Terminal Island, CA 90731. 38pp.

Julian, F. 1993. Pinniped and cetacean mortality in California gillnet fisheries: Preliminary estimates for 1992. Int.

Whal. Comm. Working Paper SC/45/022. 26pp.

Julian, F. 1994. Pinniped and cetacean mortality in California gillnet fisheries: Preliminary estimates for 1993. Int.

Whal. Comm. Working Paper SC461011.

30
Perkins, P., J. Barlow, and M. Beeson. 1994. Report on pinniped and cetacean mortality in California gillnet fisheries:

1988-90. Administrative Report LJ-94-11. National Marine Fisheries Service, Southwest Fisheries Center,

P. 0. Box 27 I, La Jolla, California, 92038. 16pp.

Polacheck, T., F. W. Wenzel, and G. Early. 1990. What do stranding data say about harbor porpoise (Phocoena

phocoena). Int. Whal. Commn. Working Paper SC/42/SM39.

Rosel, P. E. 1992. Genetic population structure and systematic relationships of some small cetaceans inferred from

mitochondrial DNA sequence variation. Ph.D. Dissertation, Univ. Calif. San Diego. 191pp.

Rosel, P. E., A. E. Dizon, and M. G. Haygood. (in press). Variability of the mitochondrial control region in populations

of the harbour porpoise. Phocoena phocoena, on inter-oceanic and regional scales, Can. J. Fish. and Aquat.

Sci. 52.

Woodley, T. H. and A. J. Read. 1991. Potential rates of increase of a harbour porpoise (Phocoena phocoena)

population subjected to incidental mortality in commercial fisheries. Can. J. Fish. Aquat. Sci. 48:2429-2435.

3 1
HARBOR PORPOISE (Phocoena phocoena): Northern California Stock

STOCK DEFINITION AND GEOGRAPHIC RANGE

In the Pacific, harbor porpoise are found in coastal and inland waters from Point Conception, California to

Alaska and across to Kamchatka and Japan (Gaskin 1984). Harbor porpoise appear to have more restricted movements

along the western coast of the continental U.S. than along the eastern coast. Regional differences in pollutant residues

in harbor porpoise indicate that they do not mix freely between California, Oregon, and Washington (Calambokidis and

Barlow 1991). That study also showed some regional differences within California (although the sample size was

small). This pattern stands as a sharp contrast to the eastern coast of the U.S. and Canada where harbor porpoise are

believed to migrate seasonally from as far south as the Carolinas to the Gulf of Maine and Bay of Fundy (Polacheck et

al. 1990). A phylogeographic analysis of genetic data from northeast Pacific harbor porpoise did not show complete

concordance between DNA sequence types and geographic location (Rose1 1992). However, an AMOVA analysis of

the same data with additional samples found significant genetic differences for 4 of the 6 pair-wise comparisons between

the four areas investigated: California, Washington, British Columbia, and Alaska (Rose1 et al, in press). These results

demonstrate that harbor porpoise along the west coast of North America are not pan-mictic or migratory, and movement

is sufficiently restricted that genetic differences have evolved.

In their assessment of harbor porpoise. Barlow and Hanan (in press) recommend that the animals inhabiting

central California (defined to be from Point Conception to the Russian River) be treated as a separate stock. The

justifications given for this were 1) fishery mortality of harbor porpoise is limited to central California, 2) movement

of individual animals appears to be restricted within California, and consequently 3) fishery mortality could cause the

local depletion of harbor porpoise if central California is not managed separately. In addition, recent genetic studies

have confirmed that movement on the west coast is limited (Rose1 et al. in press); therefore, harbor porpoise in central

California are considered a separate stock. Lacking further biological evidence, the Northern California stock was

separated from the Oregon/Washington coastal stock based on an application of a precautionary principle: dividing

stocks into units that are as small as practicable. This report addresses the harbor porpoise stock in northern California.

north of the Russian River. Other Pacific coast Marine Mammal Protection Act (MMPA) stock assessment reports for

harbor porpoise include: I) a central California stock 2) an Oregon/Washington coastal stock, 3) a Washington inlandwaters stock, and 4) an Alaska stock.

POPULATION SIZE

Barlow and Forney (1994) reviewed previous estimates of harbor porpoise abundance in northern California

and presented a new estimate of 9,250 (CV=O.23) based on a series of aerial surveys from 1988 to 1993. This estimate

only includes the region between the coast and the 50-fathom (91m) isobath. Barlow (1988) found that the vast majority

of harbor porpoise in California were within this depth range; however, Green et al. (1992) found that 24% of harbor

porpoise seen during aerial surveys of Oregon and Washington were between the 1OOm and 200m isobaths (55 to 109

fathoms). The above abundance estimates are likely to underestimate the total abundance of harbor porpoise by a nontrivial amount.

Minimum Population Estimate

The minimum population estimate for harbor porpoise in northern California is taken as the lower 20th

percentile of the log-normal distribution of abundance estimated from the 1988-93 aerial surveys (Barlow and Forney

1994) or 7,640.

Current Population Trend

Forney (in press) examines trends in relative harbor porpoise abundance in Northern California based on aerial

surveys from 1989-93. No significant trends were evident over this time period.

CURRENT AND MAXIMUM NET PRODUCTIVITY RATES

Based on what are argued to be biological limits of the species (ie. females give birth first at age 4 and produce

one calf per year until death), the theoretical, maximum-conceivable growth rate of a closed harbor porpoise population

was estimated as 9.4% per year (Barlow and Boveng 1991). [Woodley and Read (1991) calculate a maximum growth

32
rate of approximately 5% per year, but their argument for this being a maximum (i.e. that porpoise survival rates cannot

exceed those of Himalayan thar) is weak.] This maximum theoretical rate may not be achievable for any real

population. Population growth rates have not actually been measured for any harbor porpoise population. We therefore

conclude that the current and maximum net productivity rates are unknown for the northern California stock of harbor

porpoise.

POTENTIAL BIOLOGICAL REMOVAL

The potential biological removal (PBR) level for this stock is calculated as the minimum population size

(7,640) times one half the default maximum net growth rate for cetaceans (1/2 of 4%) times a recovery factor of 0.5 (for

a species of unknown status), resulting in a PBR of 76.

ANNUAL HUMAN-CAUSED MORTALITY

Fishery Information

The incidental capture of harbor porpoise in California is largely limited to set gillnet fisheries in central

California. Coastal setnets are not allowed in not-them California (to protect salmon resources there).

Fishery Mortality Rates

Because there is no known fishery mortality in northern California, the fishery mortality can be considered

insignificant and approaching zero mortality and serious injury rate.

STATUS OF STOCK

Harbor porpoise in California are not listed as threatened or endangered under the Endangered Species Act nor

as depleted under the Marine Mammal Protection Act. Because of the lack of recent or historical sources of humancaused mortality, the harbor porpoise stock in northern California has been concluded to be within their Optimum

Sustainable Population (OSP) level (Barlow and Forney 1994). Because there is no known human-caused mortality or

serious injury, this would not be considered a “strategic” stock under the MMPA.

REFERENCES

Barlow, J. 1988. Harbor porpoise (Phocoena phocoena) abundance estimation in California, Oregon and Washington:

I. Ship surveys. Fish. Bull. 86:417-432.

Barlow, J. and P. Boveng. 1991. Modelling age-specific mortality for marine mammal populations. Marine Mammal

Sci. 7(1):84-l19.

Barlow, J. and K. A. Forney. 1994. An assessment of the 1994 status of harbor porpoise in California. NOAA

Technical Memorandum NOAA-TM-NMFS-SWFSC-205. l7pp.

Barlow, J. and D. Hanan. (in press). An assessment of the status of harbor porpoise in central California. Rept. Int.

Whal., Special Issue.

Calambokidis, J. and J. Barlow. 1991. Chlorinated hydrocarbon concentrations and their use for describing population

discreteness in harbor porpoises from Washington, Oregon, and California. pp. 10l-110 In: J. E. Reynolds III

and D. K. Ode11 (eds.) Marine mammal strandings in the United States. NOAA Technical report NMFS 98. 

Forney, K. A. (In press). A decline in the abundance of harbor porpoise (Phocoena phocoena) in near-shore waters

off California, 1986-93. Fish. Bull. 93(4).

Gaskin, D. E. 1984. The harbour porpoise (Phocoena phocoena L.): regional populations, status, and information on

direct and indirect catches. Rep. int. Whal. Commn 34:569-586.

Green, G. A., J. J. Brueggeman, R. A. Grotefendt, C. E. Bowlby, M. L. Bonnell, and K. C. Balcomb, III. 1992.

Cetacean distribution and abundance off Oregon and Washington, 1989-1990. Ch. 1 In: J. J. Brueggeman

(ed.). Oregon and Washington Marine Mammal and Seabird Surveys. Minerals Management Service Contract

Report l4-12-0001-30426 prepared for the Pacific OCS Region.

Polacheck, T., F. W. Wenzel, and G. Early. 1990. What do stranding data say about harbor porpoise (Phocoena

phocoena). Int. Whal. Commn. Working Paper SC/42/SM39.

Rosel, P. E. 1992. Genetic population structure and systematic relationships of some small cetaceans inferred from

mitochondrial DNA sequence variation. Ph.D. Dissertation, Univ. Calif. San Diego. 191pp.

Rosel, P. E., A. E. Dizon, and M. G. Haygood. (in press). Variability of the mitochondrial control region in populations

33
of the harbour porpoise, Phocoena phocoena, on inter-oceanic and regional scales. Can. J. Fish. and Aquat.

Sci. 52.

Woodley, T. H. and A. J. Read. 1991. Potential rates of increase of a harbour porpoise (Phocoena phocoena)

population subjected to incidental mortality in commercial fisheries. Can. J. Fish. Aquat. Sci. 48:2429-2435.

34
HARBOR PORPOISE (Phocoena phocoena): Oregon/Washington Coast Stock

STOCK DEFINITION AND GEOGRAPHIC RANGE

In the eastern North Pacific Ocean, harbor porpoises are found coastally from the Bering Strait, Alaska, to

central California, occasionally frequenting bays, the mouths of large rivers and at times ascending freshwater streams

(Leatherwood and Reeves 1983). Aerial survey data from coastal Oregon and Washington, collected during all seasons,

suggests that harbor porpoise distribution varies by depth with 79% occurring at depths less than 50 fathoms, 18%

between 50- 100, fathoms and 3% at depths greater than the 100 fathom isobath (Green et al. 1992). Unlike the results

summarized by Gaskin (1984) for harbor porpoises in the North Atlantic Ocean, no reliable data on seasonal changes

in distribution or abundance are available to make inferences about harbor porpoise movements in the North Pacific.

Harbor porpoises are known to occur year around in the inland trans-boundary area of Washington and British

Columbia, Canada (Osborne et al. 1988) and along the Oregon/Washington coast (Barlow 1988, et al. 1988, Green et

al. 1992).

Using the 1990-91 aerial survey data of Calambokidis et al. (1993b) for water depths < 50 fathoms, Osmek

et al. (in press) found significant differences in harbor porpoise mean densities (z=5.9, p<0.01) between the waters of

coastal Oregon/Washington And inland Washington/southern British Columbia, Canada (i.e., Strait of Juan de Fuca/San

Juan Islands).

Stock discreteness was analyzed using mitochondrial DNA from samples collected along the west coast (Rose1

1992) and is summarized in Osmek et al. (1994). Two distinct mitochondrial DNA groupings or clades exist. One clade

is present in California, Washington, British Columbia and Alaska (no samples were available from Oregon), while the

other is found only in California and Washington. Although these two clades are not geographically distinct by latitude,

the results may indicate a low intrinsic mixing rate exists for harbor porpoises along the west coast. No comparisons

of genetic differences were made between harbor porpoises of coastal verses inland Washington because the sample

size from inland Washington was too small. An AMOVA analysis of the same data with additional samples found

significant genetic differences for 4 of the 6 pair-wise comparisons between the four areas investigated: California,

Washington, British Columbia, and Alaska (Rose1 et al., in press). These results demonstrate that harbor porpoise along

the west coast of North America are not pan-mictic or migratory. and movement is sufficiently restricted that genetic

differences have evolved.

Differences in organochlorine pollutant residue (OPR) ratios and concentrations by geographic area indicate

that there were increasing CDDE concentrations from north to south for coastal Washington and Oregon (Calambokidis

and Barlow 1991, Osmek et al. 1994). Calambokidis and Barlow (199 1) found, through discriminant analysis of OPR

ratios, that the state from which the harbor porpoise was collected from could be accurately predicted for 86% of the

samples. These observed differences in OPR ratios are suitable for illustrating that harbor porpoise movements on the

west coast may be limited, though no stock boundaries are apparent.

Although differences in density exist between coastal Oregon/Washington and inland Washington, a specific

stock-boundary line cannot be identified based upon biological differences in Oregon and Washington. Two stocks,

1) Oregon/Washington coast and 2) inland Washington (boundary at Cape Flattery), however, are being designated

based primarily, but not entirely, for conservation reasons because harbor porpoise movements and rates of intermixing

within the northeast Pacific are restricted and a significant decline in harbor porpoise sightings has occurred within

southern Puget Sound since the 1940’s. In the future, biological evidence for delineating stocks may come from the

analysis of environmental pollutants in tissues, from seasonal movements of individual harbor porpoises or new genetic

analytical methods.

POPULATION SIZE

Aerial surveys of the Washington coast, and parts of the southwest Strait of Juan de Fuca, were conducted

during summer 1990 (Calambokidis et al. 1991) by flying a saw-tooth design at an altitude of 183 m (600 feet), and

speeds of 185 km/hr (100 knots), from shore out to the 50 fathom isobath. During 1991 (Calambokidis et al. 1992)

surveys, using the same 1990 methods, were flown over the marine waters of coastal Oregon and coastal/inland

Washington. Because the 1990-91 surveys both covered coastal Washington and portions of the western Strait of Juan

de Fuca, these data were pooled and used to calculate abundance estimates (Calambokidis et al. 1993b) following the

methods described by Buckland et al. (1993). The program DISTANCE (Laake et al. 1993) was used to conduct the

35
analyses. Only effort and sightings made during excellent sighting conditions were used. Effort was used only during

Beaufort Wind Scale levels of Force 2 or less and cloud cover of less than 25%. A single estimate of f(0) and of group

size was calculated using data from all regions in both years. The correction factor [l/g(0)] of 3.1 and its associated

variance (g(o)=O.324, var=0.003) was used to adjust the 1990-91 harbor porpoise sighting data for groups missed by

aerial observers (Calambokidis et al. 1993a). The best corrected estimate of abundance for harbor porpoises in coastal

Oregon and Washington waters is 26,175 (CV=O.206). This estimate includes animals along the US/Canadian boundary

waters and a portion of the southern coastal waters of British Columbia along the Strait of Juan de Fuca.

Minimum Population Estimate

The minimum population estimate (NMIN) for this stock is calculated from equation 1 from the PBR Guidelines

(this volume): NMIN = Using the population estimate (N) of 26,175 and its associated

CV of 0.206, NMIN for the Oregon/Washington coastal stock of harbor porpoise is 22,049.

Current Population Trend

There are no reliable data on population trends of harbor porpoises for coastal Oregon, Washington or British

Columbia waters.

CURRENT AND MAXIMUM NET PRODUCTIVITY RATES

A reliable estimate of the maximum net productivity rate is currently not available for harbor porpoises.

Therefore, until additional data become available? it is recommended that the cetacean maximum theoretical net

productivity rate (RMAX) of 4% be employed for harbor porpoises.

POTENTIAL BIOLOGICAL REMOVAL

Under the 1994 re-authorized Marine Mammal Protection Act (MMPA), the potential biological removal (PBR)

is defined as the product of the minimum population estimate, one-half the maximum theoretical net productivity rate.

and a recovery factor: PBR = NMIN x 0.5RMAX x FR. The recovery factor (FR) for this stock is 0.5, the value for a

cetacean stock with an unknown population status (PBR Guidelines, this volume). Thus. for Oregon/Washington coastal

stock of harbor porpoise, PBR = (22,049 x 0.02 x 0.5) or 220 animals (Table 1).

TABLE 1. Corrected abundance estimates (I 990-9 1) and PBRs for harbor porpoises of Oregon and Washington

marine waters (<50 fathoms for the Oregon/Washington coast stock)(Osmek et al. in press). The Rmax and Fr

values used in the PBR calculations are 0.04 and 0.5, respectively.

ANNUAL HUMAN-CAUSED MORTALITY AND SERIOUS INJURY

Within the EEZ boundaries of coastal Oregon and Washington, human-caused (fishery) mortalities are presently

known to occur only in northern Washington.

The tribal set gillnet fishery for chinook salmon along the coast of northwest Washington is closely monitored

by NMFS observers, thus total estimates of harbor porpoise incidental takes are reliable. NMFS observer program results

for 1988-90 (Gearin et al. 1992), 1991 (Gearin et al. 1993), 1992 (Gearin et al. 1994), and 1993 (Osmek et al. in press)

are given in Table 2. Incidental take estimates for 1989-93 were derived using catch per unit effort (CPUE) information

stratified by sub-area (Gearin et al. 1994) because harbor porpoise mortality varied greatly by location. All but one of

the total harbor porpoise incidentally caught in this fishery since 1988 (n=156) were taken along the northern Washington

outer coast. Similar fishing gear is used throughout this coastal/inland Washington fisher); (i.e., 7-8 inch (18-20 cm)

multi-strand stretched mesh, 100 fathoms (200 m) maximum length, 40-90 meshes (4-9 m) deep). Gearin et al. (1994)

reported that 48% of the harbor porpoises (n-males =55 and n-females = 45) collected and necropsied from this fishery

36
during 1988-90 were reproductively immature and < two years in age. The impact of removing 9 animals per year (1990-

93 average) with these characteristics from Oregon and Washington waters is unknown.

TABLE 2. NMFS observer program results for the NW Washington set gillnet fishery (northern coastal Washington:

Area 4/4A). An incidental take estimate for 1988 would be invalid (*=not estimated) because observer coverage was

minimal and not representative of the overall fishery. Several harbor porpoises were known to be incidentally taken

in this fishery in 1994 but final results are unavailable.

Descriptioni Year

Total net days fished

Percent net days observed

Number of discrete vessels

Observed animals taken

Not observed but recovered

Reported but not recovered

Observed, recovered and repot-ted

Total estimated incidental takes

The total fishery mortality and serious injury for this stock (14) is currently less than 1O% of the calculated PBR

(22) and, therefore, can be considered an insignificant rate.

STATUS OF STOCK

The level of human-caused mortality and serious injury (9) does not exceed the PBR (220). thus the

Oregon/Washington coast stock of harbor porpoise is not classified as strategic. The status of this stock relative to OSP

and population trends are unknown.

REFERENCES

Barlow, J. 1988. Harbor porpoise, Phocoena phocoena, abundance estimation for California, Oregon and Washington: I.

Ship Surveys. Fishery Bulletin 86:417-432.

Barlow, J., C. W. Oliver, T. D. Jackson and B. L. Taylor. 1988. Harbor porpoise, Phocoena phocoena, abundance estimation

for California, Oregon and Washington: Il. Aerial Surveys. Fishery Bulletin 86:433-444.

Buckland, S. T., D. R. Anderson, K. P. Burnham, and J. L. Laake. 1993. Distance Sampling: Estimating Abundance of

Biological Populations. Chapman & Hall, London. 446 p.

Calambokidis, J. and J. Barlow. 1991. Chlorinated hydrocarbon concentrations and their use for describing population

discreteness in harbor porpoises from Washington, Oregon, and California. Eds: John E. Reynolds III and Daniel

K. Odell. Proceedings of the Second Marine Mammal Stranding Workshop: 3-5 December 1987. Miami, Florida.

NMFS, NOAA Technical Rep. NMFS 98: 10l- 110.

Calambokidis, J., J. C. Cubbage, S. J. Jeffries. P. J. Gearin and R. Brown. 1991. Harbor Porpoise Distribution and Abundance

Estimates of Washington from Aerial Surveys in 1991. Final Rep. by Cascadia Research, Olympia: WA to National

Marine Mammal Laboratory, AFSC, NMFS, Seattle, WA. 35 p.

Calambokidis. J., J. R. Evenson, J. C. Cubbage, P. J. Gearin and S. D. Osmek. 1992. Harbor porpoise distribution and

abundance off Oregon and Washington from aerial surveys in 1991. Final Rep. by Cascadia Research, Olympia,

WA to National Marine Mammal Laboratory, AFSC, NMFS, Seattle, WA. 44 p.

Calambokidis, J., J. R. Evenson, J. C. Cubbage, S. D. Osmek, D. Rugh, and J. L. Laake. 1993a. Calibration of sighting rates

of harbor porpoise from aerial surveys. Final Rep. by Cascadia Research, Olympia, WA to National Marine

Mammal Laboratory, AFSC, NMFS, Seattle, WA. 41 p.

Calambokidis, J., J. C. Cubbage, J. R. Evenson, S. D. Osmek, J. L. Laake, P. J. Gearin, B. J. Tumock, S. J. Jeffries and R. F.

Brown. 1993b. Abundance estimates of harbor porpoise in Washington and Oregon waters. Final Rep, by Cascadia

Research, Olympia, WA to National Marine Mammal Laboratory, AFSC, NMFS, Seattle, WA. 55 p.

37
Gaskin, D. E. 1984. The Harbour Porpoise Phocoena phocoena (L.): Regional Populations, Status, and lnformation on Direct

and indirect Catches. Rep. Int. Whal. Commn 34:569-586.

Gearin, P., J. Cooke, J. Thomason and S. Joner. 1992. Summary report on marine mammal observations in the Makah

chinook salmon set-net fishery in 1991. NMFS/NWR Rep. 17 p.

Gearin, P., L. Cooke, M. Gosho and S. Joner. 1993. Summary report on marine mammal observations in the northern

Washington chinook salmon marine set-net fishery in 1992. NMFS/NWR Rep. 16 p.

Gearin, P., S. R. Melin, R. L. DeLong, H. Kajimura and M. A. Johnson. 1994. Harbor porpoise interactions with a Chinook

Salmon Set-net Fishery in Washington State. Eds: Perrin, W. F., G. P. Donovan and J. Barlow. Gillnets and

cetaceans. [Incorporating the proceedings of the Symposium and Workshop on the Mortality of Cetaceans in Passive

Fishing Nets and Traps, La Jolla, 1990]. Rep. Int. Whal. Commn. Special lssue 15. 629 p.

Green, G. A., J. J. Brueggeman, R. A. Grotefendt, C. E. Bowlby, M. L. Bonnel, and K. C. Balcomb. 1992. Cetacean

distribution and abundance of Oregon and Washington, 1989-1990. Eds.: Brueggeman. Oregon and Washington

Marine Mammal and Seabird Surveys. Final Rep. OCS Study MMS 91-0093. 100 p.

Laake, J. L., S. T. Buckland, D. R. Anderson, K. P. Burnham. 1993. DISTANCE User’s Guide. Colorado Cooperative Fish

and Wildlife Research Unit, Colorado State University, Fort Collins, CO 80523, USA.

Leatherwood, S. and R. R. Reeves. 1983. Whales and dolphins. Sierra Club Handbook: San Francisco, CA. 302 p.

Osborne, R., J. Calambokidis and E. M. Dorsey. 1988. A Guide to Marine Mammals of Greater Puget Sound. Island

Publishers, Anacortes. WA. 191 p.

Osmek, S. P. Rosel, A. Dizon. and R. L. DeLong. 1994. Harbor Porpoise Phocoena phocoena population assessment studies

for Oregon and Washington in 1993. Annual report to the MMPA Assessment Program, Office of Protected

Resources, NMFS, NOAA, 1335 East-West Highway, Silver Spring, MD 20910. 14 p.

Osmek, S., J. Calambokidis, J. Laake, P. Gearin, R. DeLong, S. Jeffries and R. Brown. (In press). An Assessment of the 1994

Status Harbor porpoises, Phocoena phocoena, in Oregon and Washington. NOAA Tech. Memo. NMFS-AFSC.

(Draft rep. available through National Marine Mammal Laboratory, AFSC. NMFS.)

Rosel, P. E. 1992. Genetic population structure and systematic relationships of some small cetaceans inferred from

mitochondrial DNA sequence variation. Ph.D. Dissertation, Univ. Calif. San Diego. 191 pp.

Rosel, P. E., A. E. Dizon, and M. G. Haygood. (in press). Variability of the mitochondrial control region in populations of

the harbour porpoise, Phocoena phocoena, on inter-oceanic and regional scales. Can. J. Fish. and Aquat. Sci. 52.

Scheffer, V. B. and J. W. Slipp. 1948. The whales and dolphins of Washington State with a key to the cetaceans of the west

coast of North America. Am. Midl. Nat. 39(2), 257-337.

38
HARBOR PORPOISE (Phocoena phocoena): Inland Washington Stock

STOCK DEFINITION AND GEOGRAPHIC RANGE

In the eastern North Pacific Ocean: harbor porpoises are found coastally from the Bering Strait, Alaska, to central

California, occasionally frequenting bays, the mouths of large rivers and at times ascending freshwater streams (Leatherwood

and Reeves 1983). Aerial survey data from coastal Oregon and Washington, collected during all seasons, suggests that harbor

porpoise distribution varies by depth with 79% occurring at depths less than 50 fathoms, 18% between 50- 100, fathoms and

3% at depths greater than the 100 fathom isobath (Green et al. 1992). Unlike the results summarized by Gaskin (1984) for

harbor porpoises in the North Atlantic Ocean, no reliable data on seasonal changes in distribution or abundance are available

to make inferences about harbor porpoise movements in the North Pacific, Harbor porpoises are known to occur year around

in the inland trans-boundary area of Washington and British Columbia, Canada (Osborne et al. 1988) and along the

0regon/Washington coast (Barlow 1988, et al. 1988, Green et al. 1992).

Using the 1990-91 aerial survey data of Calambokidis et al. (1993b) for water depths < 50 fathoms, Osmek et al. (in

press) found significant differences in harbor porpoise mean densities (z=5.9, p<O.Ol) between the waters of coastal

Oregon/Washington and inland Washington/southem British Columbia, Canada (i.e., Strait of Juan de Fuca/San Juan

Islands).

Stock discreteness was analyzed using mitochondrial DNA from samples collected along the west coast (Rose1 1992)

and is summarized in Osmek et al. (1994). Two distinct mitochondrial DNA groupings or clades exist. One clade is present

in California, Washington, British Columbia and Alaska (no samples were available from Oregon), while the other is found

only in California and Washington. Although these two clades are not geographically distinct by latitude. the results may

indicate a low intrinsic mixing rate exists for harbor porpoises along the west coast. No comparisons of genetic differences

were made between harbor porpoises of coastal verses inland Washington because the sample size from inland Washington

was too small. An AMOVA analysis of the same data with additional samples found significant genetic differences for 4

of the 6 pair-wise comparisons between the four areas investigated: California, Washington, British Columbia, and Alaska

(Rose1 et al., in press). These results demonstrate that harbor porpoise along the west coast of North America are not panmictic or migratory, and movement is sufficiently restricted that genetic differences have evolved.

Differences in organochlorine pollutant residue (OPR) ratios and concentrations by geographic area indicate that

there were increasing CDDE concentrations from north to south for coastal Washington and Oregon (Calambokidis and

Barlow 199l, Osmek et al. 1994). Calambokidis and Barlow (1991) found, through discriminant analysis of OPR ratios, that

the state from which the harbor porpoise was collected from could be accurately predicted for 86% of the samples. These

observed differences in OPR ratios are suitable for illustrating that harbor porpoise movements on the west coast may be

limited, though no stock boundaries are apparent.

Although differences in density exist between coastal Oregon/Washington and inland Washington, a specific stockboundary line cannot be identified based upon biological differences in Oregon and Washington. Two stocks, 1)

Oregon/Washington coast and 2) inland Washington (boundary at Cape Flattery), however, are being designated based

primarily, but not entirely, for conservation reasons because harbor porpoise movements and rates of intermixing within the

northeast Pacific are restricted and a significant decline in harbor porpoise sightings has occurred within southern Puget Sound

since the 1940’s. In the future, biological evidence for delineating stocks may come from the analysis of environmental

pollutants in tissues, from seasonal movements of individual harbor porpoises or new genetic analytical methods.

POPULATION SIZE

Aerial surveys of the Washington coast, and parts of the southwest Strait of Juan de Fuca, were conducted during

summer 1990 (Calambokidis et al. 1991) by flying a saw-tooth design at an altitude of 183 m (600 feet), and speeds of 185

km/hr (100 knots), from shore out to the 50 fathom isobath. During 1991 (Calambokidis et al. 1992) surveys, using the same

1990 methods, were flown over the marine waters of coastal Oregon and coastal/inland Washington. Survey track-lines,

within inland Washington, were flown from shore to shore covering all depth contours. Because the 1990-91 surveys both

covered coastal Washington and portions of the western Strait of Juan de Fuca, these data were pooled and used to calculate

abundance estimates (Calambokidis et al. 3993b) following the methods described by Buckland et al. (1993). The program

DISTANCE (Laake et al. 1993) was used to conduct the analyses. Only effort and sightings made during excellent sighting

conditions were used. Effort was used only during Beaufort Wind Scale levels of Force 2 or less and cloud cover of less than

25%. A single estimate of f(0) and of group size was calculated using data from all regions in both years. The correction

39
factor [l/g(O)] of 3.1 and its associated variance (g(o)=O.324, var=0.003) was used to adjust the 1990-91 harbor porpoise

sighting data for groups missed by aerial observers (Calambokidis et al. 1993a). The best corrected estimate of abundance

for harbor porpoises of inland Washington waters is 3,352 (CV=O.270). This estimate includes animals along the northern

Strait of Juan de Fuca (Canadian waters) and the US/Canadian boundary waters of the San Juan Islands and the adjacent

waters of southern British Columbia.

Minimum Population Estimate

The minimum population estimate (NMIN for this stock is calculated from equation I from the PBR Guidelines (this

volume): Using the population estimate (N) of 3,352 and its associated CV of

0.270, NMIN for the inland Washington stock of harbor porpoise is 2.680.

Current Population Trend

There are no reliable data on population trends of harbor porpoises for most waters of Oregon, Washington or British

Columbia. In southern Puget Sound, however, harbor porpoises are now rarely observed, a sharp contrast to 1942 when

harbor porpoises were considered common there (Scheffer and Slipp 1948). Although quantitative data for this area are

lacking, marine mammal survey effort (Everitt et al. 1980). stranding records since the early 1970’s (Osmek et al. In prep.)

and the results of harbor porpoise surveys of 1991 (Calambokidis et al. 1992) and 1994 (Osmek et al. in prep.) indicate that

harbor porpoise abundance has declined in southern Puget Sound. Reasons for the decline are unknown, but it may be related

to fishery interactions. pollutants, vessel traffic and other activities that may affect harbor porpoise occurrence and distribution

in this area (Osmek et al. in prep.). Research to identifying trends in harbor porpoise abundance is also needed for the other

areas within inland Washington.

CURRENT AND MAXIMUM NET PRODUCTIVITY RATES

A reliable estimate of the maximum net productivity rate is not currently available for harbor porpoises. Hence, until

additional data become available, it is recommended that the cetacean maximum theoretical net productivity rate (RMAX of

4% be employed for harbor porpoises.

POTENTIAL BIOLOGICAL REMOVAL

Under the 1994 re-authorized Marine Mammal Protection Act (MMPA): the potential biological removal (PBR) is

defined as the product of the minimum population estimate, one-half the maximum theoretical net productivity rate, and a

recovery factor: PBR = The recovery factor (FR) for this stock is 0.5, the value for a cetacean stock with

an unknown population status (PBR Guidelines, this volume). Thus, for inland Washington stock of harbor porpoise, PBR

= (2,680 x 0.02 x 0.5) or 27 animals (Table 1).

TABLE 1. Corrected abundance estimates (1990-91) and PBRs for harbor porpoises of Oregon and Washington

marine waters (<50 fathoms for the Oregon/Washington coast stock)(Osmek et al. in press). The Rmax and Fr

values used in the PBR calculations are 0.04 and 0.5, respectively.

ANNUAL HUMAN-CAUSED MORTALITY AND SERIOUS INJURY

During 1993 and 1994, the NMFS, in cooperation with the Washington Department of Fish and Wildlife and the

Tribes, conducted observer programs to monitor incidental takes of marine mammals in commercial drift-gillnet and purse

seine fisheries within inland Washington waters. No mortalities were observed except during the 1994 sockeye-salmon gillnet

fishery (August-September) near the San Juan Islands (Area 7/7A) where one harbor porpoise mortality was observed and

one was entangled and released alive. Using the one observed harbor porpoise mortality and over 400 observed vessel trips

40
in Area 7/7A, an incidental take estimate of 15 harbor porpoises per year was calculated for this sockeye salmon fishery (Joe

Scordino, pers. comm. NW Region, NMFS, 24 February 1995). The coefficient of variation and confidence interval are not

yet available for this take estimate. Over 1000 vessels are licensed by the state to fish gillnets within inland Washington

waters: and about 500 to 600 actually fish each year. The gillnets used in this sockeye salmon fishery are made of 5-inch (I 3

cm) stretched-mesh monofilament: with a maximum net length of 300 fathoms (600 m) that is fished 150-250 meshes (10- 16

m) deep.

During 1991, a single harbor porpoise was observed taken within the tribal set gillnet fishery for chinook salmon

in the western Strait of Juan de Fuca (Area 4B). Similar fishing gear is used throughout this coastal/inland Washington fishery

(i.e., 7-8 inch (18-20 cm) multi-strand stretch mesh: 100 fathoms (200 m) maximum length, 40-90 meshes (4-9 m) deep).

The total fishery mortality and serious injury for this stock, 16 (15+ I), exceeds 10% of the calculated PBR (2.7) and,

therefore, can be considered a significant rate.

A conservative approach seems appropriate when managing the inland Washington harbor porpoise stock because:

1) the estimated take level constitutes significant mortality and is close to exceeding the PBR (i.e., one additional observed

mortality or serious injury in the sockeye drift gillnet fishery would increase the estimated annual take level above the PBR):

2) this is a trans-boundary stock with a minimum population estimate and a PBR that is based on some portion of the harbor

porpoises that occupy British Columbia waters but were within the 1991 aerial survey area (see “Population Estimates”,

Calambokidis et al. 1993b). and 3) the take rate is based on limited data.

STATUS OF STOCK

The level of human-caused mortality and serious injury (16) does not exceed the PBR (27) thus the inland

Washington harbor porpoise stock is not classified as strategic. Because the level of incidental take is based on limited

observations, it is recommended that the status of this stock be reviewed during 1996. Data are insufficient to make an OSP

determination for this stock.

REFERENCES

Barlow, J. 1988. Harbor porpoise, Phocoena phocoena, abundance estimation for California, Oregon and Washington: I.

Ship Surveys. Fishery Bulletin 86:417-432.

Barlow, J., C.W. Oliver: T. D. Jackson and B. L. Taylor. 1988. Harbor porpoise, Phocoena phocoena, abundance estimation

for California, Oregon and Washington: II. Aerial Surveys. Fishery Bulletin 86:433-444.

Buckland, S. T., D. R. Anderson, K. P. Burnham, and J. L. Laake. 1993. Distance Sampling: Estimating Abundance of

Biological Populations. Chapman & Hall, London. 446 p.

Calambokidis, J. and J. Barlow. 1991. Chlorinated hydrocarbon concentrations and their use for describing population

discreteness in harbor porpoises from Washington, Oregon and California. Eds: John E. Reynolds III and Daniel

K. Odell. Proceedings of the Second Marine Mammal Stranding Workshop: 3-5 December 1987. Miami, Florida.

NMFS, NOAA Technical Rep. NMFS 98: 101-l10.

Calambokidis, J., and R. W. Baird. 1994. Status of marine mammals in the Strait of Georgia, Puget Sound and the Juan de

Fuca Strait and Potential Human Impacts. Eds: R. C. H. Wilson, R. J. Beamish, F. Aitkens and J. Bell. Review of

the Marine Environment and Biota of Strait of Georgia, Puget Sound and Juan de Fuca Strait, Can. Tech. Rep.. of

Fish. and Aquat. Sci.:282-300.

Calambokidis, J., J. C. Cubbage, S. J. Jeffries, P. J. Gearin and R. Brown. 1991. Harbor Porpoise Distribution and Abundance

Estimates of Washington from Aerial Surveys in 1991. Final Rep. by Cascadia Research, Olympia, WA to National

Marine Mammal Laboratory: AFSC, NMFS, Seattle, WA. 35 p.

Calambokidis, J., J. R. Evenson, J. C. Cubbage. P. J. Gearin and S. D. Osmek. 1992. Harbor porpoise distribution and

abundance off Oregon and Washington from aerial surveys in 1991, Final Rep. by Cascadia Research, Olympia,

WA to National Marine Mammal Laboratory, AFSC, NMFS, Seattle, WA. 44 p.

Calambokidis, J., J. R. Evenson, J. C. Cubbage, S. D. Osmek, D. Rugh, and J. L. Laake. 1993a. Calibration of sighting rates

of harbor porpoise from aerial surveys. Final Rep. by Cascadia Research, Olympia, WA to National Marine

Mammal Laboratory, AFSC, NMFS, Seattle, WA. 41 p.

Calambokidis, J., J. C. Cubbage, J. R. Evenson, S. D. Osmek, J. L. Laake, P. J. Gearin, B. J. Turnock, S. J. Jeffries and R. F.

Brown. 1993b. Abundance estimates of harbor porpoise in Washington and Oregon waters. Final Rep. by Cascadia

Research, Olympia, WA to National Marine Mammal Laboratory, AFSC, NMFS, Seattle, WA. 55 p,

Everitt, R. D., C. H. Fiscus, R. L. DeLong. 1980. Northern Puget Sound Marine Mammals. U.S. Department of Commerce

41
EPA-6000/7-80-139, 134 p.

Gaskin, D. E. 1984. The Harbour Porpoise Phocoena phocoena (L.): Regional Populations, Status, and Information on Direct

and Indirect Catches, Rep. lnt. Whal. Commn 34:569-586.

Green, G. A., J. J. Brueggeman, R. A. Grotefendt, C. E. Bowlby, M. L. Bonnel, and K. C. Balcomb. 1992. Cetacean

distribution and abundance of Oregon and Washington, 1989-1990. Eds.: Brueggeman. Oregon and Washington

Marine Mammal and Seabird Surveys. Final Rep. OCS Study MMS 91-0093. 100 p.

Laake, J. L., S. T. Buckland, D. R. Anderson, K. P. Bumham. 1993. DISTANCE User’s Guide. Colorado Cooperative Fish

and Wildlife Research Unit, Colorado State University, Fort Collins. CO 80523, USA.

Leatherwood, S. and R.R. Reeves. 1983. Whales and dolphins. Sierra Club Handbook, San Francisco, CA. 302 p.

Osborne, R., J. Calambokidis and E. M. Dorsey. 1988. A Guide to Marine Mammals of Greater Puget Sound. Island

Publishers, Anacortes, WA. 191 p,

Osmek, S., P. Rosel, A. Dizon, and R. L. DeLong. 1994. Harbor Porpoise Phocoena phocoena population assessment studies

for Oregon and Washington in 1993. Annual rep. to the MMPA Assessment Program, Office of Protected Resources,

NMFS, NOAA, 1335 East-West Highway, Silver Spring, MD 20910. 14 p.

Osmek, S., J. Calambokidis, J. Laake. P. Gearin, R. DeLong, S. Jeffries and R. Brown. (In press). An Assessment of the 1994

Status Harbor porpoises, Phocoena phocoena, in Oregon and Washington. NOAA Tech. Memo. NMFS-AFSC.

(Draft rep. available through National Marine Mammal Laboratory, AFSC, NMFS.)

Rosel, P. E. 1992. Genetic population structure and systematic relationships of some small cetaceans inferred from

mitochondrial DNA sequence variation. Ph.D. Dissertation. Univ. Calif. San Diego. 191pp.

Rosel, P. E., A. E. Dizon, and M. G. Haygood. (in press). Variability of the mitochondrial control region in populations of

the harbour porpoise, Phocoena phocoena. on inter-oceanic and regional scales. Can. J. Fish. and Aquat. Sci. 52.

Scheffer, V. B. and J. W. Slipp. 1948. The whales and dolphins of Washington State with a key to the cetaceans of the west

coast of North America. Am. Midl. Nat. 39(2), 257-337.

42
DALL’S PORPOISE (Phocoenoides dalli):

California/Oregon/Washington Stock

STOCK DEFINITION AND GEOGRAPHIC RANGE

Dall’s porpoise are endemic to temperate waters of the North Pacific Ocean. Off the U.S. west coast, they are

commonly seen in shelf, slope and offshore waters (Morejohn 1979; Dohl et al. 1980, 1983; Green et al. 1992, 1993;

Carretta and Forney 1993; Mangels and Gerrodette 1994; Barlow 1995). Sighting patterns from recent aerial and

shipboard surveys conducted in California, Oregon and Washington at different times (Green et al. 1992, 1993; Mangels

and Gerrodette 1994; Forney et al. 1995; Barlow 1995) suggest that north-south movement between these states occurs

as oceanographic conditions change, both on seasonal and inter-annual time scales. The southern end of this population’s

range is not well-documented, but they are commonly seen off Southern California in winter, and during cold-water

periods they probably range into Mexican waters off northern Baja California. The stock structure of eastern North

Pacific Dall’s porpoise is not known but based on patterns of stock differentiation in the western North Pacific, where

they have been more intensively studied, it is expected that separate stocks will emerge when data become available

(Perrin and Brownell 1994). Although Dali’s porpoise are not restricted to U.S. territorial waters, cooperative

management agreements with Mexico exist only for the tuna purse seine fishery and not for other fisheries which may

take this species (e.g. gillnet fisheries). For the Marine Mammal Protection Act (MMPA) stock assessment reports, Dali’s

porpoises within the Pacific U.S. Exclusive Economic Zone are divided into two discrete, non-contiguous areas: 1) waters

off California, Oregon and Washington (this report). and 2) Alaskan waters.

POPULATION SIZE

Separate surveys have been conducted during different years off California and Oregon/Washington (Green et

al. 1992, 1993; Mangels and Gerrodette 1994; Barlow l995), but because animals are likely to have moved from one

region to another between surveys, the different estimates cannot be added to produce a total estimate. Forney (1994)

reviews recent abundance estimates for Dall’s porpoise along the U.S. west coast and concludes that the best estimate of

overall population size in California, Oregon and Washington is the estimate of 78,422 Dall’s porpoise (C.V. = 0.35)

obtained from the ship survey conducted off California during summer/fall 1991 (Barlow 1995).

Minimum Population Estimate

The log-normal 20th percentile of the above abundance estimate is 58,902 Dall’s porpoise.

Current Population Trend

No information is available regarding trends in abundance of Dall’s porpoise in California, Oregon and

Washington.

CURRENT AND MAXIMUM NET PRODUCTIVITY RATES

No information on current or maximum net productivity rates is available for Dali’s porpoise off the U.S. west

coast.

POTENTIAL BIOLOGICAL REMOVAL

Based on this stock’s unknown status and growth rate, the recovery factor (F,) is 0.5, and 1/2Rmax, is the default

value of 0.02. Multiplying these two values times the minimum population estimate of 58,902 yields a potential

biological removal (PBR) of 589 Dali’s porpoise per year.

ANNUAL HUMAN-CAUSED MORTALITY AND SERIOUS INJURY

Fishery Information

Dali’s porpoise are incidentally killed in drift gillnets, which have been used to catch swordfish, thresher shark,

and mako shark in offshore California, Oregon and Washington waters (Hanan et al. 1993), with approximately 149

vessels currently active (J. Cordaro, Southwest Region, NMFS, pers. comm.). Fishing effort has decreased from

approximately 10,000 sets per year in the mid-1980s to 6600 in 1993 (Barlow et al. 1994). Based on less than 1%

observer coverage of fishing effort between 1980 and 1985, no Dali’s porpoise were reported killed (Diamond et al.

43
1987). Between July 1990 and December 1993, with approximately 4-13% observer coverage of California drift gillnet

fisheries, observed mortality of Dall’s porpoise was one in 1990, two in 1991, one in 1992, and nine in 1993, resulting

in annual mortality estimates of 23 (s.e. 22) for July-December 1990, 17 (s.e. 13) for 1991, 8 (s.e. 7) for 1992, and 82

(s.e. 36) for 1993 (Lennert et al. 1994; Perkins et al. 1992; Julian 1993, 1994). The corresponding average rates of Dali’s

porpoise kill per fishing day are 0.006, 0.004. 0.002, and 0.012 for 1990, 1991 1992 and 1993, respectively. Preliminary

mortality data for 1994 indicate that two Dall’s porpoise were observed killed (NMFS, unpublished data). The average

estimated annual mortality for Dali’s porpoise in this fishery for the three complete years of monitoring, 1991-93, is 36

animals.

Similar drift gillnet fisheries for swordfish and sharks exist along the entire Pacific coast of Baja California.

Mexico and may take some Dall’s porpoise from the same population during cold-water periods. Quantitative data are

available only for the Mexican swordfish drift gillnet fishery, which has increased from two vessels in 1986 to 29 vessels

in 1992 (Sosa-Nishizaki et al. 1993). The total number of sets in this fishery in 1992 can be estimated from data provided

by these authors to be approximately 2700. with an observed rate of marine mammal bycatch of 0.13 animals per set (10

marine mammals in 77 observed sets; Sosa-Nishizaki et al. 1993). This overall mortality rate is similar to that observed

in California driftnet fisheries during 1990-93 (0. 15 marine mammals per set), but species-specific information is not

available for the Mexican fisheries.

Based on logbook data or low levels of observer coverage, additional mortality of Dall’s porpoise is known to

occur in the following three fisheries (NMFS. unpublished data): (1) the California/Oregon Washington groundfish trawl

fisheries, for which approximately 585 permits have been issued, (2) the California salmon troll fishery, which had about

1,100 active permit holders in 1994, and (3) the Washington Puget Sound salmon set and drift gillnet fishery, which has

approximately 3900 participants and is active from about May to September. Due to the uncertainties in these data

sources, however, no estimate of overall mortality can be made for these fisheries.

An experimental gillnet fishery for thresher shark off Oregon and Washington in 1986-89 also reported mortality

of Dall’s porpoise; however, this fishery was discontinued after 1989 due to the high rates of marine mammal and turtle

bycatch (Stick and Hreha, 1989).

Fishery Mortality Rate

The total fishery mortality and serious injury for this stock durin g 1991-93 (36 animals per year) is less than

10% of the calculated PBR and, therefore, can be considered to be insignificant and approaching zero mortality and

serious injury rate. This determination cannot be made for individual fisheries until the implementing regulations for

Section 118 of the MMPA have been reviewed by the public and finalized.

STATUS OF STOCK

The status of Dall’s porpoise in California, Oregon and Washington relative to OSP is not known, and there are

insufficient data to evaluate potential trends in abundance. They are not listed as “threatened” or “endangered” under

the Endangered Species Act nor as “depleted” under the MMPA. Because the average annual human-caused mortality

is estimated to be less than the PBR, they are not classified as a “strategic” stock under the MMPA.

REFERENCES

Barlow: J. 1995. The abundance of cetaceans in California waters. Part I: Ship surveys in summer/fall 1991. Fish. Bull.

93:1-14.

Barlow? J., R. W. Baird, J. E. Heyning, K. Wynne, A. M. Manville, II, L. F. Lowry, D. Hanan, J. Sease, and V. N.

Burkanov. 1994. A review of cetacean and pinniped mortality in coastal fisheries along the west coast of the

USA and Canada and the east coast of the Russian Federation. Rep. Int. Whal. Commn. Special Issue 15:405-

426.

Carretta, J. V. and K. A. Forney. 1993. Report of the two aerial surveys for marine mammals in California coastal

waters using a NOAA DeHavilland Twin Otter aircraft, March 9-April 7. 1991, February S-April 6, 1992.

NOAA Technical Memorandum NOAA-TM-KMFS-SWFSC- 185. Available from NMFS, Southwest Fisheries

Science Center, P.O. Box 271, La Jolla, California: 92038. 77p.

Diamond, S. L., J. P. Scholl and D. A. Hanan. 1987. Drift gillnet observations for the 1985-86 fishing season.

Administrative Report SWR 87-4. Available from NMFS, Southwest Region, 300 S. Ferry Street, Terminal

Island, California, 90731. 21p.

44
Dohl, T. P., R. C. Guess, M. L. Duman, and R. C. Helm. 1983. Cetaceans of central and northern California, 1980-1983:

Status, abundance and distribution. OCS Study MMS 84-0045. Minerals Management Service Contract # 14-

12-000 l-29090. 284p.

Dohl, T. P., K. S. Norris, R. C. Guess, J. D. Bryant, and M. W. Honig. 1980. Summary of marine mammal and seabird

surveys of the Southern California Bight area: 1975-1978. Part II. Cetaces of the Southern California Bight.

Final Report to the Bureau of Land Management, NTIS Rep. No. PB81248189. 414p.

Forney, K. A. 1994. Recent information on the status of odontocetes in Californian waters. NOAA Technical

Memorandum NMFS, NOAA-TM-NMFS-SWFSC-202. Available from NMFS, Southwest Fisheries Science

Center, P.O. Box 271, La Jolla, California, USA.

Forney, K. A., J. Barlow and J. V. Carretta. 1995. The abundance of cetaceans in California waters. Part II: Aerial

surveys in winter and spring of 1991 and 1992. Fish. Bull. 93:15-26.

Green, G., J. J. Brueggeman, R. A. Grotefendt, C. E. Bowlby,.M. L. Bonnell, and K. C. Balcomb. 111. 1992. Cetacean

distribution and abundance off Oregon and Washington. Ch. 1. In: Oregon and Washington Marine Mammal

and Seabird Surveys. OCS Study 9l-0093. Final Report prepared for Pacific OCS Region, Minerals

Management Service, U.S. Department of the Interior, Los Angeles. California.

Green, G., R. A. Grotefendt, M. A. Smultea, C. E. Bowlby, and R. A. Rowlett. 1993. Delphinid aerial surveys in Oregon

and Washington waters. Final Report prepared for NMFS, National Marine Mammal Laboratory, 7600 Sand

Point Way, NE, Seattle, Washington. 98115, Contract #50ABNF200058.

Hanan, D. A., D. B. Holts, and A. L. Coan, Jr. 1993. The California drift gill net fishery for sharks and swordfish, 1981-

82 through 1990-91. Fish Bulletin 175. Available from the Marine Technical Information Center, California

Department of Fish and Game? 330 Golden Shore, Suite 50, Long Beach. CA 90802.

Julian. F. 1993. Pinniped and cetacean mortality in California gillnet fisheries: Preliminary estimates for 1992. Working

paper SC/45/022 presented to the International Whaling Commission Scientific Committee, May 1993

(unpublished).

Julian. F. 1994. Pinniped and cetacean mortality in California gillnet fisheries: Preliminary estimates for 1993. Working

paper SC/46/011 presented to the International Whaling Commission Scientific Committee, May 1994

(unpublished).

Lennert, C., S. Kruse, M. Beeson: and J. Barlow. 1994. Estimates of incidental marine mammal bycatch in California

gillnet fisheries for July through December 1990. Rep. Int. Whal. Commn. Special Issue 15:449-463.

Mangels, K. F. and Gerrodette, T. 1994. Report of cetacean sightings during a marine mammal survey in the eastern

Pacific Ocean and Gulf of California aboard the NOAA ships McARTHUR and DAVID STARR JORDAN July

28 - November 6, 1993. NOAA Technical Memorandum NMFS, NOAA-TM-NMFS-SWFSC-211.

Morejohn, G. V. 1979. The natural history of Dall’s porpoise in the North Pacific Ocean. In: Winn: H. E. and B. L.

Olla (eds.), Behavior of Marine Mammals, p. 45-83. Plenum Press, New York - London.

National Marine Fisheries Service, Office of Protected Resources and Southwest Fisheries Science Center. Unpublished

data.

Perkins, P., J. Barlow and M. Beeson. 1992. Pinniped and cetacean mortality in California gillnet fisheries: 1991.

Working Paper SC/44/SM14 presented to the International Whaling Commission, May 1992 (unpublished).

Perrin, W. F. and R. L. Brownell, Jr. 1994. A brief review of stock identity in small marine cetaceans in relation to

assessment of driftnet mortality in the North Pacific. Rep. int. Whal. Commn. Special Issue 15:393-401.

Sosa-Nishizaki, O., R. De la Rosa Pacheco, R. Castro Longoria, M. Grijalva Chon, and J. De la Rosa Velez. 1993.

Estudio biologico pesquero del pez (Xiphias gludius) y otras especies de picudos (marlins y pez vela). Rep. Int.

CICESE, CTECT9306.

Stick, K. C. and Hreha, L. 1989. Summary of the 1988 Washington/Oregon experimental thresher shark gill net fishery.

State of Washington, Department of Fisheries, Progress Report 275. 40p.

45
PACIFIC WHITE-SIDED DOLPHIN (Lagenorhynchus obliquidens):

California/Oregon/Washington, Northern and Southern Stocks

STOCK DEFlNlTION AND GEOGRAPHIC RANGE

Pacific white-sided dolphins are endemic to temperate waters of the North Pacific Ocean: and are common both

on the high seas and along the continental margins. Off the U.S. west coast, Pacific white-sided dolphins have been seen

primarily in shelf and slope waters (Dohl et al. 1980, 1983; Green et al. 1992, 1993; Carretta and Forney 1993; Mangels

and Gerrodette 1994: Barlow 1995). Sighting patterns from recent aerial and shipboard surveys conducted in California,

Oregon and Washington at different times of the year (Green et al. 1992, 1993; Forney et al. 1995; Barlow 1995) suggest

seasonal north-south movements, with animals found primarily off California during the colder water months and shifting

northward into Oregon and Washington as water temperatures increase in late spring and summer (Green et al. 1992;

Forney 1994).

Stock structure throughout the North Pacific is poorly understood, but based on morphological evidence? hvo

forms are known to occur off the California coast (Walker et al. 1986; Chivers et al. 1993). Specimens belonging to the

northern form were collected from north of about 33oN, (Southern California to Alaska), and southern specimens were

obtained from about 36oN southward along the coasts of California and Baja California. Samples of both forms have

been collected in the Southern California Bight, but it is unclear whether this indicates sympatry in this region or whether

they may occur there at different times (seasonally or interannually). Recent preliminary genetic analyses have confirmed

the distinctness of animals found off Baja California from animals occurring in U.S. waters (NMFS, unpublished data).

Based on these genetic data, the current boundary between the two forms appears to be south of U.S. waters. but there

is evidence that this boundary is dynamic, as both forms have occurred in U.S. waters in the past (Walker et al. 1986).

Although there is clear evidence that two forms of Pacific white-sided dolphins occur along the U.S. west coast,

there are no known differences in color pattern, and it is not currently possible to distinguish animals without genetic or

morphometric analyses. Geographic stock boundaries appear dynamic and are poorly understood, and therefore cannot

be used to differentiate the two forms. Until means of differentiating the two forms for abundance and mortality

estimation are developed, these two stocks must be managed as a single unit; however, this is an undesirable management

situation. Furthermore, Pacific white-sided dolphins are not restricted to U.S. territorial waters, but cooperative

management agreements with Mexico exist only for the tuna purse seine fishery and not for other fisheries which may

take this species (e.g. gillnet fisheries). Additional means of differentiating the two types must be found, and cooperative

management with Mexico is particularly important for this species, given the apparently dynamic nature of geographical

stock boundaries. Until these goals are accomplished, the management stock includes animals of both forms. For the

Marine Mammal Protection Act (MMPA) stock assessment reports. Pacific white-sided dolphins within the Pacific U.S.

Exclusive Economic Zone are divided into two discrete, non-contiguous areas: 1) waters off California. Oregon and

Washington (this report), and 2) Alaskan waters.

POPULATION SIZE

Forney (1994) reviews recent abundance estimates for Pacific white-sided dolphins along the U.S. west coast

and concludes that the best estimate of overall population size in California, Oregon and Washington is the estimate

obtained from aerial surveys conducted off California during winter/spring of 1991 and 1992 (Forney et al. 1995).

Because of the observed seasonal shifts in distribution, this estimate of 121,693 animals (C.V. = 0.48) is expected to

include animals which may be found off Oregon and Washington in the summer/fall.

Minimum Population Estimate

The log-normal 20th percentile of the above abundance estimate is 82,939 Pacific white-sided dolphins,

Current Population Trend

No long-term trends in the abundance of Pacific white-sided dolphins in California, Oregon and Washington

are suggested based on historical and recent surveys (Dohl et al. 1980, 1983; Green et al. 1992, 1993; Barlow 1995;

Forney et al. 1995).

46
CURRENT AND MAXIMUM NET PRODUCTIVITY RATES

No information on current or maximum net productivity rates is available for Pacific white-sided dolphins off

the U.S. west coast.

POTENTIAL BIOLOGICAL REMOVAL

Based on this stock’s unknown status and growth rate, the recovery factor (F,) is 0.5, and 1/2Rmax is the default

value of 0.02. Multiplying these two values times the minimum population estimate of 82,939 yields a potential

biological removal (PBR) of 829 Pacific white-sided dolphins per year.

ANNUAL HUMAN-CAUSED MORTALITY AND SERIOUS INJURY

Fishery Information

Pacific white-sided dolphins are incidentally killed in California drift gillnet fisheries, which have been used

to catch swordfish, thresher shark, and mako shark in offshore California, Oregon and Washington waters (Hanan et al.

1993), with approximately 149 vessels currently active (J. Cordaro, Southwest Region, NMFS, pers. comm.). Fishing

effort has decreased from approximately 10,000 sets per year in the mid-1980s to 6600 in 1993 (Barlow et al. 1994).

Based on less than 1% observer coverage of fishing effort between 1980 and 1985, Diamond et al. (1987) report a single

take of this species, which can be extrapolated to yield a rough estimate of total mortality of 110 animals, or

approximately 18 per year. Between July 1990 and December 1993, with approximately 4- 13% observer coverage of

California drift gillnet fisheries, observed mortality of Pacific white-sided dolphins was three in 1990, five in 1991. three

in 1992, and two in 1993, resulting in annual mortality estimates of 68 (s.e. 38) for 1990, 42 (s.e. 30) for 1991, 23 (s.e.

16) for 1992, and 18 (s.e. 12) for 1993 (Lennert et al. 1994; Perkins et al. 1992; Julian 1993, 1994). The corresponding

rates of Pacific white-sided dolphin kill per fishing day are 0.0 17,0.009, 0.005, and 0.003 for 1990, 1991 1992 and 1993,

respectively. Preliminary mortality data for 1994 indicate that three Pacific white-sided dolphins were observed killed

(NMFS, unpublished data). The average estimated annual mortality for Pacific white-sided dolphins in this fishery for

the three complete years of monitoring, 1991-93, is 28 animals.

Similar drift gillnet fisheries for swordfish and sharks exist along the entire Pacific coast of Baja California,

Mexico and probably take the southern form of this species. Quantitative data are available only for the Mexican

swordfish drift gillnet fishery, which has increased from two vessels in 1986 to 29 vessels in 1992 (Sosa-Nishizaki et al.

1993). The total number of sets in this fishery in 1992 can be estimated from data provided by these authors to be

approximately 2700, with an observed rate of marine mammal bycatch of 0.13 animals per set (10 marine mammals in

77 observed sets; Sosa-Nishizaki et al. 1993). This overall mortality rate is similar to that observed in California driftnet

fisheries during 1990-93 (0.15 marine mammals per set), but species-specific information is not available for the Mexican

fisheries.

An experimental gillnet fishery for thresher shark off Oregon and Washington in 1986-89 also reported mortality

of Pacific white-sided dolphins; however, this fishery was discontinued after 1989 due to the high rates of marine

mammal and turtle bycatch (Stick and Hreha, 1989).

Fishery Mortality Rate

The total fishery mortality and serious injury for this stock during 1991-93 (28 animals per year) is less than

10% of the calculated PBR and, therefore, can be considered to be insignificant and approaching zero mortality and

serious injury rate. This determination cannot be made for individual fisheries until the implementing regulations for

Section 118 of the MMPA have been reviewed by the public and finalized.

Other removals

Additional removals of Pacific white-sided dolphins from the wild have occurred in live-capture fisheries off

California. Brownell et al. (in press) estimate a minimum total live capture of 128 Pacific white-sided dolphins between

the late 1950s and 1993. The most recent capture was in November 1993, when three animals were taken for public

display (Forney 1994). No MMPA permits are currently active for live-captures of Pacific white-sided dolphins.

STATUS OF STOCK

The status of Pacific white-sided dolphins in California, Oregon and Washington relative to OSP is not known,

and there is no indication of a trend in abundance for this stock. They are not listed as “threatened” or “endangered”

47
under the Endangered Species Act nor as “depleted” under the MMPA. They are not classified as a “strategic” stock

under the MMPA, because the average annual human-caused mortality is estimated to be less than the PBR.

REFERENCES

Barlow, J. 1995. The abundance of cetaceans in California waters. Part 1: Ship surveys in summer/fall 1991. Fish. Bull.

93:1-14.

Barlow, J., R. W. Baird, J. E. Heyning, K. Wynne, A. M. Manville, II: L. F. Lowry, D. Hanan, J. Sease, and V. N.

Burkanov. 1994. A review of cetacean and pinniped mortality in coastal fisheries along the west coast of the

USA and Canada and the east coast of the Russian Federation. Rep. Int. Whal. Commn. Special Issue 15:405-

426.

Brownell. R. L., Jr., W. A. Walker and K. A. Forney. (in press). Pacific white-sided dolphin, Lugenorhynchus

obliquidens Gill, 1865. In: Ridgway, S. H. and R. Harrison (eds.), Handbook of Marine Mammals, Vol. 6.

Carretta, J. V. and K. A. Forney. 1993. Report of the two aerial surveys for marine mammals in California coastal

waters using a NOAA DeHavilland Twin Otter aircraft. March 9-April 7, 1991, February 8-April 6, 1992.

NOAA Technical Memorandum NOAA-TM-NMFS-SWFSC- 185. Available from NMFS, Southwest Fisheries

Science Center, P.O. Box 271: La Jolla, California. 92038. 77p.

Chivers, S. J., K. M. Peltier, W. T. Norman, P. A. Akin, and J. Heyning. 1993. Population structure of cetaceans in

California coastal waters. Paper SOCCS9 presented at the Status of California Cetacean Stocks Workshop, held

in La Jolla, California, March 31 -April 2, 1993. 49p.

Diamond, S. L., J. P. Scholl and D. A. Hanan. 1987. Drift gillnet observations for the 1985-86 fishing season.

Administrative Report SWR 87-4. Available from NMFS, Southwest Region, 300 S. Ferry Street, Terminal

Island? California, 90731. 21p.

Dohl, T. P., R. C. Guess. M. L. Durnan. and R. C. Helm. 1983. Cetaceans of central and northern California, 1980-1983:

Status, abundance and distribution. OCS Study MMS 84-0045. Minerals Management Service Contract # l4-

12-0001-29090. 284p.

Dohl, T. P., K. S. Norris, R. C. Guess, J. D. Bryant, and M. W. Honig. 1980. Summary of marine mammal and seabird

surveys of the Southern California Bight area. 1975-1978. Part II. Cetaces of the Southern California Bight.

Final Report to the Bureau of Land Management, NTIS Rep. No. PB81248189. 414p.

Forney, K. A. 1994. Recent information on the status of odontocetes in Californian waters. NOAA Technical

Memorandum NMFS, NOAA-TM-NMFS-SWFSC-202. Available from NMFS, Southwest Fisheries Science

Center, P.O. Box 271, La Jolla, California, USA.

Forney, K. A., J. Barlow and J. V. Carretta. 1995. The abundance of cetaceans in California waters. Part II: Aerial

surveys in winter and spring of 1991 and 1992. Fish. Bull. 93: 15-26.

Green, G., J. J. Brueggeman, R. A. Grotefendt, C. E. Bowlby, M. L. Bonnell, and K. C. Balcomb, III. 1992. Cetacean

distribution and abundance off Oregon and Washington. Ch. I. In: Oregon and Washington Marine Mammal

and Seabird Surveys. OCS Study 91-0093. Final Report prepared for Pacific OCS Region, Minerals

Management Service, U.S. Department of the Interior, Los Angeles, California.

Green. G., R. A. Grotefendt, M. A. Smultea, C. E. Bowlby, and R. A. Rowlett. 1993. Delphinid aerial surveys in Oregon

and Washington waters. Final Report prepared for NMFS, National Marine Mammal Laboratory, 7600 Sand

Point Way, NE, Seattle, Washington, 98115, Contract *50ABNF200058.

Hanan. D. A., D. B. Holts, and A. L. Coan, Jr. 1993. The California drift gill net fishery for sharks and swordfish, 1981-

82 through 1990-91. Fish Bulletin 175. Available from the Marine Technical Information Center? California

Department of Fish and Game, 330 Golden Shore, Suite 50, Long Beach, CA 90802.

Julian, F. 1993. Pinniped and cetacean mortality in California gillnet fisheries: Preliminary estimates for 1992. Working

paper SC/45/022 presented to the International Whaling Commission Scientific Committee, May 1993

(unpublished).

Julian. F. 1994. Pinniped and cetacean mortality in California gillnet fisheries: Preliminary estimates for 1993. Working

paper SC/46/011 presented to the International Whaling Commission Scientific Committee, May 1994

(unpublished).

Lennert, C., S. Kruse, M. Beeson, and J. Barlow. 1994. Estimates of incidental marine mammal bycatch in California

gillnet fisheries for July through December 1990. Rep. Int. Whal. Commn. Special Issue 15:449-463.

Mangels, K. F. and Gerrodette, T. 1994. Report of cetacean sightings during a marine mammal survey in the eastern

48
Pacific Ocean and Gulf of California aboard the NOAA ships McARTHUR and DAVID STARR JORDAN July

28 - November 6, 1993. NOAA Technical Memorandum NMFS, NOAA-TM-NMFS-SWFSC-211.

National Marine Fisheries Service, Southwest Fisheries Science Center. Unpublished data.

Perkins, P. J. Barlow and M. Beeson. 1992. Pinniped and cetacean mortality in California gillnet fisheries: 1991.

Working Paper SC/44/SM14 presented to the International Whaling Commission, May 1992 (unpublished).

Sosa-Nishizaki, O., R. De la Rosa Pacheco, R. Castro Longoria, M. Grijalva Chon, and J. De la Rosa Velez. 1993.

Estudio biologico pesquero del pez (Xiphius gladius) y otras especies de picudos (marlins y pez vela). Rep. Int.

CICESE, CTECT9306.

Stick, K. C. and Hreha, L. 1989. Summary of the 1988 Washington/Oregon experimental thresher shark gill net fishery.

State of Washington, Department of Fisheries, Progress Report 275. 40p.

Walker, W. A., S. Leatherwood, K. R. Goodrich, W. F. Perrin and R. K. Stroud. 1986. Geographical variation and

biology of the Pacific white-sided dolphin, Lagenorhynchus obliquidens, in the north-eastern Pacific. In.

Bryden, M. M. and R. Harrison (eds.), Research on Dolphins, p. 441-465. Clarendon Press, Oxford.

49
RISSO’S DOLPHIN (Grampus griseus):

California/Oregon/Washington Stock

STOCK DEFINITION AND GEOGRAPHIC RANGE

Risso’s dolphins are distributed world-wide in tropical and warm-temperate waters. Off the U.S. West coast,

Risso’s dolphins are commonly seen on the shelf in the Southern California Bight and in slope and offshore waters of

California, Oregon and Washington. Based on sighting patterns from recent aerial and shipboard surveys conducted in

these three states during different seasons (Green et al. 1992, 1993; Forney et al. 1995; Barlow 1995): animals found off

California during the colder water months are thought to shift northward into Oregon and Washington as water

temperatures increase in late spring and summer (Green et al. 1992). The southern end of this population’s range is not

well-documented, but on a recent joint U.S./Mexican ship survey: Risso’s dolphins were sighted off northern Baja

California, and a conspicuous 500 nmi gap was present between these animals and Risso’s dolphins sighted south of Baja

California and in the Gulf of California (Mangels and Gerrodette 1994). Thus this population appears distinct from

animals found in the eastern tropical Pacific and the Gulf of California. Although Risso’s dolphins are not restricted to

U.S. waters. cooperative management agreements with Mexico exist only for the tuna purse seine fishery and not for

other fisheries which may take this species (e.g. gillnet fisheries). For the Marine Mammal Protection Act (MMPA) stock

assessment reports, Risso’s dolphins within the Pacific U.S. Exclusive Economic Zone are divided into two discrete, noncontiguous areas: I) waters off California, Oregon and Washington (this report), and 2) Hawaiian waters.

POPULATION SIZE

Forney (1994) reviews recent abundance estimates for Risso’s dolphins along the U.S. west coast and concludes

that the best estimate of overall population size in California, Oregon and Washington is the estimate obtained from aerial

surveys conducted off California during winter/spring of 1991 and 1992 (Forney et al. 1995). Because of the observed

seasonal shifts in distribution, this estimate of 32,376 animals (C.V. = 0.46) is expected to include animals which may

be found off Oregon and Washington in the summer/fall.

Minimum Population Estimate

The log-normal 20th percentile of the above abundance estimate is 22:388 Risso’s dolphins.

Current Population Trend

Although sighting records of Risso’s dolphins appear to have increased during the last two decades in some areas

off the U.S. West coast (Green et al. 1992, 1993; Shane 1994), sampling effort has also increased, and there are no

statistical estimates of historical abundance on which to base a quantitative comparison. Thus, it is possible that Risso’s

dolphin abundance off the U.S. West coast has increased, but no definitive statement regarding trends in abundance of

Risso’s dolphins off California, Oregon and Washington can be made.

CURRENT AND MAXIMUM NET PRODUCTIVITY RATES

No information on current or maximum net productivity rates is available for Risso’s dolphins in California.

POTENTIAL BIOLOGICAL REMOVAL

Based on this stock’s unknown status and growth rate, the recovery factor (F,) is 0.5, and 1/2Rmax is the default

value of 0.02. Multiplying these two values times the minimum population estimate of 22,388 yields a potential

biological removal (PBR) of 224 Risso’s dolphins per year.

ANNUAL HUMAN-CAUSED MORTALITY AND SERIOUS INJURY

Fishery Information

Risso’s dolphins are incidentally killed in drift gillnets, which have been used to catch swordfish, thresher shark,

and mako shark in offshore California, Oregon and Washington waters (Hanan et al. 1993). with approximately 149

vessels currently active (J. Cordaro, Southwest Region: NMFS, pers. comm.). Fishing effort has decreased from

approximately 10,000 sets per year in the mid-1980s to 6600 in 1993 (Barlow et al. 1994). Between July 1990 and

December 1993. with approximately 4- 13% observer coverage of California drift gillnet fisheries, observed mortality

50
of Risso’s dolphins was zero in 1990, five in 1991, five in 1992, and four in 1993, resulting in annual mortality estimates

of zero for 1990, 42 (s.e. 24) for 1991, 38 (s.e. 18) for 1992, and 36 (s.e. 27) for 1993 (Lennert et al. 1994; Perkins et

al. 1992; Julian 1993, 1994). The corresponding average rates of Risso’s dolphin kill per fishing day are 0, 0.009, 0.008,

and 0.005 for 1990, 1991, 1992 and 1993, respectively. Preliminary mortality data for 1994 indicate that one Risso’s

dolphin was observed killed (NMFS, unpublished data). The average estimated annual mortality for Risso’s dolphins

in this fishery for the three complete years of monitoring, 1991-93, is 39 animals.

Similar drift gillnet fisheries for swordfish and sharks exist along the entire Pacific coast of Baja California.

Mexico and may probably take animals from the same population. Quantitative data are available only for the Mexican

swordfish drift gillnet fishery, which has increased from two vessels in 1986 to 29 vessels in 1992 (Sosa-Nishizaki et al.

1993). The total number of sets in this fishery in 1992 can be estimated from data provided by these authors to be

approximately 2700, with an observed rate of marine mammal bycatch of 0.13 animals per set (10 marine mammals in

77 observed sets; Sosa-Nishizaki et al. 1993). This overall mortality rate is similar to that observed in California driftnet

fisheries during 1990-93 (0.15 marine mammals per set), but species-specific information is not available for the Mexican

fisheries.

Additional mortality of unknown extent has been documented for Risso’s dolphins in the squid purse seine

fishery off Southern California (Heyning et al. 1994), which currently includes approximately 145 vessels (NMFS,

unpublished data). This mortality probably represents animals killed intentionally to protect catch or gear, rather than

incidental mortality, and such intentional takes are now illegal under the 1994 Amendment to the MMPA.

An experimental gillnet fishery for thresher shark off Oregon and Washington in 1986-89 also reported mortality

of Risso’s dolphins; however, this fishery was discontinued after 1989 due to the high rates of marine mammal and turtle

bycatch (Stick and Hreha, 1989).

Fishery Mortality Rate

The total fishery mortality and serious injury for this stock during 1991-93 (39 animals per year) is greater than

10% of the calculated PBR and, therefore, cannot be considered to be insignificant and approaching zero mortality and

serious injury rate. This determination cannot be made for individual fisheries until the implementing regulations for

Section 118 of the MMPA have been reviewed by the public and finalized.

STATUS OF STOCK

The status of Risso’s dolphins off California, Oregon and Washington relative to OSP is not known, and there

are insufficient data to evaluate potential trends in abundance. They are not listed as “threatened” or “endangered” under

the Endangered Species Act nor as “depleted” under the MMPA. The average annual human-caused mortality is

estimated to be less than the PBR, so they are not classified as a “strategic” stock under the MMPA.

REFERENCES

Barlow, J. 1995. The abundance of cetaceans in California waters. Part 1: Ship surveys in summer/fall 1991. Fish. Bull.

93: l-14.

Barlow, J., R. W. Baird, J. E. Heyning, K. Wynne, A. M. Manville, II, L. F. Lowry, D. Hanan, J. Sease, and V. N.

Burkanov. 1994. A review of cetacean and pinniped mortality in coastal fisheries along the west coast of the

USA and Canada and the east coast of the Russian Federation. Rep. Int. Whal. Commn. Special Issue 15:405-

426.

Forney, K. A. 1994. Recent information on the status of odontocetes in Californian waters. NOAA Technical

Memorandum NMFS, NOAA-TM-NMFS-SWFSC-202. Available from NMFS, Southwest Fisheries Science

Center, P.O. Box 271, La Jolla, California. USA.

Forney, K. A., J. Barlow and J. V. Carretta. 1995. The abundance of cetaceans in California waters. Part II: Aerial

surveys in winter and spring of 1991 and 1992. Fish. Bull. 93:15-26.

Green, G., J. J. Brueggeman, R. A. Grotefendt, C. E. Bowlby, M. L. Bonnell, and K. C. Balcomb, III. 1992. Cetacean

distribution and abundance off Oregon and Washington. Ch. 1. In: Oregon and Washington Marine Mammal

and Seabird Surveys. OCS Study 91-0093. Final Report prepared for Pacific OCS Region, Minerals

Management Service, U.S. Department of the Interior, Los Angeles, California.

Green: G., R. A. Grotefendt, M. A. Smultea, C. E. Bowlby, and R. A. Rowlett. 1993. Delphinid aerial surveys in Oregon

and Washington waters. Final Report prepared for NMFS, National Marine Mammal Laboratory, 7600 Sand

51
Point Way, NE, Seattle, Washington, 98115, Contract #50ABNF200058.

Hanan, D. A., D. B. Holts, and A. L. Coan, Jr. 1993. The California drift gill net fishery for sharks and swordfish, l981-

82 through 1990-91, Fish Bulletin 175. Available from the Marine Technical Information Center, California

Department of Fish and Game, 330 Golden Shore, Suite 50, Long Beach, CA 90802.

Heyning, J. E., T. D. Lewis and C. D. Woodhouse. 1994. A note on odontocete mortality from fishing gear

entanglements off Southern California. Rep. Int. Whal. Commn. Special Issue 15:439-442.

Julian: F. 1993. Pinniped and cetacean mortality in California gillnet fisheries: Preliminary estimates for 1992. Working

paper SC/45/022 presented to the International Whaling Commission Scientific Committee. May 1993

(unpublished).

Julian, F. 1994. Pinniped and cetacean mortality in California gillnet fisheries: Preliminary estimates for 1993. Working

paper SC/46/011 presented to the International Whaling Commission Scientific Committee, May 1994

(unpublished).

Lennert, C., S. Kruse, M. Beeson. and J. Barlow. 1994. Estimates of incidental marine mammal bycatch in California

gillnet fisheries for July through December 1990. Rep. Int. Whal. Commn. Special Issue 15:449-463.

Mangels, K. F. and Gerrodette, T. 1994. Report of cetacean sightings during a marine mammal survey in the eastern

Pacific Ocean and Gulf of California aboard the NOAA ships AcARTHUR and DAVID STARR JORDAN July

28 - November 6, 1993. NOAA Technical Memorandum NMFS, NOAA-TM-NMFS-SWFSC-211.

National Marine Fisheries Service, Office of Protected Resources. Unpublished data.

Perkins, P., J. Barlow and M. Beeson. 1992. Pinniped and cetacean mortality in California gillnet fisheries: 1991.

Working Paper SC/44/SM14 presented to the International Whaling Commission, May 1992 (unpublished).

Shane, S. 1994. Occurrence and habitat use of marine mammals at Santa Catalina Island. California from 1983-91.

Bull. Southern California Acad. Sci. 93: 13-29.

Sosa-Nishizaki, O., R. De la Rosa Pacheco, R. Castro Longoria, M. Grijalva Chon, and J. De la Rosa Velez. 1993.

Estudio biologico pesquero del pez (Xiphius gladius) y otras especies de picudos (marlins y pez vela). Rep. Int.

CICESE, CTECT9306.

Stick: K. C. and Hreha, L. 1989. Summary of the 1988 Washington/Oregon experimental thresher shark gill net fishery.

State of Washington, Department of Fisheries, Progress Report 275. 40p.

52
BOTTLENOSE DOLPHIN (Tursiops truncatus): California Coastal Stock

STOCK DEFINITION AND GEOGRAPHIC RANGE

Bottlenose dolphins are distributed world-wide in tropical and warm-temperate waters. In many regions,

including California, separate coastal and offshore populations are known (Walker 1981; Ross and Cockcroft 1990; Van

Waerebeek et al. 1990). California coastal bottlenose dolphins are found within about one kilometer of shore (Hansen

1990; NMFS unpublished data) primarily from Point Conception south into Mexican waters, at least as far as Ensenada.

Since the 1982-83 El Niño, which increased water temperatures off California, they have been consistently sighted in

central California as far north as San Francisco. Photo-identification studies have documented north-south movements

of coastal bottlenose dolphins (Defran et al. 1986; Hansen 1990), and monthly counts based on surveys between the

U.S./Mexican border and Point Conception are variable (NMFS, unpublished data), indicating that animals are probably

moving into and out of this area. Although coastal bottlenose dolphins are not restricted to U.S. waters, cooperative

management agreements with Mexico exist only for the tuna purse seine fishery and not for other fisheries which may

take this species (e.g. gillnet fisheries). Therefore, the management stock includes only animals found within U.S. waters.

For the Marine Mammal Protection Act (MMPA) stock assessment reports, bottlenose dolphins within the Pacific U.S.

Exclusive Economic Zone are divided into three stocks: 1) California coastal stock (this report), 2) California. Oregon

and Washington offshore stock, and 3) Hawaiian stock.

POPULATION SIZE

Forney (1994) reviews recent abundance estimates for coastal bottlenose dolphins in Californian waters, and

concludes that the best abundance estimate is the combined count of 245 animals obtained on October 25,1991 based

on aerial surveys in Southern California (Pt. Conception to the U.S./Mexican border; NMFS, unpublished data) and a

shipboard photo-identification survey in Monterey Bay (Maldini 1992). This count is probably an underestimate of the

total population size? because submerged animals may be missed on aerial surveys, and because north of Point

Conception, regions other than Monterey Bay were not surveyed. Furthermore, oceanographic events appear to influence

the distribution of animals along the coasts of California and Baja California, as indicated by a change in residency

patterns along Southern California and a northward range extension into central California after the 1982-83 El Niño

(Hansen and Defran 1990; Wells et al. 1990). Therefore, the number of animals which use the California coastline over

a longer time period is likely to be greater than the count at any given time. However, without recent quantitative data

on the extent of such movement, the maximum observed number of coastal bottlenose dolphins (245) currently represents

the best estimate of population size.

Minimum Population Estimate

The minimum population estimate for coastal bottlenose dolphins in California is the count of 245 animals from

the above October 1991 surveys.

Current Population Trend

No trend in abundance of coastal bottlenose dolphins is apparent based on the available data.

CURRENT AND MAXIMUM NET PRODUCTIVITY RATES

No information on current or maximum net productivity rates is available for California coastal bottlenose

dolphins.

POTENTIAL BIOLOGICAL REMOVAL

Based on this stock’s unknown status and growth rate, the recovery factor (F,) is 0.5, and 1/2Rmax is the default

value of 0.02. Multiplying these two values times the minimum population estimate of 245 yields a potential biological

removal (PBR) of 2.5 animals per year.

ANNUAL HUMAN-CAUSED MORTALITY AND SERIOUS INJURY

Fishery Information

Due to the strictly coastal habits of this bottlenose dolphin population, it is susceptible to fishery-related

53
mortality in coastal set net fisheries. Set gillnets are used by approximately 134 vessels (J. Cordaro, Southwest Region,

NMFS, pers. comm.) to catch halibut, flounder, angel shark? yellowtail, white seabass. and white croaker in California

coastal waters. As a result of area closures, fishing effort has decreased from approximately 40,000 sets per year in the

mid-1980s to 16,000 sets in 1993 (Barlow et al. 1994). Although effort data for 1994 are still incomplete, effort appears

to have decreased as a result of new ban on fishing within 3 nmi of shore in Southern California. Between July 1990 and

December 1993, with approximately 5- 15% of California set gillnet fisheries observed, no coastal bottlenose dolphins

were recorded killed (Lennert et al. 1994; Perkins et al. 1992; Julian 1993, 1994). Preliminary mortality data for 1994

indicate that no bottlenose dolphins were observed killed (NMFS, unpublished data). Although this does not prove that

no animals were taken (because observer coverage was not 100%) it does indicate that mortality (if it occurred) was

probably only a few individuals per year. Heyning et al. (1994) report that four bottlenose dolphins stranded with

evidence of fishery interactions between 1975 and 1990, but the stock identity of these animals and the responsible

fishery are not known. Beginning in 1994, California set gillnet fisheries are no longer expected to overlap with the range

of coastal bottlenose dolphins? because they have been banned from nearshore areas. However, coastal gillnet fisheries

exist in Mexico and probably take animals from this population, but no details are available for these fisheries.

Other removals

Seven coastal bottlenose dolphins were collected during the late 1950s in the vicinity of San Diego morris and

Prescott 1961). Twenty-seven additional bottlenose dolphins were captured off California between 1966 and 1982

(Walker 1975, Reeves and Leatherwood 1984). but based on the locations of capture activities, these animals probably

were offshore bottlenose dolphins (Walker 1975). No additional captures of coastal bottlenose dolphins have been

documented since 1982, and no live-capture permits are currently active for this species.

Pollutant levels, especially DDT residues, found in Southern California coastal bottlenose dolphins have been

found to be the highest of any cetacean examined (O’Shea et al. 1980; Schafer et al. 1984). Although the effects of

pollutants on cetaceans are not well understood, they may affect reproduction or make the animals more prone to other

mortality factors (Britt and Howard 1983).

Fishery Mortality Rate

The total fishery mortality and serious injury for this stock can be considered to be insignificant and approaching

zero? because no recent fishery takes have been reported. However, the observed take of a single animal would result

in a mortality rate exceeding 1 0% of the PBR, and therefore this evaluation is tenuous.

STATUS OF STOCK

The status of coastal bottlenose dolphins in California relative to OSP is not known, and there is no evidence

of a trend in abundance. They are not listed as “threatened” or “endangered” under the Endangered Species Act nor as

“depleted” under the MMPA. Because no recent fishery takes have been documented, coastal bottlenose dolphins are

not classified as a “strategic” stock under the MMPA.

REFERENCES

Barlow, J., R. W. Baird, J. E. Heyning. K. Wynne, A. M. Manville, II, L. F. Lowry, D. Hanan, J. Sease, and V. N.

Burkanov. 1994. A review of cetacean and pinniped mortality in coastal fisheries along the west coast of the

USA and Canada and the east coast of the Russian Federation. Rep. Int. Whal. Commn. Special Issue 15:405-

426.

Britt. J. 0. and E. B. Howard. 1983. Tissue residues of selected environmental contaminants in marine mammals. In:

Howard, E. B. (ed.), Pathobiology of Marine Mammal Diseases. CRC Press, Boca Raton, Florida.

Defran, R. H., D. L. Kelly, G. M. Shultz, A. C. Weaver, and M. A. Espinoza. 1986. The occurrence and movements

of the bottlenose dolphin in the Southern California Bight. Administrative Report LJ-86-36C. Available from

NMFS, Southwest Fisheries Science Center, P.O. Box 271, La Jolla, California, USA.

Forney, K. A. 1994. Recent information on the status of odontocetes in Californian waters. NOAA Technical

Memorandum NMFS, NOAA-TM-NMFS-SWFSC-202. Available from NMFS, Southwest Fisheries Science

Center? P.O. Box 271, La Jolla, California, USA.

Hansen, L. J. 1990. California coastal bottlenose dolphins. In: S. Leatherwood and R.R. Reeves (eds.), The Bottlenose

Dolphin, p. 403-420. Academic Press, Inc., San Diego.

54
Hansen, L. J. and R. H. Defran. 1990. A comparison of photo-identification studies of California coastal bottlenose

dolphins. Rep. Int. Whal. Commn. Special Issue 12:101-104.

Heyning, J. E., T. D. Lewis and C. D. Woodhouse. 1994. A note on odontocete mortality from fishing gear

entanglements off Southern California. Rep. Int. Whal. Commn. Special Issue 15:439-442.

Julian? F. 1993. Pinniped and cetacean mortality in California gillnet fisheries: Preliminary estimates for 1992. Working

paper SC/45/022 presented to the International Whaling Commission Scientific Committee, May 1993

(unpublished).

Julian, F. 1994. Pinniped and cetacean mortality in California gillnet fisheries: Preliminary estimates for 1993. Working

paper SC/46/011 presented to the International Whaling Commission Scientific Committee, May 1994

(unpublished).

Lennert, C., S. Kruse, M. Beeson, and J. Barlow. 1994. Estimates of incidental marine mammal bycatch in California

gillnet fisheries for July through December 1990. Rep. Int. Whal. Commn. Special Issue 15:449-463.

Maldini, D. 1992. A photo-identification study of coastal bottlenose dolphins in Monterey Bay, California. Final Report

submitted to NMFS, Southwest Fisheries Science Center? P.O. Box 271, La Jolla, California, USA.

O’Shea, T. J., R. L. Brownell, Jr., D. R. Clark, W. A. Walker, M. L. Gray, and T. G. Lamont. 1980. Organochlorine

pollutants in small cetaceans from the Pacific and South Atlantic Oceans, November l968-June 1976. Pesticides

Monitoring Journal 14:35-46.

National Marine Fisheries Service, Southwest Fisheries Science Center. Unpublished data.

Norris, K. S. and J. H. Prescott. 1961. Observation on Pacific cetaceans of Californian and Mexican waters. University

of California Publications in Zoology 63:291-402. University of California Press, Berkeley and Los Angeles.

Perkins: P., J. Barlow and M. Beeson. 1992. Pinniped and cetacean mortality in California gillnet fisheries: 1991.

Working Paper SC/44/SM14 presented to the International Whaling Commission, May 1992 (unpublished).

Reeves, R. R. and S. Leatherwood. 1984. Live-capture fisheries for cetaceans in USA and Canadian waters, 1973-1982.

Rep. Int. Whal. Commn. 34:497-507.

Ross, G. J. B. and V. G. Cockcroft. 1990. Comments on Australian bottlenose dolphins and the taxonomic status of

Tursiops aduncus (Ehrenberg, 1832). In: The Bottlenose Dolphin (eds. S. Leatherwood and R. R. Reeves). pp.

101-128. Academic Press, 653pp.

Schafer, H. A., R. W. Gossett, C. F. Ward, and A. M. Westcott. 1984. Chlorinated hydrocarbons in marine mammals.

Biennial Report, 1983-84, Southern California Coastal Water Research Project, Long Beach, California.

Van Waerebeek, K., J. C. Reyes, A. J. Read, and J. S. McKinnon. 1990. Preliminary observations of bottlenose dolphins

from the Pacific coast of South America. In: The Bottlenose Dolphin (eds. S. Leatherwood and R. R. Reeves).

pp. 143-154 Academic Press, 653 pp.

Walker, W. A. 1975. Review of the live-capture fishery for smaller cetaceans taken in Southern California waters for

public display. 1966-77. J. Fish. Res. Board. Can. 32: 1197- 1211.

Walker, W. A. 1981. Geographical variation in morphology and biology of bottlenose dolphins (Tursiops) in the eastern

North Pacific. Administrative Report LJ-81-03C, available from NMFS, Southwest Fisheries Science Center,

La Jolla, CA 92038. 52p.

Wells: R. S., L. J. Hansen? A. B. Baldridge, T. P. Dohl, D. L. Kelly and R. H Defran. In: S. Leatherwood and R. R.

Reeves (eds.), The Bottlenose Dolphin, p. 421-431. Academic Press, Inc., San Diego.

55
BOTTLENOSE DOLPHIN (Tursiops truncatus):

California/Oregon/Washington Offshore Stock

STOCK DEFINITION AND GEOGRAPHIC RANGE

Bottlenose dolphins are distributed world-wide in tropical and warm-temperate waters. In many regions,

including California, separate coastal and offshore populations are known (Walker 1981; Ross and Cockcroft 1990; Van

Waerebeek et al. 1990). On surveys conducted off California: offshore bottlenose dolphins have been found in the

Southern California Bight and in offshore waters as far north as about 4l°N (Hill and Barlow 1992; Carretta and Fomey

1993; Mangels and Gerrodette 1994). and they may range into Oregon and Washington waters during warm-water

periods. Sighting records off California and Baja California (Lee 1993; Mangels and Gerrodette 1994) suggest that

offshore bottlenose dolphins have a continuous distribution in these two regions. Based on aerial surveys conducted

during winter/spring 199l-92 (Forney et al. 1995) and shipboard surveys conducted in summer/fall 1991 (Barlow 1995),

no seasonality in distribution is apparent. Although offshore bottlenose dolphins are not restricted to U.S. waters,

cooperative management agreements with Mexico exist only for the tuna purse seine fishery and not for other fisheries

which may take this species (e.g. gillnet fisheries). Therefore, the management stock includes only animals found within

U.S. waters. For the Marine Mammal Protection Act (MMPA) stock assessment reports, bottlenose dolphins within the

Pacific U.S. Exclusive Economic Zone are divided into three stocks: I) California coastal stock (this report), 2)

California, Oregon and Washington offshore stock. and 3) Hawaiian stock.

POPULATION SIZE

Formey (I 994) reviews recent abundance estimates for offshore bottlenose dolphins in Californian waters, and

concludes that the best abundance estimate is a weighted average of estimates obtained from the 199l-92 aerial surveys

(Forney et al. 1995) and the 1991 shipboard surveys (Barlow 1995). This estimate is 2:382 (C.V. = 0.36) offshore

bottlenose dolphins.

Minimum Population Estimate

The minimum population estimate for offshore bottlenose dolphins in California (defined as the log-normal 20th

percentile of the above abundance estimate) is 1,775 animals.

Current Population Trend

No information on trends in abundance of offshore bottlenose dolphins is available.

CURRENT AND MAXIMUM NET PRODUCTIVITY RATES

No information on current or maximum net productivity rates is available for this population of offshore

bottlenose dolphins.

POTENTIAL BIOLOGICAL REMOVAL

Based on this stock’s unknown status and growth rate. the recovery factor (F,) is 0.5, and 1/2Rmax is the default

value of 0.02. Multiplying these two values times the minimum population estimate of 1,775 yields a potential biological

removal (PBR) of 18 animals per year.

ANNUAL HUMAN-CAUSED MORTALITY AND SERIOUS INJURY

Fishery Information

Offshore bottlenose dolphins are incidentally killed in drift gillnet fisheries, which have been used to catch

swordfish, thresher shark, and mako shark in offshore California: Oregon and Washington waters (Hanan et al. 1993),

with approximately 149 vessels currently active (J. Cordaro, Southwest Region. NMFS, pers. comm.). Fishing effort has

decreased from approximately 10,000 sets per year in the mid- 1980s to 6600 in 1993 (Barlow et al. 1994). Based on less

than 1% observer coverage of fishing effort between 1980 and 1985, no bottlenose dolphins were reported killed

(Diamond et al. 1987). Between July 1990 and December 1993, with approximately 4-13% of California drift gillnet

fisheries observed, three offshore bottlenose dolphins were recorded killed in driftnets in 1992, resulting in annual

mortality estimates of zero for 1990, 1991 and 1993, and 23 (s.e. 21) for 1992 (Lennert et al. 1994; Perkins et al. 1992;

56
Julian 1993, 1994). Corresponding average rates of kill per fishing day are zero in 1990, 1991 and 1993, and 0.005 in

1992. Preliminary mortality data for 1994 indicate that no bottlenose dolphins were observed killed (NMFS, unpublished

data). The average estimated annual mortality for offshore bottlenose dolphins in this fishery for the three complete

years of monitoring, 1991-93, is 7.7 animals.

Similar drift gillnet fisheries for swordfish and sharks exist along the entire Pacific coast of Baja California,

Mexico and may take animals from the same population. Quantitative data are available only for the Mexican swordfish

drift gillnet fishery, which has increased from two vessels in 1986 to 29 vessels in 1992 (Sosa-Nishizaki et al. 1993). The

total number of sets in this fishery in 1992 can be estimated from data provided by these authors to be approximately

2700. with an observed rate of marine mammal bycatch of 0.13 animals per set (10 marine mammals in 77 observed sets;

Sosa-Nishizaki et al. 1993). This overall mortality rate is similar to that observed in California driftnet fisheries during

1990-93 (0. I5 marine mammals per set), but species-specific information is not available for the Mexican fisheries.

Based on logbook data for 1990-92, one additional mortality of an offshore bottlenose dolphin was documented

in the California anchovy, mackerel and tuna purse seine fishery, which includes approximately 150 vessels (NMFS,

unpublished data). Thus the minimum mortality for this period is 0.33 animals per year; however, due to the uncertainties

in this data source, no estimate of total mortality can be made for this fisheries.

Offshore bottlenose dolphins are often associated with Risso’s dolphins and pilot whales, for which mortality

has been documented in the squid purse seine fishery off Southern California (Heyning et al. 1994). Based on this

association, offshore bottlenose dolphins may also have experienced some mortality in this fishery? which currently

includes approximately 145 vessels (NMFS, unpublished data). However these would probably represent animals killed

intentionally to protect catch or gear, rather than incidental kills, and such intentional takes are now illegal under the 1994

Amendment to the MMPA.

Fishery Mortality Rate

The total fishery mortality and serious injury for this stock during 1991-93 (7.7 animals per year) is greater than

10% of the calculated PBR and, therefore, cannot be considered to be insignificant and approaching zero mortality and

serious injury rate. This determination cannot be made for individual fisheries until the implementing regulations for

Section 118 of the MMPA have been reviewed by the public and finalized.

Other removals

Twenty-seven bottlenose dolphins were captured off California between 1966 and 1982 (Walker 1975, Reeves

and Leatherwood 1984). Based on the locations of capture activities, these animals probably were offshore bottlenose

dolphins (Walker 1975). No additional captures of bottlenose dolphins off California have been documented since 1982,

and no MMPA live-capture permits are currently active for this species.

STATUS OF STOCK

The status of offshore bottlenose dolphins in California relative to OSP is not known, and there are insufficient

data to evaluate trends in abundance. They are not listed as “threatened” or “endangered” under the Endangered Species

Act nor as “depleted” under the MMPA. Because the average annual human-caused mortality is estimated to be less than

the PBR, they are not classified as a “strategic” stock under the MMPA.

REFERENCES

Barlow, J. 1995. The abundance of cetaceans in California waters. Part I: Ship surveys in summer and fall of 1991.

Fish. Bull. 93:l-14.

Barlow, J., R. W. Baird, J. E. Heyning, K. Wynne, A. M. Manville, II, L. F. Lowry, D. Hanan, J. Sease, and V. N.

Burkanov. 1994. A review of cetacean and pinniped mortality in coastal fisheries along the west coast of the

USA and Canada and the east coast of the Russian Federation. Rep. Int. Whal. Commn. Special Issue 15:405-

426.

Carretta, J. V. and K. A. Forney. 1993. Report of the two aerial surveys for marine mammals in California coastal

waters using a NOAA DeHavilland Twin Otter aircraft, March 9-April 7, 1991, February 8-April 6, 1992.

NOAA Technical Memorandum NOAA-TM-NMFS-SWFSC-185. Available from NMFS, Southwest Fisheries

Science Center, P.O. Box 27 I, La Jolla, California? 92038. 77p.

Diamond, S. L., J. P. Scholl and D. A. Hanan. 1987. Drift gillnet observations for the 1985-86 fishing season.

57
Administrative Report SWR 87-4. Available from NMFS, Southwest Region, 300 S. Ferry Street, Terminal

Island, California, 90731. 2lp.

Forney, K. A. 1994. Recent information on the status of odontocetes in Californian waters. NOAA Technical

Memorandum NMFS, NOAA-TM-N.MFS-SWFSC-202. Available from NMFS, Southwest Fisheries Science

Center, P.O. Box 271, La Jolla, California, USA.

Forney, K. A., J. Barlow and J. V. Carretta. 1995. The abundance of cetaceans in California waters. Part II: Aerial

surveys in winter and spring of 1991 and 1992. Fish. Bull. 93: 15-26.

Hanan, D. A.. D. B. Holts, and A. L. Coan, Jr. 1993. The California drift gill net fishery for sharks and swordfish, 1981-

82 through 1990-91. Fish Bulletin 175. Available from the Marine Technical Information Center, California

Department of Fish and Game, 330 Golden Shore: Suite 50, Long Beach, CA 90802.

Heyning. J. E., T. D. Lewis and C. D. Woodhouse. 1994. A note on odontocete mortality from fishing gear

entanglements off Southern California. Rep. Int. Whal. Commn. Special Issue 15:439-442.

Hill, P. S. and J. Barlow. 1992. Report on a marine mammal survey of the California coast aboard the research vessel

McARTHUR July 28 - November 5, 1991. NOAA Technical Memorandum NMFS, NOAA-TM-NMFSSWFSC- 169. Available from NMFS, Southwest Fisheries Science Center, P.O. Box 27l, La Jolla: California,

USA.

Julian, F. 1993. Pinniped and cetacean mortality in California gillnet fisheries: Preliminary estimates for 1992. Working

paper SC/45/022 presented to the International Whaling Commission Scientific Committee, May 1993

(unpublished).

Julian: F. 1994. Pinniped and cetacean mortality in California gillnet fisheries: Preliminary estimates for 1993. Working

paper SC/46/011 presented to the International Whalin g Commission Scientific Committee. May 1994

(unpublished).

Lee. T. 1993. Summary of cetacean survey data collected between the years of 1974 and 1985. NOAA Technical

Memorandum NMFS, NOAA-TM-NMFS-SWFSC- 181. Available from NMFS, Southwest Fisheries Science

Center, P.O. Box 271, La Jolla, California, USA.

Lennert, C., S. Kruse, M. Beeson, and J. Barlow. 1994. Estimates of incidental marine mammal bycatch in California

gillnet fisheries for July through December 1990. Rep. Int. Whal. Commn. Special Issue 15:449-463.

Mangels, K. F. and Gerrodette, T. 1994. Report of cetacean sightings during a marine mammal survey in the eastern

Pacific Ocean and Gulf of California aboard the NOAA ships McARTHUR and DAVID STARR JORDAN July

28 - November 6, 1993. NOAA Technical Memorandum NMFS, NOAA-TM-NMFS-SWFSC-211,

National Marine Fisheries Service? Office of Protected Resources. Unpublished data.

Perkins, P., J. Barlow and M. Beeson. 1992. Pinniped and cetacean mortality in California gillnet fisheries: 1991.

Working Paper SC/44/SM14 presented to the International Whaling Commission, May 1992 (unpublished).

Reeves, R. R. and S. Leatherwood. 1984. Live-capture fisheries for cetaceans in USA and Canadian waters, 1973-l982.

Rep. Int. Whal. Commn 34:497-507.

Ross. G. J. B. and V. G. Cockcroft. 1990. Comments on Australian bottlenose dolphins and the taxonomic status of

Tursiops aduncus (Ehrenberg, 1832). In: The Bottlenose Dolphin (eds. S. Leatherwood and R. R. Reeves). pp.

101 - 128. Academic Press, 653pp.

Sosa-Nishizaki, 0.: R. De la Rosa Pacheco, R. Castro Longoria, M. Grijalva Chon. and J. De la Rosa Velez. 1993.

Estudio biologico pesquero del pez (Xiphias gladius) y otras especies de picudos (marlins y pez vela). Rep. Int.

CICESE, CTECT9306.

Van Waerebeek, K., J. C. Reyes, A. J. Read, and J. S. McKinnon. 1990. Preliminary observations of bottlenose dolphins

from the Pacific coast of South America. In: The Bottlenose Dolphin (eds. S. Leatherwood and R. R. Reeves).

pp. 143- 154 Academic Press, 653 pp.

Walker, W. A. 1975. Review of the live-capture fishery for smaller cetaceans taken in Southern California waters for

public display, 1966-77. J. Fish. Res. Board. Can. 32:1197-1211.

Walker, W. A. 1981. Geographical variation in morphology and biology of bottlenose dolphins (Tursiops) in the eastern

North Pacific. Administrative Report LJ-81-03C, available from NMFS, Southwest Fisheries Science Center,

La Jolla: CA 92038. 52p.

58
STRIPED DOLPHIN (Stenella coeruleoalba):

California/Oregon/Washington Stock

STOCK DEFINITION AND GEOGRAPHIC RANGE

Striped dolphins are distributed world-wide in tropical and warm-temperate pelagic waters. On recent shipboard

surveys extending about 300 nmi offshore of California, they were sighted within about 100-300 nmi from the coast

(Barlow 1995; Mangels and Gerrodette 1994). No sightings have been reported for Oregon and Washington waters, but

striped dolphins have stranded in both states (Oregon Department of Fish and Wildlife, unpublished data; Washington

Department of Fish and Wildlife, unpublished data). Striped dolphins are also commonly found in the central North

Pacific. but sampling between this region and California has been insufficient to determine whether the distribution is

continuous. Based on sighting records off California and Mexico, striped dolphins appear to have a continuous

distribution in offshore waters of these two regions (Perrin et al. 1985; Mangels and Gerrodette 1994). No information

on possible seasonality in distribution is available, because the California surveys which extended 300 nmi offshore were

conducted only during the summedfall period. Although striped dolphins are not restricted to U.S. waters, cooperative

management agreements with Mexico exist only for the tuna purse seine fishery and not for other fisheries which may

take this species (e.g. gillnet fisheries). Therefore, the management stock includes only animals found within U.S. waters.

For the Marine Mammal Protection Act (MMPA) stock assessment reports, striped dolphins within the Pacific U.S.

Exclusive Economic Zone are divided into two discrete, non-contiguous areas: 1) waters off California, Oregon and

Washington (this report), and 2) waters around Hawaii.

POPULATION SIZE

Barlow (1995) estimates a population size of 19,008 (C.V. = 0.41) for striped dolphins off California, based on

the 1991 summer/fall ship survey extending 300 nmi offshore.

Minimum Population Estimate

The minimum population estimate for striped dolphins in California (defined as the log-normal 20th percentile

of the above abundance estimate) is 13,639 animals.

Current Population Trend

Prior to the 1991 shipboard survey (Barlow 1995), striped dolphins were not thought to be common off

California (Leatherwood et al. 1982), and two surveys extending approximately 200 nmi offshore of California and Baja

California in 1979 and 1980 resulted in only one sighting of three striped dolphins (Smith et al. 1986). Thus it is possible

that striped dolphin abundance off California has increased over the last decade (consistent with the observed warming

trend for these waters: Roemmich 1992); however, no definitive statement can be made, because statistical estimates of

abundance were not obtained for the earlier surveys.

CURRENT AND MAXIMUM NET PRODUCTIVITY RATES

No information on current or maximum net productivity rates is available for striped dolphins off California.

POTENTIAL BIOLOGICAL REMOVAL

Based on this stock’s unknown status and growth rate, the recovery factor (F,) is 0.5, and 1/2Rmax is the default

value of 0.02. Multiplying these two values times the minimum population estimate of 13,639 yields a potential

biological removal (PBR) of 136 animals per year.

ANNUAL HUMAN-CAUSED MORTALITY AND SERIOUS INJURY

Fishery Information

Striped dolphins are susceptible to mortality in drift gillnets, which have been used to catch swordfish, thresher

shark. and mako shark in offshore California, Oregon and Washington waters (Hanan et al. 1993), with approximately

149 vessels currently active (J. Cordaro, Southwest Region, NMFS, pers. comm.). Fishing effort has decreased from

approximately 10,000 sets per year in the mid- 1980s to 6600 in 1993 (Barlow et al. 1994). Striped dolphin mortality in

this fishery is likely to be rare, because the majority of fishing effort has occurred within about 150nm of the coastline

59
(NMFS, unpublished data), whereas striped dolphins primarily are found farther offshore (Barlow 1995). No takes of

striped dolphins were documented by observers in this gillnet fishery from 1980-85 (based on less than 1% observer

coverage; Diamond et al. 1987), or from July 1990 to December 1993. when 4- 13% of all sets were monitored (Lennert

et al. 1994; Perkins et al. 1992; Julian 1993, 1994). Preliminary mortality data for 1994 indicate that one striped dolphin

was observed killed (NMFS, unpublished data). Thus some mortality of striped dolphins does occur in this fishery, but

levels appear to be low, on the order of a few animals per year.

Similar drift gillnet fisheries for swordfish and sharks exist along the entire Pacific coast of Baja California,

Mexico and may take animals from the same population. Quantitative data are available only for the Mexican swordfish

drift gillnet fishey, which has increased from two vessels in 1986 to 29 vessels in 1992 (Sosa-Nishizaki et al. 1993). The

total number of sets in this fishery in 1992 can be estimated from data provided by these authors to be approximately

2700, with an observed rate of marine mammal bycatch of 0. 13 animals per set (10 marine mammals in 77 observed sets;

Sosa-Nishizaki et al. 1993). This overall mortality rate is similar to that observed in California driftnet fisheries during

1990-93 (0. 15 marine mammals per set), but species-specific information is nor available for the Mexican fisheries.

Fishery Mortality Rate

The total fishery mortality and serious injury for this stock can be considered to be insignificant and approaching

zero. because no striped dolphins were observed killed in 199l-93. The observed take of a single animal in 1994 is not

expected to change this conclusion, because the average annual mortality estimate will remain below 10% of the total

PBR.

STATUS OF STOCK

The status of striped dolphins in California relative to OSP is not known, and there are insufficient data to

evaluate potential trends in abundance. They are not listed as “threatened” or “endangered” under the Endangered

Species Act nor as “depleted” under the MMPA. Because of the low levels of observed human-caused mortality, they

are not classified as a “strategic” stock as defined by the MMPA.

REFERENCES

Barlow, J. 1995. The abundance of cetaceans in California waters. Part I: Ship surveys in summer and fall of 1991.

Fish. Bull. 93:1-14.

Barlow, J., R. W. Baird, J. E. Heyning, K. Wynne. A. M. Manville. II, L. F. Lowry, D. Hanan, J. Sease, and V. N.

Burkanov. 1994. A review of cetacean and pinniped mortality in coastal fisheries along the west coast of the

USA and Canada and the east coast of the Russian Federation. Rep. Int. Whal. Commn. Special Issue 15:405-

426.

Diamond, S. L., J. P. Scholl and D. A. Hanan. 1987. Drift gillnet observations for the 1985-86 fishing season.

Administrative Report SWR 87-4. Available from NMFS. Southwest Region, 300 S. Ferry Street, Terminal

Island, California, 90731. 21p.

Hanan, D. A., D. B. Holts, and A. L. Coan, Jr. 1993. The California drift gill net fishery for sharks and swordfish, 1981-

82 through 1990-91. Fish Bulletin 175. Available from the Marine Technical Information Center, California

Department of Fish and Game. 330 Golden Shore, Suite 50, Long Beach, CA 90802.

Julian, F. 1993. Pinniped and cetacean mortality in California gillnet fisheries: Preliminary estimates for 1992. Working

paper SC/45/022 presented to the International Whaling Commission Scientific Committee, May 1993

(unpublished).

Julian, F. 1994. Pinniped and cetacean mortality in California gillnet fisheries: Preliminary estimates for 1993. Working

paper SC/46/011 presented to the International Waling Commission Scientific Committee, May 1994

(unpublished).

Leatherwood. S., R. R. Reeves, W. F. Perrin, and W. E. Evans. 1982. Whales, dolphins and porpoises of the eastern

North Pacific and adjacent Arctic waters. A guide to their identification. NOAA Technical Report NMFS

Circular 444, U.S. Department of Commerce, NOAA, NMFS. 245p.

Lennert. C., S. Kruse, M. Beeson, and J. Barlow. 1994. Estimates of incidental marine mammal bycatch in California

gillnet fisheries for July through December 1990. Rep. Int. Whal. Commn. Special Issue 15:449-463.

Mangels, K. F. and Gerrodette, T. 1994. Report of cetacean sightings during a marine mammal survey in the eastern

Pacific Ocean and Gulf of California aboard the NOAA ships McARTHUR and DAVID STARR JORDAN July

60
28 - November 6, 1993. NOAA Technical Memorandum NMFS, NOAA-TM-NMFS-SWFSC-211,

National Marine Fisheries Service, Southwest Fisheries Science Center. Unpublished data.

Perkins, P., J. Barlow and M. Beeson. 1992. Pinniped and cetacean mortality in California gillnet fisheries: 1991.

Working Paper SC/44/SMl4 presented to the Intemational Whaling Commission, May 1992 (unpublished).

Perrin, W. F., M. D. Scott, G. J. Walker and V. L. Cass. 1985. Review of geographical stocks of tropical dolphins

(Srenella spp. and Delphinus delphis) in the eastern Pacific. NOAA Technical Report NMFS 28. Available

from NMFS, Southwest Fisheries Science Center, P.O. Box 271, La Jolla, California, 92038. 28p.

Roemmich, D. 1992. Ocean warming and sea level rise along the southwest U.S. coast. Science 257:373-375.

Smith, R. C., P. Dustan, D. Au, K. S. Baker, and E. A. Dunlap. 1986. Distribution of cetaceans and sea-surface

chlorophyll concentrations in the California Current. Marine Biology 91:385-402.

Sosa-Nishizaki, O., R. De la Rosa Pacheco, R. Castro Longoria, M. Grijalva Chon, and J. De la Rosa Velez. 1993.

Estudio biologico pesquero del pez (Xphias gladius) y otras especies de picudos (marlins y pez vela). Rep. Int.

CICESE, CTECT9306.

61
SHORT-BEAKED COMMON DOLPHIN (Delphinus delphis):

California/Oregon/Washington Stock

STOCK DEFINITION AND GEOGRAPHIC RANGE

Short-beaked common dolphins are the most abundant cetacean off California, and are widely distributed

between the coast and at least 300 nmi distance from shore. The abundance of this species off California has been shown

to change on both seasonal and inter-annual time scales (Dohl et al. 1986; Barlow 1995; Forney et al. 1995). Historically,

they were reported primarily south of Pt. Conception (Dohl et al. 1986), but on recent (199l/93) summer/fall surveys,

they were commonly sighted as far north as 42°N (Barlow 1995; Mangels and Gerrodette 1994). Four strandings of

common dolphins have been reported in Oregon and Washington since 1942 (B. Norberg, pers. comm.). Of these, three

were not identified to the species level, and one animal, which stranded in 1983, was identified as a short-beaked common

dolphin (J. Hodder, pers. comm.). Winter/spring surveys in 1991-92 did not result in any sightings of common dolphins

north of Point Conception (Carretta and Forney 1993) suggesting seasonal north-south movements of this species. Their

distribution is continuous southward into Mexican waters to about 13°N (Perrin et al. 1985; Wade and Gerrodette 1994;

Mangels and Gerrodette 1994) and short-beaked common dolphins off California may be an extension of the “northern

common dolphin” stock defined for management of eastern tropical Pacific tuna fisheries (Pen-in et al. 1985). However,

preliminary data on variation in dorsal fin color patterns suggest there may be multiple stocks in this region, including

at least two possible stocks in California (Farley 1995). The less abundant long-beaked common dolphin has only recently

been recognized as a different species (Heynin g and Perrin 1994; Rose1 et al. 1994) and much of the available

information has not differentiated between the two types of common dolphin. Although short-beaked common dolphins

are not restricted to U.S. waters, cooperative management agreements with Mexico exist only for the tuna purse seine

fishery and not for other fisheries which may take this species (e.g. gillnet fisheries). Under the Marine Mammal

Protection Act (MMPA): short-beaked common dolphins involved in tuna purse seine fisheries in international waters

of the eastern tropical Pacific are managed separately, and they are not included in the assessment reports. For the

MMPA stock assessment reports. there is a single Pacific management stock including only animals found within the U.S.

Exclusive Economic Zone of California, Oregon and Washington.

POPULATION SIZE

Aerial line transect surveys conducted in winter/spring of 1991-92 resulted only in a combined abundance

estimate of 305.694 (C.V. = 0.34) animals for short-beaked and long-beaked common dolphins, because species-level

identification was not possible from the air (Forney et al. 3995). Based on sighting locations, the majority of these were

probably short-beaked common dolphins. Currently: the best abundance estimate is 225,821 (C.V. = 0.28) short-beaked

common dolphins, based on a summedfall 1991 shipboard line transect survey (Barlow 1995).

Minimum Population Estimate

The log-normal 20th percentile of the above abundance estimate is 179. 185 short-beaked common dolphins.

Current Population Trend

In the past. common dolphin abundance has been shown to increase off California during the warm-water

months (Dohl et al. 1986). Although the recent 199l-92 surveys did not reveal any seasonal differences (Barlow 1995;

Formey et al. 1995). both surveys resulted in overall abundance estimates (for both types of common dolphins combined)

which were considerably greater than historical estimates (Dohl et al. 1986). This suggests a long-term increase in

common dolphin abundance during this period of gradual warning of the waters off California (Roemmich 1992). The

majority of this increase reflects an increase in the abundance of short-beaked common dolphins. Heyning and Perrin

( 1994) have detected changes in the proportion of short-beaked to long-beaked common dolphins stranding along the

California coast, with the short-beaked common dolphin stranding more frequently prior to the 1982-83 El Niño (which

increased water temperatures off California)? and the long-beaked common dolphin more commonly observed for several

years afterwards. Thus, it appears that both relative and absolute abundances of these species off California may change

with varying oceanographic conditions.

62
CURRENT AND MAXIMUM NET PRODUCTIVITY RATES

There are no estimates of current or maximum net productivity rates for short-beaked common dolphins.

POTENTIAL BIOLOGICAL REMOVAL

Based on this stock’s unknown status, the recovery factor (F,) is 0.5. Multiplying this times the default annual

growth rate (1/2Rmax) of 0.02 and the minimum abundance estimate of 179, 185 yields a potential biological removal (PBR)

of 1,792 short-beaked common dolphins per year.

ANNUAL HUMAN-CAUSED MORTALITY AND SERIOUS INJURY

Fishery Information

Short-beaked common dolphins are killed incidentally in drift gillnets, which have been used to catch swordfish,

thresher shark. and mako shark in offshore California, Oregon and Washington waters (Hanan et al. 1993), with

approximately 149 vessels currently active (J. Cordaro, Southwest Region, NMFS, pers. comm.). Fishing effort has

decreased from approximately 10,000 sets per year in the mid- 1980s to 6600 in 1993 (Barlow et al. 1994). Between July

1990 and December 1993, with approximately 4-15% of California drift and set gillnet fisheries observed, 128 common

dolphins were recorded killed in driftnets, without distinction between short-beaked and long-beaked types. Total

mortality estimates for both types of common dolphins

are 203 (se. 82) for July-December 1990; 373 (s.e. 73)

for 1991; 356 (s.e. 66) for 1992, and 253 (s.e. 69) for

1993 (Lennert et al. 1994; Perkins et al. 1992; Julian

1993? 1994). Corresponding average rates of kill per

fishing day are 0.05,0.08,0.08, and 0.03, for 1990, 1991

1992 and 1993, respectively. Preliminary mortality data

for 1994 indicate that 1O short-beaked common dolphins

and 17 unidentified common dolphins were observed

killed. Based on the locations of the takes for 1990-93

(Figure 1). it is likely that most of the killed animals were

short-beaked common dolphins. This is supported by the

recent examination of some of the biological samples,

which resulted in the identification of 36 short-beaked and

two long-beaked common dolphins (NMFS, unpublished

data). Assuming there is no bias in the likelihood of

being able to identify the two species, the proportion of

short-beaked common dolphins in the total number

identified (36/38 = 0.947) can be used to prorate the total

common dolphin mortality. yielding total estimates of

192, 353, 337, and 240 short-beaked common dolphins

for this fishery in 1990, 1991, 1992 and 1993,

respectively. The average estimated annual mortality for

short-beaked common dolphins in this fishery for the

three complete years of monitoring, 1991-93, is 3 IO

animals.

Figure 1. Locations of all observed common dolphin takes

in California set and drift gillnet fisheries, 1990-93.

Additional common dolphin mortality has been reported for set gillnets, which are used by approximately I34

vessels (J. Cordaro, Southwest Region, NMFS, pers. comm.) to catch halibut, flounder, angel shark, yellowtail, white

seabass, and white croaker in California coastal waters. As a result of area closures, fishing effort has decreased from

approximately 40,000 sets per year in the mid-1980s to 16,000 sets in 1993 (Barlow et al. 1994), and is expected to

continue to decrease because of a 1994 ban on fishing within 3 nmi of shore in Southern California. An observation

program has monitored 5-15% of all sets in halibut and angel shark fisheries from 1990-1993, yielding no common

dolphins observed killed in 1990, 1991 and 1993, and 2 observed killed in 1992. Total estimated annual common dolphin

mortality for this fishery is zero for 1990, 1991 and 1993, and I7 (s.e. 11) for 1992. Corresponding average rates of

common dolphin kill per fishing day are zero in 1990, 1991 and 1993: and 0.004 in 1992. The average estimated annual

mortality for common dolphins (type not specified) in this fishery for the three complete years of monitoring, 1991-93,

63
is six animals.

Similar drift and set gillnet fisheries exist along the entire Pacific coast of Baja California, Mexico and probably

take short-beaked common dolphins from the same population. Quantitative data are available only for the Mexican

swordfish drift gillnet fishery, which has increased from two vessels in 1986 to 29 vessels in 1992 (Sosa-Nishizaki et al.

1993). The total number of sets in this fishery in 1992 can be estimated from data provided by these authors to be

approximately 2700, with an observed rate of marine mammal bycatch of 0.13 animals per set (10 marine mammals in

77 observed sets; Sosa-Nishizaki et al. 1993). This overall mortality rate is similar to that observed in California driftnet

fisheries during 1990-93 (0.15 marine mammals per set), but species-specific information is not available for the Mexican

fisheries.

Fishery Mortality Rate

The total fishery mortality and serious injury for short-beaked common dolphins during 1991-93 (3 10-316

animals per year, depending on species composition of the set net kill) is greater than 10% of the calculated PBR and,

therefore, cannot be considered to be insignificant and approaching zero mortality and serious injury rate. This

determination cannot be made for individual fisheries until the implementing regulations for Section 118 of the MMPA

have been reviewed by the public and finalized.

Other Mortality

In the eastern tropical Pacific, ‘northern common dolphins’ have been incidentally killed in international tuna

purse seine fisheries since the late 1950’s. Cooperative international management programs have dramatically reduced

overall dolphin mortality in these fisheries during the last decade (Joseph 1994). Between 1990 and 1994, annual

mortality of northern common dolphins (potentially including both short-beaked and long-beaked common dolphins)

ranged between 81 and 1,773 animals. with an average of 564 (Hall and Boyer 1992; Hall and Lennert 1993, 1994, 1995;

Lennert and Hall 1994). Although it is unclear whether these animals are part of the same population as short-beaked

common dolphins found off California, they are managed separately under a section of the MMPA written specifically

for the management of dolphins involved in eastern tropical Pacific tuna fisheries.

STATUS OF STOCK

The status of short-beaked common dolphins in Californian waters relative to OSP is not known. The observed

increase in abundance of this species off California over the last decade probably reflects a distributional shift (Anganuzzi

et al. 1993; Barlow 1995, Forney et al. 1995), rather than an overall population increase due to growth. They are not

listed as “threatened” or “endangered” under the Endangered Species Act nor as “depleted” under the MMPA. The

average total estimated mortality for this species is lower than the PBR, so they are not a “strategic” stock under the

MMPA.

REFERENCES

Anganuzzi, A. A.. S. T. Buckland, and K. L Cattanach. 1993. Relative abundance of dolphins associated with tuna in

the eastern tropical Pacific Ocean: analysis of 1991 data. Rep. lnt. Whal. Commn 43:459-465.

Barlow, J. 1995. The abundance of cetaceans in California waters. Part I: Ship surveys in summer and fall of 1991.

Fish. Bull. 93:1-14.

Barlow, J., R. W. Baird, J. E. Heyning. K. Wynne, A. M. Manville, II, L. F. Lowry, D. Hanan, J. Sease, and V. N.

Burkanov. 1994. A review of cetacean and pinniped mortality in coastal fisheries along the west coast of the

USA and Canada and the east coast of the Russian Federation. Rep. Int. Whal. Commn. Special Issue 15:405-

426.

Carretta. J. V. and K. A. Forney. 1993. Report of the two aerial surveys for marine mammals in California coastal

waters using a NOAA DeHavilland Twin Otter aircraft, March 9-April 7, 1991, February S-April 6, 1992.

NOAA Technical Memorandum NOAA-TM-NMFS-SWFSC-185. Available from NMFS, Southwest Fisheries

Science Center, P.O. Box 271, La Jolla, California, 92038. 77p.

Dohl, T. P., M. L. Bonnell, and R. G. Ford. 1986. Distribution and abundance on common dolphin, Delphinus delphis,

in the Southern California Bight: A quantitative assessment based upon aerial transect data. Fish. Bull. 84:333-

343.

Farley, T. D. 1995. Geographic variation in dorsal fin color of short-beaked common dolphins, Delphinus delphis, in

64
the eastern Pacific Ocean. Administrative Report LJ-95-06, Available from National Marine Fisheries Service,

Southwest Fisheries Science Center, P.O. Box 271, La Jolla, California? 92038.

Forney, K. A., J. Barlow and J. V. Carretta. 1995. The abundance of cetaceans in California waters. Part II: Aerial

surveys in winter and spring of 1991 and 1992. Fish. Bull. 93: 15-26.

Hall, M. A. and S. D. Boyer. 1992. Estimates of incidental mortality of dolphins in the purse-seine fishery for tunas in

the eastern Pacific Ocean in 1990. Rep. Int. Whal. Commn. 42:529-531

Hall, M. A. and C. Lennert. 1993. Estimates of incidental mortality of dolphins in the eastern Pacific Ocean tuna fishery

in 1991. Rep. Int. Whal. Commn. 43:397-399.

Hall, M. A. and C. Lennert. 1994. Incidental mortality of dolphins in the eastern Pacific Ocean tuna fishery in 1992.

Rep. lnt. Whal. Commn. 44:349-351.

Hall, M. A. and C. Lennert. 1995. Estimates of incidental mortality of dolphins in the eastern Pacific Ocean tuna fishery

in 1994. Working paper SC/47/SMl presented to the International Whaling Commission Scientific Committee,

May 1995 (unpublished).

Hanan, D. A., D. B. Holts, and A. L. Coan, Jr. 1993. The California drift gill net fishery for sharks and swordfish, 1981-

82 through 1990-91. Fish Bulletin 175. Available from the Marine Technical Information Center, California

Department of Fish and Game, 330 Golden Shore! Suite 50, Long Beach, CA 90802.

Heyning. J. E. and W. F. Pen-in. 1994. Evidence for two species of common dolphins (Genus Delphinus) from the

eastern North Pacific. Contr. Nat. Hist. Mus. L.A. County: No. 442.

Joseph, J. 1994. The tuna-dolphin controversy in the eastern Pacific Ocean: biological, economic and political impacts.

Ocean Dev. Int. Law 25: 1-30.

Julian, F. 1993. Pinniped and cetacean mortality in California gillnet fisheries: Preliminary estimates for 1992. Working

paper SC/45/O22 presented to the International Whaling Commission Scientific Committee, May 1993

(unpublished).

Julian, F. 1994. Pinniped and cetacean mortality in California gillnet fisheries: Preliminary estimates for 1993. Working

paper SC/46/Oll presented to the International Whaling Commission Scientific Committee, May 1994

(unpublished).

Lennert. C. and M. A. Hall. 1994. Estimates of incidental mortality of dolphins in the eastern Pacific Ocean tuna fishery

in I993. Working paper SC461SM4 presented to the International Whaling Commission Scientific Committee,

May 1994 (unpublished).

Lennert, C., S. Kruse, M. Beeson, and J. Barlow. 1994. Estimates of incidental marine mammal bycatch in California

gillnet fisheries for July through December 1990. Rep. Int. Whal. Commn. Special Issue 15:449-463.

Mangels. K. F. and Gerrodette, T. 1994. Report of cetacean sightings during a marine mammal survey in the eastern

Pacific Ocean and Gulf of California aboard the NOAA ships McARTHUR and DAVID STARR JORDAN July

28 - November 6, 1993. NOAA Technical Memorandum NMFS, NOAA-TM-NMFS-SWFSC-211.

National Marine Fisheries Service, Southwest Fisheries Science Center. Unpublished data.

Perkins, P., J. Barlow and M. Beeson. 1992. Pinniped and cetacean mortality in California gillnet fisheries: 1991.

Working Paper SC/44/SMl4 presented to the International Whaling Commission, May 1992 (unpublished).

Perrin. W. F., M. D. Scott, G. J. Walker and V. L. Cass. Review of geographical stocks of tropical dolphins (Stenella

spp. and Delphinus delphis) in the eastern Pacific. NOAA Technical Report NMFS 28. Available from NMFS,

Southwest Fisheries Science Center, P.O. Box 271. La Jolla, California, 92038. 28p.

Roemmich, D. 1992. Ocean warming and sea level rise along the southwest U.S. coast. Science 257:373-375.

Rosel, P. E., A. E. Dizon and J. E. Heyning. 1994. Population genetic analysis of two forms of the common dolphin

(genus Delphinus) utilizing mitochondrial DNA control region sequences. Marine Biology 119: 159-167.

Sosa-Nishizaki, O., R. De la Rosa-Pacheco, R. Castro-Longoria, M. Grijalva Chon, and J. De la Rosa Velez. 1993.

Estudio biologico pesquero de1 pez (Xiphius gladius) y otras especies de picudos (marlins y pez vela). Rep. Int.

CICESE, CTECT9306.

65
LONG-BEAKED COMMON DOLPHIN (Delphinus capensis):

California Stock

STOCK DEFINITION AND GEOGRAPHIC RANGE

Long-beaked common dolphins have only

recently been recognized as a distinct species (Heyning

and Perrin 1994; Rose1 et al. 1994). Along the U.S. west

coast, their distribution overlaps with that of the shortbeaked common dolphin: and much historical information

has not distinguished between these two species. Longbeaked common dolphins are commonly found within

about 50 nmi of the coast, from Baja California (including

the Gulf of California) northward to about central

California (Figure 1). Stranding data and sighting records

indicate that the relative abundance of this species off

California changes both seasonally and inter-annually,

with highest densities observed during warm-water events

(Heyning and Perrin 1994). Although long-beaked

common dolphins are not restricted to U.S. waters,

cooperative management agreements with Mexico exist

only for the tuna purse seine fishery and not for other

fisheries which may take this species (e.g. gillnet

fisheries). Under the Marine Mammal Protection Act

(MMPA): long-beaked (“Baja neritic”) common dolphins

involved in eastern tropical Pacific tuna fisheries are

managed separately as part of the ‘northern common

dolphin’ stock (Perrin et al. 1985), and these animals are

Figure 1. Long-beaked common dolphin sightings based

not included in the assessment reports. For the MMPA

on 199l-93 shipboard surveys within 300 nmi of the

California and Baja California coastline (Hill and Barlow

stock assessment reports, there is a single Pacific 1992; Mangels and Gerrodette 1994).

management stock including only animals found within the

U.S. Exclusive Economic Zone of California.

POPULATION SIZE

Aerial line transect surveys conducted in winter and spring of 1991 and 1992 resulted only in a combined

abundance estimate of 305.694 (C.V. = 0.34) long-beaked and short-beaked common dolphins, because species-level

identification was not possible from the air (Forney et al. 1995). Based on sighting locations, the majority of these

animals were probably short-beaked common dolphins. Barlow (1995) presents a population estimate of 9,472 (C.V.

= 0.68) long-beaked common dolphins based on a summer/fall 1991 shipboard line transect survey. This is currently

the best available population estimate.

Minimum Population Estimate

The log-normal 20th percentile of the above abundance estimate is 5,636 long-beaked common dolphins.

Current Population Trend

Due to the historical lack of distinction between the two species of common dolphins? it is difficult to establish

trends in abundance for this species. In the past, common dolphins have been shown to increase in abundance off

California during the warm-water months (Dohl et al. 1986). Although the recent 1991-92 surveys did not reveal any

seasonal differences (Barlow 1995; Forney et al. 1995), both surveys resulted in overall abundance estimates (for both

types of common dolphins combined) which were considerably greater than historical estimates (Dohl et al. 1986). This

suggests a long-term increase in common dolphin abundance during this period of gradual warming of the waters off

California (Roemmich 1992), but it is unclear how much of this increase reflects an increase in the abundance of the long66
beaked common dolphin. Heyning and Pen-in (1994) have detected changes in the proportion of short-beaked to longbeaked common dolphins stranding along the California coast, with the short-beaked common dolphin stranding more

frequently prior to the 1982-83 El Niño (which increased water temperatures off California), and the long-beaked

common dolphin more commonly observed for several years afterwards. Thus, it appears that both relative and absolute

abundance of these species off California may change with varying oceanographic conditions.

CURRENT AND MAXIMUM NET PRODUCTIVITY RATES

There are no estimates of current or maximum net productivity rates for long-beaked common dolphins.

POTENTIAL BIOLOGICAL REMOVAL

Based on this stock’s unknown status, the recovery factor (F,) is 0.5. Multiplying this times the default annual

growth rate (1/2Rmax) of 0.02 and the minimum abundance estimate of 5,636 yields a potential biological removal (PBR)

of 56 long-beaked common dolphins per year.

ANNUAL HUMAN-CAUSED MORTALITY AND SERIOUS INJURY

Fishery Information

Long-beaked common dolphins are killed

incidentally in drift gillnets, which have been used to

catch swordfish, thresher shark, and mako shark in

offshore California, Oregon and Washington waters

(Hanan et al. 1993), with approximately 149 vessels

currently active (J. Cordaro, Southwest Region, NMFS,

pers. comm.). Fishing effort has decreased from

approximately 10,000 sets per year in the mid-1980s to

6600 in 1993 (Barlow et al. 1994). Between July 1990

and December 1993, with approximately 4-15% of

California drift and set gillnet fisheries observed, 128

common dolphins were recorded killed in driftnets,

without distinction between short-beaked and longbeaked types. Total mortality estimates for both types

of common dolphins are 203 (s.e. 82) for JulyDecember 1990; 373 (s.e. 73) for 1991; 356 (s.e. 66)

for 1992, and 253 (s.e. 69) for 1993 (Lennert et al.

1994; Perkins et al. 1992; Julian 1993, 1994).

Corresponding average rates of kill per fishing day are

0.05, 0.08, 0.08, and 0.03, for 1990, 1991 1992 and

1993, respectively. Preliminary mortality data for 1994

indicate that 17 unidentified common dolphins were figure 2. Locations of all observed common dolphin takes

observed killed. Based on the locations of the takes for in California set and drift gillnet fisheries, 1990-93.

1990-93 (Figure 1), it is likely that most of the killed

animals were short-beaked common dolphins. This is supported by the recent examination of some of the biological

samples, which resulted in the identification of 36 short-beaked and two long-beaked common dolphins (S. NMFS,

unpublished data). Assuming there is no bias in the likelihood of being able to identify the two species, the proportion

of long-beaked common dolphins in the total number identified (2/38 = 0.053) can be used to prorate the overall common

dolphin mortality, yielding estimates of 1 1, 20, 19, and 13 long-beaked common dolphins for 1990, 1991, 1992 and 1993,

respectively. The average estimated annual mortality for long-beaked common dolphins in this fishery for the three

complete years of monitoring, 1991-93, is 17 animals.

Additional common dolphin mortality has been reported for set gillnets, which are used by approximately 134

vessels (J. Cordaro, Southwest Region, NMFS, pers. comm.) to catch halibut, flounder, angel shark, yellowtail, white

seabass, and white croaker in California coastal waters. As a result of area closures, fishing effort has decreased from

approximately 40,000 sets per year in the mid-1980s to 16,000 sets in 1993 (Barlow et al. 1994), and is expected to

continue to decrease because of a 1994 ban on fishing within 3 nmi of shore in Southern California. An observation

67
program has monitored 5-15% of all sets in halibut and angel shark fisheries from 1990-1993. yielding no common

dolphins observed killed in 1990, 1991 and 1993, and 2 observed killed in 1992. Total estimated annual common dolphin

mortality for this fishery is zero for 1990, 1991 and 1993, and 17 (s.e. 11) for 1992. Corresponding average rates of

common dolphin kill per fishing day are zero in 1990, 1991 and 1993, and 0.004 in 1992. The average estimated annual

mortality for common dolphins (type not specified) in this fishery for the three complete years of monitoring, 1991-93,

is six animals.

Similar drift gillnet fisheries for swordfish and sharks exist along the entire Pacific coast of Baja California,

Mexico and may take long-beaked common dolphins from the same population. Quantitative data are available only for

the Mexican swordfish drift gillnet fishery, which has increased from two vessels in 1986 to 29 vessels in 1992 (SosaNishizaki et al. 1993). The total number of sets in this fishery in 1992 can be estimated from data provided by these

authors to be approximately 2700, with an observed rate of marine mammal bycatch of 0. 13 animals per set (10 marine

mammals in 77 observed sets; Sosa-Nishizaki et al. 1993). This overall mortality rate is similar to that observed in

California driftnet fisheries during 1990-93 (0. 15 marine mammals per set), but species-specific information is not

available for the Mexican fisheries.

Fishery Mortality Rate

The average total fishery mortality and serious injury for long-beaked common dolphins in 1991-93 (17-23

animals per year, depending on species composition of the set net kill) is greater than l0% of the PBR. and, therefore,

cannot be considered to be insignificant and approaching zero mortality and serious injury rate. This determination

cannot be made for individual fisheries until the implementing regulations for Section 118 of the MMPA have been

reviewed by the public and finalized. Furthermore, given the uncertainties in estimating long-beaked common dolphin

mortality based on overall common dolphin mortality, a re-evaluation should take place when additional species-specific

data and analyses of biological samples become available.

Other Mortality

In the eastern tropical Pacific, northern common dolphins’ have been incidentally killed in international tuna

purse seine fisheries since the late 1950’s. Cooperative international management programs have dramatically reduced

overall dolphin mortality in these fisheries during the last decade (Joseph 1994). Between 1990 and 1994, annual

mortality of northern common dolphins (potentially including both long-beaked and short-beaked common dolphins)

ranged between 81 and 1,773 animals, with an average of 564 (Hall and Boyer 1992; Hall and Lennert 1993, 1994, 1995;

Lennert and Hall 1994). Although it is likely that the long-beaked common dolphins included in the ‘northern common

dolphin’ stock are part of the same population as those found off California, they are managed separately under a section

of the MMPA written specifically for the management of dolphins involved in eastern tropical Pacific tuna fisheries.

STATUS OF STOCK

The status of long-beaked common dolphins in California waters relative to OSP is not known, and there are

insufficient data to evaluate potential trends in abundance of this species of common dolphin. They are not listed as

“threatened” or “endangered” under the Endangered Species Act nor as “depleted” under the MMPA. Because the total

estimated mortality for this species is lower than the PBR, they would not be classified as a “strategic” stock under the

MMPA.

REFERENCES

Barlow, J. 1995. The abundance of cetaceans in California waters. Part I: Ship surveys in summer and fall of 1991.

Fish. Bull. 93:1-14.

Barlow. J., R. W. Baird, J. E. Heyning, K. Wynne, A. M. Manville, II, L. F. Lowry, D. Hanan, J. Sease, and V. N.

Burkanov. 1994. A review of cetacean and pinniped mortality in coastal fisheries along the west coast of the

USA and Canada and the east coast of the Russian Federation. Rep. Int. Whal. Commn. Special Issue 15:405-

426.

Dohl, T. P., M. L. Bonnell, and R. G. Ford. 1986. Distribution and abundance on common dolphin, Delphinus delphis

in the Southern California Bight: A quantitative assessment based upon aerial transect data. Fish. Bull. 84:333-

343.

Forney. K. A., J. Barlow and J. V. Carretta. 1995. The abundance of cetaceans in California waters. Part II: Aerial

68
surveys in winter and spring of 1991 and 1992. Fish. Bull. 93:15-26.

Hall, M. A. and S. D. Boyer. 1992. Estimates of incidental mortality of dolphins in the purse-seine fishery for tunas in

the eastern Pacific Ocean in 1990. Rep. Int. Whal. Commn. 42:529-531.

Hall, M. A. and C. Lennert. 1993. Estimates of incidental mortality of dolphins in the eastern Pacific Ocean tuna fishery

in 1991. Rep. Int. Whal. Commn. 43:397-399.

Hall, M. A. and C. Lennert. 1994. Incidental mortality of dolphins in the eastern Pacific Ocean tuna fishery in 1992.

Rep. Int. Whal. Commn. 44:349-351

Hall, M. A. and C. Lennert. 1995. Estimates of incidental mortality of dolphins in the eastern Pacific Ocean tuna fishery

in 1994. Working paper SC/47/SMl presented to the International Whaling Commission Scientific Committee,

May 1995 (unpublished).

Hanan, D. A., D. B. Holts, and A. L. Coan, Jr. 1993. The California drift gill net fishery for sharks and swordfish, 198l82 through 1990-91. Fish Bulletin 175. Available from the Marine Technical Information Center, California

Department of Fish and Game, 330 Golden Shore, Suite 50, Long Beach, CA 90802.

Heyning, J. E. and W. F. Perrin. 1994. Evidence for two species of common dolphins (Genus Delphinus) from the

eastern North Pacific. Contr. Nat. Hist. Mus. L.A. County, No. 442.

Hill, P. S. and J. Barlow. 1992. Report oh a marine mammal survey of the California coast aboard the research vessel

McARTHUR July 28 - November 5, 1991. NOAA Technical Memorandum NMFS, NOAA-TM-NIMFSSWFSC-169. Available from NMFS, Southwest Fisheries Science Center, P.O. Box 271, La Jolla, California:

USA.

Joseph, J. 1994. The tuna-dolphin controversy in the eastern Pacific Ocean: biological, economic and political impacts.

Ocean Dev. Int. Law 25:1-30.

Julian. F. 1993. Pinniped and cetacean mortality in California gillnet fisheries: Preliminary estimates for 1992. Working

paper SC/45/022 presented to the International Whaling Commission Scientific Committee, May 1993

(unpublished).

Julian, F. 1994. Pinniped and cetacean mortality in California gillnet fisheries: Preliminary estimates for 1993. Working

paper SC/46/Ol1 presented to the International Whalin g Commission Scientific Committee, May 1994

(unpublished).

Lennert, C. and M. A. Hall. 1994. Estimates of incidental mortality of dolphins in the eastern Pacific Ocean tuna fishery

in 1993. Working paper SC/46/SM4 presented to the International Whaling Commission Scientific Committee,

May 1994 (unpublished).

Lennert, C., S. Kruse, M. Beeson, and J. Barlow. 1994. Estimates of incidental marine mammal bycatch in California

gillnet fisheries for July through December 1990. Rep. Int. Whal. Commn. Special Issue 15:449-463.

Mangels, K. F. and Gerrodette, T. 1994. Report of cetacean sightings during a marine mammal survey in the eastern

Pacific Ocean and Gulf of California aboard the NOAA ships McARTHUR and DAVID STARR JORDAN July

28 - November 6, 1993. NOAA Technical Memorandum NMFS, NOAA-TM-NMFS-SWFSC-211.

National Marine Fisheries Service, Southwest Fisheries Science Center. Unpublished data.

Perkins, P., J. Barlow and M. Beeson. 1992. Pinniped and cetacean mortality in California gillnet fisheries: 1991.

Working Paper SC/44/SM14 presented to the International Whaling Commission, May 1992 (unpublished).

Perrin, W. F., M. D. Scott, G. J. Walker and V. L. Cass. Review of geographical stocks of tropical dolphins (Srenella

spp. and Deiphinus delphis) in the eastern Pacific. NOAA Technical Report NMFS 28. Available from NMFS,

Southwest Fisheries Science Center, P.O. Box 271, La Jolla, California, 92038. 28p.

Roemmich. D. 1992. Ocean warming and sea level rise along the southwest U.S. coast. Science 257:373-375.

Rosel, P. E., A. E. Dizon and J. E. Heyning. 1994. Population genetic analysis of two forms of the common dolphin

(genus Delphinus) utilizing mitochondrial DNA control region sequences. Marine Biology 119: l59- 167.

Sosa-Nishizaki, O., R. De la Rosa-Pacheco, R. Castro-Longoria, M. Grijalva Chon, and J. De la Rosa Velez. 1993.

Estudio biologico pesquero del pez (Xiphias gladius) y otras especies de picudos (marlins y pez vela). Rep. Int.

CICESE, CTECT9306.

69
NORTHERN RIGHT WHALE DOLPHIN (Lissodelphis borealis):

California/Oregon/Washington Stock

STOCK DEFINITION AND GEOGRAPHIC RANGE

Northern right whale dolphins are endemic to temperate waters of the North Pacific Ocean. Off the U.S. west

coast, they have been seen primarily in slope and offshore waters. with seasonal movements into the Southern California

Bight (Leather-wood and Walker 1979; Dohl et al. 1980, 1983; NMFS. unpublished data). Sighting patterns from recent

aerial and shipboard surveys conducted in California, Oregon and Washington during different seasons (Green et al.

1992. 1993; Forney et al. 1995; Barlow 1995) suggest seasonal north-south movements? with animals found primarily

off California during the colder water months and shifting northward into Oregon and Washington as water temperatures

increase in late spring and summer (Green et al. 1992; Forney 1994). The southern end of this population’s range is not

well-documented, but during cold-water periods, they probably range into Mexican waters off northern Baja California.

Genetic analyses have not found statistically significant differences between northern right whale dolphins from the U.S.

West coast and other areas of the North Pacific (Dizon et al. 1994); however. power analyses indicate that the ability to

detect stock differences for this species is poor, given traditional statistical error levels (Dizon et al., in press). Although

northern right whale dolphins are not restricted to U.S. territorial waters, there are currently no international agreements

for cooperative management. For the Marine Mammal Protection Act (MMPA) stock assessment reports, there is a single

management stock including only animals found within the U.S. Exclusive Economic Zone of California, Oregon and

Washington.

POPULATlON SIZE

Forney (1994) reviews recent abundance estimates for northern right whale dolphins along the U.S. west coast

and concludes that the best estimate of overall population size in California. Oregon and Washington is the estimate

obtained from aerial surveys conducted off California during winter and spring of 1991 and 1992 (Forney et al. 1995).

Because of the observed seasonal shifts in distribution, this estimate of 21.332 animals (C.V. = 0.43) is expected to

include animals which may be found off Oregon and Washington in the summer/fall.

Minimum Population Estimate

The log-normal 20th percentile of the above abundance estimate is 15,080 northern right whale dolphins.

Current Population Trend

No information is available regarding trends in abundance of northern right whale dolphins in California: Oregon

and Washington.

CURRENT AND MAXIMUM NET PRODUCTIVITY RATES

No information on current or maximum net productivity rates is available for northern right whale dolphins off

the U.S. west coast.

POTENTIAL BlOLOGICAL REMOVAL

Based on this stock’s unknown status and growth rate. the recovery factor (F,) is 0.5, and 1/2Rmax is the default

value of 0.02. Multiplying these two values times the minimum population estimate of 15,080 yields a potential

biological removal (PBR) of 151 northern right whale dolphins per year.

ANNUAL HUMAN-CAUSED MORTALITY AND SERIOUS INJURY

Fishery Information

Northern right whale dolphins are incidentally killed in California drift gillnets, which have been used to catch

swordfish, thresher shark, and mako shark in offshore California: Oregon and Washington waters (Hanan et al. 1993):

with approximately 149 vessels currently active (J. Cordaro, Southwest Region, NMFS, pers. comm.). Fishing effort has

decreased from approximately 10,000 sets per year in the mid- 1980s to 6600 in 1993 (Barlow et al. 1994). Based on less

than 1% observer coverage of fishing effort between 1980 and 1985, Diamond et al. (1987) report a single take of this

species, which can be extrapolated to yield a rough estimate of total mortality of 110 animals? or roughly 18 per year.

70
Between July 1990 and December 1993, with approximately 4-13% observer coverage of California drift gillnet fisheries,

observed mortality of northern right whale dolphins was zero in 1990, seven in 1991, two in 1992, and seven in 1993,

resulting in annual mortality estimates of zero for 1990, 59 (s.e. 28) for 1991, 15 (se. 10) for 1992, and 63 (se. 25) for

1993 (Lennert et al. 1994: Perkins et al. 1992; Julian 1993, 1994). Corresponding average rates of northern right whale

dolphin kilt per fishing day are 0, 0.013, 0.003, and 0.010 for 1990, 1991 1992 and 1993, respectively. Preliminary

mortality data for 1994 indicate that seven northern right whale dolphins were observed killed (NMFS, unpublished data).

The average estimated annual mortality for northern right whale dolphins in this fishery for the three complete years of

monitoring, 1991-93, is 46 animals.

Similar drift gillnet fisheries for swordfish and sharks exist along the entire Pacific coast of Baja California,

Mexico and may take animals from the same population during cold-water periods. Quantitative data are available only

for the Mexican swordfish drift gillnet fishery, which has increased from two vessels in 1986 to 29 vessels in 1992 (SosaNishizaki et al. 1993). The total number of sets in this fishery in 1992 can be estimated from data provided by these

authors to be approximately 2700, with an observed rate of marine mammal bycatch of 0.13 animals per set (10 marine

mammals in 77 observed sets; Sosa-Nishizaki et al. 1993). This overall mortality rate is similar to that observed in

California driftnet fisheries during 1990-93 (0.15 marine mammals per set), but species-specific information is not

available for the Mexican fisheries.

An experimental gillnet fishery for thresher shark off Oregon and Washington in 1986-89 also reported mortality

of northern right whale dolphins; however, this fishery was discontinued after 1989 due to the high rates of marine

mammal and turtle bycatch (Stick and Hreha: 1989).

Fishery Mortality Rate

The total fishery mortality and serious injury for northern right whale dolphins during 1991-93 (46 animals per

year) is greater than 10% of the calculated PBR and, therefore, cannot be considered to be insignificant and approaching

zero mortality and serious injury rate. This determination cannot be made for individual fisheries until the implementing

regulations for Section 118 of the MMPA have been reviewed by the public and finalized.

STATUS OF STOCK

The status of northern right whale dolphins in California, Oregon and Washington relative to OSP is not known,

and there are insufficient data to evaluate trends in abundance. They are not listed as “threatened” or “endangered” under

the Endangered Species Act nor as “depleted” under the MMPA. The average annual human-caused mortality is

estimated to be less than the PBR. and therefore they are not classified as a “strategic” stock under the MMPA.

REFERENCES

Barlow, J. 1995. The abundance of cetaceans in California waters. Part I: Ship surveys in summer and fall of 1991.

Fish. Bull. 93:l-14.

Barlow, J., R. W. Baird, J. E. Heyning, K. Wynne, A. M. Manvitle, II, L. F. Lowry, D. Hanan, J. Sease, and V. N.

Burkanov. 1994. A review of cetacean and pinniped mortality in coastal fisheries along the west coast of the

USA and Canada and the east coast of the Russian Federation. Rep. Int. Whal. Commn. Special Issue 15:405-

426.

Diamond, S. L., J. P. Scholl and D. A. Hanan. 1987. Drift gillnet observations for the 1985-86 fishing season.

Administrative Report SWR 87-4. Available from NMFS, Southwest Region, 300 S. Ferry Street, Terminal

Island: California, 90731. 2lp.

Dizon, A., C. LeDuc, and R. LeDuc. 1994. Intraspecific structure of the northern right whale dolphin (Lissodelphis

borealis): The power of an analysis of molecular variation for differentiating genetic stocks. CalCOFI Rep.

35:61-67.

Dizon, A. E., G. M. O’Corry-Crowe, and B. L. Taylor. (In press). Why statistical power is necessary to link analyses

of molecular variation to decisions about population structure. In: J. Neilsen (ed.), Proceedings of a conference

on Evolution and the Aquatic Ecosystem Defining Unique Units in Population Conservation.

Dohl. T. P., R. C. Guess, M. L. Duman, and R. C. Helm. 1983. Cetaceans of central and northern California, 1980-1983:

Status, abundance and distribution. OCS Study MMS 84-0045. Minerals Management Service Contract # 14-

12-0001-29090. 284p.

Dohl, T. P., K. S. Norris, R. C. Guess, J. D. Bryant, and M. W. Honig. 1980. Summary of marine mammal and seabird

7 1
surveys of the Southern California Bight area, 1975-1978 Part II. Cetaces of the Southern California Bight,

Final Report to the Bureau of Land Management, NTIS Rep. No. PB81248189. 414p.

Forney, K. A. 1994. Recent information on the status of odontocetes in Californian waters. NOAA Technical

Memorandum NMFS, NOAA-TM-NMFS-SWFSC-202. Available from NMFS, Southwest Fisheries Science

Center, P.O. Box 271, La Jolla. California, USA.

Forney, K. A.. J. Barlow and J. V. Carretta. 1995. The abundance of cetaceans in California waters. Part II: Aerial

surveys in winter and spring of 1991 and 1992. Fish. Bull. 93: 15-26.

Green, G., J. J. Brueggeman, R. A. Grotefendt, C. E. Bowlby, M. L. Bonnell, and K. C. Balcomb. III. 1992. Cetacean

distribution and abundance off Oregon and Washington. Ch. 1. In: Oregon and Washington Marine Mammal

and Seabird Surveys. OCS Study 91-0093. Final Report prepared for Pacific OCS Region, Minerals

Management Service. U.S. Department of the Interior: Los Angeles, California.

Green: G., R. A. Grotefendt, M. A. Smultea, C. E. Bowlby, and R. A. Rowlett. 1993. Delphinid aerial surveys in Oregon

and Washington waters. Final Report prepared for NMFS, National Marine Mammal Laboratory, 7600 Sand

Point Way, NE, Seattle, Washington: 98115, Contract #50ABNF200058.

Hanan, D. A., D. B. Holts, and A. L. Coan, Jr. 1993. The California drift gill net fishery for sharks and swordfish, 1981-

82 through 1990-91. Fish Bulletin 175. Available from the Marine Technical Information Center, California

Department of Fish and Game, 330 Golden Shore, Suite 50, Long Beach. CA 90802.

Julian, F. 1993. Pinniped and cetacean mortality in California gillnet fisheries: Preliminary estimates for 1992. Working

paper SC/45/022 presented to the International Whaling Commission Scientific Committee, May 1993

(unpublished).

Julian? F. 1994. Pinniped and cetacean mortality in California gillnet fisheries: Preliminary estimates for 1993. Working

paper SC/46/011 presented to the International Whalin g Commission Scientific Committee, May 1994

(unpublished).

Leatherwood, S. and W. A. Walker. 1979. The not-them right whale dolphin Lissodelphis borealis Peale in the eastern

North Pacific. In: Winn. H. E. and B. L. Olla (eds.), Behavior of Marine Mammals, p. 85- 14 1. Plenum Press,

New York - London.

Lennert, C., S. Kruse, M. Beeson, and J. Barlow. 1994. Estimates of incidental marine mammal bycatch in California

gillnet fisheries for July through December 1990. Rep. Int. Whal. Commn. Special Issue 15:449-463.

National Marine Fisheries Service, Southwest Fisheries Science Center. Unpublished data.

Perkins, P., J. Barlow and M. Beeson. 1992. Pinniped and cetacean mortality in California gillnet fisheries: 1991.

Working Paper SC/44/SM14 presented to the International Whaling Commission. May 1992 (unpublished).

Sosa-Nishizaki, O., R. De la Rosa-Pacheco, R. Castro-Longoria, M. Grijalva Chon, and J. De la Rosa Velez. 1993.

Estudio biologico pesquero del pez (Xiphias gladius) y otras especies de picudos (marlins y pez vela). Rep. Int.

CICESE, CTECT9306.

Stick, K. C. and Hreha, L. 1989. Summary of the 1988 Washington/Oregon experimental thresher shark gill net fishery.

State of Washington, Department of Fisheries. Progress Report 275. 40p.

72
KILLER WHALE (Orcinus orca):

California/Oregon/Washington Pacific Coast Stock

STOCK DEFINITION AND GEOGRAPHIC RANGE

Killer whales have been observed in all oceans and

seas of the world (Leatherwood and Dahlheim 1978).

Although reported from tropical and offshore waters, killer

whales prefer the colder waters of both hemispheres, with

greatest abundance within 800 km of major continents

(Mitchell 1975). Along the west coast of North America,

killer whales occur along the entire Alaskan coast (Braham

and Dahlheim 1982), in British Columbia and Washington

inland waterways (Bigg et al. 1990) and along the outer

coasts of Washington, Oregon and California (Green et al.

1992; Barlow 1995; Forney et al. 1995). Seasonal and yearround occurrence has been noted for killer whales throughout

Alaska (Braham and Dahlheim 1982, Dahlheim in prep) and

in the intracoastal waterways of British Columbia and

Washington State, where pods have been labeled as ‘resident’

and ‘transient’ (Bigg et al. 1990) based on aspects of

morphology, ecology, genetics and behavior (Ford and Fisher

1982; Baird and Stacey 1988; Baird et al. 1992). Although

some resident pods have been sighted off the outer

Washington coast as far south as Grays Harbor (Bigg et al.

1990), most sightings of killer whales in Washington have

occurred in inland waterways.

Off California. Oregon and the Pacific coast of

Washington, killer whale sightings have been relatively

infrequent and dispersed (Figure 1; data from Dohl et al.

1980, 1983; Green et al. 1992; Hill and Barlow 1992;

Carretta and Forney 1993; Mangels and Gerrodette 1994;

NMFS, unpublished data). Although movement between

Alaska and California recently was documented for three

identifiable killer whales photographed together in both

Figure 1. Killer whale sightings based on aerial and

shipboard surveys off the Pacific coast of California,

Oregon and Washington, 1975- 1994 (see text for data

sources).

regions (Black et al. 1993, Goley and Straley 1994), it is not known what proportion of animals found off California,

Oregon and the outer Washington coast may exhibit similar long-range movements, or whether any resident pods exist

in these areas. Until additional information on movements and population structure is available, killer whales within

the U.S. Exclusive Economic Zone of offshore Washington waters (south of Cape Flattery), and in Oregon and California

should be managed as a separate stock from the resident and transient populations which have been studied in the inland

waterways of Washington and British Columbia and in Alaska. This designation also roughly corresponds to the

operating area of drift gillnet fisheries, which are most likely to take killer whales incidentally. Thus, for the Marine

Mammal Protection Act (MMPA) stock assessment reports, killer whales within the Pacific U.S. EEZ are divided into

four stocks: 1) a California, Oregon and Washington stock (this report),2) a transient stock in Alaska and Washington

inland waters, 3) a resident stock in Alaska and Washington inland water: and 4) a Hawaiian stock.

POPULATION SIZE

Killer whales generally have been sighted too infrequently off the Pacific coast of California, Oregon and

Washington to produce reliable abundance estimates. For California, Forney (1994) reviews available data and concludes

that the abundance estimate of 307 (C.V. = 1.2) obtained by Barlow (1995) based on a 1991 summer/fall ship survey

extending 300 nmi off the California coast is likely to be the most accurate, although the variance in this estimate is high.

No abundance estimates have been made for offshore Oregon and Washington waters. Thus, the California value

73
represents the only available population estimate for this stock, although it does not include any killer whales that may

have been off Oregon or Washington at the time of that survey.

Minimum Population Estimate

The log-normal 20th percentile of the above abundance estimate is 139 killer whales.

Current Population Trend

No information is available regarding trends in abundance of killer whales off California, Oregon and the outer

coast of Washington.

CURRENT AND MAXIMUM NET PRODUCTIVITY RATES

No information on current or maximum net productivity rates is available for killer whales in this region.

POTENTIAL BIOLOGICAL REMOVAL

Based on this stock’s unknown status and growth rate, the recovery factor (F,) is 0.5, and 1/2Rmax is the default

value of 0.02. Multiplying these two values times the minimum population estimate of 139 yields a potential biological

removal (PBR) of 1.4 animals per year.

ANNUAL HUMAN-CAUSED MORTALITY AND SERIOUS INJURY

Fishery Information

Killer whales are susceptible to mortality in drift gillnets, which are used by approximately 149 vessels (J.

Cordaro, Southwest Region, NMFS, pers. comm.) to catch swordfish, thresher shark, and mako shark in California

offshore waters (Hanan et al. 1993). Fishing effort has decreased from approximately 10.000 sets per year in the mid1980s to 6600 in 1993 (Barlow et al. 1994). No takes of killer whales have been documented by fishery observers in U.S.

west coast gillnet fisheries for 1980-85 (<1% observer coverage; Diamond et al. 1987), and from July 1990 to December

1994 (4- 15% observer coverage; Lennert et al. 1994; Perkins et al. 1992; Julian 1993, 1994; NMFS, unpublished data).

Although this does not prove that mortality is zero (because observer coverage was not l00%), it does indicate that

mortality is probably infrequent. Heyning et al. (1994) report one stranding of a killer whale with net marks in Southern

California in 1985, but it is not known which gillnet fishery may have been responsible.

Another potential source of killer whale mortality are set gillnets, which are used by approximately 134 vessels

(J. Cordaro, Southwest Region, NMFS, pers. comm.) to catch halibut, flounder, angel shark, yellowtail, white seabass,

and white croaker in California coastal waters. As a result of area closures, fishing effort has decreased from

approximately 40,000 sets per year in the mid-1980s to 16,000 sets in 1993 (Barlow et al. 1994): and is expected to

continue to decrease because of a 1994 ban on fishing within 3 nmi of shore in Southern California. An observation

program has monitored 5-15% of all sets in this fishery since July 1990.

Similar set and drift gillnet fisheries for swordfish and sharks exist along the entire Pacific coast of Baja

California: Mexico and may take animals from the same population. Quantitative data are available only for the Mexican

swordfish drift gillnet fishery, which has increased from two vessels in 1986 to 29 vessels in 1992 (Sosa-Nishizaki et al.

1993). The total number of sets in this fishery in 1992 can be estimated from data provided by these authors to be

approximately 2700, with an observed rate of marine mammal bycatch of 0.13 animals per set (10 marine mammals in

77 observed sets; Sosa-Nishizaki et al. 1993). This overall mortality rate is similar to that observed in California driftnet

fisheries during 1990-93 (0.15 marine mammals per set), but species-specific information is not available for the Mexican

fisheries.

Fishery Mortality Rate

No fishery mortality or serious injury has been reported for this stock of killer whales since 1985, and, therefore,

fishery mortality and serious injury can be considered to be insignificant and approaching zero.

Other mortality

California coastal whaling operations killed five killer whales between 1962 and 1967 (Rice 1974). An

additional killer whale was taken by whalers in British Columbian waters (Hoyt 198 1), but it is unknown whether this

animal may have belonged to a stock ranging south along the Pacific coast of Califonia/Oregon/Washington.

74
STATUS OF STOCK

The status of killer whales in California in relation to OSP is unknown, and there are insufficient data to evaluate

trends in abundance. They are not listed as “threatened” or “endangered” under the Endangered Species Act nor as

“depleted” under the MMPA. Because mortality in fisheries is infrequent, and no human-caused takes have been

observed in the 3990-93 observer program, killer whales off California are not classified as a “strategic” stock under the

MMPA.

REFERENCES

Baird? R. W., and P. J. Stacey. 1988. Variation in saddle patch pigmentation in populations of Killer whales (Orcinus

orca) from British Columbia, Alaska, and Washington State.

Baird, R. W., Abrams, P. A., and L. M. Dill. 1992. Possible indirect interactions between transient and resident killer

whales: implications for the evolution of foraging specializations in the genus Orcinus. Oecologia 89: 125-132.

Barlow, J. 1995. The abundance of cetaceans in California waters. Part 1: Ship surveys in summer and fall of 1991.

Fish. Bull. 93:1-14.

Barlow, J., R. W. Baird, J. E. Heyning, K. Wynne, A. M. Manville, II, L. F. Lowry, D. Hanan, J. Sease, and V. N.

Burkanov. 1994. A review of cetacean and pinniped mortality in coastal fisheries along the west coast of the

USA and Canada and the east coast of the Russian Federation. Rep. Int. Whal. Commn. Special Issue 15:405-

426.

Bigg, M. A., P. F. Olesiuk, G. M. Ellis, J. K. B. Ford, and K. C. Balcomb III. 1990. Social organization and genealogy

of resident killer whales (Orcinus orca) in the coastal waters of British Columbia and Washington State. Rep.

int. Whal. Commn Special Issue 12:386-406

Black, N., A. Schulman, D. Ellifrit, D. Shear-water, A. Baldridge, R. Temullo, D. Goley, J. Calambokidis, and M.

Webber. 1993. Photo-identification of killer whales off California. Abstract presented at the Tenth Biennial

Conference on the Biology of Marine Mammals. Galveston, Texas. November 1993.

Braham, H. W., and M. E. Dahlheim. 1982. Killer whales in Alaska documented in the Platforms of Opportunity

Program. Rep. Int. Whal. Commn., 32:643-646.

Carretta, J. V. and K. A. Forney. 1993. Report of the two aerial surveys for marine mammals in California coastal

waters using a NOAA DeHavilland Twin Otter aircraft, March 9-April 7, 1991, February 8-April 6, 1992.

NOAA Technical Memorandum NOAA-TM-NMFS-SWFSC- 185. Available from NMFS, Southwest Fisheries

Science Center, P.O. Box 271, La Jolla, California, 92038. 77p.

Dahlheim, M. E. in prep. Killer whales of Southeast Alaska. Submission to Canadian Journal of Zoology, Spring 1995.

Diamond, S. L., J. P. Scholl and D. A. Hanan. 1987. Drift gillnet observations for the 1985-86 fishing season.

Administrative Report SWR 87-4. Available from NMFS, Southwest Region. 300 S. Ferry Street, Terminal

Island, California, 90731. 21p.

Dohl. T. P., R. C. Guess, M. L. Duman, and R. C. Helm. 1983. Cetaceans of central and northern California, 1980-1983:

Status, abundance and distribution. OCS Study MMS 84-0045. Minerals Management Service Contract # 14-

12-000l-29090. 284p.

Dohl, T. P., K. S. Norris, R. C. Guess, J. D. Bryant, and M. W. Honig. 1980. Summary of marine mammal and seabird

surveys of the Southern California Bight area, 1975-1978. Part II. Cetacea of the Southern California Bight.

Final Report to the Bureau of Land Management, NTIS Rep. No. PB81248189. 414p.

Ford, J. K. B., and H. D. Fisher. 1982. Killer whale (Orcinus orca) dialects as an indicator of stocks in British

Columbia. Rep. Int. Whal. Commn 32:671-679.

Forney, K. A. 1994. Recent information on the status of odontocetes in Californian waters. NOAA Technical

Memorandum NMFS, NOAA-TM-NMFS-SWFSC-202. Available from NMFS, Southwest Fisheries Science

Center, P.O. Box 271, La Jolla, California, USA.

Forney, K. A., J. Barlow and J. V. Carretta. 1995. The abundance of cetaceans in California waters. Part II: Aerial

surveys in winter and spring of 1991 and 1992. Fish. Bull. 93:15-26.

Goley, P. D. and Straley. J. M. 1994. Attack on gray whales (Eschrichtius robustus) in Monterey Bay, California, by

killer whales (Orcinus orca) previously identified in Glacier Bay. Can. J. Zool. 72:1528-1530.

Green, G., J. J. Brueggeman, R. A. Grotefendt, C. E. Bowlby, M. L. Bonnell, and K. C. Balcomb, 111. 1992. Cetacean

distribution and abundance off Oregon and Washington. Ch. 1. In: Oregon and Washington Marine Mammal

and Seabird Surveys. OCS Study 91-0093. Final Report prepared for Pacific OCS Region, Minerals

75
Management Service, U.S. Department of the Interior, Los Angeles, California.

Hanan, D. A., D. B. Holts, and A. L. Coan, Jr. 1993. The California drift gill net fishery for sharks and swordfish: 1981-

82 through 1990-91. Fish Bulletin 175. Available from the Marine Technical Information Center, California

Department of Fish and Game, 330 Golden Shore, Suite 50. Long Beach, CA 90802.

Heyning, J. E., T. D. Lewis and C. D. Woodhouse. 1994. A note on odontocete mortality from fishing gear

entanglements off Southern California. Rep. Int. Whal. Commn. Special Issue 15:439-442.

Hill, P. S. and J. Barlow. 1992. Report on a marine mammal survey of the California coast aboard the research vessel

McARTHUR July 28 - November 5, 1991. NOAA Technical Memorandum NMFS, NOAA-TM-NMFSSWFSC-169. Available from NMFS, Southwest Fisheries Science Center, P.O. Box 271, La Jolla, California,

USA.

Hoyt, E. 1981. The Whale Called Killer. E. P. Dutton, New York.

Julian, F. 1993. Pinniped and cetacean mortality in California gillnet fisheries: Preliminary estimates for 1992. Working

paper SC/45/022 presented to the International Whaling Commission Scientific Committee. May 1993

(unpublished).

Julian, F. 1994. Pinniped and cetacean mortality in California gillnet fisheries: Preliminary estimates for 1993. Working

paper SC/46/Oll presented to the International Whalin,g Commission Scientific Committee, May 1994

(unpublished).

Leatherwood, J. S., and M. E. Dahlheim. 1978. Worldwide distribution of pilot whales and killer whales. Naval Ocean

Systems Center, Tech. Rep. 443: 1-39

Lennert, C., S. Kruse, M. Beeson, and J. Barlow. 1994. Estimates of incidental marine mammal bycatch in California

gillnet fisheries for July through December 1990. Rep. Int. Whal. Commn. Special Issue 153449-463.

Mangels, K. F. and Gerrodette. T. 1994. Report of cetacean sightings during a marine mammal survey in the eastern

Pacific Ocean and Gulf of California aboard the NOAA ships d4c.4RTHUR and DA G./D STARR .JORDAX July

28 - November 6, 1993. NOAA Technical Memorandum NMFS, NOAA-TM-NMFS-SWFSC-211.

Mitchell, E. D. 1975. Report on the meeting on small cetaceans, Montreal, April l-1 1, 1974. J. Fish. Res. Board Canada,

32:914-916.

National Marine Fisheries Service: Southwest Fisheries Science Center. Unpublished data.

Perkins, P., J. Barlow and M. Beeson. 1992. Pinniped and cetacean mortality in California gillnet fisheries: 1991.

Working Paper SC/44/SM14 presented to the lnternational Whaling Commission, May 1992 (unpublished).

Rice, D. W. 1974. Whales and whale research in eastern North Pacific. p. 170-l 95 In: W. E. Schevill (ed.), The Whale

Problem - A Status Report. Harvard University Press, Cambridge, MA.

Sosa-Nishizaki, 0., R. De la Rosa-Pacheco, R. Castro-Longoria, M. Grijalva Chon, and J. De la Rosa Velez. 1993.

Estudio biologico pesquero del pez (Xiphias gludius) y otras especies de picudos (marlins y pez vela). Rep. Int.

CICESE, CTECT9306.

76
SHORT-FINNED PILOT WHALE (Globicephala macrorhynchus):

California/Oregon/Washington Stock

sightings were made from 1984- 1992 (Jones and

Szczepaniak 1992; Hill and Barlow 1992; Carretta and

Forney 1993; Shane 1994; Green et al. 1992, 1993). In

1993, six sightings of short-finned pilot whales were

again made off California (Mangels and Gerrodette 1994;

NMFS, unpublished data), and mortality in drift gillnets

increased (Julian 1994). Figure 1 summarizes the

sighting history of short-finned pilot whales off the U.S.

west coast (sightings from Dohl et al. 1980, 1983;

Carretta and Forney 1993; Mangels and Gerrodette 1994;

STOCK DEFINITION AND GEOGRAPHIC RANGE

Short-finned pilot whales were once commonly

seen off Southern California, with an apparently resident

population around Santa Catalina Island, as well as

seasonal migrants (Dohl et al. 1980). After a strong El

Niño event in 1982-83, short-finned pilot whales virtually

disappeared from this region. and despite increased

survey effort along the entire U.S. west coast, few

NMFS. unpublished data). No sightings have been

documented for Oregon or Washington, but four

strandings of short-finned pilot whales have occurred in

Washington (B. Norberg, pers. comm.). Although the full

geographic range of the California/Oregon/Washington

population is not known, it may be continuous with

animals found off Baja California, and is morphologically

distinct from short-finned pilot whales found farther south

in the eastern tropical Pacific (Polisini 1981). Separate

southern and northern forms of short-finned pilot whales

have also been documented for the western North Pacific

(Kasuya et al. 1988; Wada 1988; Miyazaki and Amano

1994). For the Marine Mammal Protection Act (MMPA)

stock assessment reports, short-finned pilot whales within Figure I. Short-finned pilot whale sightings made during

the Pacific U.S. Exclusive Economic Zone are divided aerial and shipboard surveys conducted off California in

into two discrete, non-contiguous areas: 1) waters off 1975-83 (+) and off California, Oregon and Washington in

California, Oregon and Washington (this report), and 2) 1989-93 (0) (See text for data sources).

Hawaiian waters.

POPULATION SIZE

No estimates of population size are currently available for short-finned pilot whales off the U.S. west coast.

because the 1991-92 aerial and shipboard surveys resulted in only one sighting of this species while in transit to the

survey area. However, a population estimate is expected to become available in the near future, when ship survey data

for 1993 (Mangels and Gerrodette 1994) have been analyzed.

Minimum Population Estimate

No minimum population estimate is available for short-finned pilot whales in California. The largest

documented group size was 25 animals seen off central California in 1991 (Jones and Szczepaniak 1992). However, this

is not a meaningful minimum population estimate, as recent levels of mortality appear to exceed this value (Julian 1994).

77
Current Population Trend

Approximately nine years after the virtual disappearance of short-finned pilot whales following the 1982-83 El

Niño, they appear to have returned to California waters, as indicated by an increase in sighting records as well as

incidental fishery mortality (NMFS, unpublished data; Julian 1994). However, this cannot be considered a true growth

in the population, because it merely reflects large-scale, long-term movements of this species in response to changing

oceanographic conditions. It is not known where the animals went after the 82-83 El Niño, nor where the recently

observed animals came from. Until the range of this population and the movements of animals in relation to

environmental conditions are better documented, no inferences can be drawn regarding trends in abundance of shortfinned pilot whales off California, Oregon and Washington.

CURRENT AND MAXlMUM NET PRODUCTIVITY RATES

No information on current or maximum net productivity rates is available for short-finned pilot whales off

California, Oregon and Washington.

POTENTIAL BIOLOGICAL REMOVAL

Based on this stock’s unknown status and growth rate, the recovery factor (F,) is 0.5, and 1/2Rmax is the default

value of 0.02. However, because no minimum abundance estimate is available, no potential biological removal (PBR)

can be calculated.

ANNUAL HUMAN-CAUSED MORTALITY AND SERIOUS INJURY

Fishery Information

Short-finned pilot whales are incidentally killed in California drift gillnet fisheries. Drift gillnets are used by

approximately 149 vessels (J. Cordaro, Southwest Region, NMFS, pers. comm.) to catch swordfish, thresher shark, and

mako shark in California offshore waters (Hanan et al. 1993). Fishing effort has decreased from approximately 10,000

sets per year in the mid-1980s to 6600 in 1993 (Barlow et al. 1994). Based on less than 1% coverage of fishing effort

between 1980 and 1985, Diamond et al. (1987) report two takes of this species in 1980. However, given the observed

changes in distribution of short-finned pilot whales after 1983, it is not plausible to extrapolate to an overall mortality

estimate for the period. Between July 1990 and December 1993, with approximately 4-13% observer coverage of

California drift gillnet fisheries, observed short-finned pilot whale mortality was one in 1990, zero in 1991, one in 1992,

and 11 in 1993 (Lennert et al. 1994: Perkins et al. 1992; Julian 1993, 1994). resulting in total annual mortality estimates

of 23 (s.e. 22) in 1990, zero in 1991, 8 (se. 7) in 1992, and 100 (s.e. 43) in 1993. The corresponding average rates of

short-finned pilot whale kill per fishing day are 0.006, 0,0.002, and 0.015 for 1990, 1991, 1992 and 1993, respectively.

Preliminary mortality data for 1994 indicate that no short-finned pilot whales were observed killed (NMFS, unpublished

data). The average estimated annual mortality for short-finned pilot whales in this fishery for the three complete years

of monitoring, 199l-93, is 36 animals.

Similar drift gillnet fisheries for swordfish and sharks exist along the entire Pacific coast of Baja California,

Mexico and may take animals from the same population. Quantitative data are available only for the Mexican swordfish

drift gillnet fishery, which has increased from two vessels in 1986 to 29 vessels in 1992 (Sosa-Nishizaki et al. 1993). The

total number of sets in this fishery in 1992 can be estimated from data provided by these authors to be approximately

2700, with an observed rate of marine mammal bycatch of 0.13 animals per set (10 marine mammals in 77 observed sets;

Sosa-Nishizaki et al. 1993). This overall mortality rate is similar to that observed in California driftnet fisheries during

1990-93 (0.15 marine mammals per set). but species-specific information is not available for the Mexican fisheries.

Historically, short-finned pilot whales were also killed in squid purse seine operations off Southern California

(Miller et al. 1983; Heyning et al. 1994): although the extent of such mortality is unknown. This fishery currently

includes approximately 145 vessels (NMFS, unpublished data). No recent mortality has been reported, presumably

because short-finned pilot whales have not returned to the areas of squid purse seine fishing activity. Furthermore, past

mortality in this fishery probably represented animals killed intentionally to protect catch or gear, rather than incidental

mortality, and such intentional takes are now illegal under the 1994 Amendment to the MMPA.

Fishery Mortality Rate

The total fishery mortality and serious injury for 199l-93 (36 animals per year) cannot be considered to be

insignificant and approaching zero, because the population size of this stock of short-finned pilot whales is unknown.

78
Determinations cannot be made for individual fisheries until the implementing regulations for Section 118 of the MMPA

have been reviewed by the public and finalized.

STATUS OF STOCK

The status of short-finned pilot whales off California, Oregon and Washington in relation to OSP is unknown.

They have declined in abundance and changed their distribution since the 1982-83 El NiNo, but the nature of these

changes is not adequately understood. Shot-t-finned pilot whales are not listed as “threatened” or “endangered” under

the Endangered Species Act nor as “depleted” under the MMPA. Because there is documented fishery mortality of this

species, but no PBR can be calculated due to the lack of abundance estimates. short-finned pilot whales off California

are a “strategic” stock under the MMPA.

REFERENCES

Barlow, J., R. W. Baird, J. E. Heyning, K. Wynne, A. M. Manville, II L. F. Lowry, D. Hanan, J. Sease, and V. N.

Burkanov. 1994. A review of cetacean and pinniped mortality in coastal fisheries along the west coast of the

USA and Canada and the east coast of the Russian Federation. Rep. Int. Whal. Commn. Special Issue 15:405-

426.

Carretta: J. V. and K. A. Forney. 1993. Report of the two aerial surveys for marine mammals in California coastal

waters using a NOAA DeHavilland Twin Otter aircraft, March 9-April 7, 1991, February 8-April 6, 1992.

NOAA Technical Memorandum NOAA-TM-NMFS-SWFSC-185. Available from NMFS, Southwest Fisheries

Science Center, P.O. Box 271, La Jolla, California, 92038. 77p.

Diamond, S. L., J. P. Scholl and D. A. Hanan. 1987. Drift gillnet observations for the 1985-86 fishing season.

Administrative Report SWR 87-4. Available from NMFS, Southwest Region, 300 S. Ferry Street, Terminal

Island, California, 90731. 21p.

Dohl, T. P., R. C. Guess, M. L. Duman, and R. C. Helm. 1983. Cetaceans of central and northern California, 1980-1983:

Status, abundance and distribution. OCS Study MMS 84-0045. Minerals Management Service Contract # 14-

12-000 1-29090. 284p.

Dohl, T. P., K. S. Norris, R. C. Guess, J. D. Bryant, and M. W. Honig. 1980. Summary of marine mammal and seabird

surveys of the Southern California Bight area, 1975-1978. Part II. Cetacea of the Southern California Bight.

Final Report to the Bureau of Land Management, NTIS Rep. No. PB81248189. 414p.

Green, G., J. J. Brueggeman, R. A. Grotefendt, C. E. Bowlby, M. L. Bonnell, and K. C. Balcomb, III. 1992. Cetacean

distribution and abundance off Oregon and Washington, Ch. 1. In: Oregon and Washington Marine Mammal

and Seabird Surveys. OCS Study 91-0093. Final Report prepared for Pacific OCS Region, Minerals

Management Service, U.S. Department of the Interior, Los Angeles, California.

Green, G., R. A. Grotefendt, M. A. Smultea, C. E. Bowlby, and R. A. Rowlett. 1993. Delphinid aerial surveys in Oregon

and Washington waters. Final Report prepared for NMFS, National Marine Mammal Laboratory, 7600 Sand

Point Way, NE, Seattle, Washington, 98115, Contract #50ABNF200058.

Hanan, D. A., D. B. Holts, and A. L. Coan, Jr. 1993. The California drift gill net fishery for sharks and swordfish, l981-

82 through 1990-91. Fish Bulletin 175. Available from the Marine Technical Information Center, California

Department of Fish and Game, 330 Golden Shore, Suite 50, Long Beach, CA 90802.

Heyning, J. E., T. D. Lewis and C. D. Woodhouse. 1994. A note on odontocete mortality from fishing gear

entanglements off Southern California. Rep. lnt. Whal. Commn. Special Issue 15:439-442.

Hill, P. S. and J. Barlow. 1992. Report on a marine mammal survey of the California coast aboard the research vessel

McARTHUR July 28 - November 5, 1991. NOAA Technical Memorandum NMFS, NOAA-TM-NMFSSWFSC-169. Available from NMFS, Southwest Fisheries Science Center, P.O. Box 271, La Jolla, California:

USA.

Jones, P. A. and I. D. Szczepaniak. 1992. Report on the seabird and marine mammal censuses conducted for the longterm management strategy (LTMS), August 1990 through November 1991, for the U.S. Environmental

Protection Agency, Region IX, San Francisco, July 1992.

Julian, F. 1993. Pinniped and cetacean mortality in California gillnet fisheries: Preliminary estimates for 1992. Working

paper SC/45/022 presented to the International Whaling Commission Scientific Committee, May 1993

(unpublished).

Julian, F. 1994. Pinniped and cetacean mortality in California gillnet fisheries: Preliminary estimates for 1993. Working

79
paper SC/46/011 presented to the International Whaling Commission Scientific Committee, May 1994

(unpublished).

Kasuya, O., T. Miyashita, and F. Kasamatsu. 1988. Segregation of two forms of short-tinned pilot whales off the Pacific

coast of Japan. Sci. Rep. Whales Res. Inst. 39:77-90.

Lennert, C., S. Kruse, M. Beeson, and J. Barlow. 1994. Estimates of incidental marine mammal bycatch in California

gillnet fisheries for July through December 1990. Rep. Int. Whal. Commn. Special Issue 15:449-463.

Mangels, K. F. and Gerrodette, T. 1994. Report of cetacean sightings durin g marine mammal survey in the eastern

Pacific Ocean and Gulf of California aboard the NOAA ships McARTHUR and DAVID STARR JORDAN July

28 -November 6, 1993. NOAA Technical Memorandum NMFS, NOAA-TM-NMFS-SWFSC-211.

Miller, D. J., M. J. Herder and J. P Scholl. 1983. California marine mammal - fishery interaction study, 1979-1981.

Administrative Report LJ-83-13C. Available from NMFS; Southwest Fisheries Science Center, P.O. Box 271,

La Jolla, California, 92038. 233p.

Miyazaki, N. and M. Amano. 1994. Skull morphology of two forms of short-finned pilot whales off the Pacific coast

of Japan. Rep. Int. Whaling Commn. 44:499-508.

National Marine Fisheries Service? Southwest Fisheries Science Center. Unpublished data.

Perkins, P., J. Barlow and M. Beeson. 1992. Pinniped and cetacean mortality in California gillnet fisheries: 1991.

Working Paper SC/44/SMl4 presented to the International Whaling Commission, May 1992 (unpublished).

Polisini, J. M. 1981. A comparison of Globicephala macrorhyncha (Gray, 1846) with the pilot whale of the North

Pacific Ocean: An analysis of the skull of the broad-rostrum pilot whales of the genus Globicephala.

Dissertation Abstracts International Vol. 41, No. 08, February 1981, p. 2928-B.

Shane, S. 1994. Occurrence and habitat use of marine mammals at Santa Catalina Island, California from 1983-91.

Bull. Southern California Acad. Sci. 93: 13-29.

Sosa-Nishizaki, O., R. De la Rosa-Pacheco, R. Castro-Longoria. M. Grijalva Chon, and J. De la Rosa Velez. 1993.

Estudio biologico pesquero del pez (Xiphias gludius) y otras especies de picudos (marlins y pez vela). Rep. Int.

CICESE, CTECT9306.

Wada, S. 1988. Genetic differentiation between forms of short-finned pilot whales off the Pacific coast of Japan. Sci.

Rep. Whales Res. Inst. 39:91-101.

80
BAIRD’S BEAKED WHALE (Berardius bairdii):

California/Oregon/Washington Stock

STOCK DEFINITION AND GEOGRAPHIC RANGE

Baird’s beaked whales are distributed throughout

deep waters and along the continental slopes of the North

Pacific Ocean. They have been harvested and studied in

Japanese waters, but little is known about this species

elsewhere (Balcomb 1989). Along the U.S. west coast,

Baird’s beaked whales have been seen primarily along the

continental slope from late spring to early fall (Figure 1; data

from Dohl et al. 1980, 1983; Green et al. 1992, unpublished

data; Hill and Barlow 1992; Mangels and Gerrodette 1994;

NMFS, unpublished data). They have been seen less

frequently and are presumed to be farther offshore during the

colder water months of November through April. For the

Marine Mammal Protection Act (MMPA) stock assessment

reports, Baird’s beaked whales within the Pacific U.S.

Exclusive Economic Zone are divided into hvo discrete, noncontiguous areas: 1) waters off California, Oregon and

Washington (this report), and 2) Alaskan waters.

POPULATION SIZE

Although Baird’s beaked whales have been sighted

along the U.S. west coast on several line transect surveys

utilizing both aerial and shipboard platforms, sightings have

generally been too rare to produce reliable population 

estimates. Forney (1994) reviews all available data and

Figure 1. Baird’s beaked whale sightings based on

concludes that the best population estimate currently

aerial and shipboard surveys off California, Oregon and

available is 38 animals (C.V. = 1.03): based on a 1991 ship

Washington, 1975- 1994. Key: O = May-October; * =

survey along the California coast (Barlow 1995). However, November-April. (See text for data sources.)

in addition to being imprecise, this estimate is biased

downward by an unknown amount because of the large proportion of time this species spends submerged, and because

the ship survey covered only California waters, and thus could not observe animals off Oregon/Washington. Studies of

the proportion of time this species spends diving will be needed to obtain more accurate abundance estimates for Baird’s

beaked whales in the future.

Minimum Population Estimate

Based on the above abundance estimate and C.V., the minimum population estimate (defined as the log-normal

20th percentile of the abundance estimate) for Baird’s beaked whales in California, Oregon, and Washington is 19

animals. As with the best population estimate above, this value is an underestimate, but the degree of inaccuracy is

unknown.

Current Population Trend

Due to the rarity of sightings of this species on surveys along the U.S. West coast, no information exists

regarding trends in abundance of this population. Future studies of trends must take the apparent seasonality of the

distribution of Baird’s beaked whales into account.

CURRENT AND MAXIMUM NET PRODUCTIVITY RATES

No information on current or maximum net productivity rates is available for this species.

81
POTENTIAL BIOLOGICAL REMOVAL

Based on this stock’s unknown status and growth rate, the recovery factor (F,) is 0.5, and 1/2Rmax is the default

value of 0.02. Multiplying these two values times the minimum population estimate of 19 yields a potential biological

removal (PBR) of 0.2 animals per year.

ANNUAL HUMAN-CAUSED MORTALITY AND SERIOUS INJURY

Fishery Information

Baird’s beaked whales are susceptible to mortality in drift gillnets, which are used by approximately 149 vessels

(J. Cordaro, Southwest Region, NMFS, pers. comm.) to catch swordfish, thresher shark, and mako shark in California

offshore waters (Hanan et al. 1993). Fishing effort has decreased from approximately 10,000 sets per year in the mid1980s to 6600 in 1993 (Barlow et al. 1994). No takes of Baird’s beaked whales were documented by fishery observers

in U.S. west coast gillnet fisheries for 1980-85 (<1 % observer coverage; Diamond et al. 1987), and from July 1990 to

December 1993 (4-l5% observer coverage; Lennert et al. 1994; Perkins et al. 1992; Julian 1993, 1994). However, six

unidentified beaked whales and three unidentified cetaceans were reported entangled in drift gillnets off California since

1980, and one or more of these could have represented this species. Preliminary mortality data for 1994 indicate that

two Baird’s beaked whales and three unidentified beaked whales were observed killed (NMFS: unpublished data).

Although the average estimated annual mortality for Baird’s beaked whales in this fishery for 1991-93 is zero, the

addition of data for 1994 will result in an overall average annual mortality that substantially exceeds the PBR for this

species.

Similar drift gillnet fisheries for swordfish and sharks exist along the entire Pacific coast of Baja California:

Mexico and may take animals from the same population. Quantitative data are available only for the Mexican swordfish

drift gillnet fishery, which has increased from two vessels in 1986 to 29 vessels in 1992 (Sosa-Nishizaki et al. 1993). The

total number of sets in this fishery in 1992 can be estimated from data provided by these authors to be approximately

2700. with an observed rate of marine mammal bycatch of 0.13 animals per set (10 marine mammals in 77 observed sets;

Sosa-Nishizaki et al. 1993). This overall mortality rate is similar to that observed in California driftnet fisheries during

1990-93 (0.15 marine mammals per set): but species-specific information is not available for the Mexican fisheries.

Fishery Mortality Rate

Although no takes were reported for this species in 1990-93, two Baird’s beaked whales were reported taken

in 1994, exceeding the calculated PBR of 0.2 (or 1 animal every 5 years). Therefore, total fishery mortality and serious

injury cannot be considered to be insignificant and approaching zero. This determination cannot be made for individual

fisheries until the implementing regulations for Section 118 of the MMPA have been reviewed by the public and

finalized.

Other mortality

California coastal whaling operations killed 1.5 Baird’s beaked whales between 1956 and 1970. and 29 additional

Baird’s beaked whales were taken by whalers in British Columbian waters (Rice 1974).

STATUS OF STOCK

The status of Baird’s beaked whales in California, Oregon and Washington waters relative to OSP is not known,

and there are insufficient data to evaluate trends in abundance. They are not listed as “threatened” or “endangered” under

the Endangered Species Act nor as “depleted” under the MMPA. Although no mortality of this species was documented

for 1990-93 and the total mortality estimates for 1994 are not yet available, the two animals observed killed in 1994 will

result in an estimate of average annual mortality that exceeds the PBR, and therefore Baird’s beaked whales are classified

as a “strategic” stock under the MMPA.

REFERENCES

Balcomb, K. C., III. 1989. Baird’s beaked whale Berardius bairdii Stejneger, 1883: Arnoux’s beaked whale Berardius

arnuxii Duvernoy, 1851. In: Ridgway, S. H. and Harrison, R. (eds.), Handbook of Marine Mammals, Vol. 4.,

p. 261-288. Academic Press Limited.

Barlow, J. 1995. The abundance of cetaceans in California waters. Part 1: Ship surveys in summer and fall of 1991.

Fish. Bull. 93:1-14.

82
Barlow, J., R. W. Baird, J. E. Heyning, K. Wynne, A. M. Manville, II, L. F. Lowry, D. Hanan, J. Sease,.and V. N.

Burkanov. 1994. A review of cetacean and pinniped mortality in coastal fisheries along the west coast of the

USA and Canada and the east coast of the Russian Federation. Rep. lnt. Whal. Commn. Special Issue l5:405-

426.

Diamond, S. L., J. P. Scholl and D. A. Hanan. 1987. Drift gillnet observations for the 1985-86 fishing season.

Administrative Report SWR 87-4. Available from NMFS, Southwest Region, 300 S. Fen), Street, Terminal

Island, California, 90731. 21p.

Dohl: T. P., R. C. Guess, M. L. Duman. and R. C. Helm. 1983. Cetaceans of central and northern California, 1980-1983:

Status, abundance and distribution. OCS Study MMS 84-0045. Minerals Management Service Contract # 14-

12-0001-29090. 284p.

Dohl, T. P., K. S. Norris, R. C. Guess, J. D. Bryant, and M. W. Honig. 1980. Summary of marine mammal and seabird

surveys of the Southern California Bight area, 1975-1978. Part II. Cetacea of the Southern California Bight.

Final Report to the Bureau of Land Management, NTIS Rep. No. PB81248189. 414p.

Forney, K. A. 1994. Recent information on the status of odontocetes in Californian waters. NOAA Technical

Memorandum NMFS, NOAA-TM-NMFS-SWFSC-202. Available from NMFS, Southwest Fisheries Science

Center, P.O. Box 271, La Jolla, California, USA.

Green, G., J. J. Brueggeman, R. A. Grotefendt, C. E. Bowlby, M. L. Bonnell, and K. C. Balcomb, III. 1992. Cetacean

distribution and abundance off Oregon and Washington. Ch. 1. In: Oregon and Washington Marine Mammal

and Seabird Surveys. OCS Study 91-0093. Final Report prepared for Pacific OCS Region, Minerals

Management Service, U.S. Department of the Interior, Los Angeles, California.

Hanan, D. A., D. B. Holts, and A. L. Coan, Jr. 1993. The California drift gill net fishery for sharks and swordfish, 1981-

82 through 1990-91. Fish Bulletin 175. Available from the Marine Technical Information Center, California

Department of Fish and Game, 330 Golden Shore? Suite 50, Long Beach, CA 90802.

Hill, P. S. and J. Barlow. 1992. Report on a marine mammal survey of the California coast aboard the research vessel

McARTHUR July 28 - November 5, 1991. NOAA Technical Memorandum NMFS, NOAA-TM-NMFSSWFSC-169. Available from NMFS, Southwest Fisheries Science Center, P.O. Box 271, La Jolla, California,

USA.

Julian, F. 1993. Pinniped and cetacean mortality in California gillnet fisheries: Preliminary estimates for 1992. Working

paper SC/45/022 presented to the International Whalin,g Commission Scientific Committee, May 1993

(unpublished).

Julian. F. 1994. Pinniped and cetacean mortality in California gillnet fisheries: Preliminary estimates for 1993. Working

paper SC/46/011 presented to the International Whalin,g Commission Scientific Committee, May 1994

(unpublished).

Lennert, C. S. Kruse, M. Beeson, and J. Barlow. 1994. Estimates of incidental marine mammal bycatch in California

gillnet fisheries for July through December 1990. Rep. Int. Whal. Commn. Special Issue 15:449-463.

Mangels, K. F. and Gerrodette, T. 1994. Report of cetacean sightings during a marine mammal survey in the eastern

Pacific Ocean and Gulf of California aboard the NOAA ships McARTHUR and DAVID STARR JORDAN July

28 - November 6, 1993. NOAA Technical Memorandum NMFS, NOAA-TM-NMFS-SWFSC-211.

National Marine Fisheries Service, Southwest Fisheries Science Center. Unpublished data.

Perkins, P., J. Barlow and M. Beeson. 1992. Pinniped and cetacean mortality in California gillnet fisheries: 1991.

Working Paper SC/44/SM14 presented to the International Whaling Commission, May 1992 (unpublished).

Rice, D. W. 1974. Whales and whale research in eastern North Pacific. p. 170-195 In: W. E. Schevill (ed.), The Whale

Problem - A Status Report. Harvard University Press, Cambridge, MA.

Sosa-Nishizaki, O., R. De la Rosa-Pacheco, R. Castro-Longoria, M. Grijalva Chon, and J. De la Rosa Velez. 1993.

Estudio biologico pesquero de1 pez (Xiphias gladius) y otras especies de picudos (marlins y pez vela). Rep. Int.

CICESE, CTECT9306.

83
MESOPLODONT BEAKED WHALES (Mesoplodon spp.):

California/Oregon/Washington Stocks

Until methods of distinguishing these five

species are developed, the management unit must be

defined to include all Mesoplodon stocks in this region.

However, in the future, species-level management is

desirable, and a high priority should be placed on finding

means (i.e. genetic tests) to obtain species-specific

abundance and mortality information. For the Marine

Mammal Protection Act (MMPA) stock assessment

Figure 1. Sightings of mesoplodont beaked whales off

reports, three Mesoplodon stocks are defined: 1) all

California, Oregon and Washington based on aerial and

Mesoplodon species off California, Oregon and

shipboard surveys, 1975-1993 (data from Dohl et al. 1980,

Washington (this report), 2) M stejnegeri in Alaskan

1983; Green et al. 1992, unpublished data; Hill and Barlow

waters, and 3) M. densirostris in Hawaiian waters.

1992; Carretta and Forney 1993; Mangels and Gerrodette

1994; NMFS, unpublished data).

STOCK DEFINITION AND GEOGRAPHIC RANGE

Mesoplodont beaked whales are distributed

throughout deep waters and along the continental slopes

of the North Pacific Ocean. At least 5 species in this

genus have been recorded off the U.S. west coast, but due

to the rarity of records and the difficulty in identifying

these animals in the field, virtually no species-specific

information is available (Mead 1989). The five species

known to occur in this region are: Blainville’s beaked

whale (M. densirostris), Hector’s beaked whale, (M

hectori), Stejneger’s beaked whale (M. stejnegeri),

Gingko-toothed beaked whale (M. gingkodens), and

Hubbs’ beaked whale (M. carlhubbsi). Insufficient

sighting records exist off the U.S. west coast (Figure 1)

to determine any possible spatial or seasonal patterns in

the distribution of mesoplodont beaked whales.

POPULATION SIZE

Although mesoplodont beaked whales have been sighted along the U.S. west coast on several line transect

surveys utilizing both aerial and shipboard platforms, sightings have generally been too rare to produce reliable

population estimates, and species identification has been problematic. Forney (1994) reviews all available data and

concludes that the best population estimate currently available is 250 animals (C.V. = 0.83), based on a 1991 ship survey

along the California coast (Barlow 1995). However, in addition to being imprecise, this estimate is biased downward

by an unknown amount because of the large proportion of time mesoplodont beaked whales spend submerged: and

because the ship survey covered only California waters, and thus could not observe animals off Oregon/Washington.

Furthermore, there were a large number of unidentified beaked whale sightings. which were probably either Mesoplodon

sp. or Cuvier’s beaked whales (Ziphius cavirostris). Studies of the proportion of time spent diving by these species will

be needed to obtain more accurate abundance estimates in the future.

Minimum Population Estimate

Based on the above abundance estimate and C.V., the minimum population estimate (defined as the log-normal

20th percentile of the abundance estimate) for mesoplodont beaked whales in California, Oregon, and Washington is 136

animals. As with the best population estimate, this value is an underestimate, but the degree of inaccuracy is unknown.

Current Population Trend

Due to the rarity of sightings of these species on surveys along the U.S. West coast, no information exists

84
regarding possible trends in abundance.

CURRENT AND MAXIMUM NET PRODUCTIVITY RATES

No information on current or maximum net productivity rates is available for mesoplodont beaked whales.

POTENTIAL BIOLOGICAL REMOVAL

Based on this stock’s unknown status and growth rate, the recovery factor (F,) is 0.5, and 1/2Rmax is the default

value of 0.02. Multiplying these two values times the minimum population estimate of 136 yields a potential biological

removal (PBR) of 1.4 mesoplodont beaked whales per year.

ANNUAL HUMAN-CAUSED MORTALITY AND SERIOUS INJURY

Fishery Information

Mesoplodont beaked whales are incidentally killed in California drift gillnets, which are used by approximately

149 vessels (J. Cordaro, Southwest Region, NMFS, pers. comm.) to catch swordfish, thresher shark, and mako shark in

California offshore waters (Hanan et al. 1993). Fishing effort has decreased from approximately 10,000 sets per year

in the mid-1980s to 6600 in 1993 (Barlow et al. 1994). Based on less than 1% observer coverage of fishing effort

between 1980 and 1985, Diamond et al. (1987) report a single take of a cow/calf pair, which corresponds to a kill-per-netpull of 0.005 animals and extrapolates to a total mortality of 220 animals, or roughly 37 per year. Between July 1990

and December 1993, with approximately 4- 13% of California drift gillnet fisheries observed, four mesoplodont beaked

whales were recorded killed in driftnets (Lennert et al. 1994; Perkins et al. 1992; Julian 1993, 1994). Additionally, three

unidentified beaked whales and three unidentified cetaceans, which may have been mesoplodont beaked whales, were

reported. Based only on the identified takes, these authors report total annual mortality estimates for mesoplodont beaked

whales as 23 (s.e. 22) for July-December 1990; zero in 1991 and 1993, and 23 (s.e. 12) for 1992. The corresponding

average rates of mesoplodont beaked whale kill per fishing day are 0.006, 0, 0.005, and 0 for 1990, 1991, 1992 and 1993,

respectively. Preliminary mortality data for 1994 indicate that three unidentified beaked whales, which may have been

mesoplodont beaked whales, were observed killed (NMFS, unpublished data). The average annual estimated mortality

of whales identified to the genus Mesoplodon for the three complete years of monitoring, 1991-93, is 7.7 animals.

Similar drift gillnet fisheries for swordfish and sharks exist along the entire Pacific coast of Baja California,

Mexico and may take animals from the same population. Quantitative data are available only for the Mexican swordfish

drift gillnet fishery, which has increased from two vessels in 1986 to 29 vessels in 1992 (Sosa-Nishizaki et al. 1993). The

total number of sets in this fishery in 1992 can be estimated from data provided by these authors to be approximately

2700, with an observed rate of marine mammal bycatch of 0.13 animals per set (10 marine mammals in 77 observed sets;

Sosa-Nishizaki et al. 1993). This overall mortality rate is similar to that observed in California driftnet fisheries during

1990-93 (0.15 marine mammals per set), but species-specific information is not available for the Mexican fisheries.

Fishery Mortality Rate

The total fishery mortality and serious injury for mesoplodont beaked whales during 199l-93 (7.7 animals per

year) is greater than the calculated PBR and: therefore, cannot be considered to be insignificant and approaching zero

mortality and serious injury rate. This determination cannot be made for individual fisheries until the implementing

regulations for Section 118 of the MMPA have been reviewed by the public and finalized.

STATUS OF STOCK

The status of mesoplodont beaked whales in California, Oregon and Washington waters relative to OSP is not

known, and there are insufficient data to evaluate trends in abundance. None of the five species is listed as “threatened”

or “endangered” under the Endangered Species Act nor as “depleted” under the MMPA. The estimated fishery mortality

for mesoplodont beaked whales exceeds the PBR, and therefore this group of species is classified as a “strategic” stock

as defined by the MMPA.

REFERENCES

Barlow, J. 1995. The abundance of cetaceans in California waters. Part I: Ship surveys in summer and fall of 1991.

Fish. Bull. 93:l-14.

Barlow, J., R. W. Baird, J. E. Heyning, K. Wynne, A. M. Manville, II, L. F. Lowry, D. Hanan, J. Sease, and V. N.

85
Burkanov. 1994. A review of cetacean and pinniped mortality in coastal fisheries along the west coast of the

USA and Canada and the east coast of the Russian Federation, Rep, lnt. Whal. Commn. Special Issue 15:405-

426.

Carretta. J. V. and K. A. Forney. 1993. Report of the two aerial surveys for marine mammals in California coastal

waters using a NOAA DeHavilland Twin Otter aircraft, March 9-April 7, 1991, February 8-April 6, 1992.

NOAA Technical Memorandum NOAA-TM-NMFS-SWFSC-185. Available from NMFS, Southwest Fisheries

Science Center: P.O. Box 271. La Jolla, California, 92038. 77p.

Diamond, S. L., J. P. Scholl and D. A. Hanan. 1987. Drift gillnet observations for the 1985-86 fishing season.

Administrative Report SWR 87-4. Available from NMFS, Southwest Region, 300 S. Ferry Street, Terminal

Island, California, 90731. 21 p.

Dohl, T. P., R. C. Guess. M. L. Durnan, and R. C. Helm. 1983. Cetaceans of central and northern California, 1980-1983:

Status, abundance and distribution. OCS Study MMS 84-0045. Minerals Management Service Contract # 14-

12-0001-29090. 284p.

Dohl, T. P.. K. S. Norris, R. C. Guess, J. D. Bryant, and M. W. Honig. 1980. Summary of marine mammal and seabird

surveys of the Southern California Bight area: 1975- 1978. Part II. Cetacea of the Southern California Bight.

Final Report to the Bureau of Land Management, NTIS Rep. No. PBS 1248 189. 414p.

Forney, K. A. 1994. Recent information on the status of odontocetes in Californian waters. NOAA Technical

Memorandum NMFS, NOAA-TM-NMFS-SWFSC-202. Available from NMFS, Southwest Fisheries Science

Center, P.O. Box 27 I, La Jolla, California: USA.

Green, G., J. J. Brueggeman, R. A. Grotefendt, C. E. Bowlby, M. L. Bonnell, and K. C. Balcomb, III. 1992. Cetacean

distribution and abundance off Oregon and Washington. Ch. 1. In: Oregon and Washington Marine Mammal

and Seabird Surveys. OCS Study 91-0093. Final Report prepared for Pacific OCS Region, Minerals

Management Service, U.S. Department of the Interior? Los Angeles, California.

Hanan. D. A., D. B. Holts, and A. L. Coan, Jr. 1993. The California drift gill net fishery for sharks and swordfish, 1981-

82 through 1990-91. Fish Bulletin 175. Available from the Marine Technical Information Center! California

Department of Fish and Game, 330 Golden Shore, Suite 50, Long Beach, CA 90802.

Hill, P. S. and J. Barlow. 1992. Report on a marine mammal survey of the California coast aboard the research vessel

McARTHUR July 28 - November 5, 1991. NOAA Technical Memorandum NMFS, NOAA-TM-NMFSSWFSC-169. Available from NMFS, Southwest Fisheries Science Center, P.O. Box 271, La Jolla, California,

USA.

Julian, F. 1993. Pinniped and cetacean mortality in California gillnet fisheries: Preliminary estimates for 1992. Working

paper SC/45/022 presented to the International Whalin,g Commission Scientific Committee, May 1993

(unpublished).

Julian, F. 1994. Pinniped and cetacean mortality in California gillnet fisheries: Preliminary estimates for 1993. Working

paper SC/46/011 presented to the International Whalin,g Commission Scientific Committee, May 1994

(unpublished).

Lennert, C., S. Kruse, M. Beeson, and J. Barlow. 1994. Estimates of incidental marine mammal bycatch in California

gillnet fisheries for July through December 1990. Rep. Int. Whal. Commn. Special Issue 15:449-463.

Mangels, K. F. and Gerrodette, T. 1994. Report of cetacean sightings during a marine mammal survey in the eastern

Pacific Ocean and Gulf of California aboard the NOAA ships McARTHUR and DAVID STARR JORDAN July

28 - November 6, 1993. NOAA Technical Memorandum NMFS? NOAA-TM-NMFS-SWFSC-211.

Mead, J. G. 1989. Beaked whales of the genus Mesoplodon. In: Ridgway, S. H. and Harrison, R. (eds.), Handbook of

Marine Mammals, Vol. 4., p. 349-430. Academic Press Limited.

National Marine Fisheries Service, Southwest Fisheries Science Center. Unpublished data.

Perkins, P., J. Barlow and M. Beeson. 1992. Pinniped and cetacean mortality in California gillnet fisheries: 1991.

Working Paper SC/44/SM14 presented to the International Whaling Commission, May 1992 (unpublished).

Sosa-Nishizaki. O., R. De la Rosa-Pacheco, R. Castro-Longoria, M. Grijalva Chon. and J. De la Rosa Velez. 1993.

Estudio biologico pesquero del pez (Xiphias gladius) y otras especies de picudos (marlins y pez vela). Rep. Int.

CICESE, CTECT9306.

86
CUVIER’S BEAKED WHALE (Ziphius cavirostris):

California/Oregon/Washington Stock

STOCK DEFINITION AND GEOGRAPHIC RANGE

Cuvier’s beaked whales are distributed widely

throughout deep waters of all oceans (Heyning 1989).

Although sightings of this species off the U.S. west coast

have been infrequent (Figure 1; data from Dohl et al.

1980, 1983; Green et al. 1992, unpublished data; Hill and

Barlow 1992; Carretta and Forney 1993; Mangels and

Gerrodette 1994; NMFS, unpublished data), they are

nonetheless the most commonly encountered beaked

whale in this region. No seasonal changes in distribution

are apparent from stranding records, and morphological

evidence is consistent with the existence of a single eastern

North Pacific population from Alaska to Baja California,

Mexico (Mitchell 1968). However, there are currently no

international agreements for cooperative management of

this species. For the Marine Mammal Protection Act

(MMPA) stock assessment reports, Cuvier’s beaked whales

within the Pacific U.S. Exclusive Economic Zone are

divided into three discrete, non-contiguous areas: 1) waters

off California, Oregon and Washington (this report), 2)

Alaskan waters, and 3) Hawaiian waters.

POPULATION SIZE

Although Cuvier’s beaked whales have been

sighted along the U.S. west coast on several line transect

surveys utilizing both aerial and shipboard platforms,

sightings have generally been too rare to produce reliable Figure 1. Cuvier’s beaked whale sightings based on aertal

population estimates. Forney (1994) reviews all available and shipboard surveys off California, Oregon and

data and concludes that the best population estimate Washington, 1975-93. (See text for data sources.)

currently available is 1,621 animals (C.V. = 0.82) based

on a 1991 ship survey along the California coast (Barlow 1995). However, in addition to being imprecise, this estimate

is biased downward by an unknown amount because of the large proportion of time this species spends submerged, and

because the ship survey covered only California waters, and thus could not observe animals off Oregon/Washington.

Furthermore, there were a large number of unidentified beaked whale sightings, which were probably either Meroplodon

sp. or Cuvier’s beaked whales (Ziphius cavirostris). Studies of the proportion of tune Cuvier’s beaked whales spend

diving will be needed to obtain more accurate abundance estimates for this species in the future.

Minimum Population Estimate

Based on the above abundance estimate and C.V., the minimum population estimate (defined as the log-normal

20th percentile of the abundance estimate) for Cuvier’s beaked whales in California, Oregon, and Washington is 886

animals. As with the best population estimate above, this value is an underestimate, but the degree of inaccuracy is

unknown.

Current Population Trend

Due to the rarity of sightings of this species on surveys along the U.S. West coast, no information exists

regarding trends in abundance of this population.

87
CURRENT AND MAXIMUM NET PRODUCTIVITY RATES

No information on current or maximum net productivity rates is available for this species.

POTENTIAL BIOLOGICAL REMOVAL

Based on this stock’s unknown status and growth rate, the recovery factor (F,) is 0.5, and 1/2Rmax is the default

value of 0.02. Multiplying these two values times the minimum population estimate of 886 yields a potential biological

removal (PBR) of 8.9 animals per year.

ANNUAL HUMAN-CAUSED MORTALITY AND SERIOUS INJURY

Fishery Information

Cuvier’s beaked whales are incidentally killed in California drift gillnet fisheries, which are used by

approximately 149 vessels (J. Cordaro, Southwest Region, NMFS, pers. comm.) to catch swordfish? thresher shark, and

mako shark in California offshore waters (Hanan et al. 1993). Fishing effort has decreased from approximately 10,000

sets per year in the mid-1980s to 6600 in 1993 (Barlow et al. 1994). Between July 1990 and December 1993, with

approximately 4-13% of California drift gillnet fisheries observed, nine Cuvier’s beaked whales were recorded killed in

driftnets (Lennert et al. 1994; Perkins et al. 1992; Julian 1993. 1994). Additionally, three unidentified beaked whales

and three unidentified cetaceans, which may have been Cuvier’s beaked whales, were reported. Based only on the

identified takes, these authors report total annual mortality estimates for Cuvier’s beaked whales as zero in 1990 and 1991,

45 (s.e. 17) in 1992, and 27 (s.e. 15) for 1993. Corresponding mortality rates are 0, 0, 0.010, and 0.004 Cuvier’s beaked

whales per fishing day for 1990, 1991, 1992 and 1993, respectively. Preliminary mortality data for 1994 indicate that

six Cuvier’s beaked whales and three unidentified beaked whales were observed killed (NMFS, unpublished data). The

average annual estimated mortality of Cuvier’s beaked whales for the three complete years of monitoring, 1991-93, is

24 animals.

Similar drift gillnet fisheries for swordfish and sharks exist along the entire Pacific coast of Baja California,

Mexico and may take animals from the same population. Quantitative data are available only for the Mexican swordfish

drift gillnet fishery. which has increased from two vessels in 1986 to 29 vessels in 1992 (Sosa-Nishizaki et al. 1993). The

total number of sets in this fishery in 1992 can be estimated from data provided by these authors to be approximately

2700, with an observed rate of marine mammal bycatch of 0.13 animals per set (10 marine mammals in 77 observed sets;

Sosa-Nishizaki et al. 1993). This overall mortality rate is similar to that observed in California driftnet fisheries during

1990-93 (0.15 marine mammals per set), but species-specific information is not available for the Mexican fisheries.

Fishery Mortality Rate

The total fishery mortality and serious injury for Cuvier’s beaked whales during 199l-93 (24 animals per year)

is greater than the calculated PBR and, therefore, cannot be considered to be insignificant and approaching zero mortality

and serious injury rate. This determination cannot be made for individual fisheries until the implementing regulations

for Section 118 of the MMPA have been reviewed by the public and finalized.

STATUS OF STOCK

The status of Cuvier’s beaked whales in California, Oregon and Washington water’s relative to OSP is not known,

and there are insufficient data to evaluate trends in abundance. They are not listed as “threatened” or “endangered” under

the Endangered Species Act nor as “depleted” under the MMPA. The estimated fishery mortality of this species exceeds

the PBR, and therefore Cuvier’s beaked whales off California, Oregon and Washington are classified as a “strategic” stock

as defined by the MMPA.

REFERENCES

Barlow, J. 1995. The abundance of cetaceans in California waters. Part 1: Ship surveys in summer and fall of 1991.

Fish. Bull. 93:1-14.

Barlow, J., R. W. Baird, J. E. Heyning, K. Wynne, A. M. Manville, II, L. F. Lowry, D. Hanan, J. Sease, and V. N.

Burkanov. 1994. A review of cetacean and pinniped mortality in coastal fisheries along the west coast of the

USA and Canada and the east coast of the Russian Federation. Rep. Int. Whal. Commn. Special Issue 15:405-

426.

Carretta, J. V. and K. A. Forney. 1993. Report of the two aerial surveys for marine mammals in California coastal

88
waters using a NOAA DeHavilland Twin Otter aircraft, March 9-April 7, 1991, February 8-April 6, 1992.

NOAA Technical Memorandum NOAA-TM-NMFS-SWFSC- 185. Available from NMFS, Southwest Fisheries

Science Center, P.O. Box 271, La Jolla, California, 92038. 77p.

Dohl, T. P., R. C. Guess, M. L. Duman, and R. C. Helm. 3983. Cetaceans of central and northern California, 1980-1983:

Status? abundance and distribution. OCS Study MMS 84-0045. Minerals Management Service Contract # 14-

12-0001-29090. 284p.

Dohl, T. P., K. S. Norris, R. C. Guess, J. D. Bryant, and M. W. Honig. 1980. Summary of marine mammal and seabird

surveys of the Southern California Bight area, 1975-1978. Part II. Cetaces of the Southern California Bight.

Final Report to the Bureau of Land Management, NTIS Rep. No. PB81248189. 414p.

Forney, K. A. 1994. Recent information on the status of odontocetes in Californian waters. NOAA Technical

Memorandum NMFS, NOAA-TM-NMFS-SWFSC-202. Available from NMFS. Southwest Fisheries Science

Center, P.O. Box 271, La Jolla, California, USA.

Green, G., J. J. Brueggeman, R. A. Grotefendt, C. E. Bowlby, M. L. Bonnell, and K. C. Balcomb, III. 1992. Cetacean

distribution and abundance off Oregon and Washington. Ch. 1. In: Oregon and Washington Marine Mammal

and Seabird Surveys. OCS Study 91-0093. Final Report prepared for Pacific OCS Region, Minerals

Management Service, U.S. Department of the Interior. Los Angeles, California.

Hanan, D. A., D. B. Holts, and A. L. Coan, Jr. 1993. The California drift gill net fishery for sharks and swordfish, 1981-

82 through 1990-91. Fish Bulletin 175. Available from the Marine Technical Information Center, California

Department of Fish and Game, 330 Golden Shore, Suite 50, Long Beach, CA 90802.

Heyning, J. E. 1989. Cuvier’s beaked whale Ziphius cavirostris G. Cuvier, 1823. pp. 289-308 In: Ridgway, S. H. and

R. Harrison (eds.), Handbook of Marine Mammals, Vol. 4. Academic Press.

Hill, P. S. and J. Barlow. 1992. Report on a marine mammal survey of the California coast aboard the research vessel

McARTHUR July 28 - November 5, 1991. NOAA Technical Memorandum NMFS, NOAA-TM-NMFSSWFSC-169. Available from NMFS, Southwest Fisheries Science Center, P.O. Box 271, La Jolla, California,

USA.

Julian, F. 1993. Pinniped and cetacean mortality in California gillnet fisheries: Preliminary estimates for 1992. Working

paper SC/45/O22 presented to the International Whaling Commission Scientific Committee, May 1993

(unpublished).

Julian, F. 1994. Pinniped and cetacean mortality in California gillnet fisheries: Preliminary estimates for 1993. Working

paper SC/46/011 presented to the International Whaling Commission Scientific Committee? May 1994

(unpublished).

Lennert, C., S. Kruse, M. Beeson, and J. Barlow. 1994. Estimates of incidental marine mammal bycatch in California

gillnet fisheries for July through December 1990. Rep. Int. Whal. Commn. Special Issue 151449-463.

Mangels, K. F. and Gerrodette, T. 1994. Report of cetacean sightings during a marine mammal survey in the eastern

Pacific Ocean and Gulf of California aboard the NOAA ships McARTHUR and DAVID STARR JORDAN July

28 - November 6, 1993. NOAA Technical Memorandum NMFS, NOAA-TM-NMFS-SWFSC-211.

Mitchell, E. 1968. Northeast Pacific stranding distribution and seasonality of Cuvier’s beaked whale, Ziphius cavirostris.

Can. J. Zool. 46:265-279.

National Marine Fisheries Service, Southwest Fisheries Science Center. Unpublished data.

Perkins, P., J. Barlow and M. Beeson. 1992. Pinniped and cetacean mortality in California gillnet fisheries: 1991.

Working Paper SC/44/SMl4 presented to the International Whaling Commission? May 1992 (unpublished).

Sosa-Nishizaki, O., R. De la Rosa-Pacheco, R. Castro-Longoria, M. Grijalva Chon, and J. De la Rosa Velez. 1993.

Estudio biologico pesquero del pez (Xiphias gladius) y otras especies de picudos (marlins y pez vela). Rep. h-it.

CICESE, CTECT9306.

89
PYGMY SPERM WHALE (Kogia breviceps):

California/Oregon/Washington Stock

STOCK DEFINITION AND GEOGRAPHIC RANGE

Pygmy sperm whales are distributed throughout

deep waters and along the continental slopes of the

North Pacific and other ocean basins (Caldwell and

Caldwell 1989; Ross 1984). Along the U.S. west coast,

sightings of this species and of animals identified only as

Kogia sp. have been very rare (Figure 1: data from Dohl

et al. 1980, 1983; Green et al. 1992, unpublished data;

Hill and Barlow 1992; Mangels and Gerrodette 1994,

NMFS, unpublished data). However, this is probably a

reflection of their pelagic distribution, small body size

and cryptic behavior, rather than an indication of true

rareness. Strandings of pygmy sperm whales in this

region are known from California, Oregon and

Washington (Roest 1970; Caldwell and Caldwell 1989;

ODFG, unpublished data; NMFS, unpublished data).

Available data are insufficient to identify any seasonality

in the distribution of pygmy sperm whales, or to

delineate possible stock boundaries. For the Marine

Mammal Protection Act (MMPA) stock assessment

reports, pygmy sperm whales within the Pacific U.S.

Exclusive Economic Zone are divided into two discrete,

non-contiguous areas: 1) waters off California, Oregon

and Washington (this report), and 2) Hawaiian waters.

POPULATION SIZE

Although pygmy sperm whales have been

sighted along the U.S. west coast on several line transect

Figure 1. Kogia breviceps (o) and Kogia sp. (x) sighting

based on aerial and shipboard surveys off California, Oregon

and Washington, 197593 (see text for data sources).

surveys utilizing both aerial and shipboard platform sightings have generally been too rare to produce reliable

population estimates. Forney (1994) reviews all available data and concludes that the best population estimate currently

available is 870 animals (C.V. = 0.80) based on a 1991 ship survey along the California coast (Barlow 1995). However,

in addition to being imprecise, this estimate is biased downward by an unknown amount because pygmy sperm whales

spend a large proportion of time submerged and are very difficult to detect at the surface unless seas are calm.

Furthermore, the ship survey covered only California waters, and thus could not observe animals off Oregon/Washington.

Additional surveys and studies of the proportion of time this species spends diving will be needed to obtain more accurate

abundance estimates for this species in the future.

Minimum Population Estimate

Based on the above abundance estimate and C.V., the minimum population estimate (defined as the log-normal

20th percentile of the abundance estimate) for pygmy sperm whales in California: Oregon, and Washington is 481

animals. As with the best population estimate above, this value is an underestimate, but the degree of inaccuracy is

unknown.

Current Population Trend

Due to the rarity of sightings of this species on surveys along the U.S. West coast, no information exists

regarding trends in abundance of this population.

90
CURRENT AND MAXIMUM NET PRODUCTIVITY RATES

No information on current or maximum net productivity rates is available for this species.

POTENTIAL BIOLOGICAL REMOVAL

Based on this stock’s unknown status and growth rate, the recovery factor (F,) is 0.5, and 1/2Rmax is the default

value of 0.02. Multiplying these two values times the minimum population estimate of 481 yields a potential biological

removal (PBR) of 4.8 animals per year.

ANNUAL HUMAN-CAUSED MORTALITY AND SERIOUS INJURY

Fishery Information

Pygmy sperm whales are incidentally killed in California drift gillnet fisheries, which are used by approximately

149 vessels (J. Cordaro, Southwest Region, NMFS, pers. comm.) to catch swordfish, thresher shark, and mako shark in

California offshore waters (Hanan et al. 1993). Fishing effort has decreased from approximately 10,000 sets per year

in the mid-1980s to 6600 in 1993 (Barlow et al. 1994). Between July 1990 and December 1993, with approximately 4-

13% of California drift gillnet fisheries observed, two pygmy sperm whales were recorded killed in driftnets (Lennert

et al. 1994; Perkins et al. 1992; Julian 1993, 1994). Additionally, three unidentified cetaceans, which may have been

pygmy sperm whales, were reported in the driftnet fishery. Based only on the identified animals, total annual mortality

estimates for pygmy sperm whales are zero for 1990-91, eight (s.e. 7.0) in 1992 and nine (se. 8.6) for 1993.

Corresponding mortality rates per fishing day for pygmy sperm whales are zero in 1990-91, 0.002 animals in 1992, and

0.001 animals for 1993. Preliminary mortality data for 1994 indicate that no pygmy sperm whales, unidentified Kogia

or unidentified cetaceans were observed killed (NMFS unpublished data). The average annual estimated mortality of

pygmy sperm whales for this fishery for the three complete years of monitoring. 1991-93, is 5.7 animals.

Similar drift gillnet fisheries for swordfish and sharks exist along the entire Pacific coast of Baja California,

Mexico and may take animals from the same population. Quantitative data are available only for the Mexican swordfish

drift gillnet fishery, which has increased from two vessels in 1986 to 29 vessels in 1992 (Sosa-Nishizaki et al. 1993). The

total number of sets in this fishery in 1992 can be estimated from data provided by these authors to be approximately

2700, with an observed rate of marine mammal bycatch of 0.13 animals per set (10 marine mammals in 77 observed sets;

Sosa-Nishizaki et al. 1993). This overall mortality rate is similar to that observed in California driftnet fisheries during

1990-93 (0.15 marine mammals per set), but species-specific information is not available for the Mexican fisheries.

Fishery Mortality Rate

The total fishery mortality and serious injury for pygmy sperm whales during 1991-93 (5.7 animals per year)

is greater than the calculated PBR and, therefore, cannot be considered to be insignificant and approaching zero mortality

and serious injury rate. This determination cannot be made for individual fisheries until the implementing regulations

for Section 118 of the MMPA have been reviewed by the public and finalized.

STATUS OF STOCK

The status of pygmy sperm whales in California, Oregon and Washington waters relative to OSP is not known,.

and there are insufficient data to evaluate potential trends in abundance. They are not listed as “threatened” or

“endangered” under the Endangered Species Act nor as “depleted” under the MMPA. Because the average estimated

fishery mortality of this species in 1991-93 exceeds the PBR, pygmy sperm whales off California, Oregon and

Washington are classified as a “strategic” stock under the MMPA.

REFERENCES

Barlow, J. 1995. The abundance of cetaceans in California waters. Part I: Ship surveys in summer and fall of 1991.

Fish. Bull. 93:1-14.

Barlow, J., R. W. Baird, J. E. Heyning, K. Wynne. A. M. Manville, II, L. F. Lowry, D. Hanan, J. Sease, and V. N.

Burkanov. 1994. A review of cetacean and pinniped mortality in coastal fisheries along the west coast of the

USA and Canada and the east coast of the Russian Federation. Rep. lnt. Whal. Commn. Special Issue 15:405-

426.

Caldwell, D. K. and M. C. Caldwell. 1989. Pygmy sperm whale Kogia breviceps (de Blainville, 1838): Dwarf sperm

whale Kogiu simus Owen, 1866. pp. 235-260 In: Ridgway, S. H. and R. Harrison (eds.), Handbook of Marine

91
Mammals, Vol. 4. Academic Press.

Dohl: T. P., R. C. Guess, M. L. Duman, and R. C. Helm. 1983. Cetaceans of central and northern California, 1980-1983:

Status, abundance and distribution. OCS Study MMS 84-0045. Minerals Management Service Contract # 14-

12-000 l-29090. 284p.

Dohl, T. P.. K. S. Norris, R. C. Guess, J. D. Bryant, and M. W. Honig. 1980. Summary of marine mammal and seabird

surveys of the Southern California Bight area, 19751978. Part II. Cetaces of the Southern California Bight.

Final Report to the Bureau of Land Management, NTIS Rep. No. PB81248189. 414p.

Forney, K. A. 1994. Recent information on the status of odontocetes in Californian waters. NOAA Technical

Memorandum NMFS, NOA4-TM-NMFS-SWFSC-202. Available from NMFS, Southwest Fisheries Science

Center, P.O. Box 271, La Jolla, California, USA.

Green, G., J. J. Brueggeman, R. A. Grotefendt, C. E. Bowlby, M. L. Bonnell, and K. C. Balcomb, 111. 1992. Cetacean

distribution and abundance off Oregon and Washington. Ch. 1. In: Oregon and Washington Marine Mammal

and Seabird Surveys. OCS Study 91-0093. Final Report prepared for Pacific OCS Region, Minerals

Management Service, U.S. Department of the Interior, Los Angeles, California.

Hanan, D. A., D. B. Holts, and A. L. Coan, Jr. 1993. The California drift gill net fishery for sharks and swordfish, l981-

82 through 1990-91. Fish Bulletin 175. Available from the Marine Technical Information Center, California

Department of Fish and Game, 330 Golden Shore, Suite 50, Long Beach, CA 90802.

Hill, P. S. and J. Barlow. 1992. Report on a marine mammal survey of the California coast aboard the research vessel

McARTHUR July 28 - November 5, 1991. NOAA Technical Memorandum NMFS, NOAA-TM-NMFSSWFSC-169. Available from NMFS, Southwest Fisheries Science Center, P.O. Box 271, La Jolla, California,

USA.

Julian, F. 1993. Pinniped and cetacean mortality in California gillnet fisheries: Preliminary estimates for 1992. Working

paper SC/45/022 presented to the International Whaling Commission Scientific Committee, May 1993

(unpublished).

Julian, F. 1994. Pinniped and cetacean mortality in California gillnet fisheries: Preliminary estimates for 1993. Working

paper SC/46/011 presented to the International Whaling Commission Scientific Committee, May 1994

(unpublished).

Lennen, C., S. Kruse, M. Beeson, and J. Barlow. 1994. Estimates of incidental marine mammal bycatch in California

gillnet fisheries for July through December 1990. Rep. Int. Whal. Commn. Special Issue 15:449-463.

Mangels, K. F. and Gerrodette: T. 1994. Report of cetacean sightings during a marine mammal survey in the eastern

Pacific Ocean and Gulf of California aboard the NOAA ships McARTHUR and DAVID STARR JORDAN July

28 - November 6, 1993. NOAA Technical Memorandum NMFS, NOAA-TM-NMFS-SWFSC-211.

National Marine Fisheries Service, Southwest Fisheries Science Center. Unpublished data.

Oregon Department of Fish and Game, Unpublished data.

Perkins, P., J. Barlow and M. Beeson. 1992. Pinniped and cetacean mortality in California gillnet fisheries: 1991.

Working Paper SC/44/SM14 presented to the International Whaling Commission, May 1992 (unpublished).

Roest, A. L. 1970. Kogia simus and other cetaceans from San Luis Obispo County, California. J. Mammol. 51:410-417.

Ross, G. J. B. 1984. The smaller cetaceans of the south east coast of southern Africa. Ann. Cape Prov. Mus. Nat. Hist.

15:173-410.

Sosa-Nishizaki, O., R. De la Rosa-Pacheco, R. Castro-Longoria, M. Grijalva Chon, and J. De la Rosa Velez. 1993.

Estudio biologico pesquero del pez (Xiphias gladius) y otras especies de picudos (marlins y pez vela). Rep. Int.

CICESE, CTECT9306.

92
DWARF’ SPERM WHALE (Kogia simus):

California/Oregon/Washington Stock

STOCK DEFINITION AND GEOGRAPHIC RANGE

Dwarf sperm whales are distributed throughout

deep waters and along the continental slopes of the

North Pacific and other ocean basins (Caldwell and

Caldwell 1989; Ross 1984). This species was only

recognized as being distinct from the pygmy sperm

whale in 1966 (Handley, 1966), and early records for the

two species are confounded. Along the U.S. west coast,

no at-sea sightings of this species have been reported;

however, this may be partially a reflection of their

pelagic distribution, small body size and cryptic

behavior. A few sightings of animals identified only as

Kogia sp. have been reported (Figure 1; data from Dohl

et al. 1983; Green et al. 1992; Mangels and Gerrodette

1994), and some of these may have been dwarf sperm

whales. At least three dwarf sperm whales stranded in

California between 1967 and 1981 (Roest 1970; Jones

1981; J. Heyning, pers. comm.), and one stranding is

reported for western Canada and (Nagorsen and Stewart

1983). It is unclear whether records of dwarf sperm

whales are so rare because they are not regular

inhabitants of this region, or merely because of their

cryptic habits and offshore distribution. Available data

are insufficient to identify any seasonality in the

distribution of dwarf sperm whales, or to delineate

possible stock boundaries. For the Marine Mammal

Protection Act (MMPA) stock assessment reports, dwarf

sperm whales within the Pacific U.S. Exclusive

Economic Zone are divided into two discrete, non- Figure 1. Kogia sp. (o) sightings based on aerial and shipboard

contiguous areas: 1) waters off California, Oregon and surveys off California, Oregon and Washington, 1975-93 (see text

Washington (this report), and 2) Hawaiian waters. for data sources).

POPULATION SIZE

No information is available to estimate the population size of dwarf sperm whales off California.

Minimum Population Estimate

No information is available to obtain a minimum population estimate for dwarf sperm whales.

Current Population Trend

Due to the rarity of records for this species along the U.S. West coast, no information exists regarding trends

in abundance of this population.

CURRENT AND MAXIMUM NET PRODUCTIVITY RATES

No information on current or maximum net productivity rates is available for this species,

POTENTIAL BIOLOGICAL REMOVAL

Based on this stock’s unknown status and growth rate, the recovery factor (F,) is 0.5, and 1/2Rmax is the default

value of 0.02. However, due to the lack of abundance estimates for this species, no potential biological removal (PBR)

93
can be calculated.

ANNUAL HUMAN-CAUSED MORTALITY AND SERIOUS INJURY

Fishery Information

Dwarf sperm whales are susceptible to mortality in California drift gillnet fisheries, which are used by

approximately 149 vessels (J. Cordaro, Southwest Region, NMFS, pers. comm.) to catch swordfish, thresher shark, and

mako shark in California offshore waters (Hanan et al. 1993). Fishing effort has decreased from approximately 10,000

sets per year in the mid- 1980s to 6600 in 1993 (Barlow et al. 1994). Between July 1990 and December 1993, with

approximately 4-13% of California drift gillnet fisheries observed, no dwarf sperm whales were recorded killed in

driftnets (Lennert et al. 1994; Perkins et al. 1992; Julian 1993. 1994) but three unidentified cetaceans, which may have

been dwarf sperm whales, were reported in the driftnet fishery. Preliminary mortality data for 1994 indicate that no dwarf

sperm whales, unidentified Kogia, or unidentified cetaceans were observed killed (NMFS, unpublished data). Excluding

the unidentified cetaceans, no mortality of dwarf sperm whales species has been observed in the drift gillnet fishery.

However, based on the small body size of this species and on patterns of take for other cetaceans: it is likely that gillnet

mortality of this species will occur in the future.

Similar drift gillnet fisheries for swordfish and sharks exist along the entire Pacific coast of Baja California,

Mexico and may take animals from the same population. Quantitative data are available only for the Mexican swordfish

drift gillnet fishery, which has increased from two vessels in 1986 to 29 vessels in 1992 (Sosa-Nishizaki et al. 1993). The

total number of sets in this fishery in 1992 can be estimated from data provided by these authors to be approximately

2700, with an observed rate of marine mammal bycatch of 0. 13 animals per set (IO marine mammals in 77 observed sets;

Sosa-Nishizaki et al. 1993). This overall mortality rate is similar to that observed in California driftnet fisheries during

1990-93 (0.15 marine mammals per set), but species-specific information is not available for the Mexican fisheries.

Fishery Mortality Rate

The total fishery mortality and serious injury for this stock can be considered to be insignificant and approaching

zero, because no fishery takes have been reported.

STATUS OF STOCK

The status of dwarf sperm whales in California? Oregon and Washington waters relative to OSP is not known,

and there are insufficient data to evaluate potential trends in abundance. They are not listed as “threatened” or

“endangered” under the Endangered Species Act nor as “depleted” under the MMPA. Because there has been no

observed fishery mortality of this species. dwarf sperm whales off California: Oregon and Washington are not classified

as a “strategic” stock under the MMPA.

REFERENCES

Barlow, J., R. W. Baird, J. E. Heyning, K. Wynne: A. M. Manville, II, L. F. Lowry, D. Hanan, J. Sease, and V. N.

Burkanov. 1994. A review of cetacean and pinniped mortality in coastal fisheries along the west coast of the

USA and Canada and the east coast of the Russian Federation. Rep. Int. Whal. Commn. Special Issue 15:405-

426.

Caldwell, D. K. and M. C. Caldwell. 1989. Pygmy sperm whale Kogia breviceps (de Blainville, 1838): Dwarf sperm

whale Kogia simus Owen, 1866. pp. 235-260 In: Ridgway, S. H. and R. Harrison (eds.), Handbook of Marine

Mammals, Vol. 4. Academic Press.

Dohl, T. P., R. C. Guess, M. L. Duman, and R. C. Helm. 1983. Cetaceans of central and northern California, 1980-1983:

Status, abundance and distribution. OCS Study MMS 84-0045. Minerals Management Service Contract # 14-

12-0001-29090. 284p.

Forney. K. A. 1994. Recent information on the status of odontocetes in Californian waters. NOAA Technical

Memorandum NMFS, NOAA-TM-NMFS-SWFSC-202. Available from NMFS, Southwest Fisheries Science

Center, P.O. Box 271, La Jolla, California, USA.

Green: G., J. J. Brueggeman, R. A. Grotefendt, C. E. Bowlby, M. L. Bonnell, and K. C. Balcomb, III. 1992. Cetacean

distribution and abundance off Oregon and Washington. Ch. 1. In: Oregon and Washington Marine Mammal

and Seabird Surveys. OCS Study 91-0093. Final Report prepared for Pacific OCS Region, Minerals

Management Service, U.S. Department of the Interior, Los Angeles, California.

94
Hanan, D. A., D. B. Holts, and A. L. Coan, Jr. 1993. The California drift gill net fishery for sharks and swordfish, 198l82 through 1990-91. Fish Bulletin 175. Available from the Marine Technical Information Center, California

Department of Fish and Game, 330 Golden Shore, Suite 50, Long Beach, CA 90802.

Handley, C. 0. Jr. 1966. A synopsis of the genus Kogia (pygmy sperm whales). pp. 62-69 In: K. S. Norris (ed.),

Inhales, dolphins and porpoises. University of California Press, Berkeley.

Jones, R. E. 1981. Food habits of smaller marine mammals from northern California. Proc. California Acad. Sci.

42:409-433.

Julian, F 1993. Pinniped and cetacean mortality in California gillnet fisheries: Preliminary estimates for 1992. Working

paper SC/45/022 presented to the International Whaling Commission Scientific Committee, May 1993

(unpublished).

Julian, F. 1994. Pinniped and cetacean mortality in California gillnet fisheries: Preliminary estimates for 1993. Working

paper SC/46/011 presented to the International Whaling Commission Scientific Committee, May 1994

(unpublished).

Lennert, C., S. Kruse, M. Beeson, and J. Barlow. 1994. Estimates of incidental marine mammal bycatch in California

gillnet fisheries for July through December 1990. Rep. lnt. Whal. Commn. Special Issue 15:449-463.

Mangels, K. F. and Gerrodette, T. 1994. Report of cetacean sightings during a marine mammal survey in the eastern

Pacific Ocean and Gulf of California aboard the NOAA ships McARTHUR and DAVID STARR JORDAN July

28 - November 6, 1993. NOAA Technical Memorandum NMFS, NOAA-TM-NMFS-SWFSC-211.

Nagorsen, D. W. and G. E. Stewart. 1983. A dwarf sperm whale (Kogia simus) from the Pacific coast of Canada. J.

Mamm. 64:505-506.

Perkins, P.. J. Barlow and M. Beeson. 1992. Pinniped and cetacean mortality in California gillnet fisheries: 1991.

Working Paper SC/44/SM14 presented to the International Whaling Commission, May 1992 (unpublished).

Roest, A. I. 1970. Kogia simus and other cetaceans from San Luis Obispo County, California. J. Mammal. 51:410-417.

Ross, G. J. B. 1984. The smaller cetaceans of the south east coast of southern Africa. Ann. Cape Prov. Mus. Nat. Hist.

15:173-410.

Sosa-Nishizaki, O., R. De la Rosa-Pacheco, R. Castro-Longoria, M. Grijalva Chon, and J. De la Rosa Velez. 1993.

Estudio biologico pesquero del pez (Xiphias gladius) y otras especies de picudos (marlins y pez vela). Rep. Int.

CICESE, CTECT9306.

95
SPERM WHALE (Physeter macrocephalus):

California/Oregon/Washington Stock

STOCK DEFINITION AND GEOGRAPHIC RANGE

Sperm whales are widely distributed across the entire North Pacific, primarily south of 40°N (Gosho et al. 1984).

For management, the lnternational Whaling Commission (IWC) had divided the North Pacific into two management

regions (Donovan 1991) defined by a zig-zag line which starts at 150°W at the equator, is l6O°W between 40-5OoN, and

ends up at 180°W north of 50°N; however, the IWC has not reviewed this stock boundary in many years (Donovan

1991). Sperm whales are found year-round in California waters (Dohl et al. 1983; Barlow 1995; Forney et al. 1995)

and any possible affinity between sperm whales along the U.S. West Coast and animals found further offshore or further

south is unknown. For the Marine Mammal Protection Act (MMPA) stock assessment reports, sperm whales within the

Pacific U.S. EEZ are divided into three discrete, non-contiguous areas: I) California, Oregon and Washington waters (this

report), 2) waters around Hawaii, and 3) Alaska waters. Recent surveys in the eastern tropical Pacific (Wade and

Gerrodette 1993) show that although sperm whales are widely distributed in the tropics, their relative abundance tapers

off markedly westward towards the middle of the tropical Pacific (near the IWC stock boundary at l50°W) and tapers

off northward towards the tip of Baja California. The structure of sperm whale populations in the eastern tropical Pacific

is not known, but the only matches of known individuals from this area have been between the Galapagos Islands and

coastal waters of South America (Dufault and Whitehead 1995), suggesting that the eastern tropical animals constitute

a distinct stock.

POPULATION SIZE

Barlow (1995) estimates 756 (CV=O.49) sperm whales in California coastal waters during summer/fall based

on ship line transect surveys (95% C.I.=303-1,886). Forney et al. (1995) estimate 892 (CV=O.99) sperm whales there

during winter/spring based on aerial line-transect surveys (95% C.I.=176-4,506), but this estimate does not correct for

diving whales that were missed. Because of the long dive time of sperm whales (Leatherwood et al. 1982), it is

reasonable to assume that the true abundance would be 3 to 8 times the estimates from aerial surveys. Green et al. (1992)

report that sperm whales were the third most abundant large whale (after gray and humpback whales) in aerial surveys

of Oregon and Washington, but they did not estimate population size for that area. The only abundance estimates for

the entire eastern North Pacific is for 1982 (Gosho et al. 1984) and is based on a CPUE method which is no longer

accepted as valid by the International Whaling Commission. Using a different method (line transects), the abundance

of sperm whales has been estimated recently as 22,700 (95% C.I.=14,800-34,600) in the eastern tropical Pacific (Wade

and Gerrodette 1993), but this area does not include areas where sperm whales are taken by drift gillnet fisheries in the

U.S. EEZ and there is no evidence of sperm whale movements from the eastern tropical Pacific to the U.S. EEZ. The

most precise estimate of sperm whale abundance within the area of the drift gillnet fishery is therefore from the ship

survey estimate of Barlow (1995).

Minimum Population Estimate

The minimum population estimate for sperm whales is taken as the lower 20th percentile of the log-normal

distribution of abundance estimated from the summer/fall ship survey in California waters (Barlow 1995) or

approximately 512. More sophisticated methods of estimating minimum population size would be available if a

correction factor (and associated variance) were available to correct the aerial survey estimates for missed animals.

Additional information is needed on the abundance of sperm whales in waters off Oregon and Washington.

Current Population Trend

Sperm whale abundance appears to have been fairly stable in California coastal waters between 1979/80 and

1991 (Barlow 1994). Although the population in the eastern North Pacific is expected to have grown since large-scale

pelagic whaling stopped in 1980, the possible effects of continued unauthorized take (Yablokov 1994) and incidental ship

strikes and gillnet mortality make this uncertain.

CURRENT AND MAXIMUM NET PRODUCTIVITY RATES

There are no estimates of the growth rate for any sperm whale population (Best 1993).

96
POTENTIAL BIOLOGICAL REMOVAL

The potential biological removal (PBR) level for the California portion of this stock is calculated as the

minimum population size (5 12) times one half the default maximum net growth rate for cetaceans (l/2 of 4%) times a

recovery factor of 0.1 (for an endangered species), resulting in a PBR of 1.0.

ANNUAL HUMAN-CAUSED MORTALITY

Historic Whaling

The reported take of North Pacific sperm whales by commercial whalers totalled 258.000 between 1947 and

1987 (C. Allison, IWC, pers. comm.). There has been a prohibition on taking sperm whales in the North Pacific since

1988, but large-scale pelagic whaling stopped earlier, in 1980.

Fishery Information

Sperm whales are likely to be caught only in offshore drift gillnets. Drift gillnets are used by approximateiy

149 vessels (J. Cordaro, Southwest Region, NMFS, pers. comm.) to catch swordfish, thresher shark, and mako shark in

California offshore waters (Hanan et al. 1993). Driftnet fishing effort has decreased from approximately 10,000 sets per

year in the mid-1980s to 6,600 in 1993 (Barlow et al. 1994). Two unidentified whales, possibly sperm whales, were

taken in the approximately 1% of drift gillnets observed in 1980-85 (Hanan 1986; Heyning and Lewis 1990). Six sperm

whales have been observed taken from 1990 to 1993 in gillnet observation programs which covered 5-13% of fishing

effort (Lennert et al. 1994; Perkins et al. 1992; Julian 1993, 1994) of which, three were released alive (although probably

injured). The resulting estimates of annual mortality and serious injury for sperm whales are 23 in 1992 (Julian 1993)

and 27 in 1993 (Julian 1994). In addition, much of the gillnet mortality of large whales may go unobserved because

whales swim away with portion of the net. The deaths of two stranded sperm whales in California were attributed to

entanglement in fishing gear between 1983 and 1991 (J. Cordaro, Southwest Region, NMFS, pers. comm.).

Similar drift gillnet fisheries for swordfish and sharks exist along the entire Pacific coast of Baja California,

Mexico and may take animals from the same population. Quantitative data are available only for the Mexican swordfish

drift gillnet fishery, which has increased from two vessels in 1986 to 29 vessels in 1992-(Sosa-Nishizaki et al. 1993). The

total number of sets in this fishery in 1992 can be estimated from data provided by these authors to be approximately

2,700, with an observed rate of marine mammal bycatch of 0.13 animals per set (10 marine mammals in 77 observed sets;

Sosa-Nishizaki et al. 1993). This overall mortality rate is similar to that observed in California driftnet fisheries during

1990-93 (0.15 marine mammals per set), but species-specific information is not available for the Mexican fisheries.

Fishery Mortality Rates

Over the last 3 years, the average annual rate of mortality and serious injury in fisheries has been I7 sperm

whales per year. This exceeds the calculated PBR; therefore, total fishery mortality is not approaching zero mortality

and serious injury rate. This determination cannot be made for individual fisheries until the implementing regulations

for Section 118 of the MMPA have been reviewed by the public and finalized. In comparing gillnet mortality with the

PBR, it should be remembered that the PBR does not include sperm whales found off Oregon and Washington and does

not include animals further offshore which possibly belong to the same population. A fishery interaction problem appears

to exist for sperm whales taken in the drift gillnet fishery, but enough uncertainties exist that one should not conclude

from this information that sperm whales are necessarily declining in abundance off the U.S. West Coast. Additional

research is clearly needed for this species.

Ship Strikes

Ship strikes were implicated in the deaths of two unidentified whales (possibly sperm whales) in 1990 (J.

Cordaro, Southwest Region, NMFS, pers. comm.). Additional mortality from ship strikes probably goes unreported

because the whales do not strand or, if they do, they do not always have obvious signs of trauma.

STATUS OF STOCK

Overall, sperm whales were estimated to be at 88% (274,000 out of 3 11,000 mature whales) of historical

carrying capacity in the eastern North Pacific and 64% (198,100 out of 309,400 mature whales) in the western North

Pacific (Gosho et al. 1984). Sperm whales are formally listed as “endangered” under the Endangered Species Act (ESA),

and consequently the California to Washington stock is automatically considered as a “depleted” and “strategic” stock

97
under the MMPA. The annual rate of kill and serious injury is greater than the calculated PBR for this stock.

REFERENCES

Barlow, J. 1994. Abundance of large whales in California coastal waters: a comparison of ship surveys in 1979/80 and

in 1991. Rept. Int. Whal. Commn. 44:399-406.

Barlow, J. 1995. The abundance of cetaceans in California waters, Part I: Ship surveys in summer and fall of 1991.

Fish. Bull. 93:l-14.

Barlow, J., R. W. Baird. J. E. Heyning, K. Wynne, A. M. Manville. II. L. F. Lowry, D. Hanan, J. Sease, and V. N.

Burkanov. 1994. A review of cetacean and pinniped mortality in coastal fisheries along the west coast of the

U.S. and Canada and the east coast of the Russian Federation. Rep. Int. Whal. Commn, Special Issue 15:405-

425.

Best. P. B. 1993. Increase rates in severely depleted stocks of baleen whales. ICES J. Mar. Sci. 50: 169- 186.

Dohl: T. P., R. C. Guess, M. L. Duman, and R. C. Helm. 1983. Cetaceans of central and northern California, 1980-83:

Status? abundance, and distribution. Final Report to the Minerals Management Service, Contract No. 14- I2-

0001 -29090. 284p.

Donovan, G. P. 1991. A review of IWC stock boundaries. Rept. lnt. Whal. Commn., Special Issue 13:39-68.

Dufault, S. and H. Whitehead. 1995. The geographic stock structure of female and immature sperm whales in the South

Pacific. Rep. Int. Whal. Commn. 45:401-405.

Forney, K. A., J. Barlow, and J. V. Carretta. 1995. The abundance of cetaceans in California waters. Part IL: Aerial

surveys in winter and spring of 1991 and 1992. Fish. Bull. 93: 15-26.

Gosho. M. E., D. W. Rice, and J. M. Breiwick. 1984. The sperm whale. Mar. Fish. Rev. 46(4):54-64.

Green, G. A., J. J. Brueggeman, R. A. Grotefendt. C. E. Bowlby, M. L. Bonnell, K. C. Balcomb, III. 1992. Cetacean

distribution and abundance off Oregon and Washington, 1989-1990. Ch. 1 In: J. J. Brueggeman (ed.). Oregon

and Washington Marine Mammal and Seabird Surveys. Minerals Management Service Contract Report l4-l2-

0001-30426.

Hanan, D. A. 1986. California Department of Fish and Game coastal marine mammal study, annual report for the period

July I, 1983 - June 30. 1984. Admin. Rept. LJ-86-16 available from Southwest Fisheries Science Center, P.O.

Box 271, La Jolla, CA. 55pp.

Hanan, D. A., D. B. Holts. and A. L. Coan, Jr. 1993. The California drift gill net fishery for sharks and swordfish, l981-

82 through 1990-91. Calif. Dept. Fish and Game Fish. Bull. No. 175. 95pp.

Heyning, J. E., and T. D. Lewis. 1990. Fisheries interactions involving baleen whales off southern California. Rep. int.

Whal. Commn. 403427-431.

Julian? F. 1993. Pinniped and cetacean mortality in California gillnet fisheries: Preliminary estimates for 1992. Int.

Whal. Comm. Working Paper SC/45/022.

Julian F. 1994. Pinniped and cetacean mortality in California gillnet fisheries: Preliminary estimates for 1993. Int.

Whal. Comm. Working Paper SC/46/Oll.

Leatherwood, S., K. Goodrich, A. L. Kinter, and R. M. Truppo. 1982. Respiration patterns and ‘sightability’ of whales.

Rep. Int. Whal. Commn. 32:601-613.

Lennert, C., S. Kruse, M. Beeson, and J. Barlow. 1994. Estimates of incidental marine mammal bycatch in California

gillnet fisheries for July through December, 1990. Int. Whal. Commn., Special Issue 15:449-461.

Perkins, P., J. Barlow, and M. Beeson. 1992. Pinniped and cetacean mortality in California gillnet fisheries: 1991.

I WC Working Paper SC/44/SM14.

Rice, D. W. 1988. Sperm whale Physeter macrocephalus, Linnaeus 1758. pp. 177-233 In: S. H. Ridgway and R. J.

Harrison (eds.). Handbook of Marine Mammals, Vol. 4. Academic Press, London.

Sosa-Nishizaki, O., R. De la Rosa Pacheco, R. Castro Longoria, M. Grijalva Chon, and J. De la Rosa Velez. 1993.

Estudio biologico pesquero del pez (Xiphias gladius) y otras especies de picudos (marlins y pez vela). Rep. lnt.

CICESE, CTECT9306.

Wade, P. R. and T. Gerrodette. 1993. Estimates of cetacean abundance and distribution in the eastern tropical Pacific.

Rept. Int. Whal. Commn. 43:477-493.

Yablokov, A. V. 1994. Validity of whaling data. Nature 367: 108.

98
HUMPBACK WHALE (Megaptera novaeangliae):

California/Oregon/Washington - Mexico Stock

STOCK DEFINITION AND GEOGRAPHIC RANGE

Although the International Whaling Commission (IWC) only considered one stock (Donovan 1991), there is

now good evidence for multiple populations of humpback whales in the North Pacific (Johnson and Wolman 1984; Baker

et al. 1990). Four relatively separate migratory populations have been identified in the North Pacific (Barlow 1994a)

based on sightings of distinctively-marked individuals: the coastal California/Oregon/Washington - Mexico stock, the

Mexico offshore island stock (feeding destination unknown), the central North Pacific stock (Hawaii/Alaska), and the

western North Pacific stock (Japan/feeding destination probably the Aleutian Islands). This assessment will cover the

stock of humpback whales that ranges from Costa Rica (Steiger et al. 1991) to southern British Columbia (Calambokidis

et al. 1993) but which is most common in coastal waters of California (in summer/fall) and Mexico (in winter/spring).

Other Marine Mammal Protection Act (MMPA) stock assessment reports include the central North Pacific

(Hawaii/Alaska) stock and the western North Pacific (Japan’?) stock. Significant levels of genetic differences were found

between the California and Alaska feeding groups based on analyses of mitochondrial DNA (Baker et al. 1990) and

nuclear DNA (Baker et al. 1993). The genetic exchange rate between California and Alaska is estimated to be less than

1 female per generation (Baker 1992). Two breeding areas (Hawaii and coastal Mexico) showed fewer genetic

differences than did the two feeding areas (Baker 1992). This is substantiated by the observed movement of individuallyidentified whales between Hawaii and Mexico (Baker et al. 1990). There have been no individual matches between 607

humpbacks photographed in California and 567 humpbacks photographed in Alaska (Calambokidis et al. 1993). Few

of the whales photographed in British Columbia have matched with a California catalog (Calambokidis et al. 1993),

indicating that British Columbia is an approximate geographic boundary between feeding populations.

POPULATION SIZE

Based on whaling statistics, the pre-1905 population of humpback whales in the North Pacific was estimated

to be 15,000 (Rice 1978) but this population was reduced by whaling to approximately 1,200 by 1966 (Johnson and

Wolman 1984). The North Pacific total now almost certainly exceeds 3,000 humpback whales (Barlow 1994,). Dohl

et al. (1983) first estimated the central California feeding population to be 338 (CV=O.29) based on aerial surveys in

August through November of 1980-83; however, this estimate does not include a correction for submerged animals.

More recently, the size of the “California” feeding stock of humpback whales has been estimated by three independent

methods. 1) Calambokidis and Steiger (1994) estimated the number of humpback whales in California-Washington to

be 597 (CV=O.O7) based on mark-recapture estimates comparing their 1992 and 1993 photo-identification catalogs. 2)

Barlow (1995) estimates 626 (CV=O.41) humpbacks in California waters based on ship line-transect surveys in

summer/autumn 1991. 3) Forney et al. (1995) estimate 319 (CV=O.41) humpback whales in California coastal waters

based on aerial line-transect surveys in winter/spring 1991. In addition, Green et al. (1992) report that humpback whales

were the second most abundant large whale (after the gray whale) in aerial surveys of Oregon and Washington, but they

did not estimate population size. These estimates for the west-coast stock are not significantly different for each other,

but the survey estimates are likely to be negatively biased. The aerial surveys are likely to be biased because submerged

animals are missed, and both the ship and aerial line-transect estimates do not include members of this stock that were

in Washington, Oregon, or Mexico at the time of the survey (this is especially true of the winter/spring survey, during

which it was surprising to see any humpback whales north of Mexico). Mark-recapture estimates may also be negatively

biased due to heterogeneity in sighting probabilities (Hammond 1986). However, given that the above mark-recapture

estimate is based on a large fraction of the entire population (the 1992-93 catalog contained 480 known individuals), this

bias is likely to be minimal. Also, when methods were used which account for heterogeneity, estimates were comparable

or smaller (Calambokidis et al. 1993). The most precise and least biased estimate is likely to be the mark-recapture

estimate of 597 (CV=O.O7) humpback whales for this population.

Minimum Population Estimate

The minimum population estimate for humpback whales in the California/Mexico stock is taken as the lower

20th percentile of the log-normal distribution of 1992-93 abundance estimated from mark-recapture methods

(Calambokidis and Steiger 1994) or approximately 563.

99
Current Population Trend

There is some indication that humpback whales have increased in abundance in California coastal waters

between 1979/80 and 1991 (Barlow! 1994b), but this trend is not significant. Mark-recapture population estimates have

increased steadily from 1988/90 to l992/93 at about 5% per year (Calambokidis and Steiger 1994). Although the

population in the North Pacific is expected to have grown since being given protected status in 1966: the possible effects

of continued unauthorized take (Yablokov 1994) and incidental ship strikes and gillnet mortality make this uncertain.

CURRENT AND MAXIMUM NET PRODUCTIVITY RATES

There are no estimates of the growth rate of humpback whale populations in the North Pacific (Best 1993). The

proportion of calves in the California/Mexico stock appears much lower than has been measured for humpback whales

in other areas (Calambokidis and Steiger 1994).

POTENTIAL BIOLOGICAL REMOVAL

The potential biological removal (PBR) level for this stock is calculated as the minimum population size (563)

times one half the default maximum net growth rate for cetaceans (1/2 of 4%) times a recovey factor of 0.1 (for an

endangered species), resulting in a PBR of 1. 1. Because this stock spends approximately half its time in Mexican waters,

the PBR allocation for U.S. waters is 0.5 whales per year.

ANNUAL HUMAN-CAUSED MORTALITY

Historic Whaling

The reported take of North Pacific humpback whales by commercial whalers totalled approximately 7,700

between 1947 and 1987 (C. Allison! IWC, pers. comm.). In addition, approximately 7,300 were taken along the west

coast of North America from 19 19 to 1929 (Tonnessen and Johnsen 1982). Total 1910- 1965 catches from the CaliforniaWashington stock includes at least the 2,000 taken in Oregon and Washington, the 3,400 taken in California, and the

2,800 taken in Baja California (Rice 1978). There has been a prohibition on taking humpback whales since 1966.

Fishery Information

Humpback whales are likely to be caught only in offshore drift gillnets. Drift gillnets are used by approximately

149 vessels (J. Cordaro, Southwest Region, NMFS, pers. comm.) to catch swordfish, thresher shark. and mako shark in

California offshore waters (Hanan et al. 1993). Fishing effort has decreased from approximately 10,000 sets per year

in the mid-1980s to 6,600 in 1993 (Barlow et al. 1994). The deaths of two humpback whales in the Southern California

Bight have been attributed to entanglement in fishing gear (Heyning and Lewis 1990). Also. two unidentified whales,

possibly humpbacks, were taken in the approximately 1% of drift gillnets observed in 1980-85 (Hanan 1986; Heyning

and Lewis 1990). No humpback whales or unidentified baleen whales have been observed taken from 1990 to 1993 in

gillnet observation programs which covered 5- 13% of fishing effort (Lennert et al. 1994; Perkins et al. 1992; Julian 1993,

1994); however, much of the gillnet mortality of large whales may go unobserved because whales swim away with a

portion of the net.

Similar drift gillnet fisheries for swordfish and sharks exist along the entire Pacific coast of Baja California,

Mexico and probably take animals from the same population. Quantitative data are available only for the Mexican

swordfish drift gillnet fishery, which has increased from two vessels in 1986 to 29 vessels in 1992-(Sosa-Nishizaki et

al. 1993). The total number of sets in this fishery in 1992 can be estimated from data provided by these authors to be

approximately 2,700, with an observed rate of marine mammal bycatch of 0.13 animals per set (10 marine mammals in

77 observed sets; Sosa-Nishizaki et al. 1993). This overall mortality rate is similar to that observed in California driftnet

fisheries during 1990-93 (0.15 marine mammals per set), but species-specific information is not available for the Mexican

fisheries.

Fishery Mortality Rates

Whale mortality in gillnets cannot be measured accurately because they swim away with part of the net and the

mortality is not observed unless the entangled whales subsequently strand. However, based on observed strandings,

humpback whale mortality in California’s drift gillnet fishery is probably about 0.5 whales per year and is almost certainly

greater than 10% of the PBR. Therefore, total fishery mortality is not approaching zero mortality and serious injury rate.

This determination cannot be made for individual fisheries until the implementing regulations for Section 118 of the

100
MMPA have been reviewed by the public and finalized.

Ship Strikes

Ship strikes were implicated in the deaths of at least 2 humpback whales in 1993 and 2 unidentified whales

(possibly humpbacks) in 1990 (J. Cordaro, Southwest Region, NMFS, pers. comm.). Additional mortality from ship

strikes probably goes unreported because the whales do not strand or, if they do, they do not have obvious signs of

trauma. Several humpback whales have been photographed in California with large gashes in their dorsal surface that

appear to be from ship strikes (J. Calambokidis, pers. comm.). The average number of death by ship strikes from 1991-93

is 0.66 whales per year.

STATUS OF STOCK

Humpback whales in the North Pacific were estimated to have been reduced to 13% of carrying capacity (K)

by commercial whaling (Braham 1991). Clearly the North Pacific population is severely depleted. The initial abundance

has never been estimated separately for the “California” stock, but this stock was also probably depleted by whaling.

Humpback whales are formally listed as “endangered” under the Endangered Species Act (ESA), and consequently the

California/Mexico stock is automatically considered as a “depleted” and “strategic” stock under the MMPA. The

estimated annual mortality due to entanglement (0.5/yr) plus ship strikes (0.7/yr) in California is thus greater than the

PBR allocation of 0.5 for U.S. waters. The California stock appears to be increasing in abundance.

REFERENCES

Baker, C. S. 1992. Genetic variability and stock identity of humpback whales, world-wide. Final Contract Report to

Int. Whal. Commn. 45pp.

Baker, C. S., D. A. Gilbert, M. T. Weinrich, R. Lambertsen. J. Calambokidis: B. McArdle, G. K. Chambers: and S. J.

O’Brien. 1993. Population characteristics of DNA fingerprints in humpback whales (Megantera novaeangliae).

J. Heredity 84:281-290.

Baker, C. S., S. R. Palumbi, R. H. Lambertsen, M. T. Weinrich. J. Calambokidis, and S. J. O’Brien. 1990. Influence of

seasonal migration on geographic distribution of mitochondrial DNA haplotypes in humpback whales. Nature

344( 15):238-240.

Barlow, J. 1994a. Recent information on the status of large whales in California waters. NOAA Tech. Memo. NOAATM-NMFS-SWFSC-203. 27pp.

Barlow, J. 1994b. Abundance of large whales in California coastal waters: a comparison of ship surveys in 1979180

and in 1991. Rept. Int. Whal. Commn. 44:399-406.

Barlow, J. 1995. The abundance of cetaceans in California waters. Part I: Ship surveys in summer and fall of 1991.

Fish. Bull. 93:1-14.

Barlow, J., R. W. Baird, J. E. Heynin g, K. Wynne, A. M. Manville, II, L. F. Lowry, D. Hanan, J, Sease, and V. N.

Burkanov. 1994. A review of cetacean and pinniped mortality in coastal fisheries along the west coast of the

U.S. and Canada and the east coast of the Russian Federation. Rep. Int. Whal. Commn, Special Issue 15:405-

425.

Best, P. B. 1993. Increase rates in severely depleted stocks of baleen whales. 1CES J. Mar. Sci. 50: l69- 186.

Braham, H. W. 1991. Endangered whales: status update. A Report on the 5-year status of stocks review under the

1978 amendments to the U.S. Endangered Species Act. NMFS Unpublished Report.

Calambokidis, J., and G. H. Steiger. 1994. Population assessment of humpback and blue whales using photoidentification from 1993 surveys off California. Final Contract Report to Southwest Fisheries Science Center,

P.O. Box 271, La Jolla, CA 92038. 31pp.

Calambokidis, J., G. H. Steiger, and J. R. Evenson. 1993. Photographic identification and abundance estimates of

humpback and blue whales off California in 1991-92. Final Contract Report 50ABNF100137 to Southwest

Fisheries Science Center, P.O. Box 271, La Jolla, CA 92038. 67pp.

Dohl, T. P., R. C. Guess, M. L. Duman, and R. C. Helm. 1983. Cetaceans of central and northern California, 1980-83:

Status, abundance, and distribution. Final Report to the Minerals Management Service, Contract No. 14-12-

0001-29090.284p.

Donovan, G. P. 1991. A review of IWC stock boundaries. Rept. Int. Whal. Commn., Special Issue l3:39-68.

Forney, K. A., J. Barlow, and J. V. Carretta. 1995. The abundance of cetaceans in California waters. Part II: Aerial

101
surveys in winter and spring of 1991 and 1992. Fish. Bull. 93: 15-26.

Green, G. A., J. J. Brueggeman, R. A. Grotefendt, C. E. Bowlby. M. L. Bonnell, K. C. Balcomb, III. 1992. Cetacean

distribution and abundance off Oregon and Washington: 1989-1990. Ch. 1 In J. J. Brueggeman (ed.). Oregon

and Washington Marine Mammal and Seabird Surveys. Minerals Management Service Contract Report 14-12-

0001-30426.

Hammond, P. S. 1986. Estimating the size of naturally marked whale populations using capture-recapture techniques.

Rept. lnt. Whal. Commn., Special Issue 8:253-282.

Hanan, D. A. 1986. California Department of Fish and Game coastal marine mammal study, annual report for the period

July 1, 1983 - June 30: 1984. Admin. Rept. LJ-86-16 available from Southwest Fisheries Science Center, P.O.

BOX 27 I, La Jolla, CA. 55pp.

Hanan, D. A., D. B. Holts, and A. L. Coan, Jr. 1993. The California drift gill net fishery for sharks and swordfish, 198l82 through 1990-91. Calif. Dept. Fish and Game Fish. Bull. No. 175. 95pp.

Heyning, J. E., and T. D. Lewis. 1990. Fisheries interactions involving baleen whales off southern California. Rep.

int. Whal. Commn. 40:427-431.

Johnson, J. H., and A. A. Wolman. 1984. The humpback whale, Megantera novaeangliae. Mar. Fish. Rev. 46(4):30-37.

Julian, F. 1993. Pinniped and cetacean mortality in California gillnet fisheries: Preliminary estimates for 1992. Int.

Whal. Comm. Working Paper SC/45/022.

Julian. F. 1994. Pinniped and cetacean mortality in California gillnet fisheries: Preliminary estimates for 1993. Int.

Whal. Comm. Working Paper SC/46/0l1.

Lennert, C.: S. Kruse, M. Beeson, and J. Barlow. 1994. Estimates of incidental marine mammal bycatch in California

gillnet fisheries for July through December, 1990. Int. Whal. Commn., Special Issue 15:449-461.

Perkins! P., J. Barlow, and M. Beeson. 1992. Pinniped and cetacean mortality in California gillnet fisheries: 1991.

IWC Working Paper SC/44/SM14.

Rice. D. W. 1978. The humpback whale in the North Pacific: distribution, exploitation? and numbers. pp. 29-44 In:

K. S. Norris and R. R. Reeves (eds.). Report on a Workshop on Problems Related to Humpback Whales

(Mergantera novaeanoliae) in Hawaii. Contr. Rept. to U. S. Marine Mammal Commn. NTIS PB-280-794. 90pp.

Sosa-Nishizaki, O., R. De la Rosa Pacheco, R. Castro Longoria, M. Grijalva Chon. and J. De la Rosa Velez. 1993.

Estudio biologico pesquero de1 pez (Xiphias gludius) y otras especies de picudos (marlins y pez vela). Rep. Int.

CICESE, CTECT9306.

Steiger, G. H., J. Calambokidis, R. Sears, K. C. Balcomb, and J. C. Cubbage. 1991. Movement of humpback whales

between California and Costa Rica. Mar. Mamm. Sci. 7:306-3 IO.

Tonnessen, J. N., and A. 0. Johnsen. 1982. The History of Modem Whaling. Univ. Calif. Press, Berkeley and Los

Angeles. 798pp.

Yablokov, A. V. 1994. Validity of whaling data. Nature 367: 108.

102
BLUE WHALE (Balaenoptera musculus): California/Mexico Stock

STOCK DEFINITION AND GEOGRAPHIC RANGE

The International Whaling Commission (IWC) has formally considered only one management stock for blue

whales in the North Pacific (Donovan 1991), but now this ocean is thought to include more than one population (Ohsumi

and Wada 1972; Braham 1991). One group of animals migrates from Mexico to feed in California waters from June to

November. During this feeding period, there is an apparent hiatus in distribution south of the tip of Baja California

(Reilly and Thayer 1990; Wade and Gerrodette 1993) and north of California in Oregon and Washington (Green et al.

1992; Barlow 1995). [Two blue whales were, however? tracked using on a seafloor seismic array approximately 500 km

offshore from Astoria, Oregon in August 1990 (McDonald et al. 1994) and may have been part of the California/Mexico

stock.] Although there are blue whales near the Costa Rican Dome in the eastern tropical Pacific from June to November,

Reilly and Thayer (1990) speculate that these are likely to be part of a southern hemisphere population or an isolated

resident population. Rice (1974) hypothesized that blue whales from Baja California migrated far offshore to fed in the

eastern Aleutians or Gulf of Alaska and returned to feed in California waters; however, he has more recently concluded

that the California population is separate from the Gulf of Alaska population (Rice 1992). Recently, blue whale feeding

aggregations have not been found in Alaska despite several surveys (Leatherwood et al. 1982; Stewart et al. 1987; NMFS

unpubl. data). Blue whales are now very common in southern California in June-September (Barlow 1995). Distinctively

marked individuals have been shown to move between feeding areas in California and coastal waters of Mexico,

including the Gulf of California (Calambokidis et al. 1990). Strong evidence exists for a separate population that spends

winter/spring in Mexican coastal waters and summer/autumn in California waters, and there are no verified links to any

other feeding areas. One other stock of North Pacific blue whales (in Hawaiian waters) is recognized in the Marine

Mammal Protection Act (MMPA) Stock Assessment Reports.

POPULATION SIZE

The size of the feeding stock of blue whales in California was estimated recently by both line-transect and markrecapture methods. Barlow (1995) estimates 2,250 (CV=O.38) blue whales in California waters based on ship linetransect surveys. Calambokidis and Steiger (1994) used photographic mark-recapture and estimated population sizes

of 2,038 (CV=O.33) based on photographs of left sides and 1,997 (CV=O.42) based on right sides. The average of the

mark-recapture estimates (2,017, CV=O.38) is in surprisingly good agreement with the line-transect estimate. Markrecapture estimates are often negatively biased by individual heterogeneity in sighting probabilities (Hammond 1986);

however, Calambokidis and Steiger (1994) minimize such effects by selecting one sample that was taken randomly with

respect to distance from the coast. Similarly, the line-transect estimates may also be negatively biased because some blue

whales in this stock are probably along Baja California and: therefore, out of the study area at the time of survey (Wade

and Gerrodette 1993). The best estimate of blue whale abundance is the average of the line-transect and mark-recapture

estimates, weighted by their variances, or 2,134 (CV=O.27). No blue whales were seen in recent aerial surveys off

Oregon and Washington (Green et al. 1992), although one or two individuals were known to be present offshore of

northern Oregon in August 1990 (McDonald et al. 1994).

Minimum Population Estimate

The minimum population estimate for blue whales is taken as the lower 20th percentile of the log-normal

distribution of abundance estimated from the combined mark-recapture and line-transect estimates, or approximately

1,709.

Current Population Trend

There is some indication that blue whales have significantly increased in abundance in California coastal waters

between 1979/80 and 1991 (Barlow 1994). Although this may be due to an increase in the stock as a whole, it could also

be the result of an increased use of California as a feeding area. The size of the apparent increase is too large to be

accounted for by population growth alone. Although the population in the North Pacific is expected to have grown since

being given protected status in 1966, the possibility of continued unauthorized takes after blue whales were protected

(Yablokov 1994) and the existence of incidental ship strikes and gillnet mortality makes this uncertain.

103
CURRENT AND MAXIMUM NET PRODUCTIVITY RATES

No information exists on the rate of growth of blue whale populations in the Pacific (Best 1993).

POTENTIAL BIOLOGICAL REMOVAL

The potential biological removal (PBR) level for this stock is calculated as the minimum population size (1:709)

times one half the default maximum net growth rate for cetaceans (l/2 of 4%) times a recovery factor of 0.1 (for an

endangered species), resulting in a PBR of 3.4. Because this stock spends approximately half its time in Mexican waters,

the PBR allocation for U.S. waters is 1.7 whales per year.

ANNUAL HUMAN-CAUSED MORTALITY

Historic Whaling

The reported take of North Pacific blue whales by commercial whalers totalled 9,500 between 1910 and 1965

(Ohsumi and Wada 1972). Approximately 2,000 were taken off the west coast of North America between 1919 and

1929 (Tonnessen and Johnsen 1982). Partially overlapping with this is Rice’s (1992) repot of at least 1,378 taken by

factory ships off California and Baja California between 1913 and 1937. Between 1947 and 1987, reported takes of blue

whales in the North Pacific were approximately 2,400. Shore-based whaling stations in central California took 48 blue

whales between 1958 and 1965 (Rice 1974). Blue whales in the North Pacific were given protected status by the IWC

in 1966.

Fisheries Information

Blue whales are likely to be caught only in offshore drift gillnets. Drift gillnets are used by approximately 149

vessels (J. Cordaro, Southwest Region: NMFS, pers. comm.) to catch swordfish, thresher shark, and mako shark in

California offshore waters (Hanan et al. 1993). Fishing effort has decreased from approximately 10,000 sets per year

in the mid-1980s to 6,600 in 1993 (Barlow et al. 1994). Two unidentified whales, possibly blue whales, were taken in

the approximately 1% of drift gillnets observed in 1980-85 (Hanan 1986; Heyning and Lewis 1990). No blue whales

or unidentified baleen whales have been observed taken from 1990 to 1993 in gillnet observation programs which

covered 5-13% of fishing effort (Lennert et al. 1994; Perkins et al. 1992; Julian 1993, 1994); however, much of the

gillnet mortality of large whales may go unobserved because whales swim away with a portion of the net.

Similar drift gillnet fisheries for swordfish and sharks exist along the entire Pacific coast of Baja California?

Mexico and probably take animals from the same population. Quantitative data are available only for the Mexican

swordfish drift gillnet fishery, which has increased from two vessels in 1986 to 29 vessels in 1992-(Sosa-Nishizaki et

al. 1993). The total number of sets in this fishery in 1992 can be estimated from data provided by these authors to be

approximately 2,700, with an observed rate of marine mammal bycatch of 0. 13 animals per set (10 marine mammals in

77 observed sets; Sosa-Nishizaki et al. 1993). This overall mortality rate is similar to that observed in California driftnet

fisheries during 1990-93 (0.15 marine mammals per set), but species-specific information is not available for the Mexican

fisheries.

Fishery Mortality Rates

To date, no blue whale mortality has been associated with California gillnet fisheries. but the true mortality rate

must be considered unknown because of unobserved mortality. Therefore, we cannot evaluate whether total fishery

mortality is approaching zero mortality and serious injury rate. This determination cannot be made for individual

fisheries until the implementing regulations for Section 118 of the MMPA have been reviewed by the public and

finalized.

Ship Strikes

Ship strikes were implicated in the deaths of blue whales in 1980, 1986, 1987, and 1993, plus 2 unidentified

whales (possibly blue whales) in 1990 (J. Cordaro, Southwest Region, NMFS and J. Heyning, pers. comm.). Additional

mortality from ship strikes probably goes unreported because the whales do not strand or, if they do, they do not always

have obvious signs of trauma. Several blue whales have been photographed in California with large gashes in their dorsal

surface that appear to be from ship strikes (J. Calambokidis, pers. comm.).

104
STATUS OF STOCK

Previously, blue whales in the entire North Pacific were estimated to be at 33% (1,600 out of 4,900) of historic

carrying capacity (Minoch et al. 1984). The initial abundance has never been estimated separately for the “California”

stock, but this stock was almost certainly depleted by whaling. Blue whales are formally listed as “endangered” under

the Endangered Species Act (ESA), and consequently the California/Mexico stock is automatically considered as a

“depleted” and “strategic” stock under the MMPA. The annual incidental mortality from ship strikes is probably less

than 1 per year and is therefore less than the calculated PBR for this stock. The population appears to be growing.

REFERENCES

Barlow, J. 1994. Abundance of large whales in California coastal waters: a comparison of ship surveys in 1979/80 and

in 1991. Rept. Int. Whal. Commn. 44:399-406.

Barlow, J. 1995. The abundance of cetaceans in California waters. Part I: Ship surveys in summer and fall of 1991.

Fish. Bull. 93:1-14. 93(l):

Barlow, J., R. W. Baird, J. E. Heyning, K. Wynne, A. M. Manville, II, L. F. Lowry, D. Hanan, J. Sease, and V. N.

Burkanov. 1994. A review of cetacean and pinniped mortality in coastal fisheries along the west coast of the

U.S. and Canada and the east coast of the Russian Federation. Rep. Int. Whal. Commn, Special Issue 1.5:405-

425.

Best, P. B. 1993. Increase rates in severely depleted stocks of baleen whales. ICES J. Mar. Sci. 50: 169-186.

Braham, H. W. 1991. Endangered whales: status update. A Report on the 5-year status of stocks review under the

1978 amendments to the U.S. Endangered Species Act. NMFS Unpublished Report.

Calambokidis, J., and G. H. Steiger. 1994. Population assessment of humpback and blue whales using photoidentification from 1993 surveys off California. Final Contract Report to Southwest Fisheries Science Center,

P.O. Box 271, La Jolla, CA 92038. 3lpp.

Calambokidis, J., G. H. Steiger, J. C. Cubbage, K. C. Balcomb, C. Ewald, S. Kruse, R. Wells, and R. Sears. 1990.

Sightings and movements of blue whales off central California 1986-88 from photo-identification of individuals.

Rept. Int. Whal. Commn., Special Issue 12:343-348.

Donovan, G. P. 1991, A review of I WC stock boundaries. Rept. lnt. Whal. Commn., Special Issue 13:39-68.

Green G. A., J. J. Brueggeman, R. A. Grotefendt, C. E. Bowlby, M. L. Bonnell, K. C. Balcomb, III. 1992. Cetacean

distribution and abundance off Oregon and Washington, 1989-1990. Ch. 1 In: J. J. Brueggeman (ed.). Oregon

and Washington Marine Mammal and Seabird Surveys. Minerals Management Service Contract Report 14-12-

0001-30426.

Hammond, P. S. 1986. Estimating the size of naturally marked whale populations using capture-recapture techniques.

Rept. Int. Whal. Commn., Special Issue 8:253-282.

Hanan, D. A. 1986. California Department of Fish and Game coastal marine mammal study, annual report for the period

July 1, 1983 - June 30, 1984. Admin. Rept. LJ-86-16 available from Southwest Fisheries Science Center, P.O.

Box 271, La Jolla, CA. 55pp.

Hanan, D. A., D. B. Holts, and A. L. Coan, Jr. 1993. The California drift gill net fishery for sharks and swordfish. 1981-

82 through 1990-91. Calif. Dept. Fish and Game Fish. Bull. No. 175. 95pp.

Heyning, J. E., and T. D. Lewis. 1990. Fisheries interactions involving baleen whales off southern California. Rep.

int. Whal. Commn. 40:427-431.

Julian, F. 1993. Pinniped and cetacean mortality in California gillnet fisheries: Preliminary estimates for 1992. Int.

Whal. Comm. Working Paper SC/45/022.

Julian, F. 1994. Pinniped and cetacean mortality in California gillnet fisheries: Preliminary estimates for 1993. Int.

Whal. Comm. Working Paper SC/46/011.

Leatherwood, S., R. R. Reeves, W. F. Perrin, and W. E. Evans. 1982. Whales, dolphins. and porpoises of the eastern

North Pacific and adjacent Arctic waters: A guide to their identification. NOAA Technical Rept. NMFS

Circular 444. 245pp.

Lennert, C., S. Kruse, M. Beeson, and J. Barlow. 1994. Estimates of incidental marine mammal bycatch in California

gillnet fisheries for July through December, 1990. Int. Whal. Commn., Special Issue 15:449-461.

McDonald, M. A., J. A. Hildebrand, and S. C. Webb. 1994. Blue and tin whales observer on a seafloor array in the

Northeast Pacific. (unpubl. ms.).

Mizroch, S. A., D. W. Rice, and J. M. Breiwick. 1984. The blue whale, Balaenoptera musculus. Mar. Fish. Rev. 46: 15-

105
19.

Ohsumi, S. and S. Wada. 1972. Stock assessment of blue whales in the North Pacific. Working Paper for the 24th

Meeting of the International Whaling Commission. 2Opp.

Perkins, P., J. Barlow, and M, Beeson. 1992. Pinniped and cetacean mortality in California gillnet fisheries: 1991.

IWC Working Paper SC/44/SM14.

Reilly? S. B. and V. G. Thayer. 1990. Blue whale (Balaenoptera musculus) distribution in the eastern tropical Pacific.

Mar. Mamm. Sci. 6(4):265-277.

Rice, D. W. 1974. Whales and whale research in the eastern North Pacific. pp. 170-l95 In: W. E. Schevill (ed.). The

Whale Problem: A Status Report. Harvard Press, Cambridge, MA.

Rice, D. W. 1992. The blue whales of the southeastern North Pacific Ocean. pp. 1-3 In. Alaska Fisheries Science

Center, Quart. Rept. Oct.-Dec.

Sosa-Nishizaki, 0.: R. De la Rosa Pacheco, R. Castro Longoria, M. Grijalva Chon, and J. De la Rosa Velez. 1993.

Estudio biologico pesquero del pez (Xiphias gladius) y otras especies de picudos (marlins y pez vela). Rep. Int.

CICESE: CTECT9306.

Stewart, B. S.. S. A. Karl, P. K. Yochem. S. Leatherwood, and J. L. Laake. 1987. Aerial surveys for cetaceans in the

former Akutan: Alaska, whaling grounds. Arctic 40(1):33-42.

Tonnessen, J. N., and A. 0. Johnsen. 1982. The History of Modem Whaling. Univ. Calif. Press, Berkeley and Los

Angeles. 798pp.

Wade, P. R. and T. Gerrodette. 1993. Estimates of cetacean abundance and distribution in the eastern tropical Pacific.

Rept. Int. Whal. Commn. 43:477-493.

Yablokov, A. V. 1994. Validity ofwhaling data. Nature 367:lO8.

106
FIN WHALE (Balaenoptera physalus):

California/Oregon/Washington Stock

STOCK DEFINITION AND GEOGRAPHIC RANGE

The International Whaling Commission (IWC) recognized two stocks of fin whales in the North Pacific: the

East China Sea and the rest of the North Pacific (Donovan 1991). Mizroch et al. (1984) cites evidence for additional fin

whale subpopulations in the North Pacific. From whaling records, fin whales that were marked in winter off southern

California were later taken in commercial whaling operations between central California and the Gulf of Alaska in

summer (Mizroch et al. 1984). More recent observations show aggregations of fin whales year-round in southern/central

California (Dohl et al. 1983; Barlow 1995; Forney et al. 1995), year-round in the Gulf of California (Tershy et al. 1993),

in summer in Oregon (Green et al. 1992; McDonald 1994): and in summer/autumn in the Shelikof Strait/Gulf of Alaska

(Brueggeman et al. 1990). Fin whales appear very scarce in the eastern tropical Pacific in summer (Wade and Gerrodette

1993) and winter (Lee 1993).

There is still insufficient information to accurately determine population structure: but from a conservation

perspective it may be risky to assume panmixia in the entire North Pacific. In the North Atlantic, fin whales were locally

depleted in some feeding areas by commercial whaling (Mizroch et al. 1984), in part because subpopulations were not

recognized. This assessment will cover the stock of fin whales which is found along the coasts of California, Oregon,

and Washington. Because fin whale abundance appears lower in winter/spring in California (Dohl et al. 1983; Forney

et al. 1995) and in Oregon (Green et al. 1992), it is likely that the distribution of this stock extends seasonally outside

these coastal waters. Coincidentally, fin whale abundance in the Gulf of California increases seasonally in winter and

spring (Tershy et al. 1993). It is premature, however, to conclude that the Gulf whales are part of the U.S. west coast

population. The Marine Mammal Protection Act (MMPA) stock assessment reports recognize three stocks of fin whales

in the North Pacific: 1) the California/Oregon/Washington stock (this report), 2) the Hawaii stock, and 3) the Alaska

stock.

POPULATION SIZE

The initial pre-whaling population of fin whales in the North Pacific was estimated to be 42,000-45,000 (Ohsumi

and Wada 1974). In 1973, the North Pacific population was estimated to have been reduced to 13,620-18,680 (Ohsumi

and Wada 1974), of which 8,520-10,970 were estimated to belong to the eastern Pacific stock. A minimum of 148

individually-identified fin whales are found in the Gulf of California (Tershy et al. 1990). Recently, 935 (CV=O.63) fin

whale were estimated to be in California waters based on ship surveys in summer/autumn 1991 (log-normal 95%

C.l.=299-2,925) (Barlow 1995). Fin whale abundance in California was estimated as only 49 (CV=l .O) based on aerial

surveys in winter/spring of 1991/92 (Forney et al. 1995); however, this estimate does not include a correction for diving

animals that were missed. No estimates exist for Oregon or Washington, but fin whales were reported to be the fourth

most abundant large whale in that area (Green et al. 1992).

Minimum Population Estimate

The minimum population estimate for fin whales is taken as the lower 20th percentile of the log-normal

distribution of abundance estimated from summer/fall ship survey (Barlow 1995) or approximately 575.

Current Population Trend

There is some indication that fin whales have increased in abundance in California coastal waters. between

1979/80 and 1991 (Barlow 1994), but this trend is not significant. Although the population in the North Pacific is

expected to have grown since receiving protected status in 1976, the possible effects of continued unauthorized take

(Yablokov 1994) and incidental ship strikes and gillnet mortality make this uncertain.

CURRENT AND MAXIMUM NET PRODUCTIVITY RATES

There are no estimates of the growth rate of fin whale populations in the North Pacific (Best 1993).

POTENTIAL BIOLOGICAL REMOVAL

The potential biological removal (PBR) level for this stock is calculated as the minimum population size (575)

107
times one half the default maximum net growth rate for cetaceans (l/2 of 4%) times a recovery factor of 0.1 (for an

endangered species), resulting in a PBR of 1.1.

ANNUAL HUMAN-CAUSED MORTALITY

Historic Whaling

Approximately 46,000 fin whales were taken from the North Pacific by commercial whalers between 1947 and

1987 (C. Allison, IWC, pers. comm.), including 1,060 fin whales taken by coastal whalers in central California between

1958 and 1965 (Rice 1974). In addition, approximately 3,800 were taken off the west coast of North America between

1919 and 1929 (Tonnessen and Johnsen 1982). Fin whales in the North Pacific were given protected status by the IWC

in 1976.

Fisheries Information

Fin whales are likely to be caught only in offshore drift gillnets. Drift gillnets are used by approximately 149

vessels (J. Cordaro. Southwest Region, NMFS, pers. comm.) to catch swordfish, thresher shark, and mako shark in

California offshore waters (Hanan et al. 1993). Fishing effort has decreased from approximately 10,000 sets per year

in the mid- 1980s to 6,600 in 1993 (Barlow et al. 1994). Two unidentified whales. possibly fin whales, were taken in the

approximately 1% of drift gillnets observed in 1980-85 (Hanan 1986; Heyning and Lewis 1990). No fin whales or

unidentified baleen whales have been observed taken from 1990 to 1993 in gillnet observation programs which covered

5-l3% of fishing effort (Lennert et al. 1994; Perkins et al. 1992; Julian 1993, 1994); however? much of the gillnet

mortality of large whales may go unobserved because whales swim away with portion of the net.

Similar drift gillnet fisheries for swordfish and sharks exist along the entire Pacific coast of Baja California,

Mexico and may take animals from the same population. Quantitative data are available only for the Mexican swordfish

drift gillnet fishery, which has increased from two vessels in 1986 to 29 vessels in 1992-(Sosa-Nishizaki et al. 1993). The

total number of sets in this fishery in 1992 can be estimated from data provided by these authors to be approximately

2,700, with an observed rate of marine mammal bycatch of 0.13 animals per set (I 0 marine mammals in 77 observed sets;

Sosa-Nishizaki et al. 1993). This overall mortality rate is similar to that observed in California driftnet fisheries during

1990-93 (0.15 marine mammals per set): but species-specific information is not available for the Mexican fisheries.

Fishery Mortality Rates

To date, no fin whale mortality has been associated with California gillnet fisheries, but the true mortality rate

must be considered unknown because of unobserved mortality. Therefore, we cannot evaluate whether total fishery

mortality is approaching zero mortality and serious injury rate. This determination cannot be made for individual

fisheries until the implementing regulations for Section 118 of the MMPA have been reviewed by the public and

finalized.

Ship Strikes

Ship strikes were implicated in the deaths of one fin whale in 1991 and two unidentified whales (possibly fins)

in 1990 (J. Heyning and J. Cordaro, Southwest Region, NMFS, pers. comm.). Additional mortality from ship strikes

probably goes unreported because the whales do not strand or, if they do, they do not always have obvious signs of

trauma.

STATUS OF STOCK

Fin whales in the entire North Pacific were estimated to be at less than 38% (16,625 out of 43,500) of historic

carrying capacity (Minoch et al. 1984). The initial abundance has never been estimated separately for the “west coast”

stock, but this stock was also probably depleted by whaling. Fin whales are formally listed as “endangered” under the

Endangered Species Act (ESA), and consequently the California to Washington stock is automatically considered as a

“depleted” and “strategic” stock under the MMPA. The observed incidental mortality due to fisheries and ship strikes

appears to be less than 1 animal per year and is therefore less than the calculated PBR.

REFERENCES

Barlow, J. 1994. Abundance of large whales in California coastal waters: a comparison of ship surveys in 1979/80 and

in 1991. Rept. Int. Whal. Commn. 44:399-406.

108
Barlow, J. 1995. The abundance of cetaceans in California waters, Part 1: Ship surveys in summer and fall of 1991.

Fish. Bull. 93:1-14.

Barlow, J., R. W. Baird, J. E. Heyning, K. Wynne, A. M. Manville, II, L. F. Lowry, D. Hanan, J. Sease, and V. N.

Burkanov. 1994. A review of cetacean and pinniped mortality in coastal fisheries along the west coast of the

U.S. and Canada and the east coast of the Russian Federation. Rep. Int. Whal. Commn, Special Issue 15:405-

425.

Best, P. B. 1993. Increase rates in severely depleted stocks of baleen whales. ICES J. Mar. Sci. 50: 169- 186.

Brueggeman, J. J., G. A. Green, K. C. Balcomb, C. E. Bowlby, R. A. Grotefendt, K. T. Briggs, M. L. Bonnell, R. G.

Ford, D. H. Varoujean, D. Heinemann, and D. G. Chapman. 1990. Oregon-Washington Marine Mammal and

Seabird Survey: Information synthesis and hypothesis formulation. U.S. Department of the Interior, OCS Study

MMS 89-0030.

Dohl. T. P., R. C. Guess, M. L. Duman, and R. C. Helm. 1983. Cetaceans of central and northern California: 1980-83:

Status, abundance, and distribution. Final Report to the Minerals Management Service, Contract No. 14-12-

000l-29090. 284p.

Donovan, G. P. 1991. A review of IWC stock boundaries. Rept. Int. Whal. Commn., Special Issue 13:39-68.

Forney, K. A., J. Barlow, and J. V. Carretta. 1995. The abundance of cetaceans in California waters. Part II: Aerial

surveys in winter and spring of 1991 and 1992. Fish. Bull. 93:15-36.

Green, G. A., J. J. Brueggeman, R. A. Grotefendt, C. E. Bowlby, M. L. Bonnell. K. C. Balcomb, III. 1992. Cetacean

distribution and abundance off Oregon and Washington, 1989-1990. Ch. 1 In: J. J. Brueggeman (ed.). Oregon

and Washington Marine Mammal and Seabird Surveys. Minerals Management Service Contract Report 14- 12-

0001-30426.

Hanan, D. A. 1986. California Department of Fish and Game coastal marine mammal study, annual report for the period

July 1, 1983 - June 30, 1984. Admin. Rept. LJ-86-16 available from Southwest Fisheries Science Center, P.O.

Box 271, La Jolla, CA. 55pp.

Hanan, D. A., D. B. Holts, and A. L. Coan, Jr. 1993. The California drift gill net fishery for sharks and swordfish, 1981-

82 through 1990-91. Calif. Dept. Fish and Game Fish. Bull. No. 175. 95pp.

Heyning, J. E., and T. D. Lewis. 1990. Fisheries interactions involving baleen whales off southern California. Rep.

int. Whal. Commn. 40:427-431.

Julian, F. 1993. Pinniped and cetacean mortality in California gillnet fisheries: Preliminary estimates for 1992. Int.

Whal. Comm. Working Paper SC/45/022.

Julian. F. 1994. Pinniped and cetacean mortality in California gillnet fisheries: Preliminary estimates for 1993. Int.

Whal. Comm. Working Paper SC/46/011.

Lee, T. 1993. Summary of cetacean survey data collected berween the years of 1974 and 1985. NOAA Tech. Memo.

NOAA-TM-NMFS-SWFSC-181. 184pp.

Lennert, C., S. Kruse, M. Beeson. and J. Barlow. 1994. Estimates of incidental marine mammal bycatch in California

gillnet fisheries for July through December, 1990. Int. Whal. Commn., Special Issue 15:449-461.

McDonald, M. A., J. A. Hildebrand, and S. C. Webb. 1994. Blue and fin whales observer on a seafloor array in the

Northeast Pacific. (unpubl. ms.).

Mizroch, S. A., D. W. Rice, and J. M. Breiwick. 1984. The fin whale, Balaenoptera physalus. Mar. Fish. Rev. 46:20-24.

Ohsumi, S. and S. Wada. 1974. Status of whale stocks in the North Pacific: 1972. Rept. Int. Whal. Commn. 25:114-

126.

Perkins, P., J. Barlow, and M. Beeson. 1992. Pinniped and cetacean mortality in California gillnet fisheries: 1991.

IWC Working Paper SC/44/SM14.

Rice, D. W. 1974. Whales and whale research in the eastern North Pacific. pp. 170-195 In: W. E. Schevill (ed.). The

Whale Problem: A Status Report. Harvard Press, Cambridge, MA.

Sosa-Nishizaki, O., R. De la Rosa Pacheco, R. Castro Longoria, M. Grijalva Chon, and J. De la Rosa Velez. 1993.

Estudio biologico pesquero de1 pez (Xiphias gladius) y otras especies de picudos (marlins y pez vela). Rep. Int.

CICESE, CTECT9306.

Tershy, B. R., D. Breese, and C. S. Strong. 1990. Abundance, seasonal distribution and population composition of

balaenopterid whales in the Canal de Ballenas, Gulf of California, Mexico. Rept. lnt. Whal. Commn., Special

Issue 12:369-375.

Tershy, B. R., J. Urban-R., D. Breese, L. Rojas-B., and L. T. Findley. 1993. Are fin whales resident to the Gulf of

109
California? Rev. Invest. Cient., Univ. Auton. de Baja California Sur. 1:69-71.

Tonnessen, J. N., and A. 0. Johnsen. 1982. The History of Modem Whaling. Univ. Calif. Press: Berkeley and Los

Angeles. 798pp.

Wade: P. R. and T. Gerrodette. 1993. Estimates of cetacean abundance and distribution in the eastern tropical Pacific.

Rept. Int. Whal. Commn. 43:477-493.

Yablokov, A. V. 1994. Validity of whaling data. Nature 367: 108.

110
BRYDE’S WHALE (Balaenoptera edeni): Eastern Tropical Pacific Stock

STOCK DEFINITION AND GEOGRAPHIC RANGE

The International Whaling Commission (IWC) recognizes 3 stocks of Bryde’s whales in the North Pacific

(eastern, western, and East China Sea), 3 stocks in the South Pacific (eastern, western and Solomon Islands), and one

cross-equatorial stock (Peruvian) (Donovan 1991). Bryde’s whales are distributed widely across the tropical and warmtemperate Pacific (Leatherwood et al. 1982), and there is no real justification for splitting stocks between the northern

and southern hemispheres (Donovan 1991). Recent surveys (Wade and Gerrodette 1993; Lee 1993) have shown them

to be common and distributed throughout the eastern tropical Pacific with a concentration around the equator east of

110°W (corresponding approximately to the IWC’s “Peruvian stock”) and a reduction west of 140°W. They are also the

most common baleen whale in the central Gulf of California (Tershy et al. 1990). Only one was positively identified in

surveys of California coastal waters (Barlow 1995). Bryde’s whales in California are likely to belong to a larger

population inhabiting at least the eastern part of the tropical Pacific. For the Marine Mammal Protection Act (MMPA)

stock assessment reports, Bryde’s whales within the Pacific U.S. Exclusive Economic Zone are divided into two areas:

1) the eastern tropical Pacific (east of 150°W and including the Gulf of California and waters off California; this report),

and 2) Hawaiian waters.

POPULATION SIZE

In the western North Pacific, Bryde’s whale abundance in the early 1980s was estimated independently by tag

mark-recapture and ship survey methods to be 22,000 to 24,000 (Tillman and Mizroch 1982; Miyashita 1986). Bryde’s

whale abundance has never been estimated for the entire eastern Pacific; however, a portion of that stock in the eastern

tropical Pacific was estimated recently as 13,000 (CV=O.20: 95% C.I.=8,900-19,900) (Wade and Gerrodette 1993) and

the minimum number in the Gulf of California is 160 based on individually-identified whales (Tershy et al. 1990). Only

1 confirmed sighting of Bryde’s whales and 5 possible sightings (identified as sei or Bryde’s whales) were made in

California waters during extensive ship and aerial surveys in 1991, 1992, and 1993 (Hill and Barlow 1992; Carretta and

Forney 1993; Mangels and Gerrodette 1994). Green et al. (1992) did not report any sightings of Bryde’s whales in aerial

surveys of Oregon and Washington. The estimated abundance of Bryde’s whales in California coastal waters is 61

(CV=l .1) (Barlow 1995).

Minimum Population Estimate

The minimum population estimate for Bryde’s whales is taken as the lower 20th percentile of the log-normal

distribution of abundance estimated from the summer/fall ship surveys in 1986-90 (Wade and Gerrodette 1993) plus the

minimum of 160 whales counted in the Gulf of California (Tershy et al. 1990), or 11: 163.

Current Population Trend

There are no data on trends in Bryde’s whale abundance in the eastern tropical Pacific.

CURRENT AND MAXIMUM NET PRODUCTIVITY RATES

There are no estimates of the growth rate of Bryde’s whale populations in the Pacific (Best 1993).

POTENTIAL BIOLOGICAL REMOVAL

The potential biological removal (PBR) level for this stock is calculated as the minimum population size

(11,163) times one half the default maximum net growth rate for cetaceans (l/2 of 4%) times a recovery factor of 0.5 (for

a stock of unknown status), resulting in a PBR of 112. Only 0.5% of the stock is estimated to be in U.S. waters (61 out

of 13,000), so the PBR allocation to U.S. waters is only 0.5 Bryde’s whales per year.

ANNUAL HUMAN-CAUSED MORTALITY

Historic Whaling

The reported take of North Pacific Bryde’s whales by commercial whalers totalled 15,076 in the western Pacific

from 1946-1983 (Holt 1986) and 2,873 in the eastern Pacific from 1973-81 (Cooke 1983). In addition, 2,304 sei-orBryde’s whales were taken in the eastern Pacific from 1968-72 (Cooke 1983) (based on subsequent catches, most of these

111
were probably Bryde’s whales). None were reported taken by shore-based whaling stations in central California behveen

1958 and 1965 (Rice 1974). There has been a prohibition on taking Bryde’s whales since 1988.

Fishery Information

Bryde’s whales are likely to be caught only in offshore drift gillnets. Drift gillnets are used by approximately

149 vessels (J. Cordaro, Southwest Region, NMFS, pers. comm.) to catch swordfish, thresher shark, and mako shark in

California offshore waters (Hanan et al. 1993). Fishing effort has decreased from approximately 10,000 sets per year

in the mid-1980s to 6,600 in 1993 (Barlow et al. 1994). Two unidentified whales, possibly Bryde’s whales, were taken

in the approximately 1% of drift gillnets observed in 1980-85 (Hanan 1986; Heyning and Lewis 1990). No Bryde’s

whales or unidentified baleen whales have been observed taken from 1990 to 1993 in gillnet observation programs which

covered 5-13% of fishing effort (Lennert et al. 1994; Perkins et al. 1992; Julian 1993, 1994); however, much of the

gillnet mortality of large whales may go unobserved because whales swim away with a portion of the net.

Similar drift gillnet fisheries for swordfish and sharks exist along the entire Pacific coast of Baja California,

Mexico and probably take animals from the same population. Quantitative data are available only for the Mexican

swordfish drift gillnet fishery, which has increased from two vessels in 1986 to 29 vessels in 1992-(Sosa-Nishizaki et

al. 1993). The total number of sets in this fishery in 1992 can be estimated from data provided by these authors to be

approximately 2,700, with an observed rate of marine mammal bycatch of 0.13 animals per set (10 marine mammals in

77 observed sets; Sosa-Nishizaki et al. 1993). This overall mortality rate is similar to that observed in California driftnet

fisheries during 1990-93 (0.15 marine mammals per set), but species-specific information is not available for the Mexican

fisheries.

Fishery Mortality Rates

To date, no Bryde’s whale mortality has been associated with California gillnet fisheries (although some

mortality may have gone unobserved). The total mortality rate is not thought to be greater than the PBR; therefore, under

the MMPA, total fishery mortality is approaching zero mortality and serious injury rate. This determination cannot be

made for individual fisheries until the implementing regulations for Section 118 of the MMPA have been reviewed by

the public and finalized.

Ship Strikes

Ship strikes may occasionally kill Bryde’s whales as they are known to kill their larger relatives: blue and fin

whales.

STATUS OF STOCK

Commercial whaling of Bryde’s whales was largely limited to the western Pacific. Bryde’s whales are not listed

as “threatened” or “endangered” under the Endangered Species Act (ESA). Bryde’s whales in the eastern tropical Pacific

would not be considered a strategic stock under the MMPA.

REFERENCES

Barlow, J. 1995. The abundance of cetaceans in California waters. Part I: Ship surveys in summer and fall of 1991.

Fish. Bull. 93: l-14.

Barlow, J., R. W. Baird, J. E. Heyning, K. Wynne, A. M. Manville, II, L. F. Lowry, D. Hanan, J. Sease: and V. N.

Burkanov. 1994. A review of cetacean and pinniped mortality in coastal fisheries along the west coast of the

U.S. and Canada and the east coast of the Russian Federation. Rep. Int. Whal. Commn: Special Issue 15:405-

425.

Best, P. B. 1993. Increase rates in severely depleted stocks of baleen whales. ICES J. Mar. Sci. 50: 169-186.

Carretta, J. V. and K. A. Forney. 1993. Report on two aerial surveys for marine mammals in California coastal waters

utilizing a NOAA DeHavilland Twin Otter Aircraft: March 9-Apri17, 1991 and February S-April 6, 1992.

NOAA Tech. Memo. NOAA-TM-NMFS-SWFSC-185. 77pp.

Cooke: J. G. 1983. Estimates of the stock of Bryde’s whales fished off the coast of Peru. Rept. Int. Whal. Commn.

331453-456.

Donovan, G. P. 1991. A review of IWC stock boundaries. Rept. Int. Whal. Commn., Special Issue 13:39-68.

Green, G. A., J. J. Brueggeman, R. A. Grotefendt, C. E. Bowlby, M. L. Bonnell, K. C. Balcomb, III. 1992. Cetacean

112
distribution and abundance off Oregon and Washington, 1989-1990. Ch. 1 In: J. J. Brueggeman (ed.). Oregon

and Washington Marine Mammal and Seabird Surveys. Minerals Management Service Contract Report 14-12-

0001 -30426.

Hanan, D. A. 1986. California Department of Fish and Game coastal marine mammal study, annual report for the period

July 1, 1983 - June 30, 1984. Admin. Rept. LJ-86-16 available from Southwest Fisheries Science Center, P.O.

Box 271, La Jolla, CA. 55pp.

Hanan: D. A., D. B. Holts, and A. L. Coan, Jr. 1993. The California drift gill net fishery for sharks and swordfish, 198 l82 through 1990-91. Calif. Dept. Fish and Game Fish. Bull. No. 175. 95pp.

Heyning, J. E., and T. D. Lewis. 1990. Fisheries interactions involving baleen whales off southern California. Rep.

int. Whal. Commn. 40:427-431.

Hill, P. S. and J. Barlow. 1992. Report of a marine mammal survey of the California coast aboard the research vessel

McARTHUR July 28-November 5, 1991. NOAA Technical Memorandum NOAA-TM-NMFS-SWFSC- 169.

NTIS #PB93- 109908. 103pp.

Holt, S. 1986. Aspects of the assessment and regulation of Bryde’s whales in the Northwest Pacific. Rept. Int. Whal.

Commn. 363257-262.

Julian, F. 1993. Pinniped and cetacean mortality in California gillnet fisheries: Preliminary estimates for 1992. Int.

Whal. Comm. Working Paper SC/45/022.

Julian, F. 1994. Pinniped and cetacean mortality in California gillnet fisheries: Preliminary estimates for 1993. Int.

Whal. Comm. Working Paper SC/46/011.

Leatherwood, S., R. R. Reeves, W. F. Perrin, and W. E. Evans. 1982. Whales, dolphins. and porpoises of the eastern

North Pacific and adjacent Arctic waters: A guide to their identification. NOAA Technical Rept. NMFS

Circular 444. 245pp.

Lee, T. 3993. Summary of cetacean survey data collected between the years of 1974 and 1985. NOAA Tech. Memo.

NOAA-TM-NMFS-SWFSC- 181. 184pp.

Lennert, C., S. Kruse, M. Beeson, and J. Barlow. 1994. Estimates of incidental marine mammal bycatch in California

gillnet fisheries for July through December, 1990. Int. Whal. Commn., Special Issue 15:449-461.

Mangels, K. F. and T. Gerrodette. Report of cetacean sightings during a marine mammal survey in the eastern Pacific

Ocean and the Gulf of California aboard the NOAA ships McArthur and David Starr Jordan July 28 -

November 6, 1993. NOAA Technical Memorandum NOAA-TM-NMFS-SWFSC-221. 88pp.

Miyashita, T. 1986. Sighting estimate for the Bryde’s whale stock in the western North Pacific. Rept. Int. Whal.

Commn. 36:249-252.

Perkins, P., J. Barlow, and M. Beeson. 1992. Pinniped and cetacean mortality in California gillnet fisheries: 1991.

I WC Working Paper SC/44/SM14.

Rice, D. W. 1974. Whales and whale research in the eastern North Pacific. pp. 170- 195 In: W. E. Schevill (ed.). The

Whale Problem: A Status Report. Harvard Press, Cambridge, MA.

Sosa-Nishizaki, O., R. De la Rosa Pacheco, R. Castro Longoria, M. Grijalva Chon, and J. De la Rosa Velez. 1993.

Estudio biologico pesquero del pez (Xiphias gladius) y otras especies de picudos (marlins y pez vela). Rep. Int.

CICESE, CTECT9306.

Tershy, B. R., D. Breese, and C. S. Strong. 1990. Abundance, seasonal distribution and population composition of

balaenopterid whales in the Canal de Ballenas, Gulf of California, Mexico. Rept. Int. Whal. Commn., Special

Issue 12:369-375.

Tillman, M. F. and S. A. Minoch. 1982. Mark-recapture estimates of abundance for the western Northern Pacific stock

of Bryde’s whales. Rept. Int. Whal. Commn. 32:335-337.

Wade, P. R. and T. Gerrodette. 1993. Estimates of cetacean abundance and distribution in the eastern tropical Pacific.

Rept. Int. Whal. Commn. 43:477-493.

113
SEI WHALE (Balaenoptera borealis): Eastern North Pacific Stock

STOCK DEFINITION AND GEOGRAPHIC RANGE

The International Whaling Commission (IWC) only considers one stock of sei whales in the North Pacific

(Donovan 1991), but some evidence exists for multiple populations (Masaki 1977; Mizroch et al. 1984; Horwood 1987).

Sei whales are distributed far out to sea in temperate regions of the world and do not appear to be associated with coastal

features. The catch has been distributed continuously across the North Pacific between 45-55°N (Masaki 1977). Two

sei whales that were tagged off California were later killed off Washington and British Columbia (Rice 1974) and the

movement of tagged animals has been noted in many other regions of the North Pacific. Sei whales are now rare in

California waters (Dohl et al. 1983; Barlow 1995; Forney et al. 1995; Mangels and Gerrodette 1994), but were the fourth

most common whale taken by California coastal whalers in the 195Os-1960s (Rice 1974). They are extremely rare south

of California (Wade and Gerrodette 1993; Lee 1993). Lacking additional information on sei whale population structure,

sei whales in the eastern North Pacific (east of longitude 180”) will be considered as a separate stock.

POPULATION SIZE

Ohsumi and Wada (1974) estimate the pre-whaling abundance of sei whales to be 58,000-62,000 in the North

Pacific. Later, Tillman (1977) used a variety of different methods to estimate the abundance of sei whales in the North

Pacific and revised this pre-whaling estimate to 42,000. His estimates for the year 1974 ranged from 7,260 to 12,620.

All methods depend on using the history of catches and trends in CPUE or sighting rates; there have been no direct

estimates of sei whale abundance in the entire (or eastern) North Pacific based on sighting surveys. Only one confirmed

sighting of sei whales and 5 possible sightings (identified as sei or Bryde’s whales) were made in California waters during

extensive ship and aerial surveys in 1991, 1992, and 1993 (Hill and Barlow 1992; Carretta and Forney 1993; Mangels

and Gerrodette 1994). Green et al. (1992) did not report any sightings of sei whales in aerial surveys of Oregon and

Washington. There are no abundance estimates for sei whales along the west coast of the U.S. or in the eastern North

Pacific.

Minimum Population Estimate

Minimum population estimates do not exist for sei whales in the eastern North Pacific.

Current Population Trend

There are no data on trends in sei whale abundance in California coastal waters. Although the population in the

North Pacific is expected to have grown since being given protected status in 1976, the possible effects of continued

unauthorized take (Yablokov 1994) and incidental ship strikes and gillnet mortality make this uncertain.

CURRENT AND MAXIMUM NET PRODUCTIVITY RATES

There are no estimates of the growth rate of sei whale populations in the North Pacific (Best 1993).

POTENTIAL BIOLOGICAL REMOVAL

No estimate exists for the minimum abundance of the eastern North Pacific stock of sei whales. Estimates for

the entire North Pacific are more than 10 years old and do not include statistical estimates of precision. Consequently,

PBR levels cannot be calculated.

ANNUAL HUMAN-CAUSED MORTALITY

Historic Whaling

The reported take of North Pacific sei whales by commercial whalers totalled 61,500 behveen 1947 and 1987

(C. Allison, IWC. pers. comm.). Of these, 384 were taken by-shore-based whaling stations in central California between

1958 and 1965 (Rice 1974). There has been an IWC prohibition on taking sei whales since 1976, and commercial

whaling in the U.S. has been prohibited since 1972.

Fishery Information

Sei whales are likely to be caught only in offshore drift gillnets. Drift gillnets are used by approximately 149

114
vessels (J. Cordaro, Southwest Region, NMFS, pers. comm.) to catch swordfish, thresher shark, and mako shark in

California offshore waters (Hanan et al. 1993). Fishing effort has decreased from approximately 10,000 sets per year

in the mid-1980s to 6,600 in 1993 (Barlow et al. 1994). Two unidentified whales, possibly sei whales, were taken in the

approximately 1% of drift gillnets observed in 1980-85 (Hanan 1986; Heyning and Lewis 1990). No sei whales or

unidentified baleen whales have been observed taken from 1990 to 1993 in gillnet observation programs which covered

5-13% of fishing effort (Lennert et al. 1994; Perkins et al. 1992; Julian 1993, 1994); however, much of the gillnet

mortality of large whales may go unobserved because whales swim away with a portion of the net.

Fishery Mortality Rates

To date, no sei whale mortality has been associated with any eastern North Pacific fisheries, but the true

mortality rate must be considered unknown because of unobserved mortality. Therefore, we cannot evaluate whether

total fishery mortality is approaching zero mortality and serious injury rate. This determination cannot be made for

individual fisheries until the implementing regulations for Section 118 of the MMPA have been reviewed by the public

and finalized.

Ship Strikes

Ship strikes may occasionally kill sei whales as they have been shown to kill their larger relatives: blue and fin

whales.

STATUS OF STOCK

Previously, sei whales were estimated to have been reduced to 20% (8,600 out of 42,000) of their pre-whaling

abundance in the North Pacific (Tillman 1977). The initial abundance has never been reported separately for the eastern

North Pacific stock, but this stock was also probably depleted by whaling. Sei whales are formally listed as “endangered”

under the Endangered Species Act (ESA), and consequently the eastern North Pacific stock is automatically considered

as a “depleted” and “strategic” stock under the Marine Mammal Protection Act (MMPA).

REFERENCES

Barlow, J. 1995. The abundance of cetaceans in California waters, Part I: Ship surveys in summer and fall of 1991.

Fish. Bull. 93:1-14.

Barlow, J., R. W. Baird, J. E. Heyning, K. Wynne, A. M. Manville, II, L. F. Lowry, D. Hanan, J. Sease, and V. N.

Burkanov. 1994. A review of cetacean and pinniped mortality in coastal fisheries along the west coast of the

U.S. and Canada and the east coast of the Russian Federation. Rep. Int. Whal. Commn, Special Issue 15:405-

425.

Best, P. B. 1993. Increase rates in severely depleted stocks of baleen whales. ICES J. Mar. Sci. 50: l69- 186.

Carretta, J. V. and K. A. Forney. 1993. Report on two aerial surveys for marine mammals in California coastal waters

utilizing a NOAA DeHavilland Twin Otter Aircraft: March 9-April7, 1991 and February S-April 6, 1992.

NOAA Tech. Memo. NOAA-TM-NMFS-SWFSC- 185. 77pp.

Dohl, T. P., R. C. Guess, M. L. Duman, and R. C. Helm. 1983. Cetaceans of central and not-them California, 1980-83:

Status? abundance, and distribution. Final Report to the Minerals Management Service, Contract No. l4-l2-

0001-29090. 284p.

Donovan, G. P. 1991. A review of IWC stock boundaries. Rept. Int. Whal. Commn., Special Issue 13:39-68.

Forney, K. A., J. Barlow, and J. V. Carretta. 1995. The abundance of cetaceans in California waters. Part 11: Aerial

surveys in winter and spring of 1991 and 1992. Fish. Bull. 93:15-26.

Green: G. A., J. J. Brueggeman, R. A. Grotefendt, C. E. Bowlby, M. L. Bonnell, K. C. Balcomb, III. 1992. Cetacean

distribution and abundance off Oregon and Washington, 1989-1990. Ch. 1 In J. J. Brueggeman (ed.). Oregon

and Washington Marine Mammal and Seabird Surveys. Minerals Management Service Contract Report 14-12-

000l-30426.

Hanan, D. A. 1986. California Department of Fish and Game coastal marine mammal study, annual report for the period

July 1, 1983 - June 30, 1984. Admin. Rept. LJ-86-16 available from Southwest Fisheries Science Center, P.O.

Box 271, La Jolla, CA. 55pp.

Hanan, D. A., D. B. Holts, and A. L. Coan, Jr. 1993. The California drift gill net fishery for sharks and swordfish, 1981 -

82 through 1990-91. Calif. Dept. Fish and Game Fish. Bull. No. 175. 95pp.

I15
Heyning. J. E., and T. D. Lewis. 1990. Fisheries interactions involving baleen whales off southern California. Rep.

int. Whal. Commn. 40:427-431.

Hill, P. S. and J. Barlow. 1992. Report of a marine mamma1 survey of the California coast aboard the research vessel

McARTHUR July 28-November 5, 1991. NOAA Technical Memorandum NOAA-TM-NMFS-SWFSC- 169.

NTIS #PB93-109908. 103pp.

Horwood, J. 1987. The Sei Whale: Population Biology, Ecology and Management. Croom Helm, London, U.K.

375pp.

Julian, F. 1993. Pinniped and cetacean mortality in California gillnet fisheries: Preliminary estimates for 1992. Int.

Whal. Comm. Working Paper SC/45/022.

Julian, F. 1994. Pinniped and cetacean mortality in California gillnet fisheries: Preliminary estimates for 1993. Int.

Whal. Comm. Working Paper SC/46/011.

Lee, T. 1993. Summary of cetacean survey data collected between the years of 1974 and 1985. NOAA Tech. Memo.

NOAA-TM-NMFS-SWFSC- 181. 184pp.

Lennert, C., S. Kruse, M. Beeson: and J. Barlow. 1994. Estimates of incidental marine mammal bycatch in California

gillnet fisheries for July through December, 1990. Int. Whal. Commn., Special Issue 15:449-461.

Mangels, K. F. and T. Gerrodette. Report of cetacean sightings during a marine mammal survey in the eastern Pacific

Ocean and the Gulf of California aboard the NOAA ships McArthur and David Starr Jordan July 28 -

November 6, 1993. NOAA Technical Memorandum NOAA-TM-NMFS-SWFSC-221. 88pp.

Masaki, Y. 1977. The separation of the stock units of sei whales in the North Pacific. Rept. Int. Whal. Commn., Special

Issue 1:71-77.

Mizroch, S. A., D. W. Rice? and J. M. Breiwick. 1984. The sei whale, Balaenoptera borealis. Mar. Fish. Rev. 46:25-29.

Ohsumi, S. and S. Wada. 1974. Status of whale stocks in the North Pacific, 1972. Rept. Int. Whal. Commn. 25:114-

126.

Perkins, P., J. Barlow, and M. Beeson. 1992. Pinniped and cetacean mortality in California gillnet fisheries: 1991.

IWC Working Paper SC/44/SM14.

Rice, D. W. 1974. Whales and whale research in the eastern North Pacific. pp. 170-195 In: W. E. Schevill (ed.). The

Whale Problem: A Status Report. Harvard Press, Cambridge, MA.

Tillman, M. F. 1977. Estimates of population size for the North Pacific sei whale. Rept. Int. Whal. Commn., Special

Issue 1:98- 106.

Wade, P. R. and T. Gerrodette. 1993. Estimates of cetacean abundance and distribution in the eastern tropical Pacific.

Rept. Int. Whal. Commn. 43:477-493.

Yablokov, A. V. 1994. Validity of whaling data. Nature 367: 108.

116
MINKE WHALE (Balaenoptera acutorostrata):

California/Oregon/Washington Stock

STOCK DEFINITION AND GEOGRAPHIC RANGE

The International Whaling Commission (IWC) recognizes 3 stocks of minke whales in the North Pacific: one

in the Sea of Japan/East China Sea, one in the rest of the western Pacific west of 180°N, and one in the “remainder” of

the Pacific (Donovan 1991). The “remainder” stock only reflects the lack of exploitation in the eastern Pacific and does

not imply that only one population exists in that area (Donovan 1991). In the “remainder” area, minke whales are

relatively common in the Bering and Chukchi seas and in the Gulf of Alaska, but are not considered abundant in any other

part of the eastern Pacific (Leatherwood et al. 1982; Brueggeman et al. 1990). Minke whales are usually seen over

continental shelves (Brueggeman et al. 1990). ln the extreme north, minke whales are believed to be migratory, but in

inland waters of Washington and in central California they appear to establish home ranges (Dorsey et al. 1990). Minke

whales occur year-round in California (Dohl et al. 1983; Barlow 1995; Forney et al. 1995) and in the Gulf of California

(Tershy et al. 1990). Minke whales are present at least in summer/fall along the Baja California peninsula (Wade and

Gerrodette 1993). Because the “resident” minke whales from California to Washington appear behaviorally distinct from

migratory whales further north, minke whales in coastal waters of California, Oregon, and Washington will be considered

as a separate stock. Minke whales in Alaskan waters are considered in a separate stock assessment report.

POPULATION SIZE

No estimates have been made for the number of minke whales in the entire North Pacific. In California coastal

waters, the number of minke whales is estimated as 526 (CV=O.97; log-normal 95% C.I.=106-2,596) (Barlow 1995).

Forney et al. (1995) estimate at total of 73 (CV=O.62) in the same area based on an aerial survey, but this estimate is

negatively biased because it excludes diving whales. In addition, Green et al. (1992) report 4 sightings of minke whales

in aerial surveys of Oregon and Washington, but they did not estimate population size for that area.

Minimum Population Estimate

The minimum population estimate for minke whales is taken as the lower 20th percentile of the log-normal

distribution of abundance estimated from the summer/fall ship survey in California waters (Barlow 1995) or

approximately 265. More sophisticated methods of estimating minimum population size would be available if a

correction factor (and associated variance) were available to correct the aerial survey estimates for missed animals.

Minimum estimates of abundance are still needed for Oregon and Washington.

Current Population Trend

There are no data on trends in minke whale abundance in waters of California: Oregon and/or Washington.

CURRENT AND MAXIMUM NET PRODUCTIVITY RATES

There are no estimates of the growth rate of minke whale populations in the North Pacific (Best 1993).

POTENTIAL BIOLOGICAL REMOVAL

The potential biological removal (PBR) level for this stock is calculated as the minimum population size (265)

times one half the default maximum net growth rate for cetaceans (1 /2 of 4%) times a recovery factor of 0.5 (for a stock

of unknown status), resulting in a PBR of 2.6.

ANNUAL HUMAN-CAUSED MORTALITY

Historic Whaling

The estimated take of western North Pacific minke whales by commercial whalers was approximately 31,OOO

from 1930 to 1987 (C. Allison, IWC, pers. comm.). None were reported taken by shore-based whaling stations in central

California between 1958 and 1965 (Rice 1974), and minke whales were not harvested commercially in the eastern North

Pacific. Reported aboriginal takes of minke whales in Alaska totalled 7 between 1930 and 1987 (C. Allison, IWC, pers.

comm.).

117
Fishery Information

Minke whales may occasionally be caught in both coastal set gillnets and offshore drift gillnets. Set gillnets are

used by approximately 134 vessels (J. Cordaro, Southwest Region, NMFS: pers. comm.) to catch halibut, flounder, angel

shark, yellowtail, white seabass, and white croaker in California coastal waters, and marine mammal mortality has been

noted in all these fisheries (Barlow et al. 1994). As a result of area closures, setnet fishing effort has decreased from

approximately 40,000 sets per year in the mid- 1980s to 16,000 in 1993 (Barlow et al. 1994) and is expected to decrease

again in 1994 because of a new ban on fishing within 3 nmi of shore in southern California. Drift gillnets are used by

approximately 149 vessels (J. Cordaro, Southwest Region, NMFS. pers. comm.) to catch swordfish, thresher shark, and

mako shark in California offshore waters (Hanan et al. 1993). Driftnet fishing effort has decreased from approximately

10,000 sets per year in the mid-1980s to 6,600 in 1993 (Barlow et al. 1994). The deaths of two minke whales which

stranded in the Southern California Bight (in 1983 and 1988) have been attributed to entanglement in fishing gear

(Heyning and Lewis 1990). Also, two minke whales and two unidentified whales were taken in the approximately 1%

of drift gillnets observed in 1980-86 (one minke whale was released alive) (Hanan 1986; Hanan et al. 1993). No minke

whales or unidentified baleen whales have been observed taken from 1990 to 1993 in gillnet observation programs which

covered 5-13% of fishing effort (Lennert et al. 1994; Perkins et al. 1992; Julian 1993, 1994). One was observed killed

in the driftnet fishery in 1994 (NMFS, unpubl. data). Minke whales are also likely to be caught in salmon drift gillnets

in Puget Sound, Washington.

Similar drift gillnet fisheries for swordfish and sharks exist along the entire Pacific coast of Baja California,

Mexico and may take animals from the same population. Quantitative data are available only for the Mexican swordfish

drift gillnet fishery, which has increased from two vessels in 1986 to 29 vessels in 1992-(Sosa-Nishizaki et al. 1993). The

total number of sets in this fishery in 1992 can be estimated from data provided by these authors to be approximately

2.700. with an observed rate of marine mammal bycatch of 0.13 animals per set (10 marine mammals in 77 observed sets;

Sosa-Nishizaki et al. 1993). This overall mortality rate is similar to that observed in California driftnet fisheries during

1990-93 (0.15 marine mammals per set), but species-specific information is not available for the Mexican fisheries. The

number of set gillnets used in Mexico is unknown.

Fishery Mortality Rates

The total fishery mortality for this species is known to be at least 5 animals over the last 10 years, which gives

an annual rate (0.5) that exceeds 10% of the calculated PBR. Therefore, total fishery mortality is not approaching zero

mortality and serious injury rate. This determination cannot be made for individual fisheries until the implementing

regulations for Section 118 of the Marine Mammal Protection Act (MMPA) have been reviewed by the public and

finalized.

Ship Strikes

Ship strikes were implicated in the death of one minke whale in 1977 and 2 unidentified whales (possibly minke

whales) in 1990 (J. Heyning and J. Cordaro, pers. comm.). Additional mortality from ship strikes probably goes

unreported because the whales do not strand or, if they do, they do not always have obvious signs of trauma.

STATUS OF STOCK

There were no known commercial takes of minke whales from Baja California to Washington. Minke whales

are not listed as “endangered” under the Endangered Species Act and are not considered “depleted” under the MMPA.

The greatest uncertainty in their status is whether entanglement in commercial gillnets and ship strikes could have

reduced this relatively small population. Total fishery mortality for minke whales was not estimated for the 1980-86

observer program? but based on the 2 observed deaths in 1% of the total sets, the total mortality during this time may have

been on the order of 200 minke whales or 40 per year. Because of this, the status of the west-coast stock should be

considered “unknown”. For the past 3 years, the annual mortality due to fisheries and ship strikes appears to be less than

the calculated PBR for this stock, so they would not be considered a “strategic” stock under the MMPA. The observation

of even one entanglement per year would, however, result in an extrapolated mortality estimate that would exceed the

PBR. There is no information on trends in the abundance of this stock.

REFERENCES

Barlow, J. 1995. The abundance of cetaceans in California waters. Part J: Ship surveys in summer and fall of 1991.

118
Fish. Bull. 93:1-14.

Barlow, J., R. W. Baird, J. E. Heyning, K. Wynne, A. M. Manville, II, L. F. Lowry, D. Hanan, J. Sease, and V. N.

Burkanov. 1994. A review of cetacean and pinniped mortality in coastal fisheries along the west coast of the

U.S. and Canada and the east coast of the Russian Federation. Rep. Int. Whal. Commn, Special Issue 15:405-

425.

Best, P. B. 1993. Increase rates in severely depleted stocks of baleen whales. ICES J. Mar. Sci. 50: 169-186.

Brueggeman, J. J., G. A. Green, K. C. Balcomb, C. E. Bowlby, R. A. Grotefendt, K. T. Briggs, M. L. Bonnell, R. G.

Ford, D. H. Varoujean, D. Heinemann, and D. G. Chapman. 1990. Oregon-Washington Marine Mammal and

Seabird Survey: Information synthesis and hypothesis formulation. U.S. Department of the Interior, OCS Study

MMS 89-0030.

Dohl, T. P., R. C. Guess, M. L. Duman, and R. C. Helm. 1983. Cetaceans of central and northern California, 1980-83:

Status, abundance, and distribution. Final Report to the Minerals Management Service, Contract No. 14- 12-

0001 -29090. 284p.

Donovan, G. P. 1991. A review of IWC stock boundaries. Rept. Int. Whal. Commn., Special Issue 13:39-68.

Dorsey, E. M., S. J. Stem, A. R. Hoelzel, and J. Jacobsen. 1990. Minke whale (Balaenoptera acutorostrata) from the

west coast of North. America: individual recognition and small-scale site fidelity. Rept. Int. Whal. Commn.,

Special Issue 12:357-368.

Forney, K. A., J. Barlow, and J. V. Carretta. 1995. The abundance of cetaceans in California waters. Part II: Aerial

surveys in winter and spring of 1991 and 1992. Fish. Bull. 93:15-26.

Green, G. A., J. J. Brueggeman, R. A. Grotefendt, C. E. Bowlby, M. L. Bonnell, K. C. Balcomb, III. 1992. Cetacean

distribution and abundance off Oregon and Washington, 1989-1990. Ch. 1 In: J. J. Brueggeman (ed.). Oregon

and Washington Marine Mammal and Seabird Surveys. Minerals Management Service Contract Report 14-12-

0001-30426.

Hanan, D. A. 1986. California Department of Fish and Game coastal marine mammal study, annual report for the period

July 1, 1983 - June 30, 1984. Admin. Rept. LJ-86-16 available from Southwest Fisheries Science Center, P.O.

Box 271, La Jolla, CA. 55pp.

Hanan, D. A., D. B. Holts, and A. L. Coan, Jr. 1993. The California drift gill net fishery for sharks and swordfish, 1981-

82 through 1990-91. Calif. Dept. Fish and Game Fish. Bull. No. 175. 95pp.

Heyning, J. E., and T. D. Lewis. 1990. Fisheries interactions involving baleen whales off southern California. Rep.

int. Whal. Commn. 40:427-431.

Julian, F. 1993. Pinniped and cetacean mortality in California gillnet fisheries: Preliminary estimates for 1992. Int.

Whal. Comm. Working Paper SC/45/022.

Julian, F. 1994. Pinniped and cetacean mortality in California gillnet fisheries: Preliminary estimates for 1993. Int.

Whal. Comm. Working Paper SC/46/011.

Leatherwood, S., R. R. Reeves, W. F. Perrin, and W. E. Evans. 1982. Whales, dolphins, and porpoises of the eastern

North Pacific and adjacent Arctic waters: A guide to their identification. NOAA Technical Rept. NMFS

Circular 444. 245pp.

Lennert, C., S. Kruse, M. Beeson, and J. Barlow. 1994. Estimates of incidental marine mammal bycatch in California

gillnet fisheries for July through December, 1990. Int. Whal. Commn., Special Issue 15:449-461.

Perkins, P., J. Barlow, and M. Beeson. 1992. Pinniped and cetacean mortality in California gillnet fisheries: 1991.

IWC Working Paper SC/44/SM14.

Rice, D. W. 1974. Whales and whale research in the eastern North Pacific. pp. 170-195 In: W. E. Schevill (ed.). &

Whale Problem: A Status Report. Harvard Press, Cambridge, MA.

Sosa-Nishizaki, O., R. De la Rosa Pacheco, R. Castro Longoria, M. Grijalva Chon, and J. De la Rosa Velez. 1993.

Estudio biologico pesquero del pez (Xiphias gludius) y otras especies de picudos (marlins y pez vela). Rep. Int.

CICESE, CTECT9306.

Tershy, B. R., D. Breese, and C. S. Strong. 1990. Abundance, seasonal distribution and population composition of

balaenopterid whales in the Canal de Ballenas, Gulf of California, Mexico. Rept. Int. Whal. Commn., Special

Issue 12:369-375.

Wade, P. R. and T. Gerrodette. 1993. Estimates of cetacean abundance and distribution in the eastern tropical Pacific.

Rept. Int. Whal. Commn. 43:477-493.

119
ROUGH-TOOTHED DOLPHIN (Steno bredanensis): Hawaiian Stock

STOCK DEFINITION AND GEOGRAPHIC RANGE

Rough-toothed dolphins are found throughout the world in tropical and warm-temperate waters (Miyazaki and

Perrin 1994). They are present around all the main Hawaiian islands (Shallenberger 1981; Tomich 1986) and have been

observed at least as far northwest as French Frigate Shoals (Nitta and Henderson 1993). Five strandings have been

reported from Maui, Oahu, and the island of Hawaii (Nitta 1991). Nothing is known about stock structure for this

species in the North Pacific. For the Marine Mammal Protection Act (MMPA) stock assessment reports, there is a single

Pacific management stock including only animals found within the U.S. Exclusive Economic Zone of the Hawaiian

Islands.

POPULATION SIZE

A population estimate for this species has been made in the eastern tropical Pacific (Wade and Gerrodette

1993), but there are no data for a population estimate in Hawaiian waters.

Minimum Population Estimate

No data are available for a minimum population estimate.

Current Population Trend

No data are available on current population trend.

CURRENT AND MAXIMUM NET PRODUCTIVITY RATES

No data are available on current or maximum net productivity rate.

POTENTIAL BIOLOGICAL REMOVAL

No PBR can be calculated for this species at this time.

ANNUAL HUMAN-CAUSED MORTALITY AND SERIOUS INJURY

No estimate of annual human-caused mortality and serious injury is available: as no mortality of this species

has been documented in Hawaiian fisheries (Nitta and Henderson 1993). However, mortality of other cetacean species

has been observed in Hawaiian fisheries, and the gear types used in these fisheries are responsible for marine mammal

mortality and serious injury in other fisheries throughout U.S. waters. Gillnets appear to capture marine mammals

wherever they are used: and float lines from lobster traps and longlines can be expected to occasionally entangle whales

(Perrin, Donovan and Barlow 1994).

Fishery Information

Pelagic, bottomfish and lobster fisheries occur in Hawaiian waters. Pelagic fisheries include commercial

fisheries (troll, handline, longline: local inshore gillnet), commercial charter and recreational troll fishing. Only the

longline fishery is subject to active management through a Fishery Management Plan. The growth of the longline fleet

between 1989 and 1991 generated concerns regarding impact on fish stocks (especially swordfish), on other fisheries

(troll, handline), and on protected species (mainly sea turtles). The value of longline landings increased to almost $45

million in 1992 and 1993. Regulations established longline fishery permit and reporting requirements, area closures

in the Northwestern Hawaiian Islands (NWHI) to protect Hawaiian monk seals and in the main Hawaiian Islands to

prevent gear conflicts, a limited entry program, a mandatory observer program, and a requirement for installation and

operation of vessel monitoring equipment on longline vessels in Hawaii. Approximately 165 longline permits have been

issued. The commercial non-longline fisheries (troll: handline, gillnet) have more than 2,000 participants but account

only for about $10 - $l5 million per year in landings. The number of anglers and value of recreational fishing are

unknown. Interactions with cetaceans have been reported for all Hawaiian pelagic fisheries, and some of these

interactions involved rough-toothed dolphins (Nitta and Henderson 1993). They are known to take bait and catch from

Hawaiian sport and commercial fisheries operating near the main islands and in a portion of the northwestern islands

(Shallenberger 1981; Schlais 1984; Nitta and Henderson 1993), and they have been specifically reported to interact with

120
the day handline fishery for tuna (palu-ahi) and the troll fishery for billfish and tuna (Schlais 1984; Nitta and Henderson

1993).

The commercial lobster fishery in the NWHI is managed by federal regulations which include size limits, area

closures, seasons: gear restrictions, annual quotas and reporting requirements. Fifteen permits have been issued for this

fishery. The fishery was closed in 1993 and only five vessels operated in the fishery in 1994. No interactions between

marine mammals and this fishery have been recorded in the past five years.

The bottomfish fishery occurs throughout the NWHI and the main Hawaiian Islands using handlines. In the

NWHI, there are two zones in which fishing takes place. The Ho’omalu Zone has limited entry and the Mau Zone has

open access. There are currently 11 permits for the Ho’omalu Zone and 30 for the Mau Zone. However, in 1994, only

five vessels fished in the Ho’omalu Zone and 15-20 vessels fished in the Mau Zone. Total landings of bottomfish in

Hawaii from all waters have fluctuated little in recent years, about 400,000 pounds per year from the NWHI and about

500,000 pounds per year from the main Hawaiian Islands. Fishermen claim interactions with dolphins who steal bait

and catch are increasing.

Other Mortality

At least 22 rough-toothed dolphins were live-captured in Hawaiian waters between 1963 and 1976

(Shallenberger 1981).

Fishery Mortality Rate

The total fishery mortality and serious injury cannot be considered to be insignificant and approaching zero

because the population size of this stock of rough-toothed dolphins is unknown. Determination cannot be made for

individual fisheries until the implementing regulations for section 118 of the MMPA have been reviewed by the public

and finalized.

STATUS OF STOCK

The status of rough-toothed dolphins in Hawaiian waters is unknown. The stock’s status relative to OSP under

the MMPA is also unknown. The species is not listed as threatened or endangered under the Endangered Species Act

(1973). Although information on rough-toothed dolphins in Hawaiian waters is limited, this stock would be considered

non-strategic under the 1994 amendments to the MMPA given the absence of reported fisheries related mortality.

REFERENCES

Miyazaki, N. and W. F. Perrin. 1994. Rough-toothed dolphin Steno bredanensis (Lesson, 1828). In: S. H. Ridgway

and R. Harrison (eds.), Handbook of Marine Mammals, Vol.5: The First Book of Dolphins, pp. 1-21. Academic

Press, 416 pp.

Nitta, E. 1991. The marine mammal stranding network for Hawaii: an overview. In: J.E. Reynolds III, D.K. Odell

(eds.), Marine Mammal Strandings in the United States, pp.56-62. NOAA Tech. Rep. NMFS 98, 157 pp.

Nitta, E. and J. R. Henderson. 1993. A review of interactions between Hawaii’s fisheries and protected species. Mar.

Fish. Rev. 55(2):83-92.

Perrin, W.F., G. P. Donovan and J. Barlow. 1994. Gillnets and Cetaceans. Rep. Int. Whal. Commn., Special Issue 15,

629 pp.

Schlais, J.F. 1984. Thieving dolphins: A growing problem in Hawaii’s fisheries. Sea Front. 30(5):293-298.

Shallenberger, E.W. 1981. The status of Hawaiian cetaceans. Final report to U.S. Marine Mammal Commission. MMC77/23, 79pp.

Tomich, P. Q. 1986. Mammals in Hawaii: A Synopsis and Notational Bibliography. Bishop Museum Press, Hawaii,

375 pp.

Wade, P. R. and T. Gerrodette. 1993. Estimates of cetacean abundance and distribution in the eastern tropical Pacific.

Rep. Int. Whal. Commn. 43:477-493.

121
RISSO’S DOLPHIN (Grampus griseus): Hawaiian Stock

STOCK DEFINITION AND GEOGRAPHIC RANGE

Risso’s dolphins are found in tropical to warm-temperate waters worldwide (Kruse et al. In press). They appear

to be rare in Hawaiian waters. Of three reported sightings of this species by Shallenberger (1981). only one was

verified. There are four stranding records from the main islands (Nitta 1991). Balcomb (1987) referred to a sighting

of a large herd off the Kona Coast in February 1985. For the Marine Mammal Protection Act (MMPA) stock assessment

reports, Risso’s dolphins within the Pacific U.S. Exclusive Economic Zone are divided into two discrete, non-contiguous

areas: 1) Hawaiian waters (this report), and 2) waters off California, Oregon and Washington.

POPULATION SIZE

Population estimates have been made off Japan (Miyashita 1993) and in the eastern tropical Pacific (Wade and

Gerrodette 1993), but there are no data for a population estimate in Hawaiian waters.

Minimum Population Estimate

No data are available for a minimum population estimate.

Current Population Trend

No data are available on current population trend.

CURRENT AND MAXIMUM NET PRODUCTIVITY RATES

No data are available on current or maximum net productivity rate for Hawaiian animals.

POTENTIAL BIOLOGICAL REMOVAL

No PBR can be calculated for this species at this time.

ANNUAL HUMAN CAUSED MORTALITY AND SERIOUS INJURY

No estimate of annual human-caused mortality and serious injury is available as there are no reports of direct

or incidental takes of Risso’s dolphins in Hawaiian waters. However? mortality of other cetacean species has been

observed in Hawaiian fisheries? and the gear types used in these fisheries are responsible for marine mammal mortality

and serious injury in other fisheries throughout U.S. waters. Gillnets appear to capture marine mammals wherever they

are used, and float lines from lobster traps and longlines can be expected to occasionally entangle whales (Perrin,

Donovan and Barlow 1994).

Fishery Information

Pelagic, bottomfish and lobster fisheries occur in Hawaiian waters. Pelagic fisheries include commercial

fisheries (troll: handline, longline, local inshore gillnet), commercial charter and recreational troll fishing. Only the

longline fishery is subject to active management through a Fishery Management Plan. The growth of the longline fleet

between 1989 and 1991 generated concerns regarding impact on fish stocks (especially swordfish), on other fisheries

(troll, handline), and on protected species (mainly sea turtles). The value of longline landings increased to almost $45

million in 1992 and 1993. Regulations established longline fishery permit and reporting requirements, area closures

in the Northwestern Hawaiian Islands (NWHI) to protect Hawaiian monk seals and in the main Hawaiian Islands to

prevent gear conflicts, a limited entry program, a mandatory observer program, and a requirement for installation and

operation of vessel monitoring equipment on longline vessels in Hawaii. Approximately 165 longline permits have been

issued. The commercial non-longline fisheries (troll. handline. gillnet) have more than 2,000 participants but account

only for about $10 - $l5 million per year in landings, The number of anglers and value of recreational fishing are

unknown. Interactions with cetaceans have been reported for all Hawaiian pelagic fisheries (Nina and Henderson 1993),

but no interactions with Risso’s dolphins have been documented.

The commercial lobster fishery in the NWHI is managed by federal regulations which include size limits: area

closures. seasons, gear restrictions. annual quotas and reporting requirements. Fifteen permits have been issued for this

fishery. The fishery was closed in 1993 and only five vessels operated in the fishery in 1994. No interactions between

122
marine mammals and this fishery have been recorded in the past five years.

The bottomfish fishery occurs throughout the NWHI and the main Hawaiian Islands using handlines. In the

NWHI, there are two zones in which fishing takes place. The Ho’omalu Zone has limited entry and the Mau Zone has

open access. There are currently 11 permits for the Ho’omalu Zone and 30 for the Mau Zone. However, in 1994, only

five vessels fished in the Ho’omalu Zone and 15-20 vessels fished in the Mau Zone. Total landings of bottomfish in

Hawaii from all waters have fluctuated little in recent years, about 400,000 pounds per year from the NWHI and about

500,000 pounds per year from the main Hawaiian Islands. Fishermen claim interactions with dolphins who steal bait

and catch are increasing.

Fishery Mortality Rate

The total fishery mortality and serious injury cannot be considered to be insignificant and approaching zero

because the population size of this stock of Risso’s dolphins is unknown. Determination cannot be made for individual

fisheries until the implementing regulations for section 118 of the MMPA have been reviewed by the public and

finalized.

STATUS OF STOCK

The status of Risso’s dolphins in Hawaiian waters is unknown. The stock’s status relative to OSP under the

MMPA is also unknown. The species is not listed as threatened or endangered under the Endangered Species Act

(1973). Although information on Risso’s dolphins in Hawaiian waters is limited, this stock would be considered nonstrategic under the 1994 amendments to the MMPA given the absence of reported fisheries related mortality.

REFERENCES

Balcomb, K. C., III. 1987. The Whales of Hawaii. Marine Mammal Fund, 99 pp.

Kruse, S. K., D. K. Caldwell, and M. C. Caldwell. In press. Risso’s dolphin Grampus griseus. In: S. H. Ridgway and

R. Harrison (eds.), Handbook of Marine Mammals, Vol. 6: The Second Book of Dolphins and the Porpoises.

Academic Press.

Miyashita, T. 1993. Abundance of dolphin stocks in the western North Pacific taken by the Japanese drive fishery.

Rep. Int. Whal. Commn. 43:417-437.

Nitta, E. 1991. The marine mammal stranding network for Hawaii: an overview. In: J.E. Reynolds III, D.K. Odell

(eds.), Marine Mammal Strandings in the United States, pp.56-62. NOAA Tech. Rep. NMFS 98, 157 pp.

Nitta, E. and J. R. Henderson. 1993. A review of interactions between Hawaii’s fisheries and protected species. Mar.

Fish. Rev. 55(2):83-92.

Perrin, W.F., G. P. Donovan and J. Barlow. 1994. Gillnets and Cetaceans. Rep. Int. Whal. Commn., Special Issue 15,

629 pp.

Shallenberger, E.W. 1981. The status of Hawaiian cetaceans. Final report to U.S. Marine Mammal Commission. MMC77/23, 79pp.

Wade, P. R. and T. Gerrodette. 1993. Estimates of cetacean abundance and distribution in the eastern tropical Pacific.

Rep. Int. Whal. Commn. 43:477-493.

123
BOTTLENOSE DOLPHIN (Tursiops truncatus): Hawaiian Stock

STOCK DEFINITION AND GEOGRAPHIC RANGE

Bottlenose dolphins are widely distributed throughout the world in tropical and warm-temperate waters, The

species is primarily coastal in much of its range: but there are populations in some offshore deepwater areas as well.

Separate offshore and coastal forms have been identified along continental coasts in several areas (Ross and Cockcroft

1990; Van Waerebeek et al. 1990) and similar onshore-offshore forms may exist in Hawaiian waters.

Although only three strandings have been reported (Nina 1991), bottlenose dolphins are common throughout

the Hawaiian Islands, from the island of Hawaii to Kure Atoll (Shallenberger 1981). In the Northwestern Hawaiian

Islands, they are found primarily in relatively shallow inshore waters (Rice 1960). In the main Hawaiian Islands, they

are found in both shallow inshore waters and deep channels between islands.

In their analysis of sightings of bottlenose dolphins in the eastern tropical Pacific (ETP), Scott and Chivers

(1990) noted that there was a large hiatus between the westernmost sightings and the Hawaiian Islands. These data

suggest that the bottlenose dolphins in Hawaiian waters belong to a separate stock from those in the ETP. For the

Marine Mammal Protection Act (MMPA) stock assessment reports, bottlenose dolphins within the Pacific U.S.

Exclusive Economic Zone are divided into three stocks: 1) Hawaiian stock (this report), 2) California, Oregon and

Washington offshore stock, and 3) California coastal stock.

POPULATION SIZE

Population estimates have been made in Japanese waters (Miyashita 1993) and the eastern tropical Pacific

(Wade and Gerrodette 1993), but no data are available to make a population estimate in Hawaiian waters. In 1987, a

minimum count of 430 bottlenose dolphins was obtained from vessel and aerial surveys of inshore waters around Oahu,

Molokai, Lanai, Maui and Hawaii (Naval Ocean Systems Center unpublished data, cited in Nitta and Henderson 1993).

It is unclear what proportion of the species’ range was surveyed in this study.

Minimum Population Estimate

No data from the past five years are available to make a minimum population estimate.

Current Population Trend

No data are available on current population trend.

CURRENT AND MAXIMUM NET PRODUCTIVITY RATES

No data are available on current or maximum net productivity rates for Hawaii.

POTENTIAL BIOLOGICAL REMOVAL

No PBR can be calculated for this species at this time.

ANNUAL HUMAN-CAUSED MORTALITY

Although some mortality of bottlenose dolphins has been observed in inshore gillnets, no estimate of annual

human-caused mortality and serious injury is available. The gear types used in Hawaiian fisheries are responsible for

marine mammal mortality and serious injury in other fisheries throughout U.S. waters. Gillnets appear to capture marine

mammals wherever they are used, and float lines from lobster traps and longlines can be expected to occasionally

entangle whales (Perrin, Donovan and Barlow 1994).

Fishery Information

Pelagic, bottomfish and lobster fisheries occur in Hawaiian waters. Pelagic fisheries include commercial

fisheries (troll, handline, longline, local inshore gillnet), commercial charter and recreational troll fishing. Only the

longline fishery is subject to active management through a Fishery Management Plan. The growth of the longline fleet

between 1989 and 1991 generated concerns regarding impact on fish stocks (especially swordfish), on other fisheries

(troll, handline), and on protected species (mainly sea turtles). The value of longline landings increased to almost $45

million in 1992 and 1993. Regulations established longline fishery permit and reporting requirements, area closures

124
in the Northwestern Hawaiian Islands (NWHI) to protect Hawaiian monk seals and in the main Hawaiian Islands to

prevent gear conflicts, a limited entry program, a mandatory observer program, and a requirement for installation and

operation of vessel monitoring equipment on longline vessels in Hawaii. Approximately 165 longline permits have been

issued. The commercial non-longline fisheries (troll, handline, gillnet) have more than 2,000 participants but account

only for about $10 - $15 million per year in landings. The number of anglers and value of recreational fishing are

unknown. Monofilament small-mesh (about 5cm stretched) gillnets are commonly set on shallow reefs around all the

main islands, usually at depths of less than 10 meters (Nitta and Henderson 1993). Inshore reef fish are the targets of

this fishing. During 1992/93 the State of Hawaii received 288 applications for fishing permits that listed nets as the

primary gear and gillnets were specified in 161 additional applications for permits (Nitta and Henderson 1993).

Interactions with cetaceans have been reported for all Hawaiian pelagic fisheries, and many of these interactions

involved bottlenose dolphins (Nitta and Henderson 1993). They are one of the species commonly reported to take bait

and catch from several Hawaiian sport and commercial fisheries (Nitta and Henderson 1993; Schlais 1984).

Observations of bottlenose dolphins taking bait or catch have also been made in the day handline fishery (palu-ahi) for

tuna, the handline fishery for mackerel scad, the troll fishery for billfish and tuna, and the inshore set gillnet fishery

(Nitta and Henderson 1993). Beginning in the early 1970s the National Marine Fisheries Service received reports of

fishermen shooting at bottlenose dolphins to deter them from taking fish catches (Nitta and Henderson 1993). Nitta and

Henderson (1993) also reported that one bottlenose dolphin calf was removed from small-mesh set gillnet off Maui in

1991 and expressed surprise that bottlenose dolphins are “rarely reported entangled or raiding set gill nets in Hawaii,”

considering that they so often remove fish from fishing lines.

The commercial lobster fishery in the NWHI is managed by federal regulations which include size limits, area

closures, seasons, gear restrictions, annual quotas and reporting requirements. Fifteen permits have been issued for this

fishery. The fishery was closed in 1993 and only five vessels operated in the fishery in 1994. No interactions between

marine mammals and this fishery have been recorded in the past five years.

The bottomfish fishery occurs throughout the NWHI and the main Hawaiian Islands using handlines. In the

NWHI, there are two zones in which fishing takes place. The Ho’omalu Zone has limited entry and the Mau Zone has

open access. There are currently 11 permits for the Ho’omalu Zone and 30 for the Mau Zone. However, in 1994, only

five vessels fished in the Ho’omalu Zone and 15-20 vessels fished in the Mau Zone. Total landings of bottomfish in

Hawaii from all waters have fluctuated little in recent years, about 400,000 pounds per year from the NWHI and about

500,000 pounds per year from the main Hawaiian Islands. Nitta and Henderson (1993) indicated that bottlenose

dolphins remove bait and catch from handlines used to catch bottomfish off the island of Hawaii and Kaula Island and

on several banks of the Northwestern Hawaiian Islands. Fishermen claim interactions with dolphins who steal bait and

catch are increasing.

Other Mortality

At least 36 bottlenose dolphins were live-captured in Hawaiian waters between 1963 and 1981 (Shallenberger

1981). The main capture area was around Oahu.

Fishery Mortality Rate

The total fishery mortality and serious injury cannot be considered to be insignificant and approaching zero

because the population size of this stock of bottlenosed dolphins is unknown. Determination cannot be made for

individual fisheries until the implementing regulations for section 118 of the MMPA have been reviewed by the public

and finalized.

STATUS OF STOCK

The status of bottlenose dolphins in Hawaiian waters is unknown. The stocks status relative to OSP under the

MMPA is also unknown. They are not listed as threatened or endangered under the Endangered Species Act (1973).

Although information on bottlenose dolphins in Hawaiian waters is limited, this stock would be considered non-strategic

under the 1994 amendments to the MMPA given the insignificance of reported fisheries related mortality.

REFERENCES

Miyashita, T. 1993. Abundance of dolphin stocks in the western North Pacific taken by the Japanese drive fishery.

125
Rep. Int. Whal. Commn. 43:417-437.

Nitta, E. 1991. The marine mammal stranding network for Hawaii: an overview. In: J.E. Reynolds III, D.K. Odell

(eds.), Marine Mammal Strandings in the United States, pp.56-62. NOAA Tech. Rep. NMFS 98, 157 pp.

Nitta, E. and J. R. Henderson. 1993. A review of interactions between Hawaii’s fisheries and protected species. Mar.

Fish. Rev. 55(2):83-92.

Perrin, W.F., G. P. Donovan and J. Barlow. 1994. Gillnets and Cetaceans. Rep. Int. Whal. Commn., Special Issue 15,

629 pp.

Rice, D. W. 1960. Distribution of the bottle-nosed dolphin in the leeward Hawaiian Islands. J. Mamm. 41:407-408.

Ross, G.J.B. and V. G. Cockcroft. 1990. Comments on Australian bottlenose dolphins and the taxonomic status of

Tursiops aduncus (Ehrenberg, 1832). In: The Bottlenose Dolphin (eds. S. Leatherwood and R. Reeves). pp.

101-128. Academic Press, 653pp.

Schlais, J.F. 1984. Thieving dolphins: A growing problem in Hawaii’s fisheries, Sea Front. 30(5):293-298.

Scott, M. D. and S. J. Chivers. 1990. Distribution and herd structure of bottlenose dolphins in the eastern tropical

Pacific Ocean. In: The Bottlenose Dolphin (eds. S. Leatherwood and R. Reeves). pp. 387-402. Academic

Press, 653pp.

Shallenberger, E.W. 1981. The status of Hawaiian cetaceans. Final report to U.S. Marine Mammal Commission. MMC77/23, 79pp.

Van Waerebeek, K., J. C. Reyes, A. J. Read, and J. S. McKinnon. 1990. Preliminary observations of bottlenose

dolphins from the Pacific coast of South America. In: The Bottlenose Dolphin (eds. S. Leatherwood and R.

Reeves). pp. 143-154. Academic Press, 653 pp.

Wade, P. R. and T. Gerrodette. 1993. Estimates of cetacean abundance and distribution in the eastern tropical Pacific.

Rep. Int. Whal. Commn. 43:477-493.

126
PANTROPICAL SPOTTED DOLPHIN (Stenella attenuata): Hawaiian Stock

STOCK DEFINITION AND GEOGRAPHIC RANGE

Pantropical spotted dolphins are primarily found in tropical and subtropical waters worldwide (Perrin and Hohn

1994). Much of what is known about the species in the North Pacific has been learned from specimens obtained in the

large directed fishery in Japan and in the eastern tropical Pacific (ETP) tuna purse-seine fishery (Perrin and Hohn 1994).

These dolphins are common and abundant throughout the Hawaiian archipelago, particularly in channels between

islands, over offshore banks (e.g. Penguin Banks), and off the lee shores of the islands (see Shallenberger 1981). Nitta

(1991) only documented three strandings of this species in Hawaii. Morphological differences and distribution patterns

have been used to establish that the spotted dolphins around Hawaii belong to a stock that is distinct from those in the

ETP (Perrin 1975; Dizon et al. 1994; Perrin et al. 1994). Their possible affinities with other stocks elsewhere in the

Pacific have not been investigated. For the Marine Mammal Protection Act (MMPA) stock assessment reports, there

is a single Pacific management stock including only animals found within the U.S. Exclusive Economic Zone of the

Hawaiian Islands. Spotted dolphins involved in eastern tropical Pacific tuna purse-seine fisheries are managed

separately under the MMPA.

POPULATION SIZE

Population estimates are available for Japanese waters (Miyashita 1993) and the eastern tropical Pacific (Wade

and Gerrodette 1993), but no data are available to estimate population size for this species in any part of the central

Pacific.

Minimum Population Estimate

No data are available for a minimum population estimate.

Current Population Trend

No data are available on current population trend.

CURRENT AND MAXIMUM NET PRODUCTIVITY RATES

No data are available on current or maximum net productivity rate.

POTENTIAL BIOLOGICAL REMOVAL

No PBR can be calculated for this species at this time.

ANNUAL HUMAN-CAUSED MORTALITY AND SERIOUS INJURY

No estimate of annual human-caused mortality and serious injury is available as there are no reports of direct

or incidental takes of pantropical spotted dolphins in Hawaiian waters (Nitta and Henderson 1993). However, mortality

of other cetacean species has been observed in Hawaiian fisheries, and the gear types used in these fisheries are

responsible for marine mammal mortality and serious injury in other fisheries throughout U.S. waters. Gillnets appear

to capture marine mammals wherever they are used, and float lines from lobster traps and longlines can be expected to

occasionally entangle whales (Perrin, Donovan and Barlow 1994).

Fishery Information

Pelagic, bottomfish and lobster fisheries occur in Hawaiian waters. Pelagic fisheries include commercial

fisheries (troll, handline, longline, local inshore gillnet), commercial charter and recreational troll fishing. Only the

longline fishery is subject to active management through a Fishery Management Plan. The growth of the longline fleet

between 1989 and 1991 generated concerns regarding impact on fish stocks (especially swordfish), on other fisheries

(troll, handline), and on protected species (mainly sea turtles). The value of longline landings increased to almost $45

million in 1992 and 1993. Regulations established longline fishery permit and reporting requirements, area closures

in the Northwestern Hawaiian Islands (NWHI) to protect Hawaiian monk seals and in the main Hawaiian Islands to

prevent gear conflicts, a limited entry program, a mandatory observer program, and a requirement for installation and

operation of vessel monitoring equipment on longline vessels in Hawaii. Approximately 165 longline permits have been

127
issued. The commercial non-longline fisheries (troll, handline: gillnet) have more than 2,000 participants but account

only for about $10 - $15 million per year in landings. The number of anglers and value of recreational fishing are

unknown. Interactions with cetaceans have been reported for all Hawaiian pelagic fisheries (Nitta and Henderson 1993),

but no interactions with pantropical spotted dolphins have been documented.

The commercial lobster fishery in the NWHI is managed by federal regulations which include size limits, area

closures, seasons, gear restrictions, annual quotas and reporting requirements. Fifteen permits have been issued for this

fishery. The fishery was closed in 1993 and only five vessels operated in the fishery in 1994. No interactions between

marine mammals and this fishery have been recorded in the past five years.

The bottomfish fishery occurs throughout the NWHI and the main Hawaiian Islands using handlines. In the

NWHI, there are two zones in which fishing takes place. The Ho’omalu Zone has limited entry and the Mau Zone has

open access. There are currently 11 permits for the Ho’omalu Zone and 30 for the Mau Zone. However, in 1994, only

five vessels fished in the Ho’omalu Zone and 15-20 vessels fished in the Mau Zone. Total landings of bottomfish in

Hawaii from all waters have fluctuated little in recent years. about 400,000 pounds per year from the NWHI and about

500,000 pounds per year from the main Hawaiian Islands. Fishermen claim interactions with dolphins who steal bait

and catch are increasing.

Other Mortality

At least 52 pantropical spotted dolphins were live-captured in Hawaii between 1963 and 1978 (Shallenberger

1981).

Fishery Mortality Rate

The total fishery mortality and serious injury cannot be considered to be insignificant and approaching zero

because the population size of this stock of pantropical spotted dolphins is unknown. Determination cannot be made

for individual fisheries until the implementing regulations for section 118 of the MMPA have been reviewed by the

public and finalized.

STATUS OF STOCK

The status of pantropical spotted dolphins in Hawaiian waters is unknown. The stock’s status relative to OSP

under the MMPA is also unknown. The species is not listed as threatened or endangered under the Endangered Species

Act (1973). Although information on pantropical spotted dolphins in Hawaiian waters is limited, this stock would be

considered non-strategic under the 1994 amendments to the MMPA given the absence of reported fisheries related

mortality.

REFERENCES

Dizon, A. E., W. F. Perrin, and P. A. Akin. 1994. Stocks of dolphins (Stenella spp. and Delphinus delphis) in the

eastern tropical Pacific: a phylogeographic classification. NOAA Tech. Rep. NMFS 119, 20 pp.

Miyashita, T. 1993. Abundance of dolphin stocks in the western North Pacific taken by the Japanese drive fishery.

Rep. Int. Whal. Commn. 43:417-437.

Nitta, E. 1991. The marine mammal stranding network for Hawaii: an overview. In: J:E. Reynolds 111, D.K. Odell

(eds.), Marine Mammal Strandings in the United States, pp.56-62. NOAA Tech. Rep. NMFS 98, 157 pp.

Nitta, E. and J. R. Henderson. 1993. A review of interactions between Hawaii’s fisheries and protected species. Mar.

Fish. Rev. 55(2):83-92.

Perrin, W. F. 1975. Variation of spotted and spinner porpoise (genus Stenella) in the eastern tropical Pacific and

Hawaii. Bull. Scripps Inst. Oceanogr. 21, 206 pp.

Perrin, W. F., G. D. Schnell, D. J. Hough, J. W. Gilpatrick, Jr., and J. V. Kashiwada. 1994. Re-examination of

geographical variation in cranial morphology of the pantropical spotted dolphin, Stenella attenuata, in the

eastern Pacific. Fish. Bull. 92:324-346.

Perrin, W. F. and A. A. Hohn. 1994. Pantropical spotted dolphin Stenella altenuata. In: S. H. Ridgway and R.

Harrison (eds.), Handbook of Marine Mammals. Vol.5: The First Book of Dolphins, pp 7l-98. Academic Press,

416 pp.

Perrin, W.F., G. P. Donovan and J. Barlow. 1994. Gillnets and Cetaceans. Rep. lnt. Whal. Commn., Special lssue 15,

629 pp.

128
Shallenberger, E.W. 1981. The status of Hawaiian cetaceans. Final report to U.S. Marine Mammal Commission. MMC77/23, 79pp.

Wade, P. R. and T. Gerrodette. 1993. Estimates of cetacean abundance and distribution in the eastern tropical Pacific.

Rep. Int. Whal. Commn. 43:477-493.

129
SPINNER DOLPHIN (Stenella longirostris): Hawaiian Stock

STOCK DEFINITION AND GEOGRAPHIC RANGE

Spinner dolphins are found throughout the world in tropical and warm-temperate waters (Perrin and Gilpatrick

1994). They are common and abundant throughout the entire Hawaiian archipelago (Shallenberger 1981; Norris and

Dohl 1980; Norris et al. 1994). There is some suggestion from an intensive study of spinner dolphins off the Kona

Coast of Hawaii that the waters surrounding this island may have a large, relatively stable “resident” population (Norris

et al. 1994).

Hawaiian spinner dolphins belong to a stock that is separate from those involved in the tuna purse-seine fishery

in the eastern tropical Pacific (Perrin 1975; Dizon et al. 1994). The Hawaiian form is referrable to the subspecies S.

longirostris lougirostris, which occurs pantropically (Perrin 1990). For the Marine Mammal Protection Act (MMPA)

stock assessment reports, there is a single Pacific management stock including only animals found within the U.S.

Exclusive Economic Zone of the Hawaiian Islands. Spinner dolphins involved in eastern tropical Pacific tuna purseseine fisheries are managed separately under the MMPA.

POPULATION SIZE

Wade and Gerrodette (1993) estimated the sizes of populations in the eastern tropical Pacific. Although spinner

dolphins are clearly among the most abundant cetaceans in Hawaiian waters, available population estimates apply only

to the west coast of Hawaii. Norris et al. (1994) photoidentified 192 individuals along the west coast of Hawaii and

estimated 960 animals for this area in 1979- 1980. Ostman (1994) photoidentified 677 individual spinner dolphins in

the same area from 1989 to 1992. Using the same estimation procedures as Norris et al. (1994), Ostman (1994)

estimated a population size of 2.334 for his study area along the Kona coast of Hawaii.

Minimum Population Estimate

The available population estimates apply to only a portion of the species’ extensive range in Hawaiian waters.

Ostman’s (1994) total of 677 spinner dolphins can be regarded as a minimum count, but it must be noted that it applies

only to the west coast of the island of Hawaii.

Current Population Trend

No data on current population trend are available.

CURRENT AND MAXIMUM NET PRODUCTIVITY RATES

No information on current or maximum net productivity rate is currently available for the Hawaiian stock.

POTENTIAL BIOLOGICAL REMOVAL

Based on this species’ unknown status and growth rate. the recovery factor (FR) is 0.5 and 1/2Rmax is the default

value 0.02. Using these values and the minimum count of 677, the PBR is 6.8 animals.

ANNUAL HUMAN-CAUSED MORTALITY AND SERIOUS INJURY

Although some mortality of spinner dolphins has been observed in inshore gillnets, no estimate of annual

human-caused mortality and serious injury is available. The gear types used in Hawaiian fisheries are responsible for

marine mammal mortality and serious injury in other fisheries throughout U.S. waters. Gillnets appear to capture marine

mammals wherever they are used, and float lines from lobster traps and longlines can be expected to occasionally

entangle whales (Perrin, Donovan and Barlow 1994).

Fishery Information

Pelagic, bottomfish and lobster fisheries occur in Hawaiian waters. Pelagic fisheries include commercial

fisheries (troll, handline, longline, local inshore gillnet), commercial charter and recreational troll fishing. Only the

longline fishery is subject to active management through a Fishery Management Plan. The growth of the longline fleet

between 1989 and 1991 generated concerns regarding impact on fish stocks (especially swordfish), on other fisheries

(troll, handline), and on protected species (mainly sea turtles). The value of longline landings increased to almost $45

130
million in 1992 and 1993. Regulations established longline fishery permit and reporting requirements, area closures

in the Northwestern Hawaiian Islands (NWHI) to protect Hawaiian monk seals and in the main Hawaiian Islands to

prevent gear conflicts, a limited entry program, a mandatory observer program, and a requirement for installation and

operation of vessel monitoring equipment on longline vessels in Hawaii. Approximately 165 longline permits have been

issued. The commercial non-longline fisheries (troll, handline, gillnet) have more than 2,000 participants but account

only for about $10 - $l5 million per year in landings. The number of anglers and value of recreational fishing are

unknown. Monofilament small-mesh (about 5cm stretched) gillnets are commonly set on shallow reefs around all the

main islands, usually at depths of less than 10 meters (Nitta and Henderson 1993). Inshore reef fish are the targets of

this fishing. During 1992/93 the State of Hawaii received 288 applications for fishing permits that listed nets as the

primary gear and gillnets were specified in 161 additional applications for permits (Nitta and Henderson 1993).

Interactions with cetaceans have been reported for all Hawaiian pelagic fisheries, and there are records of spinner

dolphins taken in inshore monofilament gillnets and net fragments in Hawaiian waters (Nitta and Henderson 1993).

The commercial lobster fishery in the NWHI is managed by federal regulations which include size limits, area

closures, seasons, gear restrictions, annual quotas and reporting requirements. Fifteen permits have been issued for this

fishery. The fishery was closed in 1993 and only five vessels operated in the fishery in 1994. No interactions between

marine mammals and this fishery have been recorded in the past five years.

The bottomfish fishery occurs throughout the N WHI and the main Hawaiian Islands using handlines. In the

NWHI, there are two zones in which fishing takes place. The Ho’omalu Zone has limited entry and the Mau Zone has

open access. There are currently 11 permits for the Ho’omalu Zone and 30 for the Mau Zone. However, in 1994, only

five vessels fished in the Ho’omalu Zone and 15-20 vessels fished in the Mau Zone. Total landings of bottomfish in

Hawaii from all waters have fluctuated little in recent years, about 400,000 pounds per year from the NWHI and about

500,000 pounds per year from the main Hawaiian Islands. Fishermen claim interactions with dolphins who steal bait

and catch are increasing.

Other Mortality

At least 85 spinner dolphins were live-captured in Hawaiian waters from 1962 to 1981 (Shallenberger 1981).

The main capture area was around Oahu.

Fishery Mortality Rate

The total fishery mortality and serious injury cannot be considered to be insignificant and approaching zero

because the total annual mortality of this stock of spinner dolphins is unknown. Determination cannot be made for

individual fisheries until the implementing regulations for section 118 of the Marine Mammal Protection Act have been

reviewed by the public and finalized.

STATUS OF STOCK

The status of spinner dolphins in Hawaiian waters is unknown. The stock’s status relative to OSP under the

MMPA is alsounknown. They are not listed as threatened or endangered under the U.S. Endangered Species Act (1973).

The Hawaiian stock would not be considered a strategic stock under the 1994 amendments to the MMPA because the

level of documented take does not exceed the PBR level.

REFERENCES

Dizon, A. E., W. F. Perrin, and P. A. Akin. 1994. Stocks of dolphins (Stenella spp. and Delphinus delphis) in the

eastern tropical Pacific: a phylogeographic classification. NOAA Tech. Rep. NMFS 119, 20 pp.

Nitta, E. and J. R. Henderson. 1993. A review of interactions between Hawaii’s fisheries and protected species. Mar.

Fish. Rev. 55(2):83-92.

Norris, K. S., B. Wursig, R. S. Wells, and M. Wursig . 1994. The Hawaiian Spinner Dolphin. University of California

Press, 408 pp.

Norris, K. S. and T. P. Dohl. 1980. Behavior of the Hawaiian spinner dolphin, Stenella longirostris. Fish. Bull.

77:821-849.

Östman, J. S. O. 1994. Social organization and social behavior of Hawaiian spinner dolphins (Stenella longirostris).

Ph.D. dissertation, University of California, Santa Cruz, 114 pp.

Perrin, W. F. 1975. Variation of spotted and spinner porpoise (genus Stenella) in the eastern tropical Pacific and

131
Hawaii. Bull. Scripps Inst. Oceanogr. 21, 206 pp.

Perrin, W. F. 1990. Subspecies of Stenella longirostris (Mammalia: Cetaces: Delphinidae). Proc. Biol. Soc. Wash.

103:453-463.

Perrin, W. F. and J. W. Gilpatrick, Jr. 1994. Spinner dolphin Stenella longirostris (Gray, 1828). In: S. H. Ridgway

and R. Harrison (eds.), Handbook of Marine Mammals, Vo1.5: The First Book of Dolphins, pp. 99-128.

Academic Press, 416 pp.

Perrin. W.F., G. P. Donovan and J. Barlow. 1994. Gillnets and Cetaceans. Rep. Int. Whal. Commn.. Special Issue 15,

629 pp.

Shallenberger, E.W. 1981. The status of Hawaiian cetaceans. Final report to U.S. Marine Mammal Commission. MMC77/23, 79pp.

Wade, P. R. and T. Gerrodette. 1993. Estimates of cetacean abundance and distribution in the eastern tropical Pacific.

Rep. Int. Whal. Commn. 43:477-493.

132
STRIPED DOLPHIN (Stenella coeruleoalba): Hawaiian Stock

STOCK DEFINITION AND GEOGRAPHIC RANGE

Striped dolphins are found in tropical to warm-temperate waters throughout the world (Perrin et al. 1994).

There is an incongruity between the frequency of strandings and the infrequency of sightings of this species in Hawaii.

Nitta (1991) found more stranding records of striped dolphins (13) than of any other species between 1936 and 1988,

yet Shallenberger (1981) was aware of only two at-sea sightings, one near Niihau and one west of Oahu. The Sea Life

Park collecting crew never encountered striped dolphins from the early 1960s through the late 1970s during their livecapture operations (Shallenberger 1981).

Striped dolphins have been intensively/ exploited in the western North Pacific, where three migratory stocks

are provisionally recognized (Kishiro and Kasuya 1993). In the eastern Pacific all striped dolphins are provisionally

considered to belong to a single stock (Dizon et al. 1994). For the Marine Mammal Protection Act (MMPA) stock

assessment reports, striped dolphins within the Pacific U.S. Exclusive Economic Zone are divided into two discrete, noncontiguous areas: 1) waters off California, Oregon and Washington, and 2) waters around Hawaii (this report). Striped

dolphins involved in eastern tropical Pacific tuna purse-seine fisheries are managed separately under the MMPA.

POPULATION SIZE

Population estimates are available for Japanese waters (Miyashita 1993) and the eastern tropical Pacific (Wade

and Gerrodette 1993), but no data are available for a population estimate in Hawaiian waters.

Minimum Population Estimate

No data are available for a minimum population estimate.

Current Population Trend

No data are available on current population trend.

CURRENT AND MAXIMUM NET PRODUCTIVITY RATES

No data are available on current or maximum net productivity rate.

POTENTIAL BIOLOGICAL REMOVAL

No PBR can be calculated for this stock at this time.

ANNUAL HUMAN-CAUSED MORTALITY AND SERIOUS INJURY

No estimate of annual human-caused mortality and serious injury is available as there are no reports of direct

or incidental takes of striped dolphins in Hawaiian waters (Nitta and Henderson 1993). However, mortality of other

cetacean species has been observed in Hawaiian fisheries, and the gear types used in these fisheries are responsible for

marine mammal mortality and serious injury in other fisheries throughout U.S. waters. Gillnets appear to capture marine

mammals wherever they are used, and float lines from lobster traps and longlines can be expected to occasionally

entangle whales (Perrin, Donovan and Barlow 1994).

Fishery Information

Pelagic, bottomfish and lobster fisheries occur in Hawaiian waters, Pelagic fisheries include commercial

fisheries (troll, handline, longline, local inshore gillnet), commercial charter and recreational troll fishing. Only the

longline fishery is subject to active management through a Fishery Management Plan. The growth of the longline fleet

between 1989 and 1991 generated concerns regarding impact on fish stocks (especially swordfish): on other fisheries

(troll, handline), and on protected species (mainly sea turtles). The value of longline landings increased to almost $45

million in 1992 and 1993. Regulations established longline fishery permit and reporting requirements, area closures

in the Northwestern Hawaiian Islands (NWHI) to protect Hawaiian monk seals and in the main Hawaiian Islands to

prevent gear conflicts, a limited entry program, a mandatory observer program, and a requirement for installation and

operation of vessel monitoring equipment on longline vessels in Hawaii. Approximately 165 longline permits have been

issued. The commercial non-longline fisheries (troll, handline, gillnet) have more than 2,000 participants but account

133
only for about $ 10 - $ 15 million per year in landings. The number of anglers and value of recreational fishing are

unknown. Interactions with cetaceans have been reported for all Hawaiian pelagic fisheries (Nitta and Henderson 1993),

but no interactions with striped dolphins have been documented.

The commercial lobster fishery in the NWHI is managed by federal regulations which include size limits, area

closures, seasons, gear restrictions, annual quotas and reporting requirements. Fifteen permits have been issued for this

fishery. The fishery was closed in 1993 and only five vessels operated in the fishery in 1994. No interactions between

marine mammals and this fishery have been recorded in the past five years.

The bottomfish fishery occurs throughout the NWHI and the main Hawaiian Islands using handlines. In the

NWHI, there are two zones in which fishing takes place. The Ho’omalu Zone has limited entry and the Mau Zone has

open access. There are currently 11 permits for the Ho’omalu Zone and 30 for the Mau Zone. However, in 1994, only

five vessels fished in the Ho’omalu Zone and 15-20 vessels fished in the Mau Zone. Total landings of bottomfish in

Hawaii from all waters have fluctuated little in recent years, about 4OO,OOO pounds per year from the NWHI and about

500,000 pounds per year from the main Hawaiian Islands. Fishermen claim interactions with dolphins who steal bait

and catch are increasing.

Fishery Mortality Rate

The total fishery mortality and serious injury cannot be considered to be insignificant and approaching zero

because the population size of this stock of striped dolphins is unknown. Determination cannot be made for individual

fisheries until the implementing regulations for section 118 of the MMPA have been reviewed by the public and

finalized.

STATUS OF STOCK

The status of striped dolphins in Hawaiian waters is unknown. The stock’s status relative to OSP under the

MMPA is also unknown. This species is not listed as threatened or endangered under the Endangered Species Act

(1973). Although information on striped dolphins in Hawaiian waters is limited. this stock would be considered nonstrategic under the 1994 amendments to the MMPA given the absence of reported fisheries related mortality.

REFERENCES

Dizon, A. E., W. F. Perrin, and P. A. Akin. 1994. Stocks of dolphins (Stenella spp. and Delphinus delphis) in the

eastern tropical Pacific: a phylogeographic classification. NOAA Tech. Rep. NMFS 119, 20 pp.

Kishiro, T. and T. Kasuya. 1993. Review of Japanese dolphin drive fisheries and their status. Rep. Int. Whal. Commn.

43:439-452.

Miyashita, T. 1993. Abundance of dolphin stocks in the western North Pacific taken by the Japanese drive fishery.

Rep. Int. Whal. Commn. 43:417-437.

Nitta, E. 1991. The marine mammal stranding network for Hawaii: an overview. In: J.E. Reynolds III. D.K. Odell

(eds.), Marine Mammal Strandings in the United States, pp.56-62. NOAA Tech. Rep. NMFS 98, 157 pp.

Nitta, E. and J. R. Henderson. 1993. A review of interactions between Hawaii’s fisheries and protected species. Mar.

Fish. Rev. 55(2):83-92.

Pen-in, W. F., C. E. Wilson, and F. I. Archer, II. 1994. Striped dolphin Stenella coeruleoalba (Meyen, 1833). In: S.

H. Ridgway and R. Harrison (eds.), Handbook of Marine Mammals, Vo1.5: The First Book of Dolphins, pp

129- 159. Academic Press, 4 16 pp.

Perrin, W.F., G. P. Donovan and J. Barlow. 1994. Gillnets and Cetaceans. Rep. lnt. Whal. Commn., Special Issue 15,

629 pp.

Shallenberger, E.W. 1981. The status of Hawaiian cetaceans. Final report to U.S. Marine Mammal Commission. MMC77/23, 79pp.

Wade, P. R. and T. Gerrodette. 1993. Estimates of cetacean abundance and distribution in the eastern tropical Pacific.

Rep. Int. Whal. Commn. 43:477-493.

134
MELON-HEADED WHALE (Peponocephala efectra): Hawaiian Stock

STOCK DEFINITION AND GEOGRAPHIC RANGE

Melon-headed whales are found in tropical and warm-temperate waters throughout the world. The distribution

of reported sightings suggests that the oceanic habitat of this species is primarily equatorial waters (Perryman et al.

1994). Small numbers have been taken in the eastern tropical Pacific, and they are occasionally killed in direct fisheries

in Japan and elsewhere in the western Pacific. Large herds are seen regularly in Hawaiian waters, especially off the

Waianae coast of Oahu, the north Kohala coast of Hawaii? and the leeward coast of Lanai (Shallenberger 1981). Little

is known about this species elsewhere in its range, and most knowledge about its biology comes from mass strandings

(Perryman et al. 1994). Ten strandings are known from Hawaii (Nishiwaki and Norris 1966; Shallenberger 1981; Nitta

1991). For the Marine Mammal Protection Act (MMPA) stock assessment reports, there is a single Pacific management

stock including only animals found within the U.S. Exclusive Economic Zone of the Hawaiian Islands.

POPULATION SIZE

An estimate of melon-headed whales is available for the eastern tropical Pacific (Wade and Gerrodette 1993),

but there are no data for population estimates elsewhere. In Hawaii, the size of herds is often reported to exceed 500

individuals (Shallenberger 1981). A group of 75-100 animals was consistently observed off the north Kohala coast of

Hawaii during the 1970s (Shallenberger 1981).

Minimum Population Estimate

No data are available for making a minimum population estimate.

Current Population Trend

No data are available on current population trend.

CURRENT AND MAXIMUM NET PRODUCTIVITY RATES

No data are available on current or maximum net productivity rate.

POTENTIAL BIOLOGICAL REMOVAL

It is not possible to calculate a PBR for this stock at this time.

ANNUAL HUMAN-CAUSED MORTALITY AND SERIOUS INJURY

Melon-headed whales are not known to be taken directly or incidentally in Hawaiian waters and no mortality

of this species has been documented in Hawaiian fisheries (Nitta and Henderson 1993). However, mortality of other

cetacean species has been observed in Hawaiian fisheries, and the gear types used in these fisheries are responsible for

marine mammal mortality and serious injury in other fisheries throughout U.S. waters. Gillnets appear to capture marine

mammals wherever they are used, and float lines from lobster traps and longlines can be expected to occasionally

entangle whales (Perrin, Donovan and Barlow 1994).

Fishery Information

Pelagic, bottomfish and lobster fisheries occur in Hawaiian waters. Pelagic fisheries include commercial

fisheries (troll, handline, longline, local inshore gillnet), commercial charter and recreational troll fishing. Only the

longline fishery is subject to active management through a Fishery Management Plan. The growth of the longline fleet

between 1989 and 1991 generated concerns regarding impact on fish stocks (especially swordfish), on other fisheries

(troll: handline), and on protected species (mainly sea turtles). The value of longline landings increased to almost $45

million in 1992 and 1993. Regulations established longline fishery permit and reporting requirements, area closures

in the Northwestern Hawaiian Islands (NWHI) to protect Hawaiian monk seals and in the main Hawaiian Islands to

prevent gear conflicts, a limited entry program, a mandatory observer program, and a requirement for installation and

operation of vessel monitoring equipment on longline vessels in Hawaii. Approximately 165 longline permits have been

issued. The commercial non-longline fisheries (troll, handline, gillnet) have more than 2,000 participants but account

only for about $10 - $15 million per year in landings. The number of anglers and value of recreational fishing are

135
unknown. Interactions with cetaceans have been reported for all Hawaiian pelagic fisheries (Nitta and Henderson 1993),

but no interactions with melon-headed whales have been documented.

The commercial lobster fishery in the NWHI is managed by federal regulations which include size limits, area

closures, seasons: gear restrictions, annual quotas and reporting requirements. Fifteen permits have been issued for this

fishery. The fishery was closed in 1993 and only five vessels operated in the fishery in 1994. No interactions between

marine mammals and this fishery have been recorded in the past five years.

The bottomfish fishery occurs throughout the NWHI and the main Hawaiian Islands using handlines. In the

NWHI, there are two zones in which fishing takes place. The Ho’omalu Zone has limited entry and the Mau Zone has

open access. There are currently 11 permits for the Ho’omalu Zone and 30 for the Mau Zone. However, in 1994, only

five vessels fished in the Ho’omalu Zone and 15-20 vessels fished in the Mau Zone. Total landings of bottomfish in

Hawaii from all waters have fluctuated little in recent years, about 400,000 pounds per year from the NWHI and about

500,000 pounds per year from the main Hawaiian Islands. Fishermen claim interactions with dolphins who steal bait

and catch are increasing.

Historical Mortality

Peale (1848) reported that 60 whales of this species were driven ashore by natives in Hilo Bay, Hawaii in 1841.

At least three melon-headed whales were live-captured for public display between 1966 and 1978 (Shallenberger 1981).

Fishery Mortality Rate

The total fishery mortality and serious injury cannot be considered to be insignificant and approaching zero

because the population size of this stock of melon-headed whales is unknown. Determination cannot be made for

individual fisheries until the implementing regulations for section 118 of the MMPA have been reviewed by the public

and finalized.

STATUS OF STOCK

The status of melon-headed whales in Hawaiian waters is unknown. The stock’s status relative to OSP under

the MMPA is also unknown. This species is not listed as threatened or endangered under the Endangered Species Act

(1973). Although information on melon-headed whales in Hawaiian waters is limited, this stock would be considered

non-strategic under the 1994 amendments to the MMPA given the absence of reported fisheries related mortality.

REFERENCES

Nishiwaki. M. and K. S. Norris. 1966. A new genus, Peponocephala, for the odontocete cetacean species Electra

electra. Sci. Rep. Whales Res. Inst. 20:95-100.

Nitta, E. 1991. The marine mammal stranding network for Hawaii: an overview. In: J.E. Reynolds III, D.K. Odell

(eds.), Marine Mammal Strandings in the United States, pp.56-62. NOAA Tech. Rep. NMFS 98, 157 pp.

Nitta, E. and J. R. Henderson. 1993. A review of interactions between Hawaii’s fisheries and protected species. Mar.

Fish. Rev. 55(2):83-92.

Peale, T. R. 1848. United States Exploring Expedition. During the Years 1838, 1839: 1840, 1841, 1842. Under the

Command of Charles Wilkes, U.S.N. Vol. VIII. Mammalia and Ornithology. C Sherman. Philadelphia, 338

pp.

Perrin, W.F., G. P. Donovan and J. Barlow. 1994. Gillnets and Cetaceans. Rep. Int. Whal. Commn., Special Issue 15,

629 pp.

Perryman, W. L., D. W. K. Au, S. Leatherwood, and T. A. Jefferson. 1994. Melon-headed whale Peponocephala

electra Gray, 1846. In: S. H. Ridgway and R. Harrison (eds.), Handbook of Marine Mammals, Vol.5: The First

Book of Dolphins, pp. 363-386. Academic Press, 416 pp.

Shallenberger, E.W. 1981. The status of Hawaiian cetaceans. Final report to U.S. Marine Mammal Commission. MMC77/23, 79pp.

Wade, P. R. and T. Gerrodette. 1993. Estimates of cetacean abundance and distribution in the eastern tropical Pacific.

Rep. lnt. Whal. Commn. 43:477-493.

136
PYGMY KILLER WHALE (Feresa attenuata): Hawaiian Stock

STOCK DEFINITION AND GEOGRAPHIC RANGE

Pygmy killer whales are found in tropical and subtropical waters throughout the world (Ross and Leather-wood

1994). They are poorly known in most parts of their range. Small numbers have been taken directly and incidentally

in both the western and eastern Pacific. Most knowledge of this species is from stranded or live-captured specimens.

Pryor et al. (1965) stated that pygmy killer whales have been observed several times off the lee shore of Oahu,

and that “they seem to be regular residents of the Hawaiian area.” Although all sightings up to that time had been off

Oahu and the Big Island, Shallenberger (1981) stated that this species might be found elsewhere in Hawaii, as well.

Nitta (1991) documented five strandings from Maui and the island of Hawaii. For the Marine Mammal Protection Act

(MMPA) stock assessment reports, there is a single Pacific management stock including only animals found within the

U.S. Exclusive Economic Zone of the Hawaiian Islands.

POPULATION SIZE

A population estimate has been made for this species in the eastern tropical Pacific (Wade and Gerrodette

1993), but no data are available to estimate population size in any other area of the North Pacific.

Minimum Population Estimate

No data are available for a minimum population estimate.

Current Population Trend

No data are available on current population trend.

CURRENT AND MAXIMUM NET PRODUCTIVITY RATES

No data are available on current or maximum net productivity rate.

POTENTIAL BIOLOGICAL REMOVAL

No PBR can be calculated for this species at this time.

ANNUAL HUMAN-CAUSED MORTALITY AND SERIOUS INJURY

No estimate of annual human-caused mortality and serious injury is available as there are no reports of direct

or incidental takes of pygmy killer whales in Hawaiian waters. However, mortality of other cetacean species has been

observed in Hawaiian fisheries, and the gear types used in these fisheries are responsible for marine mammal mortality

and serious injury in other fisheries throughout U.S. waters. Gillnets appear to capture marine mammals wherever they

are used, and float lines from lobster traps and longlines can be expected to occasionally entangle whales (Perrin,

Donovan and Barlow 1994).

Fishery Information

Pelagic, bottomfish and lobster fisheries occur in Hawaiian waters. Pelagic fisheries include commercial

fisheries (troll, handline, longline, local inshore gillnet), commercial charter and recreational troll fishing. Only the

longline fishery is subject to active management through a Fishery Management Plan. The growth of the longline fleet

between 1989 and 1991 generated concerns regarding impact on fish stocks (especially swordfish), on other fisheries

(troll, handline), and on protected species (mainly sea turtles). The value of longline landings increased to almost $45

million in 1992 and 1993. Regulations established longline fishery permit and reporting requirements, area closures

in the Northwestern Hawaiian Islands (NWHI) to protect Hawaiian monk seals and in the main Hawaiian Islands to

prevent gear conflicts, a limited entry program, a mandatory observer program, and a requirement for installation and

operation of vessel monitoring equipment on longline vessels in Hawaii. Approximately 165 longline permits have been

issued. The commercial non-longline fisheries (troll, handline, gillnet) have more than 2,000 participants but account

only for about $10 - $15 million per year in landings. The number of anglers and value of recreational fishing are

unknown. Interactions with cetaceans have been reported for all Hawaiian pelagic fisheries (Nitta and Henderson 1993),

137
but no interactions with pygmy killer whales have been documented.

The commercial lobster fishery in the NWHI is managed by federal regulations which include size limits, area

closures, seasons, gear restrictions, annual quotas and reporting requirements. Fifteen permits have been issued for this

fishery. The fishery was closed in 1993 and only five vessels operated in the fishery in 1994. No interactions between

marine mammals and this fishery have been recorded in the past five years.

The bottomfish fishery occurs throughout the NWHI and the main Hawaiian Islands using handlines. In the

NWHI, there are two zones in which fishing takes place. The Ho’omalu Zone has limited entry and the Mau Zone has

open access. There are currently 11 permits for the Ho’omalu Zone and 30 for the Mau Zone. However, in 1994, only

five vessels fished in the Ho’omalu Zone and 15-20 vessels fished in the Mau Zone. Total landings of bottomfish in

Hawaii from all waters have fluctuated little in recent years, about 400,000 pounds per year from the NWHI and about

500,000 pounds per year from the main Hawaiian Islands. Fishermen claim interactions with dolphins who steal bait

and catch are increasing.

Other Mortality

Three specimens were live-captured by Sea Life Park between 1963 and 1971 (Pryor et al. 1965; Pryor 1975;

Shallenberger 1981).

Fishery Mortality Rate

The total fishery mortality and serious injury cannot be considered to be insignificant and approaching zero

because the population size of this stock of pygmy killer whales is unknown. Determination cannot be made for

individual fisheries until the implementing regulations for section 118 of the MMPA have been reviewed by the public

and finalized.

STATUS OF STOCK

The status of pygmy killer whales in Hawaiian waters is unknown. The stock’s status relative to OSP under

the MMPA is also unknown. This species is not listed as threatened or endangered under the U.S. Endangered Species

Act (1973). Although information on pygmy killer whales in Hawaiian waters is limited, this stock would be considered

non-strategic under the 1994 amendments to the MMPA given the absence of reported fisheries related mortality.

REFERENCES

Nitta, E. 1991. The marine mammal stranding network for Hawaii: an overview. In: J.E. Reynolds III, D.K. Ode11

(eds.): Marine Mammal Strandings in the United States, pp.56-62. NOAA Tech. Rep. NMFS 98, 157 pp.

Nitta, E. and J. R. Henderson. 1993. A review of interactions between Hawaii’s fisheries and protected species. Mar.

Fish. Rev. 55(2):83-92.

Perrin, W.F., G. P. Donovan and J. Barlow. 1994. Gillnets and Cetaceans. Rep. lnt. Whal. Commn., Special Issue 15,

629 pp.

Pryor, K. 1975. Lads Before the Wind: Adventures in Porpoise Training. Harper and Row. New York, 278 pp.

Pryor, T., K. Pryor and K. S. Norris. 1965. Observations on a pygmy killer whale (Feresa attenuata Gray) from

Hawaii. J. Mamm. 46:450-461.

Ross, G. J. B. and S. Leatherwood. 1994. Pygmy killer whale Feresa attenuata Gray, 1874. In: S. H. Ridgway and

R. Harrison (eds.), Handbook of Marine Mammals? Vol.5: The First Book of Dolphins. pp.387-404. Academic

Press, 4 16 pp.

Shallenberger, E.W. 1981. The status of Hawaiian cetaceans. Final report to U.S. Marine Mammal Commission. MMC77/23,79pp.

Wade, P. R. and T. Gerrodette. 1993. Estimates of cetacean abundance and distribution in the eastern tropical Pacific.

Rep. Int. Whal. Commn. 43:477-493.

138
FALSE KILLER WHALE (Pseudorca crassidens): Hawaiian Stock

STOCK DEFINITION AND GEOGRAPHIC RANGE

False killer whales are found worldwide mainly in tropical and warm-temperate waters (Stacey et al. 1994).

In the North Pacific? this species is well known from southern Japan, Hawaii, and the eastern tropical Pacific. It occurs

around all the main Hawaiian Islands, but its presence around the Northwestern Hawaiian Islands has not yet been

established (Nitta and Henderson 1993). There are only 4 stranding records from Hawaiian waters (Nitta 1991). Large

numbers of false killer whales have been taken in direct fisheries in southern Japan, and small numbers have been taken

incidental to fishing operations in the eastern tropical Pacific. Most knowledge about this species comes from outside

Hawaiian waters (Stacey et al. 1994). For the Marine Mammal Protection Act (MMPA) stock assessment reports, there

is a single Pacific management stock including only animals found within the U.S. Exclusive Economic Zone of the

Hawaiian Islands.

POPULATION SIZE

Population estimates for this species have been made from shipboard surveys in Japan (Miyashita 1993) and

the eastern tropical Pacific (Wade and Gerrodette 1993) but there are no estimates for any area of the central Pacific.

A series of aerial surveys was flown in 1989 to obtain a minimum count of false killer whales. These surveys, which

only covered portions of the lee shores of Hawaii, Lanai, and Oahu to a maximum distance of 30 nm offshore, produced

a minimum count of 470 false killer whales (Leatherwood and Reeves 1989).

Minimum Population Estimate

No data from the past five years are available to make a minimum population estimate.

Current Population Trend

No data are available on current population trend.

CURRENT AND MAXIMUM NET PRODUCTIVITY RATES

No data are available on current or maximum net productivity rate.

POTENTIAL BIOLOGICAL REMOVAL

No PBR can be calculated for this stock at this time.

ANNUAL HUMAN-CAUSED MORTALITY AND SERIOUS INJURY

No estimate of annual human-caused mortality and serious injury is available as there are no reports of direct

or incidental takes of false killer whales in Hawaiian waters (Nitta and Henderson 1993). However, mortality of other

cetacean species has been observed in Hawaiian fisheries, and the gear types used in these fisheries are responsible for

marine mammal mortality and serious injury in other fisheries throughout U.S. waters. Gillnets appear to capture marine

mammals wherever they are used, and float lines from lobster traps and longlines can be expected to occasionally

entangle whales (Perrin, Donovan and Barlow 1994).

Fishery Information

Pelagic, bottomfish and lobster fisheries occur in Hawaiian waters. Pelagic fisheries include commercial

fisheries (troll, handline, longline, local inshore gillnet), commercial charter and recreational troll fishing. Only the

longline fishery is subject to active management through a Fishery Management Plan. The growth of the longline fleet

between 1989 and 1991 generated concerns regarding impact on fish stocks (especially swordfish), on other fisheries

(troll, handline), and on protected species (mainly sea turtles). The value of longline landings increased to almost $45

million in 1992 and 1993. Regulations established longline fishery permit and reporting requirements, area closures

in the Northwestern Hawaiian Islands (NWHI) to protect Hawaiian monk seals and in the main Hawaiian Islands to

prevent gear conflicts, a limited entry program, a mandatory observer program, and a requirement for installation and

operation of vessel monitoring equipment on longline vessels in Hawaii. Approximately 165 longline permits have been

issued. The commercial non-longline fisheries (troll, handline, gillnet) have more than 2,000 participants but account

139
only for about $10 - $15 million per year in landings. The number of anglers and value of recreational fishing are

unknown. Interactions with cetaceans have been reported for all Hawaiian pelagic fisheries, and false killer whales have

been identified in fishermen’s logs as taking catches from pelagic longlines (Nitta and Henderson 1993). They have also

been observed feeding on mahi mahi, Cotyphaena hippurus, and yellowfin tuna, Thunnus albacares, and frequently

steal large fish (up to 70 pounds) (Shallenberger 1981) from the trolling lines of both commercial and recreational

fishermen (S. Kaiser, pers. comm.).

The commercial lobster fishery in the NWHI is managed by federal regulations which include size limits, area

closures, seasons? gear restrictions, annual quotas and reporting requirements. Fifteen permits have been issued for this

fishery. The fishery was closed in 1993 and only five vessels operated in the fishery in 1994. No interactions between

marine mammals and this fishery have been recorded in the past five years.

The bottomfish fishery occurs throughout the NWHI and the main Hawaiian Islands using handlines. In the

NWHI, there are two zones in which fishing takes place. The Ho’omalu Zone has limited entry and the Mau Zone has

open access. There are currently 11 permits for the Ho’omalu Zone and 30 for the Mau Zone. However, in 1994: only

five vessels fished in the Ho’omalu Zone and 15-20 vessels fished in the Mau Zone. Total landings of bottomfish in

Hawaii from all waters have fluctuated little in recent years, about 400,000 pounds per year from the NWHI and about

500,000 pounds per year from the main Hawaiian Islands. Fishermen claim interactions with dolphins who steal bait

and catch are increasing.

Other Mortality

Since the early 1960’s, at least 12 false killer whales have been live-captured by aquaria or the Navy (Pryor

1975; Shallenberger 1981; J. Thomas pers. comm.).

Fishery Mortality Rate

The total fishery mortality and serious injury cannot be considered to be insignificant and approaching zero

because the population size of this stock of false killer whales is unknown. Determination cannot be made for individual

fisheries until the implementing regulations for section 118 of the MMPA have been reviewed by the public and

finalized.

STATUS OF STOCK

The status of false killer whales in Hawaiian waters is unknown. The stock’s status relative to OSP under the

MMPA is also unknown. This species is not listed as threatened or endangered under the Endangered Species Act

(1973). Although information on false killer whales in Hawaiian waters is limited, this stock would be considered nonstrategic under the 1994 amendments to the MMPA given the absence of reported fisheries related mortality.

REFERENCES

Leather-wood, S. and R. R. Reeves. 1989. Aerial survey for false killer whales off Hawaii, June 1989. Unpublished

report to the U.S. Marine Mammal Commission, 13 pp.

Miyashita, T. 1993. Abundance of dolphin stocks in the western North Pacific taken by the Japanese drive fishery.

Rep. Int. Whal. Commn. 43:417-437.

Nitta. E. 1991. The marine mammal stranding network for Hawaii: an overview. In: J.E. Reynolds III, D.K. Ode11

(eds.), Marine Mammal Strandings in the United States: pp.56-62. NOAA Tech. Rep. NMFS 98, 157 pp.

Nitta, E. and J. R. Henderson. 1993. A review of interactions between Hawaii’s fisheries and protected species. Mar.

Fish. Rev. 55(2):83-92.

Perrin, W.F., G. P. Donovan and J. Barlow. 1994. Gillnets and Cetaceans. Rep. Int. Whal. Commn., Special Issue 15,

629 pp.

Pryor, K. 1975. Lads Before the Wind: Adventures in Porpoise Training. Harper and Row, New York, 278 pp.

Shallenberger, E. W. 1981. The status of Hawaiian cetaceans. Final report to U.S. Marine Mammal Commission. MMC77/23, 79pp.

Stacey, P. J., S. Leatherwood, and R. W. Baird. 1994. Pseudorca crassidens. Mamm. Spec. 456:l-6.

Wade, P. R. and T. Gerrodette. 1993. Estimates of cetacean abundance and distribution in the eastern tropical Pacific.

Rep. Int. Whal. Commn. 43:477-493.

140
KILLER WHALE (Orcinus orca): Hawaiian Stock

STOCK DEFINITION AND GEOGRAPHIC RANGE

Killer whales are found worldwide in tropical to polar waters (Heyning and Dahlheim 1988). They are rare

in Hawaiian waters. One stranding from the island of Hawaii was reported in 1950 (Richards 1952). Two sightings

have been reported, one in January 1978 off the Waianae Coast of Oahu and another in December 1979 near Kauai

(Shallenberger 1981). Except in the northeastern Pacific where “resident” and “transient” stocks have been described

for coastal waters of Alaska, British Columbia, and Washington (Bi gg 1982; Leatherwood et al. 1990), little is known

about stock structure of killer whales in the North Pacific. For the Marine Mammal Protection Act (MMPA) stock

assessment reports, killer whales within the Pacific U.S. EEZ are divided into four stocks: 1) aHawaiian stock (this

report), 2) a transient stock in Alaska and Washington inland waters, 3) a resident stock in Alaska and Washington

inland water, and 4) a California, Oregon and Washington stock.

POPULATION SIZE

Population sizes for killer whales in the coastal waters of British Columbia and Washington are known from

photoidentification studies (Bigg et al. 1990). The population of killer whales in the eastern tropical Pacific has been

estimated from shipboard sightings surveys (Wade and Gerrodette 1993). No data to estimate population size are

available for the central Pacific.

Minimum Population Estimate

No data are available to provide a minimum population estimate.

Current Population Trend

No data are available on current population trend.

CURRENT AND MAXIMUM NET PRODUCTIVITY RATES

No data are available on current and maximum net productivity rate in Hawaiian waters.

POTENTIAL BIOLOGICAL REMOVAL

No PBR can be calculated for this stock at this time.

ANNUAL HUMAN-CAUSED MORTALITY AND SERIOUS INJURY

No estimate of annual human-caused mortality and serious injury is available. In 1990, a solitary killer whale

was reported to have removed the catch from a longline in Hawaii (Dollar 1991). No other fisheries interactions

involving killer whales have been reported. However, mortality of other cetacean species has been observed in

Hawaiian fisheries, and the gear types used in these fisheries are responsible for marine mammal mortality and serious

injury in other fisheries throughout U.S. waters. Gillnets appear to capture marine mammals wherever they are used,

and float lines from lobster traps and longlines can be expected to occasionally entangle whales (Perrin, Donovan and

Barlow 1994).

Fishery Information

Pelagic, bottomfish and lobster fisheries occur in Hawaiian waters. Pelagic fisheries include commercial

fisheries (troll, handline, longline, local inshore gillnet), commercial charter and recreational troll fishing. Only the

longline fishery is subject to active management through a Fishery Management Plan. The growth of the longline fleet

between 1989 and 1991 generated concerns regarding impact on fish stocks (especially swordfish), on other fisheries

(troll, handline), and on protected species (mainly sea turtles). The value of longline landings increased to almost $45

million in 1992 and 1993. Regulations established longline fishery permit and reporting requirements, area closures

in the Northwestern Hawaiian Islands (NWHI) to protect Hawaiian monk seals and in the main Hawaiian Islands to

prevent gear conflicts, a limited entry program, a mandatory observer program, and a requirement for installation and

operation of vessel monitoring equipment on longline vessels in Hawaii. Approximately 165 longline permits have been

issued. The commercial non-longline fisheries (troll, handline, gillnet) have more than 2,000 participants but account

141
only for about $10 - $15 million per year in landings. The number of anglers and value of recreational fishing are

unknown. Interactions with cetaceans have been reported for all Hawaiian pelagic fisheries (Nitta and Henderson 1993),

but no interactions with killer whales have been documented.

The commercial lobster fishery in the NWHI is managed by federal regulations which include size limits, area

closures, seasons: gear restrictions, annual quotas and reporting requirements. Fifteen permits have been issued for this

fishery. The fishery was closed in 1993 and only five vessels operated in the fishery in 1994. No interactions between

marine mammals and this fishery have been recorded in the past five years.

The bottomfish fishery occurs throughout the NWHI and the main Hawaiian lslands using handlines. In the

NWHI, there are two zones in which fishing takes place. The Ho’omalu Zone has limited entry and the Mau Zone has

open access. There are currently 11 permits for the Ho’omalu Zone and 30 for the Mau Zone. However, in 1994, only

five vessels fished in the Ho’omalu Zone and 15-20 vessels fished in the Mau Zone. Total landings of bottomfish in

Hawaii from all waters have fluctuated little in recent years, about 400,000 pounds per year from the NWHI and about

500,000 pounds per year from the main Hawaiian Islands. Fishermen claim interactions with dolphins who steal bait

and catch are increasing.

Fishery Mortality Rate

The total fishery mortality and serious injury cannot be considered to be insignificant and approaching zero

because the population size of this stock of killer whales is unknown. Determination cannot be made for individual

fisheries until the implementing regulations for section 118 of the MMPA have been reviewed by the public and

finalized.

STATUS OF STOCK

The status of killer whales in Hawaiian waters is unknown. The stocks status relative to OSP under the MMPA

is unknown. This species is not listed as threatened or endangered under the Endangered Species Act (1973). Although

information on killer whales in Hawaiian waters is limited, this stock would be considered non-strategic under the 1994

amendments to the MMPA given the insignificance of reported fisheries related mortality.

REFERENCES

Bigg, M. A. 1982. An assessment of killer whale (Orcinus orca) stocks off Vancouver Island, British Columbia. Rep.

Int. Whal. Commn. 32:655-666.

Bigg, M. A., P. F. Olesiuk, G. M. Ellis, J. K. B. Ford, and K. C. Balcomb, III. 1990. Social organization and genealogy

of resident killer whales (Orcinus orca) in the coastal waters of British Columbia and Washington State. Rep.

Int. Whal. Commn. (Spec. Iss. 12):383-405.

Dollar, R. A. 1991. Summary of swordfish longline observations in Hawaii, July l990-March 1991. Southwest Fish.

Cent. Admin. Rep. H-91-09, 13 pp.

Heyning, J. E. and M. E. Dahlheim. 1988. Orcinus orca. Mamm. Spec.304:l-9.

Leatherwood, S., C. O. Matkin, J. D. Hall, and G. M. Ellis. 1990. Killer whales, Orcinus orca, photo-identified in

Prince William Sound, Alaska, 1976 through 1987. Can Field-Nat. 104:362-371.

Nitta, E. and J. R. Henderson. 1993. A review of interactions between Hawaii’s fisheries and protected species. Mar.

Fish. Rev. 55(2):83-92.

Perrin, W.F., G. P. Donovan and J. Barlow. 1994. Gillnets and Cetaceans. Rep. lnt. Whal. Commn., Special Issue 15,

629 pp.

Richards, L. P. 1952. Cuvier’s beaked whale from Hawaii. J. Mamm. 33:255.

Shallenberger, E.W. 1981. The status of Hawaiian cetaceans. Final report to U.S. Marine Mammal Commission. MMC77/23, 79pp.

Wade, P. R. and T. Gerrodette. 1993. Estimates of cetacean abundance and distribution in the eastern tropical Pacific.

Rep. lnt. Whal. Commn. 433477-493.

142
SHORT-FINNED PILOT WHALE (Globicephala macrorhynchus):

Hawaiian Stock

STOCK DEFINITION AND GEOGRAPHIC RANGE

Short-fumed pilot whales are found in all oceans, primarily in tropical and warm-temperate waters. They are

commonly observed around the main Hawaiian Islands and are probably also present around the Northwestern Hawaiian

Islands (Shallenberger 1981). Several mass strandings have been reported from the main islands (Tomich 1986; Nitta

1991). In Japanese waters, two stocks have beenidentified based on pigmentation patterns and differences in the shape

of the heads of adult males (Kasuya et al. 1988). The pilot whales in Hawaiian waters are similar to the Japanese

“southern form.” Stock structure of short-finned pilot whales has not been adequately studied in the North Pacific,

except in Japanese waters. Preliminary photoidentification work with pilot whales in Hawaii indicated a high degree

of site fidelity around the main island of Hawaii (Shane and McSweeney 1990). For the Marine Mammal Protection

Act (MMPA) stock assessment reports, short-finned pilot whales within the Pacific U.S. Exclusive Economic Zone are

divided into two discrete, non-contiguous areas: 1) Hawaiian waters (this report), and 2) waters off California, Oregon

and Washington.

POPULATION SIZE

Estimates of short-fumed pilot whale populations have been made off Japan (Miyashita 1993) and in the eastern

tropical Pacific (Wade and Gerrodette 1993), but there are no data to make a population estimate in Hawaiian waters.

Minimum Population Estimate

No minimum population estimate is available,

Current Population Trend

No data are available on current population trend.

CURRENT AND MAXIMUM NET PRODUCTIVITY RATES

No data are available on current or maximum net productivity rate.

POTENTIAL BIOLOGICAL REMOVAL

No PBR can be calculated for this stock at this time.

ANNUAL HUMAN-CAUSED MORTALITY AND SERIOUS INJURY

No estimate of annual human-caused mortality and serious injury is available as there are no reports of direct

or incidental takes of short-finned pilot whales in Hawaiian waters, However, mortality of other cetacean species has

been observed in Hawaiian fisheries, and the gear types used in these fisheries are responsible for marine mammal

mortality and serious injury in other fisheries throughout U.S. waters. Gillnets appear to capture marine mammals

wherever they are used, and float lines from lobster traps and longlines can be expected to occasionally entangle whales

(Perrin, Donovan and Barlow 1994).

Fishery Information

Pelagic, bottomfish and lobster fisheries occur in Hawaiian waters. Pelagic fisheries include commercial

fisheries (troll, handline, longline, local inshore gillnet), commercial charter and recreational troll fishing. Only the

longline fishery is subject to active management through a Fishery Management Plan. The growth of the longline fleet

between 1989 and 1991 generated concerns regarding impact on fish stocks (especially swordfish), on other fisheries

(troll, handline), and on protected species (mainly sea turtles). The value of longline landings increased to almost $45

million in 1992 and 1993. Regulations established longline fishery permit and reporting requirements, area closures

in the Northwestern Hawaiian Islands (NWHI) to protect Hawaiian monk seals and in the main Hawaiian Islands to

prevent gear conflicts, a limited entry program, a mandatory observer program, and a requirement for installation and

operation of vessel monitoring equipment on longline vessels in Hawaii. Approximately 165 longline permits have been

issued. The commercial non-longline fisheries (troll, handline, gillnet) have more than 2,000 participants but account

143
only for about $10 - $15 million per year in landings. The number of anglers and value of recreational fishing are

unknown. Interactions with cetaceans have been reported for all Hawaiian pelagic fisheries (Nitta and Henderson 1993)

but no interactions with short-finned pilot whales have been documented.

The commercial lobster fishery in the NWHI is managed by federal regulations which include size limits, area

closures, seasons, gear restrictions, annual quotas and reporting requirements. Fifteen permits have been issued for this

fishery. The fishery was closed in 1993 and only five vessels operated in the fishery in 1994. No interactions between

marine mammals and this fishery have been recorded in the past five years.

The bottomfish fishery occurs throughout the NWHI and the main Hawaiian Islands using handlines. In the

NWHI, there are two zones in which fishing takes place. The Ho’omalu Zone has limited entry and the Mau Zone has

open access. There are currently 11 permits for the Ho’omalu Zone and 30 for the Mau Zone. However, in 1994. only

five vessels fished in the Ho’omalu Zone and 1.5-20 vessels fished in the Mau Zone. Total landings of bottomfish in

Hawaii from all waters have fluctuated little in recent years, about 400,000 pounds per year from the NWHI and about

500,000 pounds per year from the main Hawaiian Islands. Fishermen claim interactions with dolphins who steal bait

and catch are increasing.

Other Mortality

Since 1963, at least 20 short-finned pilot whales have been live-captured from Hawaiian waters by Sea Life

Park/Oceanic Foundation (Shallenberger 1981).

Fishery Mortality Rate

The total fishery mortality and serious injury cannot be considered to be insignificant and approaching zero

because the population size of this stock of short-finned pilot whales is unknown. Determination cannot be made for

individual fisheries until the implementing regulations for section 118 of the MMPA have been reviewed by the public

and finalized.

STATUS OF STOCK

The status of short-finned pilot whales in Hawaiian waters is unknown. The stock’s status relative to OSP under

the MMPA is unknown. This species is not listed as threatened or endangered under the U.S. Endangered Species Act

(1973). Although information on short-finned pilot whales in Hawaiian waters is limited, this stock would be considered

non-strategic under the 1994 amendments to the MMPA given the absence of reported fisheries related mortality.

REFERENCES

Kasuya, T. T. Miyashita. and F. Kasamatsu. 1988. Segregation of two forms of short-finned pilot whales off the

Pacific coast of Japan. Sci. Rep. Whales Res. Inst. 39:77-90.

Miyashita, T. 1993. Abundance of dolphin stocks in the western North Pacific taken by the Japanese drive fishery.

Rep. Int. Whal. Commn. 433417-437.

Nitta, E. 1991. The marine mammal stranding network for Hawaii: an overview. In: J.E. Reynolds III, D.K. Ode11

(eds.), Marine Mammal Strandings in the United States, pp.56-62. NOAA Tech. Rep. NMFS 98, 157 pp.

Nitta, E. and J. R. Henderson. 1993. A review of interactions between Hawaii’s fisheries and protected species, Mar.

Fish. Rev. 55(2):83-92.

Perrin, W.F., G. P. Donovan and J. Barlow. 1994. Gillnets and Cetaceans. Rep. Int. Whal. Commn., Special Issue 15,

629 pp.

Shallenberger, E.W. 1981. The status of Hawaiian cetaceans. Final report to U.S. Marine Mammal Commission. MMC77/23, 79pp.

Shane, S. H. and D. McSweeney. 1990. Using photo-identification to study pilot whales social organization. Rep. Int.

Whal. Commn. (Spec. Iss. 12):259-263.

Tomich, P. Q. 1986. Mammals in Hawaii: A Synopsis and Notational Bibliography. Bishop Museum Press, Hawaii,

375 pp.

Wade, P. R. and T. Gerrodette. 1993. Estimates of cetacean abundance and distribution in the eastern tropical Pacific.

Rep. Int. Whal. Commn. 43:477-493.

144
BLAINVILLE’S BEAKED WHALE (Mesoplodon densirostris):

Hawaiian Stock

STOCK DEFINITION AND GEOGRAPHIC RANGE

Blainville’s beaked whale has a cosmopolitan distribution in tropical and temperate waters, apparently the most

extensive known distribution of any Mesoplodon species (Mead 1989). Two strandings were reported in 1961 from

Midway Island (Galbreath 1963) and another in 1983 from Laysan Island (Nitta 1991). Sixteen sightings were reported

from the main islands by Shallenberger (1981), who suggested that Blainville’s beaked whales were present off the

Waianae Coast of Oahu for prolonged periods annually. Balcomb (1987) speculated that this species is “more common

in Hawaii than anywhere else in the world.” Although all identified Mesoplodon records from Hawaiian waters are of

M. densirostris, several other species in the genus Mesoplodon are known from the North Pacific and may be recorded

in Hawaiian waters in the future (see Mead 1989). There is no information on stock structure of Blainville’s beaked

whale. For the Marine Mammal Protection Act (MMPA) stock assessment reports, three Mesoplodon stocks are defined:

1) M. densirostris in Hawaiian waters (this report), 2) M stejnegeri in Alaskan waters, and 3) all Mesoplodon species

off California, Oregon and Washington.

POPULATION SIZE

No data are available to estimate population size.

Minimum Population Estimate

No data are available for a minimum population estimate.

Current Population Trend

No data are available on current population trend.

CURRENT AND MAXIMUM NET PRODUCTIVITY RATES

No data are available on current or maximum net productivity rate.

POTENTIAL BIOLOGICAL REMOVAL

No PBR can be calculated for this species at this time.

ANNUAL HUMAN-CAUSED MORTALITY AND SERIOUS INJURY

No estimate of annual human-caused mortality and serious injury is available as there are no reports of direct

or incidental takes of Blainville’s beaked whales in Hawaiian waters (Nitta and Henderson 1993). However, mortality

of other cetacean species has been observed in Hawaiian fisheries, and the gear types used in these fisheries are

responsible for marine mammal mortality and serious injury in other fisheries throughout U.S. waters. Gillnets appear

to capture marine mammals wherever they are used, and float lines from lobster traps and longlines can be expected to

occasionally entangle whales (Perrin, Donovan and Barlow 1994).

Fishery Information

Pelagic? bottomfish and lobster fisheries occur in Hawaiian waters. Pelagic fisheries include commercial

fisheries (troll, handline, longline, local inshore gillnet), commercial charter and recreational troll fishing. Only the

longline fishery is subject to active management through a Fishery Management Plan. The growth of the longline fleet

between 1989 and 1991 generated concerns regarding impact on fish stocks (especially swordfish), on other fisheries

(troll, handline), and on protected species (mainly sea turtles). The value of longline landings increased to almost $45

million in 1992 and 1993. Regulations established longline fishery permit and reporting requirements, area closures

in the Northwestern Hawaiian Islands (NWHI) to protect Hawaiian monk seals and in the main Hawaiian Islands to

prevent gear conflicts, a limited entry program, a mandatory observer program, and a requirement for installation and

operation of vessel monitoring equipment on longline vessels in Hawaii. Approximately 165 longline permits have been

issued. The commercial non-longline fisheries (troll, handline, gillnet) have more than 2,000 participants but account

only for about $10 - $15 million per year in landings. The number of anglers and value of recreational fishing are

145
unknown. Interactions with dolphins are reported for all pelagic fisheries, and humpback whales have been entangled

in longlines off the Hawaiian Islands (Nitta and Henderson 1993). but no takes of Blainville’s beaked whales have been

documented.

The commercial lobster fishery in the NWHI is managed by federal regulations which include size limits, area

closures, seasons, gear restrictions, annual quotas and reporting requirements. Fifteen permits have been issued for this

fishery. The fishery was closed in 1993 and only five vessels operated in the fishery in 1994. No interactions between

marine mammals and this fishery have been recorded in the past five years.

The bottomfish fishery occurs throughout the NWHI and the main Hawaiian Islands using handlines. In the

NWHI, there are two zones in which fishing takes place. The Ho’omalu Zone has limited entry and the Mau Zone has

open access. There are currently 11 permits for the Ho’omalu Zone and 30 for the Mau Zone. However, in 1994, only

five vessels fished in the Ho’omalu Zone and 15-20 vessels fished in the Mau Zone. Total landings of bottomfish in

Hawaii from all waters have fluctuated little in recent years, about 400,000 pounds per year from the NWHI and about

500,000 pounds per year from the main Hawaiian Islands. Fishermen claim interactions with dolphins who steal bait

and catch are increasing.

Fishery Mortality Rate

The total fishery mortality and serious injury cannot be considered to be insignificant and approaching zero

because the population size of this stock of Blainville’s beaked whales is unknown. Determination cannot be made for

individual fisheries until the implementing regulations for section 118 of the MMPA have been reviewed by the public

and finalized.

STATUS OF STOCK

The status of Blainville’s beaked whales in Hawaiian waters is unknown. The status of this stock relative to

OSP under the MMPA is also unknown. This species is not listed as threatened or endangered under the Endangered

Species Act (1973). Although information on Blainville’s beaked whales in Hawaiian waters is limited, this stock would

be considered non-strategic under the 1994 amendments to the MMPA given the absence of reported fisheries related

mortality.

REFERENCES

Balcomb, K. C., III. 1987. The Whales of Hawaii. Marine Mammal Fund, 99 pp.

Galbreath, E. C. 1963. Three beaked whales stranded on the Midway Islands, central Pacific Ocean. J.

Mamm. 44:422-423.

Galbreath, E. C. 1963. Three beaked whales stranded on the Midway Islands, central Pacific Ocean. J. Mamm.

44:422-423.

Mead, J. G. 1989. Beaked whales of the genus Mesoplodon. In: S. H. Ridgway and R. Harrison (eds.), Handbook of

Marine Mammals. Vol. 4: The River Dolphins and Larger Toothed Whales, pp. 349-430. Academic Press: 442

pp.

Nitta, E. 1991, The marine mammal stranding network for Hawaii: an overview. In: J.E. Reynolds III, D.K. Ode11

(eds.), Marine Mammal Strandings in the United States, pp.56-62. NOAA Tech. Rep. NMFS 98, 157 pp.

Nitta, E. and J. R. Henderson. 1993. A review of interactions between Hawaii’s fisheries and protected species. Mar.

Fish. Rev. 55(2):83-92.

Perrin, W. F., G. P. Donovan and J. Barlow. 1994. Gillnets and Cetaceans. Rep. lnt. Whal. Commn., Special Issue 15,

629 pp.

Shallenberger, E. W. 1981. The status of Hawaiian cetaceans. Final report to U.S. Marine Mammal Commission.

MMC-77/23, 79pp.

146
CUVIER’S BEAKED WHALE (Ziphius cavirostris): Hawaiian Stock

STOCK DEFINITION AND GEOGRAPHIC RANGE

Cuvier’s beaked whales occur in all oceans and major seas (Heyning 1989). In Hawaii, strandings have been

reported from Midway Islands, Pearl and Hermes Reef, Oahu, and Hawaii Islands (Shallenberger 1981; Galbreath 1963;

Richards 1952; Nitta 1991). Sightings, have been reported off Lanai and Maui (Shallenberger 1981). Nothing is known

about stock structure for this species. For the Marine Mammal Protection Act (MMPA) stock assessment reports,

Cuvier’s beaked whales within the Pacific U.S. Exclusive Economic Zone are divided into three discrete, non-contiguous

areas: 1) Hawaiian waters (this report), 2) Alaskan waters, and 3) waters off California, Oregon and Washington.

POPULATION SIZE

Wade and Gerrodette (1993) made an estimate for Cuvier’s beaked whales in the eastern tropical Pacific, but

no data are available for population estimates elsewhere in the North Pacific.

Minimum Population Estimate

No data are available for a minimum population estimate.

Current Population Trend

No data are available on current population trend.

CURRENT AND MAXIMUM NET PRODUCTIVITY RATES

No data are available on current or maximum net productivity rate.

POTENTIAL BIOLOGICAL REMOVAL

No PBR can be calculated for this stock at this time.

ANNUAL HUMAN-CAUSED MORTALITY AND SERIOUS INJURY

No estimate of annual human-caused mortality and serious injury is available as there are no reports of direct

or incidental takes of Cuvier’s beaked whales in Hawaiian waters (Nitta and Henderson 1993). However, mortality of

other cetacean species has been observed in Hawaiian fisheries, and the gear types used in these fisheries are responsible

for marine mammal mortality and serious injury in other fisheries throughout U.S. waters. Gillnets appear to capture

marine mammals wherever they are used, and float lines from lobster traps and longlines can be expected to occasionally

entangle whales (Perrin, Donovan and Barlow 1994).

Fishery Information

Pelagic, bottomfish and lobster fisheries occur in Hawaiian waters. Pelagic fisheries include commercial

fisheries (troll, handline, longline, local inshore gillnet), commercial charter and recreational troll fishing. Only the

longline fishery is subject to active management through a Fishery Management Plan. The growth of the longline fleet

between 1989 and 1991 generated concerns regarding impact on fish stocks (especially swordfish), on other fisheries

(troll, handline), and on protected species (mainly sea turtles). The value of longline landings increased to almost $45

million in 1992 and 1993. Regulations established longline fishery permit and reporting requirements, area closures

in the Northwestern Hawaiian Islands (NWHI) to protect Hawaiian monk seals and in the main Hawaiian Islands to

prevent gear conflicts: a limited entry program, a mandatory observer program! and a requirement for installation and

operation of vessel monitoring equipment on longline vessels in Hawaii. Approximately 165 longline permits have been

issued. The commercial non-longline fisheries (troll, handline, gillnet) have more than 2,000 participants but account

only for about $10 - $15 million per year in landings. The number of anglers and value of recreational fishing are

unknown. Interactions with dolphins are reported for all pelagic fisheries, and humpback whales have been entangled

in longlines off the Hawaiian Islands (Nitta and Henderson 1993), but no takes of Cuvier’s beaked whales have been

documented.

The commercial lobster fishery in the NWHI is managed by federal regulations which include size limits, area

closures, seasons, gear restrictions, annual quotas and reporting requirements. Fifteen permits have been issued for this

147
fishery, The fishery was closed in 1993 and only five vessels operated in the fishery in 1994. No interactions between

marine mammals and this fishery have been recorded in the past five years.

The bottomfish fishery occurs throughout the NWHI and the main Hawaiian Islands using handlines. In the

NWHI, there are two zones in which fishing takes place. The Ho’omalu Zone has limited entry and the Mau Zone has

open access. There are currently 11 permits for the Ho’omalu Zone and 30 for the Mau Zone. However, in 1994, only

five vessels fished in the Ho’omalu Zone and 15-20 vessels fished in the Mau Zone. Total landings of bottomfish in

Hawaii from all waters have fluctuated little in recent years, about 400,000 pounds per year from the NWHI and about

500,000 pounds per year from the main Hawaiian Islands. Fishermen claim interactions with dolphins who steal bait

and catch are increasing.

Fishery Mortality Rate

The total fishery mortality and serious injury cannot be considered to be insignificant and approaching zero

because the population size of this stock of Cuvier’s beaked whales is unknown. Determination cannot be made for

individual fisheries until the implementing regulations for section 118 of the MMPA have been reviewed by the public

and finalized.

STATUS OF STOCK

The status of Cuvier’s beaked whales in Hawaiian waters is unknown. The stock’s status relative to OSP under

the MMPA is also unknown. The species is not listed as threatened or endangered under the Endangered Species Act

(1973). Although information on Cuvier’s beaked whales in Hawaiian waters is limited. this stock would be considered

non-strategic under the 1994 amendments to the MMPA given the absence of reported fisheries related mortality.

REFERENCES

Galbreath, E. C. 1963. Three beaked whales stranded on the Midway Islands, central Pacific Ocean. J. Mamm.

44:422-423,

Heyning, J. E. 1989. Cuvier’s beaked whale Ziphius cavirostris G. Cuvier, 1823. In: S. H. Ridgway and R. Harrison

(eds.), Handbook of Marine Mammals, Vol. 4: The River Dolphins and Larger Toothed Whales, pp. 289-308.

Academic Press, 442 pp.

Nitta, E. 1991. The marine mammal stranding network for Hawaii: an overview. In: J.E. Reynolds III. D.K. Odell

(eds.), Marine Mammal Strandings in the United States, pp.56-62. NOAA Tech. Rep. NMFS 98, 157 pp.

Nitta, E. and J. R. Henderson. 1993. A review of interactions between Hawaii’s fisheries and protected species. Mar.

Fish. Rev. 55(2):83-92.

Perrin, W.F., G. P. Donovan and J. Barlow. 1994. Gillnets and Cetaceans. Rep. Int. Whal. Commn., Special Issue 15,

629 pp.

Richards, L. P. 1952. Cuvier’s beaked whale from Hawaii. J. Mamm. 33:255.

Shallenberger, E.W. 1981. The status of Hawaiian cetaceans. Final report to U.S. Marine Mammal Commission. MMC77/23,79pp.

Wade, P. R. and T. Gerrodette. 1993. Estimates of cetacean abundance and distribution in the eastern tropical Pacific.

Rep. lnt. Whal. Commn. 43:477-493.

148
PYGMY SPERM WHALE (Kugia breviceps): Hawaiian Stock

STOCK DEFINITION AND GEOGRAPHIC RANGE

Pygmy sperm whales are found throughout the world in tropical and warm-temperate waters (Caldwell and

Caldwell 1989). Between the years 1949 and 1982, at least nine strandings of this species were reported in the Hawaiian

Islands (Tomich 1986; Nitta 1991). Shallenberger (1981) reported three sightings off Oahu and Maui. A stranded calf

was held for several days at Sea Life Park (Pryor 1975:94). Nothing is known about stock structure for this species.

For the Marine Mammal Protection Act (MMPA) stock assessment reports, pygmy sperm whales within the Pacific U.S.

Exclusive Economic Zone are divided into two discrete, non-contiguous areas: 1) Hawaiian waters (this report), and

2) waters off California, Oregon and Washington.

POPULATION SIZE

No data are available to estimate population size for this species in the central Pacific.

Minimum Population Estimate

No data are available to provide a minimum population estimate.

Current Population Trend

No data are available on current population trend.

CURRENT AND MAXIMUM NET PRODUCTIVITY RATES

No data are available on current or maximum net productivity rate.

POTENTIAL BIOLOGICAL REMOVAL

No PBR can be calculated for this stock at this time.

ANNUAL HUMAN-CAUSED MORTALITY AND SERIOUS INJURY

No estimate of annual human-caused mortality and serious injury is available as there are no reports of direct

or incidental takes of pygmy sperm whales in Hawaiian waters (Nitta and Henderson 1993). However, mortality of

other cetacean species has been observed in Hawaiian fisheries? and the gear types used in these fisheries are responsible

for marine mammal mortality and serious injury in other fisheries throughout U.S. waters. Gillnets appear to capture

marine mammals wherever they are used, and float lines from lobster traps and longlines can be expected to occasionally

entangle whales (Perrin, Donovan and Barlow 1994).

Fishery Information

Pelagic, bottomfish and lobster fisheries occur in Hawaiian waters. Pelagic fisheries include commercial

fisheries (troll, handline, longline, local inshore gillnet), commercial charter and recreational troll fishing. Only the

longline fishery is subject to active management through a Fishery Management Plan. The growth of the longline fleet

between 1989 and 1991 generated concerns regarding impact on fish stocks (especially swordfish), on other fisheries

(troll, handline), and on protected species (mainly sea turtles). The value of longline landings increased to almost $45

million in 1992 and 1993. Regulations established longline fishery permit and reporting requirements, area closures

in the Northwestern Hawaiian Islands (NWHI) to protect Hawaiian monk seals and in the main Hawaiian Islands to

prevent gear conflicts, a limited entry program, a mandatory observer program? and a requirement for installation and

operation of vessel monitoring equipment on longline vessels in Hawaii. Approximately 165 longline permits have been

issued. The commercial non-longline fisheries (troll, handline , gillnet) have more than 2,000 participants but account

only for about $10 - $15 million per year in landings. The number of anglers and value of recreational fishing are

unknown. Interactions with cetaceans have been reported for all Hawaiian pelagic fisheries (Nitta and Henderson 1993),

but no interactions with pygmy sperm whales have been documented.

The commercial lobster fishery in the NWHI is managed by federal regulations which include size limits, area

closures, seasons, gear restrictions, annual quotas and reporting requirements. Fifteen permits have been issued for this

fishery. The fishery was closed in 1993 and only five vessels operated in the fishery in 1994. No interactions between

149
marine mammals and this fishery have been recorded in the past five years.

The bottomfish fishery occurs throughout the NWHI and the main Hawaiian Islands using handlines. In the

NWHI, there are two zones in which fishing takes place. The Ho’omalu Zone has limited entry and the Mau Zone has

open access. There are currently 11 permits for the Ho’omalu Zone and 30 for the Mau Zone. However, in 1994, only

five vessels fished in the Ho’omalu Zone and 15-20 vessels fished in the Mau Zone. Total landings of bottomfish in

Hawaii from all waters have fluctuated little in recent years. about 400,000 pounds per year from the NWHI and about

500,000 pounds per year from the main Hawaiian Islands. Fishermen claim interactions with dolphins who steal bait

and catch are increasing.

Fishery Mortality Rate

The total fishery mortality and serious injury cannot be considered to be insignificant and approaching zero

because the population size of this stock of pygmy sperm whales is unknown. Determination cannot be made for

individual fisheries until the implementing regulations for section 118 of the MMPA have been reviewed by the public

and finalized.

STATUS OF STOCK

The status of pygmy sperm whales in Hawaiian waters is unknown. The stock’s status relative to OSP under

the MMPA is also unknown. This species is not listed as threatened or endangered under the Endangered Species Act

(1973). Although information on pygmy sperm whales in Hawaiian waters is limited, this stock would be considered

non-strategic under the 1994 amendments to the MMPA given the absence of reported fisheries related mortality.

REFERENCES

Caldwell, D. K. and M. C. Caldwell. 1989. Pygmy sperm whale Kogia breviceps (de Blainville, 1838): Dwarf sperm

whale Kogiu simus Owen, 1866. In: S. H. Ridgway and R. Harrison (eds.), Handbook of Marine Mammals?

Vol. 4: The River Dolphins and Larger Toothed Whales, pp. 235-260. Academic Press, 442 pp.

Nitta, E. 1991, The marine mammal stranding network for Hawaii: an overview. In: J.E. Reynolds III, D.K. Odell

Nitta, E. and J. R. Henderson. 1993. A review of interactions between Hawaii’s fisheries and protected species. Mar.

Fish. Rev. 55(2):83-92.

Perrin. W.F., G. P. Donovan and J. Barlow. 1994. Gillnets and Cetaceans. Rep. Int. Whal. Commn., Special Issue 15,

629 pp.

Pryor, K. 1975. Lads Before the Wind: Adventures in Porpoise Training. Harper and Row, New York, 278 pp.

Shallenberger, E.W. 1981. The status of Hawaiian cetaceans. Final report to U.S. Marine Mammal Commission. MMC77123, 79pp.

Tornich, P. Q. 1986. Mammals in Hawaii: A Synopsis and Notational Bibliography. Bishop Museum Press, Hawaii,

375 pp.

150
DWARF SPERM WHALE (Kogia simus): Hawaiian Stock

STOCK DEFINITION AND GEOGRAPHIC RANGE

Dwarf sperm whales are found throughout the world in tropical to warm-temperate waters (Nagorsen 1985).

One sighting in an unspecified locality, one stranding on Oahu (Tomich 1986): and one stranding on Lanai (Nitta 1991)

constitute the only evidence that this species inhabits Hawaiian waters (Tomich 1986). The difficulty of detecting and

identifying it at sea, as well as its confusion with the pygmy sperm whale, may partially explain the paucity of records.

For the Marine Mammal Protection Act (MMPA) stock assessment reports, dwarf sperm whales within the Pacific U.S.

Exclusive Economic Zone are divided into two discrete, non-contiguous areas: 1) Hawaiian waters (this report), and

2) waters off California, Oregon and Washington.

POPULATION SIZE

Wade and Gerrodette (1993) provided an estimate for the eastern tropical Pacific, but no data are available to

estimate population size for this species in the central Pacific.

Minimum Population Estimate

No data are available for a minimum population estimate.

Current Population Trend

No data are available on current population trend.

CURRENT AND MAXIMUM NET PRODUCTIVITY RATES

No data are available on current or maximum net productivity rate.

POTENTIAL BIOLOGICAL REMOVAL

No PBR can be calculated for this species at this time.

ANNUAL HUMAN-CAUSED MORTALITY AND SERIOUS INJURY

No estimate of annual human-caused mortality and serious injury is available as there are no reports of direct

or incidental takes of dwarf sperm whales in Hawaiian waters (Nitta and Henderson 1993). However, mortality of other

cetacean species has been observed in Hawaiian fisheries, and the gear types used in these fisheries are responsible for

marine mammal mortality and serious injury in other fisheries throughout U.S. waters. Gillnets appear to capture marine

mammals wherever they are used, and float lines from lobster traps and longlines can be expected to occasionally

entangle whales (Perrin, Donovan and Barlow 1994).

Fishery Information

Pelagic, bottomfish and lobster fisheries occur in Hawaiian waters. Pelagic fisheries include commercial

fisheries (troll, handline, longline, local inshore gillnet), commercial charter and recreational troll fishing. Only the

longline fishery is subject to active management through a Fishery Management Plan. The growth of the longline fleet

between 1989 and 1991 generated concerns regarding impact on fish stocks (especially swordfish), on other fisheries

(troll, handline), and on protected species (mainly sea turtles). The value of longline landings increased to almost $45

million in 1992 and 1993. Regulations established longline fishery permit and reporting requirements, area closures

in the Northwestern Hawaiian Islands (NWHI) to protect Hawaiian monk seals and in the main Hawaiian Islands to

prevent gear conflicts, a limited entry program, a mandatory observer program, and a requirement for installation and

operation of vessel monitoring equipment on longline vessels in Hawaii. Approximately 165 longline permits have been

issued. The commercial non-longline fisheries (troll, handline, gillnet) have more than 2,000 participants but account

only for about $10 - $15 million per year in landings. The number of anglers and value of recreational fishing are

unknown. Interactions with cetaceans have been reported for all Hawaiian pelagic fisheries (Nitta and Henderson 1993),

but no interactions with dwarf sperm whales have been documented.

The commercial lobster fishery in the NWHI is managed by federal regulations which include size limits, area

closures, seasons, gear restrictions, annual quotas and reporting requirements. Fifteen permits have been issued for this

151
fishery, The fishery was closed in 1993 and only five vessels operated in the fishery in 1994. No interactions between

marine mammals and this fishery have been recorded in the past five years.

The bottomfish fishery occurs throughout the NWHI and the main Hawaiian Islands using handlines. In the

NWHI, there are two zones in which fishing takes place. The Ho’omalu Zone has limited entry and the Mau Zone has

open access. There are currently 11 permits for the Ho’omalu Zone and 30 for the Mau Zone. However, in 1994, only

five vessels fished in the Ho’omalu Zone and 15-20 vessels fished in the Mau Zone. Total landings of bottomfish in

Hawaii from all waters have fluctuated little in recent years, about 400,000 pounds per year from the NWHI and about

500,000 pounds per year from the main Hawaiian Islands. Fishermen claim interactions with dolphins who steal bait

and catch are increasing.

Fishery Mortality Rate

The total fishery mortality and serious injury cannot be considered to be insignificant and approaching zero

because the population size of this stock of dwarf sperm whales is unknown. Determination cannot be made for

individual fisheries until the implementing regulations for section 118 of the MMPA have been reviewed by the public

and finalized.

STATUS OF STOCK

The status of dwarf sperm whales in Hawaiian waters is unknown. The stock’s status relative to OSP under

the MMPA is unknown. This species is not listed as threatened or endangered under the Endangered Species Act

(1973). Although information on dwarf sperm whales in Hawaiian waters is limited, this stock would be considered

non-strategic under the 1994 amendments to the MMPA given the insignificance of reported fisheries related mortality.

REFERENCES

Nagorsen, D. 1985. Kogia simus. Mamm. Spec. 239:3-6.

Nitta, E. 1991. The marine mammal stranding network for Hawaii: an overview. In: J.E. Reynolds III, D.K. Odell

(eds.), Marine Mammal Strandings in the United States. pp.56-62. NOAA Tech. Rep. NMFS 98, 157 pp.

Nitta, E. and J. R. Henderson. 1993. A review of interactions between Hawaii’s fisheries and protected species. Mar.

Fish. Rev. 55(2):83-92.

Perrin, W.F., G. P. Donovan and J. Barlow. 1994. Gillnets and Cetaceans. Rep. Int. Whal. Commn., Special Issue 15.

629 pp.

Tomich, P. Q. 1986. Mammals in Hawaii: A Synopsis and Notational Bibliography. Bishop Museum Press, Hawaii,

375 pp.

Wade? P. R. and T. Gerrodette. 1993. Estimates of cetacean abundance and distribution in the eastern tropical Pacific.

Rep. Int. Whal. Commn. 43:477-493.

152
SPERM WHALE (Physeter macrocephalus): Hawaiian Stock

STOCK DEFINlTION AND GEOGRAPHIC RANGE

Sperm whales are found in tropical to polar waters throughout the world (Rice 1989). The Hawaiian Islands

marked the center of a major nineteenth century whaling ground for sperm whales (Gilmore 1959; Townsend 1935).

Since 1936, at least five strandings have been reported from Oahu, Kauai (Nitta 1991) and Kure Atoll (Woodward

1972). Sperm whales have also been sighted around several of the Northwestern Hawaiian Islands (Rice l960), off the

main island of Hawaii (Lee 1993), in the Kauai Channel and in the Alenuihaha Channel between Maui and the island

of Hawaii (Shallenberger 1981). In addition, the sounds of sperm whales have been recorded throughout the year off

Oahu (Thompson and Fried1 1982).

The stock identity of sperm whales in the North Pacific has been inferred from historical catch records

(Bannister and Mitchell 1980) and from trends in CPUE and tag-recapture data (Ohsumi and Masaki 1977), but much

uncertainty remains. For the Marine Mammal Protection Act (MMPA) stock assessment reports, sperm whales within

the Pacific U.S. EEZ are divided into three discrete? non-contiguous areas: 1) waters around Hawaii (this report), 2)

California, Oregon and Washington waters, and 3) Alaskan waters.

POPULATION SIZE

Gosho et al. (1984) summarized I WC estimates of “initial” (191O) and “current” (1982) stock sizes for sperm

whales in the North Pacific based on a CPUE model. Wade and Gerrodette (1993) estimated 22,700 sperm whales for

the eastern tropical Pacific from data collected on ship line-transect surveys. Forney et al. (1995) estimated 892 sperm

whales in California waters during winter/spring. However, there are no data available for estimating the number of

sperm whales in Hawaiian waters.

Minimum Population Estimate

No data are available to make a minimum population estimate.

Current Population Trend

No data on current population trend are available.

CURRENT AND MAXIMUM NET PRODUCTIVITY RATES

No data on current or maximum net productivity rate are available.

POTENTIAL BIOLOGICAL REMOVAL

No PBR can be calculated for this stock at this time.

ANNUAL HUMAN-CAUSED MORTALITY AND SERIOUS INJURY

No estimate of annual human-caused mortality and serious injury is available as there are no reports of recent

direct or incidental takes of sperm whales in Hawaiian waters (Nitta and Henderson 1993). However, mortality of other

cetacean species has been observed in Hawaiian fisheries, and the gear types used in these fisheries are responsible for

marine mammal mortality and serious injury in other fisheries throughout U.S. waters. Gillnets appear to capture marine

mammals wherever they are used, and float lines from lobster traps and longlines can be expected to occasionally

entangle whales (Perrin, Donovan and Barlow 1994).

Fishery Information

Pelagic, bottomfish and lobster fisheries occur in Hawaiian waters. Pelagic fisheries include commercial

fisheries (troll, handline: longline, local inshore gillnet), commercial charter and recreational troll fishing. Only the

longline fishery is subject to active management through a Fishery Management Plan. The growth of the longline fleet

between 1989 and 1991 generated concerns regarding impact on fish stocks (especially swordfish), on other fisheries

(troll: handline), and on protected species (mainly sea turtles). The value of longline landings increased to almost $45

million in 1992 and 1993. Regulations established longline fishery permit and reporting requirements, area closures

in the Northwestern Hawaiian Islands (NWHI) to protect Hawaiian monk seals and in the main Hawaiian Islands to

153
prevent gear conflicts, a limited entry program, a mandatory observer program, and a requirement for installation and

operation of vessel monitoring equipment on longline vessels in Hawaii. Approximately 165 longline permits have been

issued. The commercial non-longline fisheries (troll, handline, gillnet) have more than 2,000 participants but account

only for about $10 - $15 million per year in landings. The number of anglers and value of recreational fishing are

unknown. Interactions with dolphins are reported for all pelagic fisheries, and humpback whales have been entangled

in longlines off the Hawaiian Islands (Nitta and Henderson 1993): but no takes of sperm whales have been documented.

The commercial lobster fishery in the NWHI is managed by federal regulations which include size limits, area

closures, seasons, gear restrictions, annual quotas and reporting requirements. Fifteen permits have been issued for this

fishery. The fishery was closed in 1993 and only five vessels operated in the fishery in 1994. No interactions between

marine mammals and this fishery have been recorded in the past five years.

The bottomfish fishery occurs throughout the NWHl and the main Hawaiian Islands using handlines. In the

NWHI. there are two zones in which fishing takes place. The Ho’omalu Zone has limited entry and the Mau Zone has

open access. There are currently 11 permits for the Ho’omalu Zone and 30 for the Mau Zone. However, in 1994. only

five vessels fished in the Ho’omalu Zone and 15-20 vessels fished in the Mau Zone. Total landings of bottomfish in

Hawaii from all waters have fluctuated little in recent years, about 400,000 pounds per year from the NWHI and about

500,000 pounds per year from the main Hawaiian Islands. Fishermen claim interactions with dolphins who steal bait

and catch are increasing.

Historical Mortality

Sperm whales were exploited throughout their range in the North Pacific and equatorial Pacific during the

nineteenth century (see Tillman and Donovan 1983). Approximately 268,972 sperm whales were killed by modem

whaling operations in the North Pacific from 1910 to 1976 (Ohsumi 1980). Factory ships operated as far south as 20°N

(Ohsumi 1980). Pelagic whaling for sperm whales in the North Pacific ended after the 1979 season (IWC l981), and

coastal whaling for this species ended after the 1988 season (IWC 1989). Some of the whales taken during the whaling

era were certainly from a population or populations that occur within Hawaiian waters.

Fishery Mortality Rate

The total fishery mortality and serious injury cannot be considered to be insignificant and approaching zero

because the population size of this stock of sperm whales is unknown. Determination cannot be made for individual

fisheries until the implementing regulations for section 118 of the Marine Mammal Protection Act have been reviewed

by the public and finalized.

STATUS OF STOCK

The status of sperm whales in Hawaiian waters is unknown. The stock’s status relative to OSP under the

MMPA is also unknown. The species is listed as endangered under the U.S. Endangered Species Act (1973); therefore,

the Hawaiian stock is classified as a strategic stock according to the 1994 amendments to the MMPA.

REFERENCES

Bannister, J. and E. Mitchell. 1980. North Pacific sperm whale stock identity: distributional evidence from Maury and

Townsend charts. Rep. Int. Whal. Commn. (Spec. Iss. 2):219-230.

Forney, K. A., J. Barlow and J. V. Carretta. 1995. The abundance of cetaceans in California waters. Part II: Aerial

surveys in winter and spring of 1991 and 1992. Fish Bull. 93: 15-26.

Gilmore: R. M. 1959. On the mass strandings of sperm whales. Pac. Nat. l(9-10):3-15.

Gosho, M. E., D. W. Rice, and J. M. Breiwick. 1984. The sperm whale Physeter macrocephalus. Mar. Fish. Rev.

46(4):54-64.

International Whaling Commission. 1981. Japan. Progress report on cetacean research June l979-May 1980. Rep. Int.

Whal. Commn. 3 1: 195-200.

International Whaling Commission. 1989. Japan. Progress report on cetacean research June 1987 to April 1988. Rep.

Int. Whal. Commn. 39:201-204.

Lee, T. 1993. Summary of cetacean survey data collected behween the years of 1974 and 1985. NOAA Tech.Mem.

NMFS 181, 184pp.

Nitta, E. 1991. The marine mammal stranding network for Hawaii: an overview. In: J.E. Reynolds III, D.K. Odell

154
(eds.): Marine Mammal Strandings in the United States, pp.56-62. NOAA Tech. Rep. NMFS 98: 157 pp.

Nitta, E. and J. R. Henderson. 1993. A review of interactions between Hawaii’s fisheries and protected species. Mar.

Fish. Rev. 55(2):83-92.

Ohsumi, S. 1980. Catches of sperm whales by modem whaling in the North Pacific. Rep. Int. Whal. Commn. (Spec.

Iss. 2):11-18.

Ohsumi, S. and Y. Masaki. 1977. Stocks and trends of abundance of the sperm whale in the North Pacific. Rep. Int.

Whal. Commn. 27:167-175.

Perrin, W.F., G. P. Donovan and J. Barlow. 1994. Gillnets and Cetaceans. Rep. Int. Whal. Commn., Special Issue 15,

629 pp.

Rice, D. W. 1960. Distribution of the bottle-nosed dolphin in the leeward Hawaiian Islands. J. Mamm. 41:407-408.

Rice, D. W. 1989. Sperm whale Physeter macrocephalus Linneaus, 1758. In: S. H. Ridgway and R. Harrison (eds.),

Handbook of Marine Mammals. Vol. 4: The River Dolphins and Larger Toothed Whales, pp. 177-233.

Academic Press, 442 pp.

Shallenberger, E.W. 1981. The status of Hawaiian cetaceans. Final report to US. Marine Mammal Commission. MMC77123, 79pp.

Thompson, P. 0. and W. A. Friedl. 1982. A long term study of low frequency sound from several species of whales

off Oahu, Hawaii. Cetology 45:1-19.

Tillman, M. F. and G. P. Donovan. 1983. Special Issue on Historical Whaling Records. Rep. Int. Whal. Comm. (Spec.

Iss. 5), 269 pp.

Townsend, C. H. 1935. The distribution of certain whales as shown by logbook records of American whaleships.

Zoologica 19:1-50.

Wade, P. R. and T. Gerrodette. 1993. Estimates of cetacean abundance and distribution in the eastern tropical Pacific.

Rep. Int. Whal. Commn. 43:477-493.

Woodward, P. W. 1972. The natural history of Kure Atoll, northwestern Hawaiian Islands. Atoll Res. Bull. 164:302.

155
BLUE WHALE (Balaenoptera musculus): Hawaiian Stock

STOCK DEFINITION AND GEOGRAPHIC RANGE

Blue whales are found in tropical to polar waters throughout the world. No sightings or strandings of blue

whales have been reported in Hawaii. The only evidence that blue whales occur in this area comes from acoustic

recordings made off Oahu and Midway Islands (Northrop et al. 1971; Thompson and Friedl 1982). Although the exact

positions of the whales producing the sounds could not be determined, at least some of them were almost certainly

within the U.S. Exclusive Economic Zone. The recordings made off Oahu showed bimodal peaks throughout the year,

suggesting that the animals were migrating into the area in summer and winter. The stock structure of blue whales in

the North Pacific is uncertain (Mizroch et al. 1984; Reilly and Thayer 1990). For management in U.S. Pacific waters

outside the continental EEZ, the Hawaiian stock includes only those whales within the EEZ of the Hawaiian Islands.

One other stock of North Pacific blue whales (off California and Mexico) is recognized in the Marine Mammal

Protection Act (MMPA) stock Assessment Reports.

POPULATION SIZE

From ship line-transect surveys, Wade and Gerrodette (1993) estimated 1.400 blue whales for the eastern

tropical Pacific. Also from ship line-transect surveys, Barlow (1995) estimated 2,250 blue whales in the

Califomia/Mexico stock. No data are available to estimate population size for any other North Pacific blue whale

population.

Minimum Population Estimate

No data are available to provide a minimum population estimate.

Current Population Trend

No data are available on current population trend.

CURRENT AND MAXIMUM NET PRODUCTIVITY RATES

No data are available on current or maximum net productivity rate.

POTENTIAL BIOLOGICAL REMOVAL

No PBR can be calculated for this stock at this time.

ANNUAL HUMAN-CAUSED MORTALITY AND SERIOUS INJURY

No estimate of annual human-caused mortality and serious injury is available as there are no reports of recent

direct or incidental takes of blue whales in Hawaiian waters. However, mortality of other cetacean species has been

observed in Hawaiian fisheries? and the gear types used in these fisheries are responsible for marine mammal mortality

and serious injury in other fisheries throughout U.S. waters. Gillnets appear to capture marine mammals wherever they

are used, and float lines from lobster traps and longlines can be expected to occasionally entangle whales (Perrin,

Donovan and Barlow 1994).

Fishery Information

Pelagic, bottomfish and lobster fisheries occur in Hawaiian waters. Pelagic fisheries include commercial

fisheries (troll, handline, longline: local inshore gillnet), commercial charter and recreational troll fishing. Only the

longline fishery is subject to active management through a Fishery Management Plan. The growth of the longline fleet

between 1989 and 1991 generated concerns regarding impact on fish stocks (especially swordfish), on other fisheries

(troll, handline), and on protected species (mainly sea turtles). The value of longline landings increased to almost $45

million in 1992 and 1993. Regulations established longline fishery permit and reporting requirements, area closures

in the Northwestern Hawaiian Islands (NWHI) to protect Hawaiian monk seals and in the main Hawaiian Islands to

prevent gear conflicts. a limited entry program, a mandatory observer program, and a requirement for installation and

operation of vessel monitoring equipment on longline vessels in Hawaii. Approximately 165 longline permits have been

issued. The commercial non-longline fisheries (troll. handline ,gillnet) have more than 2,000 participants but account

156
only for about $10 - $15 million per year in landings. The number of anglers and value of recreational fishing are

unknown. Interactions with dolphins are reported for all pelagic fisheries, and humpback whales have been entangled

in longlines off the Hawaiian Islands, but no takes of blue whales have been documented (Nitta and Henderson 1993).

The commercial lobster fishery in the NWHI is managed by federal regulations which include size limits, area

closures, seasons, gear restrictions, annual quotas and reporting requirements. Fifteen permits have been issued for this

fishery. The fishery was closed in 1993 and only five vessels operated in the fishery in 1994. No interactions between

marine mammals and this fishery have been recorded in the past five years.

The bottomfish fishery occurs throughout the NWHI and the main Hawaiian Islands using handlines. In the

NWHI, there are two zones in which fishing takes place. The Ho’omalu Zone has limited entry and the Mau Zone has

open access. There are currently 11 permits for the Ho’omalu Zone and 30 for the Mau Zone. However, in 1994, only

five vessels fished in the Ho’omalu Zone and 15-20 vessels fished in the Mau Zone. Total landings of bottomfish in

Hawaii from all waters have fluctuated little in recent years, about 400,000 pounds per year from the NWHI and about

500,000 pounds per year from the main Hawaiian Islands. Fishermen claim interactions with dolphins who steal bait

and catch are increasing.

Historical Mortality

At least 9500 blue whales were taken by commercial whalers throughout the North Pacific between 1910 and

1965 (Ohsumi and Wada 1972). Some proportion of this total may have been from a population or populations that

migrate seasonally into the Hawaiian EEZ. The species has been protected in the North Pacific by the IWC since 1966.

Fishery Mortality Rate

The total fishery mortality and serious injury cannot be considered to be insignificant and approaching zero

because the population size of this stock of blue whales is unknown. Determination cannot be made for individual

fisheries until the implementing regulations for section 118 of the MMPA have been reviewed by the public and

finalized.

STATUS OF STOCK

The status of blue whales in Hawaiian waters is unknown. The status of this stock relative to OSP under the

MMPA is also unknown. The species is listed as endangered under the Endangered Species Act (1973); therefore, the

Hawaiian stock is classified as a strategic stock according to the 1994 amendments to the MMPA.

REFERENCES

Barlow, J. 1995. The abundance of cetaceans in California waters. Part I: Ship surveys in summer and fall of 1991.

Fish. Bull. 93(1):1-14.

Mizroch, S. A., D. W. Rice, and J. M. Breiwick. 1984. The blue whale, Balaenoptera musculus. Mar. Fish. Rev.

46(4):15-19.

Nitta, E. and J. R. Henderson. 1993. A review of interactions between Hawaii’s fisheries and protected species. Mar.

Fish. Rev. 55(2):83-92.

Northrop, J., W. C. Cummings? and M. F. Morrison. 1971. Underwater 20-Hz signals recorded near Midway Island.

J. Acoust. Soc. Am. 49:1909-1910.

Ohsumi, S. and S. Wada. 1972. Stock assessment of blue whales in the North Pacific. Int. Whal. Commn. Sci. Comm.

Rep., 20 pp.

Perrin, W.F., G. P. Donovan and J. Barlow. 1994. Gillnets and Cetaceans. Rep. Int. Whal. Commn., Special lssue 15,

629 pp.

Reilly, S. B. and V. G. Thayer. 1990. Blue whale (Bahenoptera musculus) distribution in the eastern tropical Pacific.

Mar. Mamm. Sci. 6:265-277.

Thompson, P. 0. and W. A. Friedl. 1982. A long term study of low frequency sound from several species of whales

off Oahu, Hawaii. Cetology 45:1-19.

Wade, P. R. and T. Gerrodette. 1993. Estimates of cetacean abundance and distribution in the eastern tropical Pacific.

Rep. Int. Whal. Commn. 43:477-493.

157
FIN WHALE (Balaenoptera physalus): Hawaiian Stock

STOCK DEFINITION AND GEOGRAPHIC RANGE

Fin whales are found throughout all oceans and seas of the world from tropical to polar latitudes. They are rare

in Hawaiian waters. There have been only two confirmed sightings off Oahu and a single stranding on Maui

(Shallenberger 1981). Balcomb (1987) observed 8- 12 fin whales in a multispecies feeding assemblage on 20 May 1966

approx. 250 mi. south of Honolulu. Thompson and Friedl (1982; and see Northrop et al. 1968) suggested that fin whales

migrate into Hawaiian waters mainly in fall and winter, based on acoustic recordings off Oahu and Midway Islands.

Although the exact positions of the whales producing the sounds could not be determined, at least some of them were

almost certainly within the U.S. Exclusive Economic Zone. The stock structure of fin whales in the North Pacific is

uncertain (Mizroch et al. 1984). The Marine Mammal Protection Act (MMPA) stock assessment reports recognize three

stocks of fin whales in the North Pacific: 1) the Hawaii stock (this report), 2) the California/Oregon/Washington stock,

and 3) the Alaska stock.

POPULATION SIZE

No data are available to estimate population size.

Minimum Population Estimate

No data are available to provide a minimum population estimate.

Current Population Trend

No data are available on current population trend

CURRENT AND MAXIMUM NET PRODUCTIVITY RATES

No data are available on current or maximum net productivity rate.

POTENTIAL BIOLOGICAL REMOVAL

No PBR can be calculated for this stock at this time.

ANNUAL HUMAN-CAUSED MORTALITY AND SERIOUS INJURY

No estimate of annual human-caused mortality and serious injury is available as there are no reports of recent

direct or incidental takes of fin whales in Hawaiian waters. However. mortality of other cetacean species has been

observed in Hawaiian fisheries, and the gear types used in these fisheries are responsible for marine mammal mortality

and serious injury in other fisheries throughout U.S. waters. Gillnets appear to capture marine mammals wherever they

are used, and float lines from lobster traps and longlines can be expected to occasionally entangle whales (Pen-in,

Donovan and Barlow 1994).

Fishery Information

Pelagic, bottomfish and lobster fisheries occur in Hawaiian waters. Pelagic fisheries include commercial

fisheries (troll, handline. longline, local inshore gillnet), commercial charter and recreational troll fishing. Only the

longline fishery is subject to active management through a Fishery Management Plan. The growth of the longline fleet

between 1989 and 1991 generated concerns regarding impact on fish stocks (especially swordfish), on other fisheries

(troll, handline), and on protected species (mainly sea turtles). The value of longline landings increased to almost $45

million in 1992 and 1993. Regulations established longline fishery permit and reporting requirements, area closures

in the Northwestern Hawaiian Islands (NWHI) to protect Hawaiian monk seals and in the main Hawaiian Islands to

prevent gear conflicts, a limited entry program, a mandatory observer program, and a requirement for installation and

operation of vessel monitoring equipment on longline vessels in Hawaii. Approximately 165 longline permits have been

issued. The commercial non-longline fisheries (troll, handline, gillnet) have more than 2.000 participants but account

only for about $10 - $15 million per year in landings. The number of anglers and value of recreational fishing are

unknown. Interactions with dolphins are reported for all pelagic fisheries, and humpback whales have been entangled

in longlines off the Hawaiian Islands (Nitta and Henderson 1993) but no takes of fin whales have been documented.

158
The commercial lobster fishery in the NWHI is managed by federal regulations which include size limits, area

closures, seasons, gear restrictions, annual quotas and reporting requirements. Fifteen permits have been issued for this

fishery. The fishery was closed in 1993 and only five vessels operated in the fishery in 1994. No interactions between

marine mammals and this fishery have been recorded in the past five years.

The bottomfish fishery occurs throughout the NWHI and the main Hawaiian Islands using handlines. In the

NWHl, there are two zones in which fishing takes place. The Ho’omalu Zone has limited entry and the Mau Zone has

open access. There are currently 11 permits for the Ho’omalu Zone and 30 for the Mau Zone. However, in 1994, only

five vessels fished in the Ho’omalu Zone and 15-20 vessels fished in the Mau Zone. Total landings of bottomfish in

Hawaii from all waters have fluctuated little in recent years, about 400,000 pounds per year from the NWHI and about

500,000 pounds per year from the main Hawaiian Islands. Fishermen claim interactions with dolphins who steal bait

and catch are increasing.

Historical Mortality

Large numbers of fin whales were taken by commercial whalers throughout the North Pacific from the early

20th century until the 1970s (Tonnessen and Johnsen 1982). Some of the whales taken may have been from a

population or populations that migrate seasonally into the Hawaiian EEZ. The species has been protected in the North

Pacific by the IWC since 1976.

Fishery Mortality Rate

The total fishery mortality and serious injury cannot be considered to be insignificant and approaching zero

because the population size of this stock of fin whales is unknown. Determination cannot be made for individual

fisheries until the implementin g regulations for section 118 of the MMPA have been reviewed by the public and

finalized.

STATUS OF STOCK

The status of fin whales in Hawaiian waters is unknown. This stocks status relative to OSP under the MMPA

is also unknown. This species is listed as endangered under the Endangered Species Act (1973); therefore, the Hawaiian

stock is classified as a strategic stock under the 1994 amendments to the MMPA.

REFERENCES

Balcomb, K. C., III. 1987. The Whales of Hawaii. Marine Mammal Fund, 99 pp.

Minoch, S. A., D. W. Rice: and J. M. Breiwick. 1984. The fin whale, Balaenopteraphysalus Mar. Fish. Rev. 46(4):20-

24.

Nitta, E. and J. R. Henderson. 1993. A review of interactions between Hawaii’s fisheries and protected species. Mar.

Fish. Rev. 55(2):83-92.

Northrop, J., W. C. Cummings, and P. 0. Thompson. 1968. 20-Hz signals observed in the central Pacific. J. Acoust.

Soc. Am. 43:383-384.

Perrin, W.F., G. P. Donovan and J. Barlow. 1994. Gillnets and Cetaceans. Rep. lnt. Whal. Commn., Special Issue 15,

629 pp.

Shallenberger, E.W. 1981. The status of Hawaiian cetaceans. Final report to U.S. Marine Mammal Commission. MMC77/23, 79pp.

Thompson, P. 0. and W. A. Friedl. 1982. A long term study of low frequency sound from several species of whales

off Oahu, Hawaii. Cetology 45: 1- 19.

Tonnessen, J. N. and A. 0. Johnsen. 1982. The History of Modem Whaling. Hurst, 789 pp.

159
BRYDE’S WHALE (Balaenoptera edeni): Hawaiian Stock

STOCK DEFINITION AND GEOGRAPHIC RANGE

Bryde’s whales occur in tropical and warm temperate waters throughout the world. Shallenberger (1981)

reported a sighting of a Bryde’s whale southeast of Nihoa in April 1977 (see DeLong and Brownell 1977; Leatherwood

et al. 1982: Fig. 39c). Leatherwood et al. (1982) described the species as relatively abundant in summer and fall on the

Mellish and Miluoki banks northeast of Hawaii and around Midway Islands, but the basis for this statement was not

explained. Ohsumi and Masaki (1975) reported the ta,, Doing of “many” Bryde’s whales between the Bonin and Hawaiian

Islands in the winters of 1971 and 1972 (Ohsumi 1977). With presently available evidence, there is no biological basis

for defining separate stocks of Bryde’s whales in the central North Pacific. Bryde’s whales also occasionally occur off

southern California (Morejohn and Rice 1973). For the MMPA stock assessment reports, Bryde’s whales within the

Pacific U.S. Exclusive Economic Zone are divided into two areas: I) Hawaiian waters (this report), and 2) the eastern

tropical Pacific (east of 150°W and including the Gulf of California and waters off California).

POPULATlON SIZE

Tillman (1978) concluded from Japanese and Soviet CPUE data that the stock size in the North Pacific pelagic

whaling grounds, mostly to the west of the Hawaiian Islands, declined from approximately 22,500 in 1971 to 17,800

in 1977. An estimate of 13,000 (CV=O.202) Bryde’s whales was made from vessel surveys in the eastern tropical Pacific

between 1986 and 1990 (Wade and Gerrodette 1993). The area to which this estimate applies is mainly east and

somewhat south of the Hawaiian Islands.

Minimum Population Estimate

No data are available for a minimum population estimate.

Current Population Trend

No data are available on current population trend

CURRENT AND MAXIMUM NET PRODUCTIVITY RATES

No data are available on current or maximum net productivity rate.

POTENTIAL BIOLOGICAL REMOVAL

No PBR can be calculated for this stock at this time.

ANNUAL HUMAN-CAUSED MORTALITY AND SERIOUS INJURY

No estimate of annual human-caused mortality and serious injury is available as there are no reports of recent

direct or incidental takes of Bryde’s whales in Hawaiian waters. However, mortality of other cetacean species has been

observed in Hawaiian fisheries, and the gear types used in these fisheries are responsible for marine mammai mortality

and serious injury in other fisheries throughout U.S. waters. Gillnets appear to capture marine mammals wherever they

are used, and float lines from lobster traps and longlines can be expected to occasionally entangle whales (Perrin

Donovan and Barlow 1994).

Fishery Information

Pelagic. bottomfish and lobster fisheries occur in Hawaiian waters. Pelagic fisheries include commercial

fisheries (troll, handline, longline. local inshore gillnet), commercial charter and recreational troll fishing. Only the

longline fishery is subject to active management through a Fishery Management Plan. The growth of the longline fleet

between 1989 and 1991 generated concerns regarding impact on fish stocks (especially swordfish), on other fisheries

(troll, handline), and on protected species (mainly sea turtles). The value of longline landings increased to almost $45

million in 1992 and 1993. Regulations established longline fishery permit and reporting requirements, area closures

in the Northwestern Hawaiian Islands (NWHI) to protect Hawaiian monk seals and in the main Hawaiian Islands to

prevent gear conflicts: a limited entry program, a mandatory observer program, and a requirement for installation and

operation of vessel monitoring equipment on longline vessels in Hawaii. Approximately 165 longline permits have been

160
issued. The commercial non-longline fisheries (troll, handline, gillnet) have more than 2,000 participants but account

only for about $10 - $15 million per year in landings. The number of anglers and value of recreational fishing are

unknown. Interactions with dolphins are reported for all pelagic fisheries, and humpback whales have been entangled

in longlines off the Hawaiian Islands (Nitta and Henderson 1993), but no takes of Bryde’s whales have been

documented.

The commercial lobster fishery in the NWHI is managed by federal regulations which include size limits, area

closures, seasons, gear restrictions, annual quotas and reporting requirements. Fifteen permits have been issued for this

fishery. The fishery was closed in 1993 and only Jive vessels operated in the fishery in 1994. No interactions between

marine mammals and this fishery have been recorded in the past five years.

The bottomfish fishery occurs throughout the NWHI and the main Hawaiian Islands using handlines. In the

NWHJ: there are two zones in which fishing takes place. The Ho’omalu Zone has limited entry and the Mau Zone has

open access. There are currently 11 permits for the Ho’omalu Zone and 30 for the Mau Zone. However, in 1994, only

five vessels fished in the Ho’omalu Zone and 15-20 vessels fished in the Mau Zone. Total landings of bottomfish in

Hawaii from all waters have fluctuated little in recent years, about 400,000 pounds per year from the NWHI and about

500.000 pounds per year from the main Hawaiian Islands. Fishermen claim interactions with dolphins who steal bait

and catch are increasing.

Historical Mortality

Small numbers of Bryde’s whales were taken near the Northwestern Hawaiian Islands by Japanese and Soviet

whaling fleets during the early 1970s (Ohsumi 1977). Pelagic whaling for Bryde’s whales in the North Pacific ended

after the 1979 season (IWC I981), and coastal whaling for this species ended in the western Pacific in 1987 (IWC 1989).

Fishery Mortality Rate

The total fishery mortality and serious injury cannot be considered to be insignificant and approaching zero

because the population size of this stock of Bryde’s whales is unknown. Determination cannot be made for individual

fisheries until the implementing regulations for section 118 of the MMPA (MMPA) have been reviewed by the public

and finalized.

STATUS OF STOCK

The status of Bryde’s whales in Hawaiian waters is unknown. This species is not listed as threatened or

endangered under the Endangered Species Act (1973). The status of this stock relative to OSP under the MMPA is

unknown. Although information on Bryde’s whales in Hawaiian waters is limited, this stock would be considered nonstrategic under the 1994 amendments to the MMPA given the absence of reported fisheries related mortality.

REFERENCES

DeLong, R. L. and R. L. Brownell, Jr. 1977. Hawaiian monk seal (Monachus schauinslandi) habitat and population

survey in the northwestern (Leeward) Hawaiian Islands. April 1977. Northwest Alaska Fish Cent. Proc.

Rep., 43 pp.

International Whaling Commission. 1981. Japan. Progress report on cetacean research June 1979-May 1980. Rep. Int.

Whal. Commn. 3 1: 395-200.

International Whaling Commission. 1989. Japan. Progress report on cetacean research June 1987 to April 1988. Rep.

Int. Whal. Commn. 39:201-204.

Leatherwood, S., R. R. Reeves, W. F. Perrin, and W. E. Evans. 1982. Whales, dolphins! and porpoises of the eastern

North Pacific and adjacent arctic waters: A guide to their identification. NOAA Tech. Rep. NMFS 444, 245

PP.

Morejohn, G. V. and D. W. Rice. 1973. First record of Bryde’s whale (Balaenoptera edeni) off California. Cal. Fish

Game 59:313-315.

Nitta, E. and J. R. Henderson. 1993. A review of interactions between Hawaii’s fisheries and protected species. Mar.

Fish. Rev. 55(2):83-92.

Ohsumi, S. 1977. Stocks and trends of abundance of the sperm whale in the North Pacific. Rep. Int. Whal. Commn.

27:167-175.

Ohsumi, S. and Y. Masaki. 1975. Japanese whale marking in the North Pacific, 3963-72. Bull. Far Seas Fish. Res.

161
Lab. 12:171-219.

Perrin, W.F., G. P. Donovan and J. Barlow. 1994. Gillnets and Cetaceans, Rep. Int. Whal. Commn., Special Issue 15,

629 pp.

Shallenberger. E.W. 1981. The status of Hawaiian cetaceans. Final report to U.S. Marine Mammal Commission. MMC77:23, 79pp.

Tillman. M. F. 1978. Modified Delury estimates of the North Pacific Bryde’s whale stock. Rep. Int. Whal. Commn.

28:315-317.

Wade, P. R. and T. Gerrodette. 1993. Estimates of cetacean abundance and distribution in the eastern tropical Pacific.

Rep. Int. Whal. Commn. 43:477-493.

162
RECENT TECHNICAL MEMORANDUMS

Copies of this and other NOAA Technical Memorandums are available from the National Technical

Information Service, 5285 Port Royal Road, Springfield, VA 22167. Paper copies vary in price. Microfiche

copies cost $9.00. Recent issues of NOAA Technical Memorandums from the NMFS Southwest Fisheries

Science Center are listed below:

NOAA-TM-NMFS-SWFSC-209 The physical oceanography off the central California coast during March

and May-June, 1993: a summary of CTD data from pelagic

young-of-the-year rockfish surveys.

K.M. SAKUMA, H.A. PARKER, S. RALSTON, F.B. SCHWING,

D.M. HUSBY, and E.M. ARMSTRONG

(September 1994)

210 The Hawaiian monk seal at French Frigate Shoals, 1990-91.

M.P. CRAIG, J.L. MEGYESI, C.S. HALL, J.L. GLUECK, L.P. LANIAWE,

E.A. DELANEY, S.S. KEEFER, M.A. McDERMOND, M. SCHULZ, G.L.

NAKAI, B.L. BECKER, L.M. HIRUKI, and R.J. MORROW

(September 1994)

211 Report of cetacean sightings during a marine mammal survey in the

eastern Pacific ocean and the gulf of California aboard the NOAA

ships McArthur and David Starr Jordan July 28-November 6,1993.

K.F. MANGELS, T. GERRODETTE

(October 1994)

212 An evaluation of oocyte size in multiple regressions predicting gonad

weight from body weight: A test using Hawaiian ehu, Etelis carbunculus.

B.B. LAU and E.E. DeMARTlNl

(Ocotober 1994)

213 The Hawaiian monk seal on Laysan Island, 1987 and 1989.

B.L. BECKER, P.A. CHING, L.M. HIRUKI, and S.A. ZUR

(October 1994)

214 The Hawaiian monk seal on Laysan Island, 1991.

B.L. BECKER, K.E. O’BRIEN, K.B. LOMBARD, and L.P. LANIAWE

(February 1995)

215 Seasonal, vertical, and horizontal distribution of four species of

copepods around Oahu, Hawaii: Data report

R.P. HASSETT, and G.W. BOEHLERT

(February 1995)

216 The Hawaiian monk seal in the northwestern Hawaiian Islands, 1992.

T.C. JOHANOS, L.M. HIRUKI, and T.J. RAGEN

(March 1995)

217 Report of 1993-1994 marine mammal aerial surveys conducted

within the U.S. Navy outer sea trust range off southern California.

J.V. CARRETTA, K.A. FORNEY, and J. BARLOW

(March 1995)

218 The effectiveness of California’s commercial rockfish port

sampling program

D.E. PEARSON and G. ALMANY

(June 1995)