31

NOAA Technical Report NMFS 31

Shark Catches

From Selected Fisheries

Off the U.S. East Coast

July 1985

u.s. DEPARTMENT OF COMMERCE

National Oceanic and Atmospheric Administration

National Marine Fisheries Service
NOAA TECHNICAL REPORTS NMFS

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copies may be obtained from: U.S. Department of Commerce, National Technical Information Service, 5285 Port Royal Road,

Springfield, VA 22161.
NOAA Technical Report NMFS 31

Shark Catches

From Selected Fisheries

Off the U.S. East Coast

July 1985

u.s. DEPARTMENT OF COMMERCE

Malcolm Baldrige, Secretary

National Oceanic and Atmospheric Administration

John V. Byrne, Administrator

National Marine Fisheries Service

William G. Gordon, Assistant Administrator for Fisheries
The National Marine Fisheries Service (NMFS) does not approve, recommend or endorse any proprietary product or proprietary material mentioned in this publication. No reference shall be made to NMFS, or to this

publication furnished by NMFS, in any advertising or sales promotion

which would indicate or imply that NMFS approves, recommends or

endorses any proprietary product or proprietary material mentioned herein,

or _which has as its purpose an intent to cause directly or indirectly the

advertised product to be used or purchased because of this NMFS

publication.
CONTENTS

ANDERSON, EMORY D. Analysis of various sources of pelagic shark catches in the Northwest and Western Central Atlantic

Ocean and Gulf of Mexico with comments on catches of other large pelagics .

CASEY, JOHN G., and JOHN J. HOEY. Estimated catches of large sharks by U.S. recreational fishermen in the Atlantic and

Gulf of Mexico 15

WITZELL, W. N. The incidental capture of sharks in the Atlantic United States Fishery Conservation Zone by the Japanese tuna

longline fleet. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 21

iii
iv
Analysis of Various Sources of Pelagic Shark Catches

in the Northwest and Western Central Atlantic Ocean

and Gulf of Mexico with Comments on Catches of

Other Large Pelagics

EMORY D. ANDERSON!

ABSTRACT

Various sources of catch of pelagic sharks during 1960-81 in the Northwest and Western Central Atlantic

Ocean and Gulf of Mexico, particularly within the United States Fishery Conservation Zone (FCZ), were identified and quantified. These sources included reported statistics, but principally unreported bycatch in fisheries

directed towards other species. Total catch estimates during 1965-80 averaged 9,800 t (metric tons) per year and

peaked at 17,300 t in 1977 in the Atlantic FCZ and averaged 6,800 t per year and peaked at 10,200 tin 1980 in the

Gulf FCZ. The major source of catch in the Atlantic FCZ was the U.S. recreational fishery, followed by the

United States and Canadian swordfish longline fisheries and the Japanese tuna longline fisheries. The major

sources of catch in the Gulf FCZ were the recreational fishery and the U.S. shrimp, groundfish, and snappergrouper fisheries. A comparison between long.term average catches and recent levels in both areas suggests that

pelagic sharks may be excessively exploited at the present time.

INTRODUCTION

Pelagic sharks (defined here as all sharks except dogfish) have

been taken in a variety of foreign and domestic fisheries in the

Northwest and Western Central Atlantic Ocean and Gulf of Mexico. Much has been as bycatch from fisheries directed towards

other species, although there have been some directed fisheries for

sharks. Due to the incidental nature of most shark catches, accurate statistics have invariably been lacking or only intermittently

estimated.

In the late 1970's, the Gulf of Mexico Fishery Management

Council and the Mid-Atlantic Fishery Management Council

began developing fishery management plans (FMP's) for sharks

found within the United States Fishery Conservation Zone (FCZ)

in the Gulf of Mexico and Atlantic, respectively. In response to a

request by the Mid-Atlantic Council for catch data to be used in

developing their FMP, an attempt was made to assemble a data

base comprised of reported and estimated unreported catches from

various foreign and domestic fisheries. This paper presents the

results of that attempt and includes 1) reported commercial

catches, 2) estimates of U.S. recreational catch, 3) estimates of bycatch in the United States and Canadian longline fisheries for

swordfish, 4) estimates of bycatch in the distant-water-fleet trawl

fishery for squid, and 5) estimates of bycatch in the Japanese

longline fishery for tuna. Information is also provided on the catch

of other large pelagics in the swordfish fisheries and the squid

trawl fisheries. Other possible sources of shark bycatch are indicated, and the general limitations and inadequacies of the

assembled data base are discussed.

INortheast Fisheries Center. Woods Hole Laboratory. National Marine Fisheries

Service, NOAA, Woods Hole, MA 02543. Address as of I Aug. 1985: International

Council for the Exploration of the Sea, Palaegade 2-4, DK-1261 Copenhagen K,

Denmark.

'R. L. Schween and E. A. Poetzschke, National Fishery Statistics Program, National Marine Fisheries Service. NOAA, Washington, DC 20235, pers. commun. July 1983.

REPORTED COMMERCIAL CATCH

Northwest Atlantic

Reported commercial catches (defined here as the live weight

equivalent of landings) of pelagic sharks from the Northwest

Atlantic were obtained from ICNAF (International Commission

for the Northwest Atlantic Fisheries) and NAFO (Northwest

Atlantic Fisheries Organization which replaced ICNAF in 1979)

Statistical Bulletin~ 10-31 for 1960-81, U.S. Statistical Digests

(Fishery Statistics of the United States, Nos. 53-69) for 1960-76,

and unpublished National Marine Fisheries Service (NMFS) data

for 1977-81 (Schween and Poetzschke2; Newlin3 ).

Shark catches reported from ICNAF/NAFO Subareas 1-6 (Fig.

1) are presented in Tables 1-3. Catches reported by the Faroe

Islands and Greenland were combined and listed under Denmark,

although the Faroese catches accounted for most of the total.

Although dogfish catches are reported separately from other

sharks in ICNAF/NAFO statistics, U.S.S.R. dogfish catches prior

to 1974 were reported as sharks. It was later verified that most, if

not all, of the U.S.S.R. shark catches were dogfish (ICNAF

Secretariat4 ); therefore, all U.S.S.R. shark catches were considered

to be dogfish. In the Statistical Digests, dogfish and other sharks

were combined for many years, although data since 1974 have

been reported separately for dogfish (or grayfish) and unclassified

sharks. Catches from states bordering on Subareas 5 and 6 (SA 5

and 6) were summed, and the ratio of unclassified to total sharks

for each area each year was applied to the shark catch reported to

ICNAF/NAFO to define more accurately the U.S. commercial

pelagic shark catch.

3K. Newlin, Southeast Fisheries Center. National Marine Fisheries Service,

NOAA, 75 Virginia Beach Drive, Miami, FL 33149, pers. commun. JUly 1983.

4ICNAF Secretariat, International Commission for the Northwest Atlantic Fisheries, P.O. Box 638, Dartmouth, Nova Scotia B2Y 3Y9. pers. commun. September

1978.
Table l,--Reported commercial catch (I) of pelagic sharks hy country and subareas in the ICNAF/NAFO area, 1960-8!.

Subarea I Subarea 2 Subarea 3

Den- DenYear mark FRG GDR Iceland Japan Total FRG GDR Others Total Canada mark France FRG GDR Iceland Japan Norway US Others Total

1960 5 5 - - - -- 2 - - 2

1961 - 245 10 255 27 - - 27 - - 9 I 152 - 162

1962 204 3 207 1 - I - - I - - - I

1963 129 8 137 2 - 2 - I 2 2 - 5

1964 54 100 - 2 156 6 - -- 6 I - 67 7 7 52 - - 134

1965 10 120 130 26 26 5 1,078 - 8 - - 1,091

1966 - 48 14 62 5 - 5 6 741 102 - 849

1967 - I I 8 589 143 740

1968 _•.. - I I I I - 662 I I 2 666

1969 299 - 299 -- -- I _. - I 2

1970 - - - -- - 205 - 205

1971 252 - - -- - 252 - - - I -- - - I

1972 - - - 8 8 3 8 I 29 --- - 41

1973

1974

1975 - 27 - 27 14 14

1976 -- II - - 11

1977 - 27 27 14 14 - 4 10 - - 14

1978 --- 38 38 2 2 20 -- 20

1979 152 -- - 152 98 - 2 2 102

1980 - - 24 24 - 111 - - 7 118

1981 -- 16 - - 16 19 - 4 23 ~.>

Subarea 4 Subarea 5 Subareo 6 NK' ._---- Den Den- Roma- Rl)maYear Canada mark France FRG Japan Norway US Others Total Canada mark Japan Norway ow US Others Total Canada FRG Japan Norway nia Spain US Others Total Norw,ly ---- - -----

1960 - - - - 6 -_. 6 - -- - 62 - 62

1961 - - - 23 23 140 -- 10 150 24 - 24 1,509

1962 - - - - - - - - 16 .- 16 - 37 37 2,216

1963 :1 - 3 -'- - 16 -- 16 48 48 5,761

1964 16 - 19 I -- 101 137 - 299 - 6 305 61 - 61 7,608

1965 15 - 15 8 - 142 150 - 77 - 77 4,045

19b6 2 - 9 - - - 11 20 - - 23 3 46 52 - 868 75 995 505

1967 11 - 4 - - - - 15 8 - 6 .- 14 24 36 - I -- 61

1968 7 - 7 - - I 15 2 4 .- 6 18 30 125 4 5 134 270

1969 5 865 3 - 873 132 29 - 161 I 73 - 19 93

1970 4 - - 15 - 19 334 - 13 - 347 I 325 37 _.. 363

1971 231 - 81 - 312 64 40 7 - III 76 - 18 94

1972 - 29 - - 29 260 20 5 12 306 - 2 31 34 - 67

1973 269 - - - - 269 5 5 - 33 33

1974 - - - -- - 28 6 - 34 77 52 129

1975 - 20 - - 20 - 60 - 20 80 - -- 90 - 90

1976 - 290 - - - 2 292 17 3 13 - 33 I 52 53

1977 288 - - _.• - 288 3 12 37 I 53 - 4 2 49 3 58

1978 1 101 - - - - - 102 I 21 22 - - 70 70

1979 3 201 - 1 I 206 - 20 24 - 44 - 2 I 39 - 42

1980 I 312 - 2 - - 315 2 13 175 - 190 6 82 88

1981 1 325 - I 327 6 99 105 - - 81 81

lNot known.
,o01

1

Table 2.-Reported commercial catch (t) of pelagic sharks by

subarea in the ICNAF/NAFO area, 1960-81.

Subarea

Year 2 4 6 NK' Total

1960 5 2 6 62 75

f 1961 255 27 162 23 150 24 1,509 2,150

1962 207 1 1 16 37 2,216 2,478

1963 137 2 5 3 16 48 5,761 5,972

1964 156 6 134 137 305 61 7,608 8,407

1965 130 26 1,091 15 150 77 4,045 5,534

1966 62 5 849 II 46 995 505 2,473

1967 1 740 15 14 61 831

,,0· 1968 I I 666 15 30 134 270 1,117

1969 299 2 873 161 93 1,428

1970 205 19 347 363 934

1971 252 I 312 111 94 770

1972 41 29 306 67 451

1973 269 5 33 307

1974 34 129 163

1975 27 14 20 80 90 231

50· 1976 11 292 33 53 389

1977 27 14 14 288 53 58 454

1978 38 2 20 102 22 70 254

1979 152 102 206 44 42 546

1980 24 118 315 190 88 735

1981 16 23 327 105 81 552

'Not known. 70% of this catch each year is assumed to have

come from SA 5 and 6 (see text).

4

1:> ,5·

'"

Figure I.-Map showing ICNAF/NAFO Subareas 1-6.

Table 3.-Reported commercial catch (t) of pelagic sharks by country in Ihe ICNAF/NAFO area, 1960-81.

Country

Den- RomaYear Canada mark France FRG GDR Iceland Japan Norway nia Spain U.S. Others Total

1960 7 68 75

1961 281 II 1,824 34 2,150

1962 205 4 2,216 53 2,478

1963 3 132 10 5,763 64 5,972

1964 17 54 86 114 9 8,060 67 8,407

1965 28 1,088 154 4,045 219 5,534

1966 80 741 111 53 14 1,373 98 3 2,473

1967 51 589 147 36 7 1 831

1968 9 662 138 270 10 27 1,117

1969 7 1,164 208 48 1,428

1970 5 205 674 50 934

1971 483 221 40 25 770

1972 260 2 16 87 36 46 451

1973 269 38 307

1974 105 58 163

1975 80 41 110 231

1976 307 II 3 I 67 389

1977 295 51 16 2 86 -: 454

1978 121 40 I 91 254

1979 299 154 23 66 546

1980 425 24 21 264 735

1981 344 16 7 184 552

::;
The total international pelagic shark catch from the entire

ICNAF/NAFD area during 1960-81 varied between 75 (1960)

and 8,407 t (metric tons) (1964) (Tables 1-3). Catches in SA 5

and 6 (comparable with the U.S. FCZ) during this period averaged

about 250 tlyr. The only known directed fisheries were those conducted by the Faroe Islands and Norway for porbeagle, Lamna

nasus. Catches reported by other countries were assumed to have

occurred incidentally in fisheries directed towards other species.

During 1961-68, Norway reported shark catches as high as 7,600

t, but did not specify the area. The Norwegian longline fishery

operated from the Middle Atlantic (SA 6) to Newfoundland (SA

3) (Aasen 1963; Casey et al. 1978; MyklevoIl5 ). During 1961,

1964, and 1966, some Norwegian catches were reported from SA

3,4,5, and 6, although the bulk was undesignated. In the absence

of any information concerning the locations (subareas) of the

undesignated catches, they were assumed to be distributed in proportion to those reported by subarea. In 1961, 1964, and 1966,

44, 66, and 100%, respectively, of the Norwegian catch reported

by subarea came from SA 5 and 6. The average percentage (70%)

was applied to the undesignated Norwegian catch in 1961-68 to

estimate the amount from SA 5 and 6, which may have been as

high as 5,300 t in 1964. The Faroese porbeagle fishery was conducted mainly in SA 3 and 4, with small catches reported from

U.S. waters (SA 5) only in 1972,1975-77, and 1980. The only

other significant reported foreign catch in SA 5 and 6 was by

Japan during 1967-71. The U.S. catch in SA 5 and 6 during

1960-81 averaged 70 t/yr. The total catch in SA 5 and 6 in 1981

was 186 t, of which 180 t was reported by the United States.

Western Central Atlantic and Gulf of Mexico

Reported commercial catches of pelagic sharks from the

Western Central Atlantic and Gulf of Mexico (FAD Area 31) (Fig.

2) for 1965-81 were obtained from FAD Yearbooks of Fishery

Statistics (Vols. 36, 38,42,44,46,48,50, and 52), U.S Statistical

Digests, and unpublished NMFS data.

Total international catches of pelagic sharks in Area 31 [considered to be those listed as requiem (Carcharhinidae) and various

sharks in the FAD statistics] increased from 4,800 t in 1965 to

13,700 t in 1977, declined to 9,400 t in 1979, then increased

sharply to 19,000 t in 1981 (Table 4). Cuba, Mexico, and Venezuela accounted for an average of 82% of the total each year. The

Cuban catch increased from 700 t in 1966 to a high of 3,800 t in

1977, dropped to an average of 2,200 t during 1978-80, then increased in 1981 to 3,400 t. The amount taken by Cuba in U.S.

waters (Gulf of Mexico) increased steadily from about 100 t in

1972 to 1,000 t in 1976 (Table 5); no catch has been reported in

U.S. waters since 1976. The extent of Cuban catches in U.S.

waters prior to 1972 is unknown, although the West Florida shelf

was historically a Cuban fishing area. Mexican catches in Area 31

climbed from 100 tin 1965 to 9,800 t in 1981. Although Mexico

borders the United States in the Gulf of Mexico, it is believed that

most of the Mexican catch originated from Mexican waters in the

vicinity of the Campeche Banks bordering the Yucatan Peninsula.

Catches by Venezuela have similarly undergone a continuous increase, going from 1,700 t in 1966 to 4,700 t in 1981. It is believed that most, if not all, of this has been from non-U.S. waters.

'5. Myklevoll, Institute of Marine Research, P.O. Box 1870, 50 II BergenNordnes, Norway, pers. commun. November 1978.

4

Figure 2.-Map showing FAO Areas 21 (ICNAF/NAFO area) and 31.

Among the remaining countries reporting shark catches from

\rea 31 (except for the United States), only Japan, by virtue of its

wide-ranging fishing operations for tuna, is believed to have taken

any significant amounts of sharks from U.S. waters. The reported

Japanese catch in Area 31, which declined from 800 t in 1965 to

as low as 3 t in 1980, was assumed to be spatially distributed in

proportion to their fishing effort reported by 5° Marsden squares

(see Japanese Tuna Longline Bycatch). The catch taken within the

U.S. FCZ was calculated in proportion to the amount of effort

reported for those 5° Marsden squares located within the FCZ.

Japanese catch rates for sharks were also assumed to be nearly 4

times higher in the Atlantic than in the Gulf of Mexico based on

1978-82 data (Witzell 1985). Results from this estimation procedure indicated an average of only 26 tlyr from the Atlantic FCZ

and 14 t from the Gulf FCZ during 1965-81 (Table 5).

The reported U.S. catch from Area 31 has been relatively small,

averaging only 1.4% (118 t/yr) of the international total during

1965-81 (Table 4), but has exhibited an increase in recent years.

The U.S. catch in 1981 was about 400 t, double the amount in

1980. The catch during 1960-81 averaged 55 tlyr in both the

Atlantic and Gulf regions of Area 31 (Table 6).
Table 4.-Reporled commercial catch (t) of pelagic sharks in the western central Atlantic and Gulf of Mexico (FAO Area 31), 1965-81.

Country

Costa French Marti- South Trinidad

Year Colombia Rica Cuba Guiana Grenada Japan nique Mexico Norway Korea Tobago U.S. U.S.S.R. Venezuela Others TOlal'

1965 200 1.300 100 800 400 100 18 100 1,800 4,800

1966 200 700 100 700 400 200 700 43 700 1,700 5,400

1967 100 1,100 100 200 500 200 601 400 1,900 100 5,200

1968 2,700 100 100 100 200 49 2,100 100 5,400

1969 2,500 100 200 100 200 17 2,400 200 5,700

1970 2,200 200 100 1,000 200 10 2,200 100 6,000

1971 100 100 2,500 200 100 1,000 300 13 2,300 100 6,700

1972 100 200 2,500 100 100 1,200 300 9 2,400 1,000 7,900

1973 100 2,800 100 100 2,600 400 161 3,200 1,000 10,500

1974 100 5 3,100 74 172 3,189 407 23 2,820 1,000 10.900

1975 4 3,600 147 95 3,004 41 375 39 3,064 1,000 11,400

1976 3 3,600 76 193 3,014 74 430 86 2,714 490 10,700

1977 2 3,800 255 32 140 4,697 28 543 118 3,436 644 13,700

1978 3 2,200 279 4 154 4,189 11 624 152 2,887 200 10,700

1979 5 2,000 7 II 181 4,051 379 70 2,462 219 9,400

1980 5 2,504 7 3 181 5,321 368 203 4,181 59 12,800

1981 9 3,396 32 56 181 9,790 17 368 398 4,707 73 19,000

RECREATIONAL CATCH

Tho recreational catch of pelagic sharks in the United States has

been poorly documented. Estimates of recreational catch were obtained from national surveys conducted in 1960 (Clark 1962),

1965 (Deuel and Clark 1968), and 1970 (Deuel 1973), and from

regional surveys conducted in 1974-75 (DeueI6 ) and 1977-78

'D. G. Deuel, Statistics and Markel News Division, Narragansett Laboratory, National Marine Fisheries Service, NOAA, RR7, South Ferry Road, Narragansett, RI

02882, pers. commun. September 1976.

5

(hereafter referred to as the 1978 survey) (Hamm and Slater

1979); since 1979, annual catch estimates have been made by the

NMFS Marine Recreational Fishery Statistics Survey (MRFSS).

Coverage by the regional surveys included Maine-Virginia in

1974, North Carolina-Texas in 1975, and Maine-Texas in

1977-78. Casey and Hoey (1985) reviewed the estimates of shark

catch obtained from the pre-1979 surveys, while focusing

primarily on the results of the 1978 survey.
Estimates of the recreational catch of sharks must be interpreted with caution. Sampling design and survey methodology

have differed among the various surveys. The 1960, 1965, and

1970 national surveys were each based on a 1-yr recall period.

Response-bias errors, such as prestige-bias errors resulting from

exaggeration and memory-bias errors associated with guessing,

were inherent in these three surveys and likely caused overestimation of catches (Deuel and Clark 1968; Deuel 1973). The

1974-75 regional surveys employed different methods than used

in the previous national surveys and were based on a 2-mo recall

period. The methodology incorporated into the MRFSS was

significantly different from that employed in the earlier surveys

(U.S. Department of Commerce 1980) and was intended to improve the reliability of the catch estimates. As a result of these

changes, catch estimates from the earlier surveys are not directly

comparable with those beginning in 1979.

The total weight of the catch was determined differe.ntly for the

surveys beginning in 1979 than for those conducted earlier. In the

earlier surveys, interviewed anglers provided estimates of the

number and average weight of fish caught. From this information,

an estimated total weight was determined. In the surveys beginning in 1979, catches were estimated in terms of numbers of fish

which were 1) available for identification by the interviewer, and

2) not available for identification (butchered, discarded dead,

released alive, etc.). Mean weights were obtained only from fish

available for identification. In this paper, mean weights obtained

from fish in the first category were also applied to fish in the second category in order to obtain an estimate of weight for the total

catch.

A further complicating factor associated with the estimates of

the recreational catch of sharks is that catches of dogfish were included in some surveys. Dogfish are defined as spiny dogfish,

Squalus acanthias, smooth dogfish, Mustelus canis, any other

species of dogfish, and other small sharks weighing < 5 Ibs.

Dogfish were estimated separately in the 1965, 1970, and 1979

and later surveys. but were combined with other sharks in the

1960 and 1974-75 surveys. Dogfish catches were not estimated in

the 1978 survey.

The estimated recreational catch of sharks (excluding dogfish)

in the Atlantic and Gulf of Mexico was 2,623 tin 1965,9,854 tin

1970. 9,759 t in 1978, and 15,907 t in 1980 (Table 7). The 1979

survey (U.S. Department of Commerce 1980) indicated a total

Atlantic and Gulf catch of 56,270 t, grossly in excess of all other

annual estimates. This estimate was considered to be extremely

biased and invalid because interviewers focused their sampling efforts on shark tournaments where trip catch rates were much

higher than normal (Deuel and Holliday?). The estimated mean

weights in 1980 (Deuel and Holliday footnote 7) were quite low

relative to other years even though the overall weight estimate appeared consistent with the apparently increasing trend in recreational shark catches. The Gulf catch was 43% of the total in 1965,

69% in 1970,20% in 1978, and 38% in 1980. The catch estimated for the Gulf in both 1965 and 1970 appears to be high in

comparison with that for the Atlantic and is inconsistent with the

level of commercial catch in the Gulf relative to the Atlantic. In

the Atlantic, the area from Maine to Virginia had a higher estimated catch each year than the North Carolina-East Florida area,

averaging 70% of the east coast total in 1965, 1970, 1978, and

1980.

'D. G. Deuel and M. Holliday, National Fishery Statistics Program, National

Marine Fisheries Service, NOAA, Washington, DC 20235, pers. commun. July

1983.

6

An attempt was made to estimate the amount of pelagic sharks

included in the combined shark-dogfish estimates for 1960 and

1974-75. The proportion of sharks in the combined shark-dogfish

catch in 1965 and 1970 was 84 and 87%, respectively, for MaineVirginia, 53 and 76% for North Carolina-East Florida, and 40 and

96% for the Gulf of Mexico, The mean of the percentages for each

area was applied to the shark-dogfish catch in 1960 and 1974-75.

The results suggested an estimated catch of sharks in MaineVirginia of 9,853 tin 1960 and 2,483 tin 1974, in North Carolina-East Florida of 3,712 t in 1960 and 2,172 t in 1975, and in

the Gulf of Mexico of 5,116 t in 1960 and 2,460 t in 1975. The

total for all areas for 1960 of 18,141 t appeared unusually high

compared with 9,854 t in 1970,9,759 t in 1978, and 15,907 tin

1980. Based on the general increase in recreational fishing for

sharks since the mid-1960's (Casey et al. 1978), the catch in 1960

should have been no greater than in later years and more likely

less, The high estimate for 1960 is likely a reflection of serious

survey response-bias errors.

Estimates were made of recreational catch for years lacking

angler surveys in order to ootain a continuous data series for comparison with other sources of catch, Since there were generally no

unusual or sharp fluctuations in estimated catches from surveys

from 1965 to 1980, values for the years lacking surveys were estimated merely by interpolation. These results are given in Table 7.

The total estimated recreational catch for all areas increased

from about 2,600 t in 1965 to a rather constant level from 1969 to

1978, during which time estimated catches averaged about 8,700

tlyr, before increasing further to about 15,900 t in 1980. Several

trends were apparent within areas, notably a general decline in the

Gulf from 1970 to 1978 followed by sharp increases in 1979 and

1980, and a continuous increase in the Atlantic from 1965 to

1980.

Table 7,-Estimated U.S, recreational catch (t) of pelagic sharks by area in the

Atlantic Ocean and Gulf of Mexico, 1965-80, Values for years lacking survey

estimates obtained by interpolation.

North Carolina- West FloridaYear Maine-Virginia East Florida Texas Total ----_.

1965 '992 '511 11,120 2,623

1966 1,344 469 2,255 4.068

1967 1,697 428 3,391 5,516

1968 2,049 386 4,527 6,962

1969 2,401 345 5,663 8,409

1970 '2,753 '303 16,798 9,854

J971 2,686 677 5,931 9,294

1972 2,618 1,051 5,063 8,732

1973 2,551 1,424 4,195 8,170

1974 "'2,483 1,798 3,327 7,608

1975 3,186 "2,172 "2,460 7,818

1976 3,889 2,292 2,284 8,465

1977 4,592 2,412 2,108 9,112

1978 '5,295 '2,532 '1,932 9,759

1979 5,331 3,498 4,004 12,833

1980 '5,367 '4,463 '6,077 15,907

1From angler surveys.

'Survey estimate included dogfish; pelagic sharks estimated assuming mean of

1965 and 1970 dogfish/pelagic shark ratios.
SWORDFISH LONGLINE BYCATCH

Records maintained by some U.S. fishermen (Casey8) indicate a

significant bycatch of pelagic sharks in longlining operations for

swordfish, Xiphias gladius. Because sharks caught (and discarded)

in the swordfish fishery have not been reported in official statistics, this component of the overall shark catch was estimated using

available bycatch percentages.

Longlining for swordfish was initiated by both U.S. and Canadian fishermen in 1962 as a result of reports of the incidental capture of swordfish by Japanese and Norwegian longliners fishing

for tuna and porbeagle sharks, respectively (Caddy 1976; Beckett

1971 9 ). In late 1970-early 1971, the swordfish fishery nearly

ceased when U.S. Food and Drug Administration (FDA) regulations prohibited the sale of fish with a tissue content of mercury in

excess of 0.5 ppm. Some swordfish continued to be caught and

sold for local consumption, thus remaining technically immune

from FDA regulations; some catches were reported, but apparently many operations were conducted in secrecy and significant

quantities of swordfish were landed and not reported. The mercury

action level was raised to 1.0 ppm in 1978 and was thought to

reduce underreporting to minimal levels in 1978 and succeeding

years.

U.S. longline catches of swordfish were obtained from U.S.

Statistical Digests for 1962-76 and unpublished NMFS data for

1977-81 (Schween and Poetzshke footnote 2; Newlin footnote 3).

The proportion of the U.S. catch taken in the U.S. FCZ in the

Northwest Atlantic (SA 5 and 6) and in Canadian waters (SA 3

and 4) was ascertained from data obtained from ICNAF and

NAFO Statistical Bulletins. Reported statistics during 1971-77,

however, are inaccurate due to unreported catches stemming from

the mercury problem.

Commercial catch data from the American Swordfish Association (ASA) for Massachusetts, Rhode Island, and Maine for

1974-77 (Booz, Allen & Hamilton, Inc. 1980 10) were used as a

basis for estimating actual catches during 1971-77. ASA statistics

for these three states combined were 173, 160.221, and 531% of

the official reported catches for 1974,1975,1976, and 1977,

respectively. Reported catches from these states during 1974-77

averaged 90% of the U.S. Atlantic and Gulf of Mexico total.

Assuming a similar level of underreporting everywhere during this

time, the above percentages were applied to reported catches for

all states in the appropriate years in order to estimate actual

catches. During 1971-73, it is believed, as fishermen slowly and

cautiously resumed operations following the near cessation of the

fishery in early 1971, that underreporting of catches steadily increased (Casey footnote 8). A linear increase was assumed in the

proportion of actual versus reported catches from 100% in 1970

(i.e., actual and reported catches were equal) to 173% in 1974.

Values of 118, 137, and 155% were applied to reported catches in

1971,1972, and 1973, respectively, in order to estimate actual

catches.

Canadian catches of swordfish from SA 3-6 for 1962-81 were

obtained from lCNAF and NAFO Statistical Bulletins. Longlinecaught swordfish averaged 91 % of the Canadian catch during

'J. G. Casey, Northeast Fisheries Center Narragansett Laboratory, National

Marine Fisheries Service, NOAA, RR7, South Ferry Road, Narragansett, RI 02882,

pers. commun. November 1979.

·Beckett. J. S. 197 J. Canadian swordfish longline fishery. Int. Comm. Cons.

Atl. Tunas, SCRS Doc. 71/36, J4 p. (Mimeogr.)

10Booz. Allen & Hamilton, Inc. 1980. Final Report: Description of the sword·

fish fishery. Prepared for South Atl. Fish. Manage. Counc., Charleston, SC, April

1980, 17 I p. (Mimeogr.)

7

1963-67,98% during 1968-70, and 100% during 1973-81 (Caddy 1976; ICNAF/NAFO Statistical Bulletins). Because the Canadian swordfish fishery "officially" ceased on I February 1971

(Beckett footnote 9) as a result of restrictions on mercury levels in

fish, reported Canadian swordfish catches after 1970 were negligible in SA 5 and 6, but increased sharply in 1978 in SA 3 and 4

to 3,053 t (Table 8). During 1971-77, some Canadian vessels continued to fish for swordfish which they purportedly sold and offloaded at sea to U.S. vessels. The increase in U.S. swordfish landings (both reported and actual) in the mid-1970's undoubtedly

reflected some continued Canadian swordfishing activities.

The estimated United States and Canadian swordfish longline

catches by area for 1962-81 (Table 8) were converted from metric

tons to numbers of fish using annual mean weights of catches ob··

tained for each area from various sources (Caddy 1976; Casey and

Hoey 1985; Beckett footnote 9; Berkeley and Houde 1981; Hurley

and IIes 1981 11 ; South Atlantic Fishery Management Council

198212 ). The dressed weight-live weight ratio was assumed to be

0.75. Weighted (by sample size) averages were used when areayear mean weights were available from multiple sources. When a

mean weight was not available for a particular area-year, the

value for the adjacent year or the mean of the preceding and succeeding years was used. Mean weights were not available for the

North Carolina-East Florida area in 1964-66, but were estimated

by assuming that values for those years were 16% smaller than

those in the Maine-Virginia area. This was the average difference

in mean weights between the two areas in 1970 and 1974-81. The

same mean weights were applied to both United States and Canadian catches in a given area.

The bycatch of sharks in the United States and Canadian longline fisheries for swordfish was estimated from data obtained by

Casey (footnote 8) from U.S. swordfish longline fishermen. Longline catch data were summarized by area from a total of I) 628

sets (649.273 hooks) north of Cape Hatteras over a period of 10

yr, 2) 28 sets (29,150 hooks) between Cape Hatteras and the

Florida Keys during a 4-yr period, and 3) 198 sets (220,021

hooks) in the Gulf of Mexico during a 5-yr period. The total

number of sharks caught in proportion to the number of swordfish

was determined for each area for all years combined. The results

were rather consistent among areas, indicating a 234% bycatch of

sharks north of Cape Hatteras, a 296% bycatch between Cape

Hatteras and the Florida Keys, and a 213% bycatch in the Gulf of

Mexico. These percentages were applied to the estimated numbers

of swordfish taken in all years by longline in the four areas to obtain the estimated bycatch (in numbers) of sharks (Table 8). The

estimated numbers of sharks were converted to metric tons by use

of a mean shark weight of 41 kg for Nova Scotia-Newfoundland

and Maine-Virginia, 42 kg for North Carolina-East Florida, and

36 kg for the Gulf of Mexico. The above values were weighted

mean weights obtained by applying the mean weights for individual species (Casey and Hoey 1985) to the numbers of sharks of

each species in the swordfish longline bycatch data base.

Estimated annual shark bycatch in the swordfish longline

fisheries in the Nova Scotia-Newfoundland area during 1963-70

ranged between 1,300 and 5,700 t and averaged about 3,200 t

11 Hurley, P. C. F., and T. D. Isles. 1981. Status and assessment of Northwest

Atlantic swordfish stocks. Can. Atl. Fish. Sci. Adv. Comm., Res. Doc. 81/15, 18 p.

(Mimeogr.)

"South Atlantic Fishery Management Council. 1982. Source document for

the Swordfish Fishery Management Plan. May 1982,242 p. (Mimeogr.)
Table 8.-Estimated bycatch of pelagic sharks in the United States and Canadian swordfish longline fisheries, 1962-81.

Swordfish Sharks Swordfish Sharks

Mean Est. Mean Mean Est. Mean Catch (I) round Catch catch I round Est. calch (t) Catch (t) round Catch catchl round Est. catch (I)

Year U.S. Canada TOlal wI. (kg) (numbers) (numbers) wI. (kg) U.S. Canada Total U.S. Canada TOlal wI. (kg) (numbers) (numbers) wI. (kg) U.S. Canada TOlal

- - - - - - - - - - - - - - - - - - - - - Nova Scotia-Newfoundland - - - - - - - . - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - Maine- Virginia - - - - - - - - - - - - - - - - - - - - - - - - -

1962 4 287 291 120 2,425 5,675 41 3 230 233 62 68 130 120 1,083 2,534 41 50 54 104

1963 101 5,049 5,150 123 41,870 97.976 41 79 3,938 4,017 951 2,593 3,544 83 42,699 99,916 41 1,099 2,998 4,097

1964 28 3,861 3,889 106 36,689 85,852 41 25 3,495 3,520 1,033 3,961 4,994 84 59,452 139,118 41 1,180 4,524 5,704

1965 24 1,542 1,566 117 13,385 31,321 41 20 1,264 1,284 862 2,403 3,265 74 44,122 103,245 41 1,118 3,115 4,233

1966 13 1,734 1,747 91 19,198 44,923 41 14 1,828 1,842 486 1,835 2,321 74 31,365 73,394 41 630 2,379 3,009

1967 2,693 2,693 75 35,907 84,022 41 3,445 3,445 340 1,852 2,192 65 33,723 78,912 41 502 2,733 3,235

1968 7 2,238 2,245 72 31,181 72,964 41 9 2,983 2,992 174 2,109 2,283 56 40,768 95,397 41 298 3,613 3,911

1969 2,175 2,175 70 31,07 ! 72,706 41 2,981 2,981 93 2,030 2,123 54 39,315 91,997 41 165 3,607 3,772

1970 3,145 3,145 53 59,340 138,856 41 5,693 5,693 32 1,552 1,584 36 44,000 102,960 41 85 4,136 4,221

1971 - - - - 2 2 42 48 112 41 5 - 5

1972 41 - 41 42 976 2,284 41 94 94

1973 90 90 49 1,837 4,299 41 176 - 176 254 14 268 49 5,469 12,797 41 498 27 525

1974 1,081 2 1,083 61 17,754 41,544 41 1,700 3 1,703 792 792 55 14,400 33,696 41 1,382 - 1,382

1975 995 13 1,008 75 13,440 31,450 41 1,272 17 1,289 1,644 7 1,651 61 27,066 63,334 41 2,586 11 2,597

1976 1,185 4 1,189 73 16,288 38,114 41 1,558 5 1,563 1,968 II 1,979 49 40,388 94,508 41 3,853 22 3,875

1977 1,444 97 1,541 84 18,345 42,927 41 1,649 III 1,760 4,429 16 4,445 49 90,714 212,271 41 8,672 31 8,703

1978 48 3,053 3,101 72 43,069 100,781 41 64 4,068 4,132 1,837 - 1,837 50 36,740 85,972 41 3,525 - 3,525

1979 537 2,375 2,912 81 35,951 84,125 41 636 2,813 3,449 980 595 1,575 67 23,507 55,006 41 1,403 852 2,255

1980 364 1,692 2,056 77 26,701 62,480 41 454 2.108 2,562 819 155 974 67 14,537 34,017 41 1,173 222 1,395

co 1981 311 551 862 64 13,469 31,517 41 466 826 1,292 697 - 697 59 11,814 27,645 41 1,133 1,133

- .. - - - - - .. - - - - - - - . - - - - -North Carolina-Easl Florida- ..... - - - - - - - - - - - - - - .. - - .. - - - - - - - ...... - . - - - - - - - - - -Wesl Florida-Texas - - - - - - - ... - - - - . - - - - - ..

1962

1963

1964 219 219 71 3,085 9,132 42 384 - 384

1965 238 - 238 62 3,839 11,363 42 477 477

1966 35 - 35 62 565 1,672 42 70 - 70

1967

1968

1969 - - - -. 1 I 48 21 45 36 2 2

1970 - - 156 - 156 48 3,250 6,923 36 249 249

1971

1972

1973 - - 10 10 36 278 592 36 21 21

1974 - - - - - 68 - 68 36 1,889 4,024 36 145 145

1975 - - - - 108 108 41 2,634 5,610 36 202 202

1976 263 263 42 6,262 18,536 42 779 779 360 360 47 7,660 16,316 36 587 587

1977 275 275 39 7,051 20,871 42 877 877 5 5 36 139 296 36 II II

1978 708 708 43 16,465 48,736 42 2,047 2,047 24 24 50 480 1,022 36 37 37

1979 1,214 1,214 59 20,576 60,905 42 2,558 - 2,558 197 197 55 3,582 7,630 36 275 275

1980 1,966 - 1,966 59 33,322 98,633 42 4,143 - 4,143 829 829 44 18,841 40,131 36 1,445 1,445

1981 1,659 - 1,659 51 32,529 96,286 42 4,044 4,044 535 535 29 18,448 39,294 36 1,415 1,415

I Assuming a shark bycatch in all years of 234% of the swordfish catch in the Nova Scotia-Newfoundland and Maine-Virginia areas, 296% in the North Carolina-East Florida area, and 213% in the West FloridaTexas area.
(Table 8). Bycatch was nonexistent during 1971-72, but averaged

about 1,600 t during 1974-77. After rising to 4,100 t in 1978,

bycatch gradually declined to about 1,300 t in 1981.

The estimated shark bycatch in the Maine-Virginia area was

fairly steady during 1963-70, averaging 4,000 t/yr (Table 8).

After dropping to only 5 t in 1971, bycatch climbed steadily to an

estimated 8,700 t in 1977 after which it declined every year to

about 1,100 t in 1981.

Prior to 1976, the only estimated shark bycatch in the North

Carolina-East Florida area occurred in 1964-66 (average of 310

t/yr). However, beginning in 1976, estimated bycatch increased

sharply from 800 to 4,100 t in 1980-81 (Table 8).

Estimated bycatch in the West Florida-Texas area did not begin

until 1969, and was relatively low (average of 170 t in 1969-70

and 1973-79) until it increased sharply to 1,400 t in 1980-81

(Table 8).

DISTANT-WATER-FLEET SQUID

TRAWL BYCATCH

The bycatch of sharks, as well as other large pelagic species, in

the distant-water-f1eet (DWF) trawl fishery for squid in U.S.

waters of the northwest Atlantic (lCNAF/NAFO SA 5 and 6) was

estimated for 1965-81 based on NMFS foreign fisheries observer

catch reports for 1978. The capture of sharks and other large

pelagics in conjunction with fishing operations directed towards

squid appears logical from an ecological basis. Squid are an important prey item for many shark and tuna species, swordfish, and

marine mammals such as pilot whales, Globicephala melaena

(Bigelow and Schroeder 1953; Scott and Tibbo 1968; Stevens

1973; Tibbetts 1977; Casey and Hoenig 1977; Dragovich 1969;

Maurer 1975 13 ; Mercer 197414). These predators should, therefore, be susceptible to capture in trawls while feeding on the squid.

Following implementation of the Magnuson Fishery Conservation and Management Act of 1976 (P.L. 94-265) in March 1977,

observers were placed aboard foreign fishing vessels to monitor

and quantify the catch of all species. Vessel nationality, fishing

area, number of days fished while the observer was aboard, and

the total bycatch (kg) of sharks, swordfish, and other large

pelagics for 1978 were obtained from the "Monthly Summary

Reports on Foreign Fisheries Observer Program - Data on Bycatch

and Catch Estimates" prepared by the NMFS Northeast Region,

Foreign Fisheries Observer Program. Vessel days fished and the

bycatch for each species were summed for each month by country.

The number of vessel days on grounds each month by country was

obtained from the "Monthly Summary of Fishing Activity, United

States Northeast Coast," NEREIS Report 008, generated by the

NMFS Northeast Regional Enforcement Information System

(NEREIS).

U.S. foreign fisheries observers provided coverage aboard

vessels from seven countries a total of 1,594 vessel days in 1978

(Table 9). The total number of reported days on grounds by DWF

vessels in 1978 was 8,520 (Table 10). Eight countries were

represented, with fishing activity greatest during NovemberDecember and January-March. With the exception of the U.S.S.R.

"Maurer, R. 1975. A preliminary description of some importanl feeding relalionships. Int. Comm. Northwest All. Fish., Res. Doc. 75/1XIl30, Ser. No. 3681,

15 p. (Mimeogr.)

14Mercer, M. C. 1974. Modified Leslie-DeLury assessments of the northern

pilot whale (Globicephala melaena) and annual production of the short-finned squid

(1I1e illecebrosus) based upon their interaclion at Newfoundland. Int. Comm.

Northwest All. Fish., Res. Doc. 74/49, Ser. No. 3256, 14 p. (Mimeogr.)

9

Table 9.-Number of vessel days fished with U.S. foreign fisheries observer

coverage by country and month in the U.S. Fishery Conservation Zone in the

northwest Atlantic in 1978.

Country

Bul- Mex- RomaMonth garia Cuba Italy Japan ieo nia Spain U.S.S.R. Total

Jan. 57 22 2 65 146

Feb. 21 52 13 39 49 174

Mar. 11 88 100 199

Apr. 4 33 61 98

May 2 17 19

June 37 37

July 30 30 116 176

Aug. 72 24 132 228

Sept. '53 8 26 87

Oct. 22 52 46 120

Nov. 74 29 13 40 156

Dec. 35 51 12 13 35 .154

TOlal 2 262 267 195 13 620 235 1,594

1August and Seplember.

Table 10.-Number of vessel days on grounds by country and month in the U.S.

Fishery Conservation Zone in the northwest Atlantic in 1978.

Country

Bul- Mex- RomaMonth garia Cuba Italy Japan ieo nia Spain U.S.S.R. Total

Jan. 219 186 3 320 136 864

Feb. 154 173 27 428 304 1,086

Mar. 67 40 398 416 921

Apr. 22 95 414 531

May 5 9 20 101 135

June 12 69 127 43 251

July 88 82 411 60 641

Aug. 34 87 123 235 73 552

Sept. 31 17 26 78 62 214

Oct. 107 32 80 163 62 444

Nov. 207 162 I~O 30 468 86 1,073

Dec. 280 469 293 31 584 151 1,808

Total 9 1,032 1,293 885 61 3,327 1,908 8.520

vessels which fished primarily for silver hake, Merluccius bilinearis, vessels from the other countries were involved in directed

fisheries for long-finned, Loligo pealei, and short-finned, lllex iilecebrosus, squid. Periods and areas of open fishing in 1978 are

detailed in Figures 3 and 4. Gear used was primarily pelagic otter

trawls.

Total bycatch of sharks, swordfish, and other large pelagics in

the DWF fishery in 1978 was estimated by expanding the observed bycatch by the appropriate country-month ratios between

vessel days on grounds (Table 10) and vessel days with observer

coverage (Table 9). Twelve species of sharks (Table 11); swordfish; four species of tuna; ocean sunfish, Mala mala; and pilot

whales were observed. The total estimated bycatch included 128 t

of sharks, 71 t of swordfish, and lOt of other large pelagics (Table

12). Carcharhinid sharks (44%), hammerheads (23%), and angel

sharks (19%) accounted for the bulk of the shark bycatch which

was greatest in November (52%), followed by July (21%) and

August (8%). Swordfish bycatch was greatest in December (65%)

The seasonality of the shark bycatch suggests differences in

abundance by season and area. Less than 10% was during

January-June when most fishing activity was in areas 4 and 5 and

to a lesser extent in area 2 (Fig. 3). The catch during this period
Figure 3.-Foreign fishing areas in the U.S. Fishery Conservation Zone, northwest Atlantic, 1971l.

Figure 4.-Foreign rlShing gear restrictions by rlShing area (see Figure 3) in the

U.S. Fishery Conservation Zone, northwest Atlantic, 1978.

SEP OCT NOV DEC

Carcharodon carcharias

Cetorhinus maximus

Isurus oxyrinchus

Lamna nasus

Carcharhinus limbatus

Carcharhinus plumbeus

Carcharhinus obscurus

Ga/eocerdo cuvieri

Prionace g/auca

Sphyrna spp.

Sphyrna Lewini

Squarina dumerili

Thunnus abesus

Thunnus albacares

Sardo sardo

Euthynnus alletteratus

JlA. AUG

PELAGIC GEAR ONLY

BOTTOM GEAR AND PELAGIC GEAR

FEB WoR APR

Table ll.-Common and scientific names of shark and tuna

species observed in catches by the distant-water-fleet in the

U.S. Fishery Conservation Zone, northwest Atlantic, 1971l.

Great white shark

Basking shark

Shortfin mako

Porbeagle

Blacktop shark

Sandbar shark

Dusky shark

Tiger shark

Blue shark

Hammerhead (N.S.)

Scalloped hammerhead

Atlantic angel shark

Rigeye tuna

Yellowfin tuna

Atlantic bonito

Little tunny

AREA

CD Ju"E 13 - SEPTEMBER l~

®JU"E l' JULY l~

® 40-20' ~0-13'

70-30' 70-<>0'

Table 12.-Estimated bycatch (kg) of sharks, swordfish, and other large pelagics by the distant-water-fleet trawl fishery by month in the

U.S. Fishery Conservation Zone in the northwest Atlantic in 1978.

Month

Species Jan. Feb. Mar. Apr. May June July Aug. Sept. Oct. Nov. Dec. Total

Lamnidae 3,446 1.331 990 144 3,059 255 9,225

Great white 138 138

Basking 3,446 1,331 678 2,611 8,066

Shortfit mako 117 117

Porbeagle 312 144 448 904

Carcharhinidae 280 5,019 5,848 1,666 681 41,685 1,338 56,517

Blacktip 35 200 235

Sandbar 14,016 14,016

Dusky 280 3,809 123 12 266 25,859 888 31,237

Tiger 379 379

Blue 1,210 5,725 1,654 415 1,396 250 10,650

Sphyrnidae 18,602 4,055 583 231 3,726 2,454 29,651

Hammerhead (N.S.) 13,978 2,891 466 2,162 2,454 21,951

Scalloped hammerhead 4,624 1,164 117 231 1,564 7,700

Squatinidae

Atlantic angel 69 70 20 20,888 3,875 24,922

Sharks (N.S.) 2,132 679 12 3,777 952 290 II 7,853

Total sharks 3,515 1,401 3,122 823 12 3,339 27,398 10,855 2,539 932 66,565 7,667 128,168

Swordfish 392 5,848 5,932 2,794 3,627 6,152 46,384 71,129

Tuna 655 73 347 243 195 1,107 1,946 4,576

Bigeye 655 91 195 951

Yellowfin 73 256 243 572

Atlantic bonito 8 1,234 1,242

Little tunny 1,099 712 1,811

Ocean sunfish 558 225 783

Pilot whale 4,252 245 4,497

10
was primarily lamnids (mainly basking sharks). Fishing activity

during July-September was almost entirely in area 2. All areas

were fished during October-December, but most of the shark bycatch during that time was in area I. Over 80% of the shark bycatch for the year was from areas I and 2, the southernmost of the

five areas with the warmest water temperatures where the abundance of sharks might be expected to be higher than in the northern, cooler areas. During the months of July, August, and November, which accounted for 81 % of the shark bycatch, the catch rate

of sharks averaged 41.5 kg/vessel day on the grounds. During the

remaining 9 mo, the catch rate averaged only 4.7 kg/d, suggesting

lower abundance during that time and in the areas fished than during the above 3 mo and the areas fished then. Species composition

of the shark bycatch also differed during the year as lamnids were

predominant during January-June (Table 12) while carcharhinids

and hammerheads were predominant during July-December.

These differences in species composition reflected primarily the

different areas fished during those two periods.

Spanish vessels accounted for 57% of the estimated shark bycatch, with Mexican and Japanese vessels contributing 20 and

17%, respectively (Table 13). U.S.S.R., Italian, and Romanian

vessels took the remaining 6%. Japanese vessels took 68% of the

estimated swordfish bycatch.

Assuming that the ratio between shark bycatch and DWF squid

catch as determined in 1978 was also applicable to other years,

estimates of shark bycatch ranged from 1 t in 1965 to 266 t in

1973 and averaged 134 t/yr during 1965-81 (Table 14). If fishing

practices or shark abundance did not change appreciably during

this period, this assumption may be valid. Because the offshore

squid fisheries have been somewhat seasonal (Loligo, winterspring; /llex, summer-autumn) due to the distributional

characteristics of the species, seasonal fishing patterns have not

changed greatly. Although fishing by DWF vessels was restricted

by month and area following extended jurisdiction (Figs. 3, 4),

previous patterns of fishing were not altered significantly. There

have also not been any significant changes in the fishing gear used

by the DWF.

Prior to extended jurisdiction in 1977, distant-water fleets

fishing in what is now the U.S. FCZ caught large quantities of

many species besides squid. The non-U.S. catch of all species in

ICNAF SA 5 and 6 peaked at 1,021,360 t in 1972 (lCNAF Statistical Bulletin 23), of which only 47,500 t was squid. Given the

large amount of fishing effort exerted by the DWF fishery in the

1960's and 1970's, sharks and other large pelagics may have been

inadvertently captured, discarded, and not accounted for in

reported catch statistics. However, evidence from the 1978 DWF

fishery suggests.that sharks and other large pelagics are more likely to be caught during a squid fishery than during fisheries for finfish. Comparisons of the estimated bycatch of sharks and other

large pelagics as well as daily catch rates among countries in 1978

(Table 15) indicate very low values for the U.S.S.R. relative to

other countries. Catch per day of large pelagics was 2.1 kg for

U.S.S.R. vessels and 31.3 kg for vessels from the other five countries combined. The U.S.S.R. fishery was directed primarily

towards silver hake (74% of total catch) and red hake, Urophycis

chuss (11 % of total catch), whereas the other countries fished

mainly for squid.

JAPANESE TUNA LONGLINE BYCATCH

Witzell (1985) reported the bycatch of sharks in the Japanese

tuna longline fishery during 1978-82 in the U.S. FCZ in the

Atlantic Ocean and Gulf of Mexico based on information provided from Japanese fishing logbooks. Bycatch varied from 523 to

2,642 t in the Atlantic FCZ and from 0 to 619 t in the Gulf FCZ

(Table 16).

Table 13.-Estimated bycatch (kg) of sharks, swordfish, and other large pelagics by the distant· Table 14.-Estimated bycatch (t) of

water-neet trawl fishery by country in the U.S. Fishery Conservation Zone in the northwest Atlantic pelagic sharks in the dlstant·water.neet

in 1978. squid trawl fishery in the U.S. Fishery

Conservation Zone in the northwest

Country Atlantic (ICNAF/NAFO SA 5 and 6),

Species Italy Japan Mexico Romania Spain U.S.S.R. Total 1965-81. The 1965-77 and 1979-81 estimates of bycatch were calculated using

Lamnidae 1,331 3,197 4,385 312 9,225 the 1978 squid/shark by-catch ratio.

Great white 138 138

Basking 1,331 2.61 I 4,124 8,066 Squid Estimated shark

Shortfin mako 117 117 Year catch bycatch

Porbeagle 448 144 312 904

Carcharhinidae 1,793 :0,529 13,929 250 30,016 56,517 1965 176 I

Blacktip 235 235 1966 389 2

Sandbar 9,628 4,388 14,016 1967 833 4

Dusky 12 6,903 2,888 21,434 31,237 1968 4,917 24

Tiger 84 295 379 1969 8,463 41

Blue 1,781 3,542 1.118 250 3,959 10,650 1970 18,824 91

Sphyrnidae 75\ 7,631 4,256 14,559 2,454 29,65 ! 1971 21,028 101

Hammerhead (N.S.) 634 6.764 4,025 8,074 2,454 21,951 1972 47,500 229

Scalloped hammerhead 11 7 867 231 6,485 7,700 1973 55,133 266

Squatinidae 1974 53,106 256

Atlantic angel 188 591 4,787 19,356 24,922 1975 49,972 241

Sharks (N.S.) 110 2,143 4,909 691 7,853 1976 46,389 223

Total sharks 2,842 22,225 26,169 250 73,225 3.457 128.168 1977 39,628 191

Swordfish 7,655 48,328 2.012 1.335 11.233 566 71,129 1978 26.576 128

Tuna 1,197 1,767 492 38 1.082 4,57/> 1979 29,172 141

Bigeye 195 756 951 1980 37,279 180

Yellowfin 80 73 419 572 1981 34,304 165

Atlantic bonito 176 938 73 38 17 1.242

Little tunny 746 1,065 1,811

Ocean sunfish 344 439 783

Pilot whale 245 4,252 4,497

11
Table IS.-Comparative statistics by country for the estimated bycatch of

sharks, swordfish, and other large pelagics, vessel days on grounds, catch of

large pelagics per vessel day on grounds,squid catch, and reported catch of all

other species in the U.S. Fishery Conservation Zone in the northwest Atlantic in

1978.

Catch of large Vessel days Pelagic catch Catch of Catch of other

Country pelagics (kg) on grounds (kg) per day squid (t) species (t)

Italy 11,939 1,032 11.6 3,378 1,834

Japan 72,664 1,293 56.2 6,016 1,106

Mexico 28,673 885 32.4 3,822 132

Romania 1,623 61 26.6 76 147

Spain 90,231 3,327 27.1 13,250 662

U.S.S.R. 4,023 1,908 2.1 34 18,255

creased in the 1970's. Estimates for 1960-69 averaged about 500

t/yr in the Atlantic, with the bulk attributed to effort near Puerto

Rico and the Virgin Islands; estimates for 1970-79 averaged

1,113 t/yr. During 1963-69, the estimated bycatch averaged 18

t/yr in the Gulf; estimates for 1970-79 averaged 190 t/yr. The increase in estimated bycatch in the 1970's occurred as a result of

an increase in Japanese effort in the U.S. FCZ. During 1960-69,

about 10% of the total Japanese effort each year in FAO Areas 21

and 31 (Fig. 2) was in U.S. waters, compared with 40% during

1970-77.

OTHER SOURCES OF BYCATCH

'Includes the FCZ around Puerto Rico and the Virgin Islands.

Table I6.-Estimated bycatch (t) of pelagic sharks in the Japanese tuna longline

fIShery in the U.S. Fishery Conservation Zone, Atlantic Ocean and Gulf of Mexico

1960-82. '

ISJ. R. Zuboy and w. N. Witzell, Southeast Fisheries Center, National Marine

Fisheries Service, NOAA, 75 Virginia Beach Drive, Miami, FL 33149, pers. commun. January 1979.

1960 73,352 27

1961 2,806 1

1962 1,873,899 702

1963 2,102,733 788 248,568 25

1964 2,791,978 1,046 410,336 41

1965 2,926,192 1,097 336,791 34

1966 2,546,665 954

1967 440,499 165 103,977 10

1968 300,322 113 101,990 10

1969 244,496 92 41,201 4

1970 1,542,150 578 392,610 40

1971 6,706,653 2,513 1,053,745 106

1972 3,036,248 1,138 949,478 96

1973 3,756,843 1,408 658,876 66

1974 1,929,780 723 700,429 71

1975 1,335,924 501 2,100,629 212

1976 2,732,919 1,024 4,156,365 419

1977 875,427 328 4,390,028 442

1978 3,378,053 1,594 2,190,997 196

1979 2,774,165 1,323 3,540,331 253

1980 3,784,626 1,230 1,828,549 142

1981 7,094,278 2,642 3,769,192 619

1982 2,296,906 523

DISCUSSION

Reported commercial catches of pelagic sharks in the Atlantic

and Gulf FCZ, as well as estimates of recreational catches and by·

catches from several sources, have been presented in this paper. In

order to properly evaluate and interpret these results, it must be

understood that these estimates are generally imprecise and require the broad application of various assumptions. Assumptions

concerning mean weights, extrapolation and interpolation of

catches and catch rates, and the like all represent sources of error.

Particular errors associated with the recreational catch estimates

were mentioned earlier. In addition, all sharks caught as bycatch

in longline fisheries for swordfish and tuna and released are

assumed to be dead or die thereafter. This assumption may not be

valid, but data on the survival of released sharks was not available.

Therefore, the estimates presented must not be treated as accurate

measures of catch, but as approximations. They do, however,

represent the first attempt to identify and quantify the major

sources of shark catch in U.S. waters of the Atlantic and Gulf of

Mexico.

A further limitation of the results is the inability to provide

catch estimates by species. For some components of the overall

catch in particular years and areas, species composition may be

approximately known. Some of this information is available from

other sources (e.g., Casey and Hoey 1985; Gulf of Mexico Fishery

Management Council, see Table 5, footnote 2; Casey unpubl.

data). For example, a high percentage of both the recreational

catch and the bycatch in the swordfish longline fishery in the

northwest Atlantic consists of blue sharks, Prionace glauca. The

Norwegian and Faroese longline fisheries of the 1960's were for

porbeagles. Bycatch in the swordfish longline fishery in the Gulf

of Mexico includes a high proportion of sharks of the genus Carcharhinus.

In spite of the uncertainty of all the various estimates of catch

presented, it is useful to examine totals and trends within each

area (Atlantic FCZ and Gulf FCZ). Because of the incompleteness

of the estimates (particularly the recreational component), total

catches can only be compared during 1965-80 (Table 17).

Additional bycatch of pelagic sharks occurs in fisheries other

than those described above; however, data on which to base such

estimates, at least in the Atlantic, are not available. In the Gulf of

Mexico, there apparently is a significant bycatch of sharks in the

U.S. trawl fisheries for shrimp and groundfish. The total shark bycatch by U.S. shrimp vessels in the Gulf FCZ has been estimated

to exceed 5 million lb (2,270 t) annually, and an additional annual

bycatch of about 250,000 lb (113 t) has been estimated to occur

in the Gulf from the snapper-grouper fishery and other miscellaneous sources (Gulf of Mexico Fishery Management Council see

Table 5, footnote 2).

12

Estimated shark

bycatch

Number of

hooks

Gulf of Mexico

Estimated shark

bycatch

Atlantic'

Number of

hooks

An attempt was made to estimate the shark bycatch from the

Japanese longline fishery in previous years in what is now the

U.S. FCZ: The mean of the 1978-82 catch rates (for the Atlantic

and Gulf separately) reported by Witzell (1985) was applied to the

reported number of hooks fished yearly by the Japanese to obtain

an estimate of shark bycatch during 1960-77. Effort data (number

of hooks fished) reported by 50 Marsden squares for the Japanese

longline fishery in the entire Atlantic Ocean were obtained for

1960-77 (Zuboy and WitzeIl15 ). Effort from those 50 Marsden

squares located within the U.S. FCZ in the Atlantic (including

Puerto Rico and the Virgin Islands) and Gulf was tabulated for

each year (Table 16). Applying the mean 1978-82 catch rate of

37.48 t of sharks per 100,000 hooks fished for the Atlantic FCZ

and 10.07 til 00,000 hooks for the Gulf FCZ resulted in estimated

shark bycatches ranging from 1 t (1961) to 2,513 t (1971) in the

Atlantic and from no bycatch in 1960-62 and 1966 to 442 t in

1977 in the Gulf (Table 16).

Estimated shark bycatch by the Japanese longline fishery in-
Table 17.-Estimated total catch (t) of pelagic sharks in the U.S. Fishery Conservation Zone in the Atlantic Ocean and Gulf of Mexico by fishery and country (U.S. and

others), 1960-81.

Atlantic Gulf of Mexico

Recre- Recre- SwordCommercial ational Swordfish Squid Tuna All fisheries Commercial ational fish Tuna Other All fisheries

Year U.S. Olher U.S. U.S Other Other Other U.S. Other Total U.S. Olher U.s. U.S. Other U.S. U.S. Other Total

1960 78 ., 27 .2 27 .2 3 ., ., 2,383 .2 .2 .2

1961 45 1,196 *' I .2 1,197 02 312 ., ., 2,383 .2 .2 .2

1962 70 1,551 ., 50 54 702 .2 2,307 .2 4 ., ., 2.383 .2 .2 .2

1963 83 4,033 ., 1,099 2,998 788 .2 7,819 .2 2 ., ., 25 2,383 .2 02 .2

1964 82 5,625 ., 1,564 4,524 1,046 .2 11,195 .2 2 ., ., 41 2,383 .2 .2 .2

1965 236 2,958 1,503 1,595 3,115 I 1,097 3,334 7,170 10,504 I 4 1,120 34 2,383 3,504 38 3,542

1966 140 1,452 1,813 700 2,379 2 954 2,653 4,787 7,440 I 2,255 2,383 4,639 4,639

1967 605 86 2,125 502 2,733 4 165 3,232 2,988 6,220 3 I 3,391 10 2,383 5,777 11 5,788

1968 57 349 2,435 298 3.613 24 113 2,790 4,099 6,889 2 I 4,527 10 2,383 6,912 11 6,923

1969 59 216 2,746 165 3,607 41 92 2,970 3,956 6,926 6 I 5,663 2 4 2,383 8,054 5 8,059

1970 55 679 3,056 85 4,136 91 578 3,196 5,484 8,680 5 4 6,798 249 40 2,383 9,435 44 9,479

1971 30 206 3,363 5 101 2,513 3,398 2,820 6,218 8 8 5,931 106 2,383 8,322 114 8,436

1972 49 344 3,669 94 229 1,138 3,812 1,711 5,523 6 137 5,063 96 2,383 7,452 233 7,685

1973 54 16 3,975 498 27 266 1,408 4,527 1,717 6,244 145 435 4,195 21 66 2,383 6,744 501 7,245

1974 70 119 4,281 1,382 256 723 5,733 1,098 6,831 II 624 3,327 145 7 I 2,383 5,866 695 6,561

1975 129 77 5,358 2,586 II 241 501 8,073 830 8,903 20 907 2,460 202 212 2,383 5,065 1,119 6,184

1976 99 31 6,181 4,632 22 223 1,024 10,912 1,300 12,212 52 1,051 2,284 587 419 2,383 5,306 1,470 6,776

1977 128 26 7.004 9,549 31 191 328 16,681 576 17,257 76 28 2,108 II 442 2,383 4,578 470 5,048

1978 146 I 7,827 5,572 128 1,594 13,545 1,723 15,268 97 4 1,932 37 196 2,383 4,449 200 4,649

1979 96 24 8,829 3,961 852 141 1,323 12,886 2,340 15,226 37 6 4,004 275 253 2,383 6,699 259 6,958

1980 306 22 9,830 5,316 222 180 1,230 15,452 1,654 17,106 154 I 6,077 1,445 142 2,383 10,059 143 10,202

1981 327 13 ., 5,177 165 2,642 .2 2,820 .2 251 36 ., 1,415 619 2,383 .2 655 .2

I Not estimated.

21ncomplete data.

'Not available.

Estimated total shark catches in the Atlantic FCZ during

1965-80 averaged about 9,800 t/yr (range = 5,500-17,300 t)

(Table 17). Catches increased sharply in the early 1960's to about

14,300 t in 1964 (assuming a recreational catch of about 1,500 t

as in 1965). This increase was due to the start of the Norwegian

porbeagle fishery in 1961 and the advent of longlining for swordfish by the United States and Canada in 1962. The decrease to

6,200 t in 1967 was due in large part to the virtual collapse of the

porbeagle fishery. Norwegian catch per unit effort (CPUE)

decreased from 9.1 sharks/ I00 hooks in 1961 to 2.9 in 1964

(Myklevoll footnote 5). The catch rate presumably decreased further as the Norwegian catch in the ICNAF area declined from

8,060 t in 1964 to only 270 t in 1968 (Table 3). The Faroese

porbeagle fishery similary experienced a drastic decline in CPUE

after the mid-1960's and also a proportionate decrease in the

average size of fish caught (Hoydap6). The total catch was relatively stable during 1966-75 and ranged only from 5,500 to 8,900

t/yr (average = 7,000 t). The total catch began increasing in the

mid-1970's due to improving recreational catches and bycatches

in the expanding U.S. swordfish fishery, reached a peak of 17,300

t in 1977, and averaged 16,200 t annually during 1977-80.

Shark catches in the Atlantic FCZ during 1965-80 attributed to

U.S. fishing activity exceeded those by other countries in all years

except 1965-66 and 1968-70 (Table 17). U.S. catches ranged between 2,700 (1966) and 16,700 t (1977) and averaged about

3,1.00 t annually during 1965-71 (42% of the total). Catches then

increased until 1977, when they leveled off averaging 14,600 t/yr

(1977 -80) and 90% of the total. The major ;;ource of U.S. catch

was the recreational fishery, followed by the swordfish longline

fishery. The principal source of catch by other countries was the

16K. Hoydal, Fiskiranns6knarstovan, Debessartrlld, 3800 T6rshavn, Faroe Islands,

pers. commun. November 1978.

13

Norwegian porbeagle fishery in the early 1960's, followed by the

Canadian swordfish longline fishery during 1963-70, and the

Japanese tuna longline fishery throughout the entire period.

Estimated shark catches in the Gulf of Mexico FCZ averaged

about 6,800 t yearly during 1965-80 (range = 3,500-10,200 t)

(Table 17). A constant annual bycatch of 2,383 t was assumed

from the U.S. shrimp, groundfish, and snapper-grouper fisheries.

Catches reached an apparent peak in the Gulf in 1970 at about

9,500 t due to increased recreational catches, followed by a

gradual decrease to 4,600 t in 1978. Catches then again increased

sharply to a high of 10,200 t in 1980. U.S. catches during

1965-80 averaged about 6,400 t/yr (about 95% of the total). The

major source of U.S. catch was the recreational fishery. As indicated earlier, the recreational catch estimates for the Gulf in

1965 and particularly in 1970 appear to be excessive relative to

the Atlantic and are inconsistent with commercial catch trends in

the two areas.

It is possible that some of the shark bycatch estimated in this

paper and assumed to be nonreported could have been landed and

included in reported commercial statistics resulting in some double counting. In the case of U.S. fisheries, the reported commercial

catch of sharks has been so small relative to the estimated recreational catch and swordfish bycatch that any double counting

would not significantly alter the total estimate. The estimated

amounts taken by the DWF squid fishery (average of 200 t/yr during 1972-81) would also not affect the final results. The reported

Japanese shark catch does not represent the total amount actually

taken in their tuna longline fishery. The amounts estimated as bycatch in their longline fishery (Table 16) generally exceed their

reported catches in FAO Area 31 (Table 4), especially during

1970-81. Only in several of the years in the 1960's did the estimated Japanese longline bycatch correspond well with the catch

reported to FAO for Area 31. The Japanese shark catches reported
in the ICNAF/NAFO area are not indicated as being taken by

longline gear. Any double counting of Japanese catches will not

significantly affect the total estimated catch.

No attempt was made in this paper to estimate maximum sustainable yield (MSY) based on an analysis of catch and effort data.

Catch data are uncertain, and the inclusion of multiple species in

the catch estimates generates an unknown response of this mixture to fishing mortality. There is a lack of fishing effort data for

sharks. although Otto et al. (1977 17 ) used Japanese longline effort

data to calculate an MSY estimate for sharks in the western North

Atlantic. The Schaefer (1954, 1957) surplus-yield model, which

employs catch and effort data to estimate MSY, assumes, among

other things, 1) an immediate increase in population size (through

recruitment) following a population decrease, and 2) the rate of

population increase is independent of the population's age composition. Neither of these assumptions is valid for sharks (Holden

1974, 1977). Sharks have a very low reproductive potential compared with teleost fishes, a delayed and slower recovery from exploitation, and exhibit a close relationship between stock and

;ecruitment (i.e.. reproductive potential is greatest at virgin

biomass levels and decreases as the population decreases). Shark

populations would be very vulnerable to fishing. dnd, therefore,

due caution and consideration must be exercised in developing a

fishery for sharks.

One approach to estimate long-term potential yield is to examine historical catch levels. As mentioned above, the 1965-80

average level of estimated catch in the U.S. FCZ in the Atlantic

was about 9,800 t, and about 6,800 t in the Gulf FCZ. These esti-

:nates would be first-order approximations of long-term yield,

although the average level for the Gulf is probably too high as a

result of apparent overestimates in recreational catch in some

years.

The 1980 estimates of shark catch in the FCZ were about

17,100 t in the Atlantic and 10,200 t in the Gulf. These estimates

were 7,300 t above the 1965-80 average in the Atlantic and 3,400

t above the 1965-80 average in the Gulf. Sharks in both the Atlantic and the Gulf may be excessively exploited at the present time'if

the 1965-80 average catch levels represent valid estimates of

MSY. However, since catch rates and trends for individual species

are lacking to indicate any changes in abundance, this caP-IIot be

confirmed. The fact that sharks are very vulnerable to fishing has

been demonstrated in various situations such as the Norwegian

(Myklevoll footnote 5) and Faroese (Hoydal footnote 16)

porbeagle fisheries in the northwest Atlantic. the California soup..

fin shark fishery (Ripley 1946), the Scottish-Norwegian spiny

dogfish fishery (Holden 1968), and the Australian school shark

fishery (Olsen 1959). The increasing trend in estimated catches in

the Atlantic FCZ since the early 1970's and in the Gulf FCZ since

the late 1970's reflects increased fishing pressure, which, if continued, may result in a decline in the overall abundance of pelagic

sharks. Further attempts to evaluate the general abundance of

sharks will require information on catch rates or other indices of

abundance over a period of years.

170tto, R. 5., 1. R. Zuboy, and G. T. Sakagawa. 1977. Slatus of Northwest

Atlantic billfish and shark stocks. Report of the La Jolla Working Group, March

28-April 8,1977. (Mimeogr.)

LITERATURE CITED

....ASEN, O.

1963. Length and growth of the porbeagle (Lamna nasus, Bonnaterre) in the

Nonh West Atlantic. Rep. Norw. Fish. Marit. Invest. 13(6):20-37.

14

BERKELEY, S. A., and E. D. HOUDE

1Q81. Population parameter estimates and catch-effon statistics in the

broadbill swordfish (Xiphtas gladiuJj fishery of the Florida Staits. ICES

C.M. 1981/H:35

BIGELOW, H B., and W. C. SCHROEDER.

1953. Fishes of the Gulf of Maine. U.S. Fish Wildl. Serv., Fish. Bull. 53, 577 p.

CADDY, j F.

1976. A review of some factors relevant to management ofswordfish fishenes

in the Northwest Atlantic. Can. Fish. Mar. Serv., Tech. Rep. 633, 36 p.

C....SEY, J. G., and J. M. HOENIG.

1Q77. Apex predators in Deepwater Dumpsite 106. NOAA Dumpsite Evalua·

tion Report 77-1, Baseline Repon of Environmental Conditions 10 Deepwater Dumpsite 106. Vol. II. Biological characteristics, p. 309-376.

CASEY, J. G., and J. 1. HOEY.

1985. Estimated catches of large sharks by U.S. recreational fishermen in the

Atlantic and Gulf of Mexico. U.S. Dep. Commer., NOAA Tech. Rep.

NMFS 31, p. 15-19.

CASEY, J. G., F. J. MATHER III, J. M. MASON, Jr., and J. HOENIG.

1978. Offshore fisheries of the Middle Atlantic Bight. In H. Clepper (editor),

Marine Recreational Fisheries 3, Proc. Third Annu. Mar. Rec. Fish. Symp..

p. 107-129. Sport Fish. Inst., Wash., DC.

CLARK, J. R.

1962. The 1960 salt-water angling survey. U.S. Fish Wildl. Serv., Circ. 153,36 P

DEUEL, D. G.

1973. 1970 salt-water angling survey. U.S. Dep. Commer., NOAA, Natl.

Mar. Fish. Serv., Curro Fish. Stat. 6200, 54 p.

DEUEL, D. G., and J. R. CLARK.

1968. The 1965 salt-water angling survey. U.S. Fish Wildl. Serv., Resour.

Publ. 67, 51 p.

DRAGOVICH, A.

1969. Review of studies of tuna food in the Atlantic Ocean. U.S. Fish

Wildl. Serv., Spec. Sci. Rep.-Fish. 593,21 p.

HAMM, D. C., and B. M. SLATER.

1979. Survey of the recreational. billfish and shark fisheries May 1. 1977 to

April 30, 1978. NOAA Tech. Memo. NMFS-SEFC-5, 168 p.

HOLDEN, M. 1.

1968. The rational exploitation of the ScottiSh-Norwegian stock of spurdogs,

Squalus canchias I.. Fish. Invest., Lond., Ser 2, 25(8), 27 p.

1974. Problems in the rational exploitation of elasmobranch populations and

some suggested solutions. In F. R. Harden Jones (editor), Sea fisheries

research, p. 117-137. Elek (Sci. Books), Lond.

1977. Elasmobranchs. In J. A. Gulland (editor), Fish population dynamics,

p.187-215. John Wiley & Sons, N.Y.

OLSEN, A. M.

1959. The status of the school shark fishery in south-eastern Australian

waters. Aust. J. Mar. Freshwater Res. 10:150-176.

RIPLEY, W E.

1946. The soupfin shark and the fishery. In The biology of the soupfin

Galeorhinu.'i l.yopterus and biochemical studies of the liver, p. 7-37. Calif.

Dep. Fish Game. Pish Bull. 64.

SCHAEFFER, M. B.

1954. Some aspects of t.he dynamics ot populations imponant to the management of commercial marine tisheries. lnter-Am. Trop. Tuna Camm., Bull.

1:25-56.

1957. A study of the dynamics of the fishery for yellowfin tuna in the eastern

t.ropical Pacific Ocean. [In Engl. and Span.] Inter-Am. Trop. Tuna Comm.,

Bull. 2'245-285.

SCOTT, W. B.. and S. N. TlBBO.

1968. Food and feeding habits of swordfish, Xiphias gladius, in the western

Nonh Atlantic. J. Fish. Res. Board Can. 25:903-919.

STEVENS. J. D.

1973 Stomach contents of the blue shark (Prionuce glauca 1..) off south-west

England. J. Mar. BIOI. Assoc. UK 53:357-361.

TIBBETTS, A. M.

1977. Squid fisherie~ (Loligo pealei and l//er i/lecebrosus) off the northeastern

coast of the United States of America, 1963-74. Int. Comm. Northw. Atl.

Fish., Sel Pap. 2:85- 109.

U.S. DEPARTMENT OF COMMERCE.

1980. Marine recreatIOnal fishery statistics survey, Atlantic and Gulf Coasts,

1979. U.S. Dep. Commer., NOAA, Natl. Mar. Fish. Serv., Curr. Fish.

Stat. 8063, 139 p.

WITZELL, W. N

1985. The incidental capture of sharks in the Atlantic United States Fishery

Conservation Zone bv the Japanese tuna longline fleet. U.S. Dep. Commer ,

NOAA Tech. Rep. NMFS 31, p. 21-22.
Estimated Catches of Large Sharks by U.S.

Recreational Fishermen in the Atlantic

and Gulf of Mexicol

JOHN G. CASEY and JOHN J. HOEy2

INTRODUCTION

Table i.-List of common and scientific names used in this

report,

'Preliminary Fishery Management Plan for Atlantic Billfishes and Sharks, Federal

Register 43(19):3818-3835, Jan. 27,1978.

'David Crestin, Chief, International and Oceanic Fisheries Branch, National

Marine Fisheries Service, NOAA, State Fish Pier, Gloucester, MA 01930, pers.

commun. Dec. 1982.

1964 annual catches increased from 1,800 to 9,300 t then declined sharply to about 200 t (Casey et al. 1978). Growth to maturity

in the porbeagle shark takes about 6 to 9 yr (Aasen 1961) and normally four young are produced. The slow growth rate and low

reproductive potential, characteristic of many elasmobranchs,

may explain the above decline in porbeagle catches, The susceptibility of other shark species to intensive fishing is discussed by

Holden (1973, 1974, 1977) and Ripley (1946).

The probability of increased fishing mortality on sharks has

given rise to concern among recreational fishermen and some

members of fishery management councils. The Preliminary

Management Plan (PMP) for sharks now in place for the U.S, FCZ

in the Atlantic allows for a total allocation of 1,150 t of sharks for

foreign fisheries 3 Only the Faroe Islanders have requested and

received an allocation of sharks under the PMP. Since 1978 they

have had an allocation of 500 t of porbeagle sharks with a 100 t

bycatch allocation of finfish. They have never completely utilized

their allocation, catching only 5 t in 1980 and approximately 100

t in 1982.4 In 1983 and 1984 the Faroe Islanders did not fish in

the U.S. FCZ.

Several species of large Atlantic sharks are an important

resource to the U.S. recreational fishery (Table 1). Sharks have

been fished commercially in the past (Springer 1952) and, despite

their present low value, the stocks are considered potentially valuable to U.S. commercial interests. World landings of elasmobranch fishes (sharks, skates, rays) in 1981 were 600,607 t

(metric tons), or about one-fourth of the world's combined landings of tuna, swordfish, and billfishes (Thompson 1983). In the

face of increasing world demand for food and byproducts from the

sea, an increase in the harvest of sharks in the U.S. Fishery

Conservation Zone is assured.

In the Atlantic, new fisheries for sharks are likely to develop

along several lines as the demand for recreational opportunities,

and the value of flesh, fins, or byproducts increases. Judging from

the recent growth of the recreational fishery for sharks off the U.S.

northeast coast and the continuing interest of fishermen in sharks

as "big game fish," recreational fishing for large sharks will continue to increase along the entire Atlantic coast. Currently a high

percentage of the sharks caught by recreational fishermen are

released or discarded with the remainder being mounted for

trophies or brought home for food. Some species, such as the

shortfin mako, are highly prized for home consumption and often

sold to processors to defray the costs of offshore fishing trips.

Should the commercial value of sharks increase, some of the

vessels now regarded as sport boats would move into commercial

operations and thereby increase fishing mortality on the more

common or desirable species including blue and mako sharks. In

addition, existing United States and Canadian longline fisheries

for swordfish, and foreign longline fisheries for tunas, could be

quite easily directed to sharks. Longline catch data for swordfish

and tuna from United States and foreign vessels indicate that the

bycatches of sharks can often exceed (sometimes doubling or tripling) the catches of the target species (Casey and Hoenig 1977).

Considering that these fisheries attempt to avoid sharks, it follows

that the longline catch of sharks could be increased dramatically

(if temporarily) with little or no additional investment. Intensive

commercial fisheries for sharks are likely to reduce the abundance

of some species in only a few years. In 1960 a longline fishery for

porbeagle sharks, Lamna nasus, was established in the western

North Atlantic (primarily by the Norwegians). From 1961 to

'MARMAP Contribution MED/NEFC 82-71.

'Northeast Fisheries Center Narragansett Laboratory, National Marine Fisheries

Service, NOAA, Narragansett, Rl 02882. Present address of John Hoey: Southeast

Fisheries Center, National Marine Fisheries Service, NOAA, Miami, FL 33149.

15

Blue shark

Bull shark

Dusky shark

Lemon shark

Nurse shark

Oceanic whitetip shark

Porbeagle

Sandbar (brown) shark

Shortfin mako

Silky shark

Tiger shark

White shark

BJacktip shark

Hammerhead shark

Bigeye thresher

Swordfish

Prionace glauco

Carcharhinus leucas

Carcharhinus obscurus

Negaprion brevirostris

Ginglymostoma cirratum

Carcharhinus longimanus

Lamna nasus

Carcharhinus plumbeus

Isurus Dxyrinchus

Carcharh/nus falcifoml/s

Galeocerdo cuvier;

Carcharodon carcharias

Carcharh/nus sp.

Sphyma sp.

A/opias superciliosus

X/ph/as glad/us
The purpose of this report is to provide estimates of the total

number and weight of the large sharks caught by recreational

fishermen along the Atlantic coast of the United States, including

the Gulf of Mexico. The estimates were calculated by applying

weight and species composition data on sharks to results of a 1978

marine recreational fishing survey by Hamm and Slater (1979).

Previous surveys of marine recreational fishing which included

sharks were conducted in 1960, 1965, 1970, and 1974-75. These

earlier surveys were based on broad sampling of the general

fishing public in order to estimate the total marine recreational

catch. The sampling design focused on catches of smaller abundant gamefish species (flounders, mackerel, bluefish, etc.).

Reports of large tuna, swordfish, and sharks were considered rare

events in the sampling scheme. 5 In addition, these surveys did not

distinguish between the different species of large sharks and were

inconsistent by listing dogfishes (Squalus sp. and Mustelus sp.)

separately in some years, and including them under "all sharks" in

others (Table 2). The Hamm and Slater (1979) survey differed in

that it was designed to estimate only the catch of billfish and large

sharks and was based on sampling from registrations of large offshore sport boats (18-65 ft). Because the survey estimated the

catches from a specific component of the shark fishery, and

because it provided information on species composition, we considered the results to be the best available data for calculating the

total weight of large sharks caught by recreational fishermen

along the U.S. east coast including the Gulf of Mexico.

In a second estimate, we calculated the weight of sharks caught

in each region separately (Table 4a, b, c). As in the preceeding

calculations, we applied average weight for each species to the

dominant species reported in each region. The weight values for

the regional catch were estimated by utilizing the described proportional relationship between the dominant species with assigned weights and the total catch. By summing the regional weight

estimates, a second estimate of the total weight for all regions was

obtained.

RESULTS

Average fork lengths (cm) and weights (Ib) for eight species of

Atlantic sharks are presented in Table 3. These values were calculated from sharks examined at sport fishing tournaments in New

Jersey and New York, and on research cruises in the FCZ primarily between Cape Hatteras, NC, and Georges Bank.

Species composition data from the Hamm and Slater (1979)

survey are presented in Table 5 together with information from

the NMFS Cooperative Shark Tagging Program and longline

records representing 41,353 sharks of 32 species. Based on these

sources of species composition data the sharks listed in Table 5

include the most common species taken by recreational

fishermen.

Hamm and Slater (1979) reported the following numbers of

sharks caught within the U.S. FCZ in the Atlantic and Gulf of

Mexico:

MATERIALS AND METHODS

DISCUSSION

The calculated total weights of sharks caught in each region are:

The calculated weight of sharks caught in all regions combined

is 10,277 t (22,656,576 Ib) (Table 4). This estimate is very close

to the first estimate of 10,255 t (22,607,639 Ib) obtained by expanding the species composition information from each area.

Estimates of the U.S. recreational catch of sharks from several

national surveys show wide variation in the numbers and average

weights for the different years (Table 2). For all areas combined,

the average weights from the national surveys ranged from 13.8 to

98.5 lb with much lower values in the early years compared with

the most recent survey (Hamm and Slater 1979). The lower

average weights for the 1960 and 1974-75 surveys may, in part,

be due to including dogfish and sharks as a single category in those

years. However, that would not explain why the average weights

for the 1965 and 1970 surveys also appear low when dogfish were

recorded separately. Rather than speculate on the sources of variation among the early national surveys where detailed information

is lacking, we considered it more useful to base our analysis on the

1978 survey (Hamm and Slater 1979). Results of that survey provided data on the numbers of sharks caught that could be com124,226

59,788

46,405

230,419

5,502 t (12,129,450 Ib)

2,780 t (6,127,885Ib)

1,973 t (4,350,3041b)

10,255 t (22,607,6391b)

Atlantic-North of Virginia

Atlantic-South of Virginia

Gulf of Mexico

Total

Atlantic-North of Virginia

Atlantic-South of Virginia

Gulf of Mexico

Total catch

'David G. Deuel, Fishery Biologist, Office of Data and (nfonnation Management,

National Marine Fisheries Service, NOAA, 3300 Whitehaven Street, NW.,

Washington, DC 20235, pers. commun. June 1982.

No. of dominant shark species. Tot. wt. of dominant shark species

No. of all sharks caught . Tot. wt. of all sharks caught

The Hamm and Slater (1979) survey provided species composition information and estimated numbers of large sharks caught by

sportsmen for five regions in the western North Atlantic. For our

analysis we used three regions by combining the Hamm and Slater

data from North Carolina to Florida; Florida East Coast and Keys;

Puerto Rico and U.S. Virgin Islands; and "Other Waters" into a

single region which we designated Atlantic-South of Virginia. The

other two regions were Atlantic-North of Virginia and Gulf of

Mexico. Estimates of the total weight of the recreational catch of

large sharks in each region were calculated by applying average

weight data from biological sampling of tournament and research

vessel shark catches (Apex Predator Task/NMFS/NEFC/Narr. RI),

(Table 3), to the species composition information from the Hamm

and Slater survey. Two methods were used and compared to obtain weight estimates. The first estimate was obtained by expanding the species composition information using all areas combined.

The average weight data in Table 3 were multiplied by the

number of each species reported for all regions (Table 4d). Data

for southern sharks were limited because most of the biological

sampling occurred north of Cape Hatteras, NC, so it was not

possible to assign an average weight to every species reported. The

estimate of the total weight of sharks caught was calculated by

establishing a proportion which related the number and total

weight of dominant shark species to the number and total weight

of all sharks:

16
Table 2.-Number and weight (in thousands) ofsharks caught by U.S. recreational fishermen in the northwest Atlantic from national surveys of marine recreational fishing (1960-78).

'D. G. Deuel (see text footnote 5).

6Hamm and Slater (1979).

'Value for all regions combined (Table 40).

1.176 1.293

17.2 34.0

68 38

13,823 1,167

100.9 17.1

137 68

North Atlantic Mid Atlantic South Atlantic Total Atlantic

Tol. WI. Ib Average Tol. Wt. Ib Average Tol. WI. Ib Average Tol. WI. Ib Average

Data N weight N weight N weight N weight

SourceI (1,000) (lb) (1,000) (lb) (1,000) (lb) (1,000) (lb)

1960' 21,880 3,426 10,900 36,206

40.0 15.0 100.0 40.9

547 228 109 884

1965' 2,187 1,127 3,314

8.5 Not reported 28.1 11.2

256 40 296

1970' 4,795 1,276 669 6,740

I 1.4 13.8 33.4 12.7

419 92 20 531

1974-75' 6,374 Inc. in No. Atl. 7,463 13,837

7.0 23.3 11.2

908 321 1,229

1978' 12,129 6,128 18,257

978 102.1 99.2

124 60 184

'Values reported in the 1960 and 1974-75 surveys include dogfish, the 1965, 1970, and 1978 surveys exclude dogfish.

'Clark (1962).

'Deuel and Clark (1968).

'Deuel (1973).

::i

Table 3.-Average fork lengths (em) and weights ((b) of Atlantic sharks.'

East Gulf

Tol. WI. Ib Average

N weight

(1,000) (lb)

West Gulf

Tol. WI. Ib Average

N weight

(1,000) (lb)

Total Atlantic and Gulf combined

Total Gulf Total

TOI. WI. Ib Average Total weight Average

N weight number (lb) weight

(1,000) (Ib) (1,000) (1.000) (lb)

16,600 52,806

25.0 34.1

664 1.548

2,469 5,783

23.2 14.3

106 402

14,990 21,730

73.1 29.5

205 736

7,981 21,818

22.2 13.8

359 1,588

4,350 '22,657

94.6 '98.5

46 230

Males Females Sex. unknown All data combined

Species X Length X Weight X Length X Weight XLength X Weight X Length X Weight

Shortfin mako 172 133 172 144 241 376 175 151

No. of individuals 325 312 253 247 25 31 603 590

White shark 156 92 158 III 256 556 159 114

No. of individuals 47 36 42 30 2 2 91 68

Tiger shark 181 181 182 187 1,430 182 '184

No. of indi viduals 19 16 28 19 I 47 36

Scalloped hammerhead 160 129 152 92 30 151 110

No. of indi vi duals 26 22 33 22 2 61 44

Dusky shark 123 63 161 156 145 116

No. of individuals 63 63 81 81 144 144

Sandbar shark 114 42 130 69 124 '58

No. of individuals 539 540 844 847 1.383 1,387

Blue shark 183 94 160 72 172 85

No. of individuals 1,499 1,093 1,264 796 2,763 1,889

Bigeye thresher 183 203 190 224 184 209

No. of individuals 10 10 4 4 14 14

'Source: NMFS Narragansett Laboratory. Data primarily from Bayshore (NY) Shark Tournament; other tournaments north of Cape Halleras; and

longline catch data from research cruises.

'Average weight of tiger sharks excluding large individual of unknown sex.

'Average weight based primarily on sample from Mid-Atlantic Bight. Xfor Florida and Gulf of Mexico expected to be higher but data lacking.
Table 4.-Estimated total weight of sharks caught by recreational fishermen in

the Atlantic north of Virginia, Atlantic south of Virginia, Gulf of Mexico, and all

areas combined.

Weight of

Number of Average dominant

Area dominant weight species

Species composition I species Ob) (Ib)

A) Atlantic north of Virginia

Blue 60.3% 74,908 85 6,367,180

Mako 10.7% 13,292 151 2,007,092

Dusk y2 8.6% 10,683 116 1,239.228

Hammerhead 2.7% 3,354 110 368,940 --- Total 82.3% 102.237 9,982,440

Other 21,989

Total weight all species' 12.129,450 (5,502 t)

B) Atlantic south of Virginia

Hammerhead 28.6% 17,099 IIG 1,880.890

Blacktip4 11.6% 6.935 455 381,425

Bull' 5.4% 3,229 '103 332,587

Blue 5.3% 3,169 85 269,365

Dusky2 4.4% 2,631 116 305,196

Mako 4.2% 2,511 151 379,161

Tiger 2.0% 1,196 184 220,064

Total 61.5% 36,770 3,768,688

Other 23,018

Total weight all species' 6,127,885 (2,780 t)

C) Gulf of Mexico

Blackti p4 27.6% 12,808 455 704,440

Hammerhead 22.6% 10,487 110 1,153,570

Bull' 7.0% 3,248 '103 334,544

Tiger 4.9% 2.274 184 420,690

Dusk y2 3.4% 1,578 116 183,048

Mako 2.0% 928 151 140,128

Total 67.5% 31,323 2,936,420

Other 15,082

Total weight all species' 4,350,304 (1,973 t)

D) All Areas

Blue 42.7% 98,389 85 8.363.065

Hammerhead 10.2% 23.503 110 2,585,330

Mako 7.8% 17,973 150 2,695,950

Blacktip4 6.9% 15,899 455 874,445

Dusky2 6.8% 15,668 116 1,817.488

White6 2.3% 5,300 114 6604,200

Bull' 2.1% 4,839 '103 498,417

Tiger 2.1% 4,839 184 890.376 --

Total 80.9% 186,410 18,329,271

Other 44.009

Total weight all species' 22,656,576 (10,277 t)

'From Hamm and Slater (1979).

2Includes sandbar sharks and other carcharhinid species.

'Calculated from:

No. of dominant shark species Tot. wt. of dominant shark species

No. of all sharks caught Tot. wt. of all sharks caught

4Blacktip average length = 129 em based on 73 specimens (Dodrill 1977). We

assume that the blacktip and sandbar have a similar length-weight relationship

which is 55 Ib for a 129 em blacktip.

'Bull shark average length = 160 em based on 14 specimens (Dodrill 1977). We

assume that the dusky and bull have a similar length-weight relationship which is

103 Ib for a 160 em bull shark.

6This estimate appears high based on our knowledge of this species. This appears

to be an example of a "glamorous" species being overestimated.

18

pared and integrated with the weight data on sharks we measured

at tournaments and on research vessels. In addition, the 1978

results were more in line with our observations of the recreational

fishery for large sharks during the past 15 yr in terms of the

species composition, sizes of vessels participating, and average

daily catch rates. Nevertheless, the 1978 survey introduced

sources of bias that should be noted. The survey was designed

primarily to evaluate the sport catch of billfishes and was limited

to offshore fishing from larger sport boats. Consequently, the incidental recreational catch of sharks from shore and small boats

was not included.6 Inshore landings, particularly of juvenile and

smaller sharks, are not reported and are considerable in some

areas.

Offshore fishermen tend to use heavier gear which selects for

larger sharks. Consequently, the average weight of sharks in the

1978 survey (and our data base) is higher than if all segments of

the recreational fishery were represented. Another possible source

of error arises from the fact that many fishermen tend to report

only more distinctive species of sharks (e.g., hammerhead, tiger,

mako, etc.). In addition, the most desirable species are more likely

remembered and their relative abundance overestimated. Finally,

many sharks are released in the recreational fishery. Although this

is a source of mortality, some survive and are caught more than

once. From tagging studies of 45,000 sharks, the overall recapture

rate is 3.2% (J. G. Casey, unpubl. data). The release of large

numbers of sharks would produce higher than actual estimates of

the population. Despite these shortcomings, the 1978 survey

presents the best available estimate of the current recreational

catch of large sharks in terms of the numbers caught and the

species composition of the catch.

By applying our average weight data from over 5,000 sharks of

eight species and distribution information from 45,000 tagged

sharks, we estimate the recreational catch of large sharks from the

Atlantic in 1978 was 10,277 t (22.6 million Ib). This estimate is

based primarily on sharks caught offshore from sport fishing boats

and does not include dogfishes, sharks caught from shore, or small

sharks caught incidentally to other gamefish species. Consequently, we believe the estimated catch of 22.6 million lb is conservative. Moreover, fishing effort for sharks has continued to increase in recent years and likely will continue to do so particularly

along the southeast coast and in the Gulf of Mexico.

ACKNOWLEDGMENTS

We thank Mark Holiday for providing catch data and Kenneth

Sherman for helpful comments on the manuscript. Nancy Kohler

and Patricia Hadfield provided valuable editorial assistance.

6The most recent estimates of the total number of sharks (excluding dogfishes)

caught by recreational fishermen in the Atlantic arc 3.0 million in 1980; 1.9 million

in 1981; and 1.4 million in 1982. (Mark Holiday, Fishery Biologist, Statistical

Branch, National Marine Fisheries Service, NOAA. 3300 Whitehaven Street NW.,

Washington, DC 20235.)
Table S.-Species composition of sharks from selected rod and reel and longline fisheries in the western North Atlantic.

Atlantic north of Virginia Atlantic south of Virginia Gulf of Mexico Total - All areas combined

Tagged Longline Tagged Longline 'Tagged 'Longline Tagged Longtine

'1979 sharks data '1979 sharks data 11979 sharks data 1979 sharks data

Survey 1962-82 1,753 sets Survey 1962-82 310 sets Survey 1962-82 278 sets Survey 1962-82 2.341 sets

Species % % % % % % % % % % % %

Blue 60.3 63.2 68.0 5.3 6.5 16.3 1.6 0.9 2.1 42.7 54.2 50.1

Hammerhead 2.7 2.0 5.8 28.6 15.3 22.6 22.6 11.6 7.3 10.2 4.0 7.3

Mako 10.7 2.4 5.6 4.2 0.7 1.8 2.1 7.5 1.8 7.8 2.4 4.5

Blacktip. 0.1 0.1 0.3 11.6 16.0 5.2 27.6 13.0 24.9 6.9 2.7 6.0

Dusky 8.6 6.7 3.0 4.4 '7.5 6.8 3.4 8.0 0.5 6.8 6.8 2.7

Sandbar 1.0 13.1 3.5 0.8 12.3 9.6 1.2 5.3 0.7 0.9 12.2 3.4

White 3.7 0.1 0.0 0.1 0.1 1.0 2.3 0.1

Bull <0.1 0.1 5.4 1.9 7.0 4.3 2.1 0.5

Tiger 1.5 0.7 0.4 2.0 4.8 3.5 4.9 6.1 1.3 2.1 1.4 0.8

Lemon 0.2 0.02 6.0 4.2 1.3 2.4 1.3 0.6

Nurse <0.1 0.05 4.1 3.3 2.0 .5 1.0 0.5

Sand 2.0 18.2 20.3 7.7

Brown 7.4 4.0 1.3 5.5

Other 1.8 '11.6 13.4 5.4 "27.4 34.2 4.6 '39.4 61.4 2.7 '14.6 25.2

1Hamm and Slater (1979).

'Survey data for Atlantic south of Virginia combined the following Hamm and Slater (1979) areas: North Carolina to Florida, Florida East Coast and Keys,

Puerto Rico and U.S. Virgin Islands, and Other Water.

'Casey (unpub I. data) includes tagged sharks caught primarily on rod and reel and long/ine gear.

'Hoey and Casey (1981) includes 10ngline data from commercial and research cruise logbooks.

'Silky, sharpnose, blacknose, whitetip, finetooth, thresher, night, bignose, and sand sharks account for 18.5% of the Other category.

"Silky, sharpnose, blacknose, whitetip, finelOoth, thresher, night, bignose, and reef sharks account for 80.3% of the Other category.

'Silky, sharpnose, blacknose, whitetip, finetooth, and thresher sharks account for 83.1 % of the Other category.

'Silky, sharpnose, blacknose, whitetip, finetooth, thresher, night, bignose, and reef sharks account for 37% of the Other category.

LITERATURE CITED

AASEN, O.

1961. Some observations on the biology of the porbeagle shark (Lamna nasus

L.) ICES North Sea Comm. C.M. 1961!No. 109.

CASEY, J. G., and J. M. HOENIG.

1977. Apex predators in deepwater dumpsite 106. NOAA Dumpsite Evaluation Report 77 -I, Baseline Report of Environmental Conditions in Deepwater Dumpsite 106. Vo!. II. Biological characteristics, p. 309-376.

CASEY, J. G., F. J. MATHER Ill, J. M. MASON, Jr., and J. HOENIG.

1978. Offshore fisheries of the Middle Atlantic Bight. In H. Clepper (editor),

Marine Recreational Fisheries 3, Proc. Third Annu. Mar. Rec. Fish. Symp.,

p. 107-129. Sport Fish. Inst., Wash., DC.

CLARK, J. R.

1962. The 1960 salt-water angling surveys. U.S. Fish Wildl. Serv., Circ.

153,36 p.

DEUEL, D. G.

1973. The 1970 salt-water angling survey. U.S. Dep. Commer., NOAA,

Natl. Mar. Fish. Serv., Curr. Fish. Stat. 6200, 54 p.

DEUEL, D. G., and J. R. CLARK.

1968. The 1965 salt-water angling survey. U.S. Fish Wildl. Serv., Resour.

Pub!. 67, 51 p.

DODRILL, J. W.

1977. A hook and line survey of the sharks found within five hundred meters

of shore along Melbourne Beach, Brevard County, Florida. M.S. Thesis,

Florida Institute of Technology, Melbourne, 304 p.

19

HAMM, D. c., and B. M. SLATER.

1979. Survey of the recreational billfish and shark fisheries May I, 1977 to

April 30, 1978. NOAA Tech. Memo. NMFS-SEFC-5, 168 p.

HOEY, J., and J. G. CASEY.

1981. Species composition and catch rales from selected longline fisheries in

the western North Atlantic. ICES C.M. 1981/H:62.

HOLDEN, M. J.

1973. Are long-term sustainable fisheries for elasmobranchs possible?

Rapp. P.-v. Reun. Cons. int. Explor. Mer 164:360-367.

1974. Problems in the rational exploitation of elasmobranch populations and

some suggested solutions. In F. R. Harden Jones (editor), Sea fisheries

research, p. 117-137. Elek (Sci. Books), Lond.

1977. Elasmobranchs. In J. A. Gulland (editor), Fish population dynamics,

p. 187-215. John Wiley & Sons, N.Y.

RIPLEY, W. E.

1946. The soupfin shark and the fishery. In The biology of the soupfin

Galeorhinus zyopterus and biochemical studies of the liver, p. 7-37. Calif.

Dep. Fish Game, Fish Bull. 64.

SPRINGER, S.

1952. The effect of fluctuations in the availability of sharks on a shark

fishery. Proc. Gulf Caribb. Fish. Inst. 4:140-145.

THOMPSON, B. G.

1983. Fisheries of the United States, 1982. U.S. Dep. Commer., NOAA,

Natl. Mar. Fish. Serv., Curro Fish. Stat. 8300, 117 p.
20
The Incidental Capture of Sharks in the Atlantic

United States Fishery Conservation Zone

Reported by the Japanese Tuna Longline Fleet

W. N. WITZELU

ABSTRACT

An analysis of pelagic sharks captured incidentally by the Japanese tuna longline fleet was performed for the

years 1978 through 1982. The overall CPUE and percentage ofsharks reportedly killed in the Gulf of Mexico and

the Atlantic varied considerably, 0.1335 (14.7%) and 0.5988 (7.2%), respectively. These differences are probably

due to the fact that the fishery is dynamic, and changes in gear and methods frequently occur, depending on the

geographic location and the target species.

INTRODUCTION

The U.S. offshore fisheries are managed inside a 200 nmi

Fishery Conservation Zone (FCZ) as promulgated by the Fishery

Conservation and Management Act (FCMA) of 1976. All foreign

vessels wanting to fish within the FCZ must obtain a permit,

maintain accurate fishing records showing amount and location of

catch and effort, release all nontarget species (dead or alive), and

allow U.S. observers on board vessels. The incidental capture of

large pelagic fishes, particularly sharks, by commercial fishing

fleets in U.S. waters has been inadequately addressed. Several

commercial fisheries incidentally capture pelagic sharks in the

U.S. waters, but published accounts are limited (Lopez et al.

1979). The quantification of the incidental capture rate of sharks

by each fishery is necessary when formulating conservation and

management strategies as mandated by the FCMA. This paper

analyzes the incidental capture of sharks by the Japanese tuna

longline fleet inside the U.S. Atlantic FCZ for the years 1978

through 1982.

The Japanese tuna longline fishery is fished from vessels

ranging in length from 50 to 70 m. A mainline, 100 to 135 km

long, is suspended horizontally from the surface by a series of

floats. Suspended vertically from the mainline are a series of

branch lines, 15 to 25 m long, each line terminating with a hook

baited with mackerel, saury, or squid. The longline is set between

0000 and 0800 from a moving vessel and hauled back from 1200

to 0000. The fishery is dynamic, and changes in gear and methods

frequently occur, depending on the geographic location and the

target species. The Japanese tuna longline fishery in the U.S. Gulf

of Mexico has been described in detail by Lopez et al. (1979).

MATERIALS AND METHODS

Three available computerized data sources are pertinent to the

longline fishery: I) the U.S. observer file, used here to describe the

fishery; 2) the actual numbers of incidentally caught fish and effort reported quarterly by the Japanese fishing logbooks; and 3)

the average weights of sharks captured by the National Marine

Fisheries Service exploratory longline surveys. These three data

'Southeast Fisheries Center, National Marine Fisheries Service, NOAA, 75

Virginia Beach Drive. Miami, FL 33149.

21

bases are maintained by the National Marine Fisheries Service,

Southeast Fisheries Center (SEFC), Miami, FL. The fishing

materials and methods used by the Japanese longline fleet are

described by Lopez et al. (1979), and by Bullis (1955) and Captiva (1955) for the SEFC exploratory longline surveys. The

observed incidental catch by the Japanese longline fleet and the

exploratory incidental catch data were collected opportunistically

during tuna and swordfish surveys, and it is felt that comprehensive statistical analyses of these data are inappropriate.

For the purpose of this report, the U.S. Atlantic Ocean FCZ is

divided into two subareas: Atlantic (off the eastern U.S. coast) and

Gulf of Mexico. The catch-per-unit-effort (CPUE) is the number

of sharks caught per 100 hooks fished.

RESULTS AND DISCUSSION

The overall CPUE of sharks in the Gulf of Mexico and Atlantic

varies considerably, 0.1335 and 0.5988, respectively (Table I).

This is probably due to the large numbers of blue sharks, Prionace

glauca, normally found in the Cape Hatteras area (Casey 1976),

where the Japanese longliners have concentrated their fishing effort for tuna over the years. There is no readily discernable

seasonal pattern of shark CPUE in either the Gulf or the Atlantic

and annual variations of shark CPUE are also difficult to interpret

(Table 2). The variations of CPUE-geographical, seasonal, and

annual-possibly reflect the dynamic nature of the fishery. The

vessel. captains change fishing strategies temporally, spatially, or

both, as each situation demands in order to maintain high catch

levels of target fish and to reduce shark catch. Longline fisheries

targeting sharks have a higher CPUE. For instance, the CPUE for

blue shark longlining between Cape Hatteras and Cape Cod, MA,

was 6.3 (Casey 1976), and Bullis (1976) reported maximum

CPUE's ranging from 4.1 to 12.2 in the U.S. southeast Atlantic

area.

The incidentally captured sharks are combined into a single

species group because the observers were often unable to accurately identify sharks in the water from a moving vessel.

However, the mean weights of sharks captured during exploratory

surveys in the South Atlantic area (62.4 kg) and Gulf of Mexico

(80.4 kg) are broken down by species in Table 3. The mean

weight of the Atlantic sharks is considered high for this analysis
Table I.-Monthly reported catch rates ofsharks captured inciden·

tally by the Japanese tuna longline neet in the FCZ, 1978-82.

Table 2.-Annual reported catch rates of sharks captured incidentally by the

Japanese Tuna 10ngHne neet in the FCZ, 1978-82.

Month

Number of

sharks

Number of

hooks

CPUE

(Sharks/l 00 hooks) Year

Number of

sharks

Total weight

(t)·

Number of

hooks

CPUE

(SharksilOO hooks)

-------------------------------Gulf of Mexico------------------------------- --------------------------------------Gulf of Mexico--------------------------------------

--------------------------------------Atlantic Ocean--------------------------------------

--------------------------------------Gulf of Mexico--------------------------------------

Table 3.-Numbers and weights of pelagic sharks caught on National Marine

Fisheries Service, Southeast Fisheries Center exploratory longline cruises.'

1978 25,238 1,594.5 3,378,053 0.747\

1979 20,941 1,323.1 2,774,165 0.7548

1980 19,475 1,230.4 3,784,626 0.5145

1981 41,813 2,641.8 7,094,278 0.5893

1982 8,276 522.9 2,296,906 0.3603

Total 115,743 7,312.7 19,328,028 0.5988

0.1312

0.1098

0.0877

0.0954

0.2018

Mean weight of

sharks (kg)

Total weight

sharks (kg)

2,190,997

3,540,33\

1,828,549

3.769,\92

11,329,069

Number

sharks

195.8

252.6

141.9

619.1

1,209.4

2,407

3,105

1,745

7,609

14.866

1978

1979

1980

1981

1982

Total

January 1,791 379,801 0.4715

February 2,976 2,207,578 0.1348

March 4,858 4,253,327 0.1142

April 3,623 3,296,313 0.1099

May 622 463,953 0.1340

June 651 320,702 0.2029

July 343 204,945 0.1673

August 2 2,450 0.0816

Total 14,866 11,129.069 0.1335

------------------ ---··--------Atlantic Ocean--------------- ----------------

January 5.639 1,149,769 0.4Q04

February 2,144 411,453 0.5210

March 627 47,475 1.3206

April 399 119,080 0.3350

May 1,463 106,550 1.3730

June 1,079 123,736 0.8720

July 11.664 1,983,987 0.5879

August 13,769 2,738,897 0.5027

September 19,187 3,634,198 0.5279

October 25,542 2,902,652 0.8799

November 21,483 3,400,952 0.6316

December 12,747 2,709,279 0.4704

Total 115,743 19,328,028 0.5988

because the exploratory surveys were primarily conducted south

of Cape Hatteras, NC, and therefore do not include the smaller

blue shark which is most frequently captured in the northern

Atlantic by the Japanese fleet. The mean weights of sharks caught

during exploratory surveys are used to calculate total shark

weights. The total weights of the sharks (Table 2) caught in the

Gulf of Mexico, 1,209.4 t, and Atlantic, 7,312.7 t, reflect the differences in CPUE and total fishing effort between these two areas.

However, the percentage of sharks killed, reported by U.S.

observers on Japanese tuna vessels in the Gulf and Atlantic. is

low, 14.7 and 7.2%, respectively.

Carcharhinus longimanus 372 35,220.6 94.6

Carcharhinus falciform is 314 21,883.5 69.6

Carcharhinus obscurus 72 9,774.0 135.7

Sphyrna spp. 116 3,946.9 34.0

Other' 74 5,399.1 72.9

Total 948 76,224.1

Mean 80.4

--- - - ---- --- 00 - - - - - __ - - - - - - - - - - 00- - - - - Atlantic Ocean-------------------------- _

Carcharhinus longimanus 146 8,087.8 55.3

Carcharhinus fatciformis 249 12,802.5 51.4

Carcharhinus obscurus 73 6,594.7 90.3

Sphyrna spp. 61 3,091.5 50.6

Other' 76 7,196.4 94.6

Total 605 37,772.9

Mean 62.4

I Data from NMFS, SEFC Pascagoula Laboratory longline files.

2[ncludes Isurus spp., Alopias spp., Galeocerdo cuvieri, and Carcharhinus limba/lls.

Jlncludes !surus spp., Alopias spp., Galeocerdo cuvieri, and Prionance glauca.

LITERATURE CITED

BULLIS, H. R., Jr.

1955. Preliminary report on exploratory long-line fishing for tuna in the Gulf

of Mexico and the Caribbean Sea. Commer. Fish. Rev. 17(10): 1-15.

1976. Observations on the pelagic sharks off the southeastern United States.

In W. Seaman, Jr. (editor), Sharks and man-a perspective, p. 14. Fla. Sea

Grant Rep. 10.

CAPTIVA, F. J.

1955. Long-line gear used in yellowfin tuna exploration. Commer. Fish.

Rev. 17(10):16-20.

CASEY, J. G.

1976. Migrations and abundance of sharks along the Atlantic coast. In W.

Seaman, Jr. (editor), Sharks and man-a perspective, p. 13 ·14 Fl•. Soa

Grant Rep. 10.

LOPEZ, A. M., D. B. McCLELLAN, A. R. BERTOLINO, and M. D. LANGE.

1979. The Japanese longline fishery in the Gulf of Mexico, 1978. Mar.

Fish. Rev. 41 (10):23-28.

22