NOAA Technical Report NMFS 11 7

Distribution, Abundance, and

Biological Characteristics of

Groundfish off the Coast of

Washington, Oregon, and

California, 1977-1986

Thomas A. Dark

Mark E. Wilkins

u.s. Department of Commerce

May 1994
U.S. Departnlent

of Conunerce

Ronald H. Brown

Secretary

National Oceanic and

Atmospheric Adnrlnistration

D. James Baker

Under Secretary for Oceans and

Atmosphere

National Marine

Fisheries Service

Rolland A. Schmitten

Assistant Administrator for

Fisheries

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NOAA Technical Report NMFS 117

A Technical Report of the Fishery Bulletin

Distribution, Abundance, and

Biological Characteristics of

Groundfish off the Coast of

Washington, Oregon, and

California, 1977-1986

Thomas A. Dark

Mark E. Wilkins

May 1994

u.s. Department of Commerce

Seattle, Washington

Distribution, Abundance, and Biological Characteristics of

Groundfish off the Coast of Washington, Oregon, and California,

1977-1986

THOMAS A. DARK. and MARK. E. WILKINS

Resource Assessment & Conservation Engineering Division

Alaska Fisheries Science Center, NOAA/NMFS

7600 Sand Point Way NE

Seattle, WA 98115-0070

ABSTRACT

We compare results of bottom trawl surveys off Washington, Oregon, and California in

1977, 1980, 1983, and 1986 to discern trends in population abundance, distribution, and

biology. Catch per unit of effort, area-swept biomass estimates, and age and length compositions for 12 commercially important west coast groundfishes are presented to illustrate

trends over the lO-year period. We discuss the precision, accuracy, and statistical significance of observed trends in abundance estimates. The influence of water temperature on

the distribution of groundfishes is also briefly examined. Abundance estimates of canary

rockfish, Sebastes pinniger, and yellowtail rockfish, S. Jlavidus, declined during the study

period; greater declines were observed in Pacific ocean perch, S. alutus, lingcod, Ophiodon

elongatus, and arrowtooth flounder, Atheresthes stomias. Biomass estimates of Pacific hake,

Merluccius productus, and English, rex, and Dover soles (Pleuronectes vetulus, Errex zachirus,

and Microstomus pacificus) increased, while bocaccio, S. paucispinis, and chilipepper, S.

goodei, were stable. Sablefish, Anoplopoma fimbria, biomass estimates increased markedly

from 1977 to 1980 and declined moderately thereafter. Precision was lowest for rockfishes,

lingcod, and sablefish; it was highest for flatfishes because they were uniformly distributed.

The accuracy of survey estimates could be gauged only for yellowtail and canary rockfish

and sablefish. All fishery-based analyses produced much larger estimates of abundance than

bottom trawl surveys-indicative of the true catchability ofsurvey trawls. Population trends

from all analyses compared well except in canary rockfish, the species that presents the

greatest challenge to obtaining reasonable precision and one that casts doubts on the

usefulness of bottom trawl surveys for estimating its abundance.

Introduction

The National Marine Fisheries Service (NMFS), NOAA,

has conducted groundfish surveys in the northeastern

Pacific Ocean for over 30 years. The earliest exploratory efforts, conducted under the agency's former title

of the Bureau of Commercial Fisheries, aimed at providing information on little used or unknown resources.

Fishing gear development was also an important objective during many early surveys. When foreign fishing

fleets began to harvest substantial quantities of groundfish off the Pacific coast during the late 1960's, we

designed and implemented surveys to determine the

status of the primary target species, Pacific hake,

Merluccius productus, and to monitor changes in population characteristics. In 1976, NMFS increased the scope

of the Pacific hake surveys and made a commitment to

build a comprehensive groundfish database from intensive and extensive bottom trawl and hydroacoustic

surveys to monitor long-term changes in groundfish

distribution, abundance, and biological features. Scientists incorporate survey results with analyses of commercial fishery data to develop periodic stock assessments

and provide these assessments to the Pacific Fishery

Management Council (PFMC) as advice for its annual

management recommendations.

Major triennial surveys of west coast groundfish resources were conducted by NMFS in 1977, 1980, 1983,

and 1986. Detailed information on the latter three

surveys was published in a series of data reports

(Weinberg et aI., 1984; Coleman, 1986 and 1988).

Gunderson and Lenarz (1980) discussed studies based

on data from the 1977 survey. Dark et ai. (1983) compared the results of the 1977 and 1980 surveys for

selected rockfish species. Further comparisons were

delayed until sufficient data allowed examination of
2 NOAA Technical Report NMFS 117

longer term population trends. Although the four years

of information now available allow for comparisons,

results of additional surveys will add measurably to the

understanding ofthe variability common to groundfish

communities. A better grasp ofthis variability is particularly important now that the west coast groundfish industry is capable of easily meeting or exceeding annual

optimum yields. The development of new fisheries, the

addition ofsignificant new fishing effort, and the evolution of harvesting technology have created major management challenges for the PFMC and have increased

the demand for resource information.

This report compiles and compares the results of

groundfish surveys conducted in 1977, 1980,1983, and

1986 and examines population trends during this period. Specific objectives of the study were to 1) determine trends in distribution and abundance of major

groundfish species, 2) characterize estimates of length

composition and age composition of populations of key

species, 3) evaluate recruitment and year class strength,

and 4) examine changes in sea temperature and possible effects on groundfish distribution.

Methods _

The survey objectives and design in 1977 were somewhat different from those of the 1980, 1983, and 1986

surveys, but not so different as to preclude meaningful

comparisons. The 1977 bottom trawl and hydroacoustic

survey was conducted from Port Hueneme, Calif. (lat.

34°00'N), to Cape Flattery, Wash. (lat. 48°30'N), to obtain information on the distribution, abundance, and

biological characteristics of a variety of important rockfishes, Sebastes spp., inhabiting the 91-457 m (50-250

fm) zone (Gunderson and Sample, 1980). Subsequent

surveys were aimed primarily at determining the distribution, abundance, and biological features of Pacific

hake and two rockfishes: yellowtail rockfish, Sebastes

Jlavidus, and canary rockfish, S. pinniger (Dark et a1.,

1983; Weinberg et a1., 1984; Coleman, 1986 and 1988).

The 1980 and 1983 surveys were conducted between

Monterey Bay, Calif. (Jat. 36°48'N), and central

Vancouver Island, British Columbia (lat. 49°15'N), between depths of 55 and 366 m (30-200 fm). The 1986

survey covered much of the same area, except that no

sampling was conducted north of the U.S.-Canada border. Only that portion of the survey area common to all

four years (Fig. 1) was considered in our analyses and

comparisons. All surveys were conducted from July to

October, when Pacific hake and rockfish movements are

thought to be minimal. Therefore, the probability of

censusing fish schools more than once as the vessels passed

through the survey area was minimized.

The sampling design was shaped mainly by the need

for multispecies assessments and our desire to estimate

abundance with the greatest possible precISIon. We

allocated bottom trawl samples over the survey area in

proportion to the abundance of commercial landings

of Pacific hake and key rockfishes. Because sample

variability is correlated with the mean catch per unit of

effort (CPUE), more samples were assigned in areas of

anticipated high abundance to reduce variance. In 1977,

1980, and 1983, the survey area was subdivided into

different sampling strata using historical commercial

catch data for Pacific hake (Edwards et a1., 1981) and

several valuable rockfish species. We allocated samples

along transects drawn approximately perpendicular to

the 55 m (30 fm; 91 m or 50 fm in 1977) isobath.

Varying the distance between transects allowed us to raise

or lower the intended sampling density for a stratum.

The 1977 survey area comprised 14 latitudinal sampling strata for rockfish, each of which was sampled at

either "low" (transects every 18.5 km) or "high" (transects every 9.3 km) densities. Because abundance of

target species was known to vary over the depths surveyed, the survey area was also stratified into four 91-m

depth zones (91-183 m, 184-274 m, 275-366 m, and

367-457 m), which also influenced the location of bottom trawl stations on a given transect. The number of

trawl stations on a transect within a depth stratum was

proportional to the length ofthe transect segment within

the stratum. Stations were then placed randomly along

transects with the proviso that no two stations could

occur within 3.7 km (2 nmi) of one another.

We modified the experimental design of1977 for the

1980 survey to better accommodate the changes in

study objectives. The southern boundary of the survey

area was moved northward from Port Hueneme to

Monterey Bay to describe an area that included most of

the adult Pacific hake, canary rockfish, and yellowtail

rockfish populations. The bathymetric boundaries were

changed to 55-366 m to better reflect the depth distribution ofthe target species. The area was also restratified

using commercial catch data to define important canary and yellowtail rockfish areas. This resulted in three

levels of sampling density and three depth strata (91-

183 m, 184-219 m, and 220-366 m). We established a

minimum sampling intensity of one trawl haul per 130

km2 because past survey experience had shown that this

level of sampling effort produced reasonably precise

Pacific hake biomass estimates in areas of moderate

abundance. This "low" sampling density was achieved

by spacing transects 22.2 km apart. Sampling intensity

was doubled to create "medium" density strata (transects

11.1 km apart) where high Pacific hake abundance was

expected (lat. 42°00'-45°OO'N). Sampling was doubled

again to create "high" density strata (transects 5.6 km

apart) in the rockfish areas (lat. 42°50'-44°18'N and

46"10'-4T20'N) because of the high variability associated with rockfish catches.
Sampling

Densltle8

Dark and Wilkins: Groundfish off Washington, Oregon, and California 3

4800

4600

4400

Cape Blanco

4200

4000

3800

130W 127 124 121

Figure I

Survey boundaries and relative sampling densities established for the 1977,

1980, 1983, and 1986 National Marine Fisheries Service bottom trawl surveys.
4 NOAA Technical Report NMFS 117

The 1983 survey design was identical to the 1980

design, except for the addition of stations in a small

area off northern Washington. These stations were

added to improve estimates ofshelfrockfish abundance

in an area of growing commercial importance.

In 1986 we restratified the survey area again and

allocated sampling effort differently to improve further

the precision of canary and yellowtail rockfish abundance estimates. Stratification of the survey area was

based on previous survey results and commercial CPUE

data1 for these two rockfish species. Optimum stratification was selected from among three possible schemes

suggested by the geographic distribution ofCPUE. Variation in CPUE was expressed in a linear model using

year, area, and depth as components of variation to

determine the scheme that best isolated areas of disparate rockfish densities. The criteria for selection of an

optimum stratification were minimization of

within-stratum variation in CPUE for canary and yellowtail rockfish and maximization of between-strata variation. The analysis resulted in six geographic strata (Fig.

1) and four depth intervals (55-91 m, 92-183 m, 184-

219 m, and 220-366 m), instead ofthe eight geographic

strata and three depths used in 1980 and 1983.

We considered various allocation schemes for distributing samples among strata. Monte Carlo simulations

using canary and yellowtail rockfish CPUE data from

previous surveys were used to estimate the probability

of detecting different magnitudes of changes in abundance of the two species. The results of these efforts

indicated that an allocation proportional to the product ofstratum size and the standard deviation ofCPUE

for the stratum ("approximate Neyman allocation"),

which simultaneously minimized the variances of both

canary and yellowtail rockfish abundance estimates,

would perform best. The resulting allocation scheme,

tempered by the condition that all strata contain at

least three samples, was adopted for the 1986 survey.

The stations allocated to each stratum were systematically placed along east-west transects spaced 3.7 km

apart. Beginning at the shallow end of the southernmost transect, stations were placed at equal intervals

along the cumulative length of the transects in that

stratum. This resulted in different sampling densities

for each stratum that were strictly proportional to the

station allocation. More detailed descriptions of the

triennial survey sampling designs were presented by

Gunderson and Sample (1980), Dark et al. (1983),

Weinberg et al. (1984), and Coleman (1988).

I Tagart, J. V., Washington Department of Fisheries, Natural

Resources Building, Olympia, WA 98504. Personal commun.,

May 1986. Golden, J. T., Oregon Department of Fish and

Wildlife, Hatfield Marine Science Center, Newport, OR 97365.

Personal commun., May 1986.

Bottom trawl vessels ranged in size from the chartered vessel Commando (19.8 m) to the NOAA ship

David Starr Jordan (52.1 m). Four trawlers were employed in 1977, and two in each of the later surveys. We

did not have the opportunity to conduct comparative

fishing power studies, so we took special efforts to ensure that trawl gear and trawling procedures were standardized to minimize differences in fishing power

among vessels. Additionally, in 1980, 1983, and 1986,

the two vessels sampled alternate transects throughout

the survey area so that differences in fishing power

would not affect inter-areal comparisons ofresults. There

were minor differences in trawl door weights and tail

chain lengths to accommodate specific vessel configurations, but all vessels used Noreastern trawls that were

otherwise rigged identically (Gunderson and Sample,

1980). These trawls were constructed with 8.9-cm (3.5-in)

nylon mesh in the intermediate and codend; codends

were also lined with 3.2-cm (l.25-in) mesh to retain

juvenile groundfish. An exception occurred in 1986

when one vessel fished alternately with two Noreastern

trawls, one constructed of nylon and the other of polyethylene materials. Polyethylene construction was employed because it was reputed to be more durable and

was expected to result in less time lost to gear damage.

The trawls were otherwise identical except that the

wings of the polyethylene trawl were slightly modified

to reduce snagging. The relative fishing efficiency of

the two trawls is presently being evaluated in more

detail. The area swept by the two trawls differed by

about 8%, therefore all catches by polyethylene trawls

were standardized to nylon trawl catches prior to distribution and abundance calculations (Coleman, 1988).

In situ measurements indicated that the nylon trawl

had an average wing-tip to wing-tip distance of 13.4 m

(remeasured at 12.8 m in 1986) and a footrope to

headrope distance of 8.8 m (7.2 m in 1986). Scope

ratios used by all vessels were similar and towing speeds

were held as close as possible to 1.5 m/second.

If rough seabeds prevented trawling at a designated

site, all alternative station site was selected nearby. If no

suitable alternative sites were found, the station was

considered to be untrawlable and the vessel proceeded

to the next station. Vessels trawled for 30 minutes at

each station. Catches were sorted and weighed by species, and subsampled for a variety of biological data. We

measured fork length of fish in random samples of

target species. Procedures used for representative sampling of catches were described in detail by Gunderson

and Sample (1980).

Sea surface temperatures were collected at most stations with bucket thermometers. The bottom temperature data used in this study were, in most cases, collected with expendable bathythermographs (XBT's), but

the expanded collection of bottom temperature infor-
Dark and Wilkins: Groundfish off Washington, Oregon, and California 5

mation in 1986 was possible through the use of a temperature sensor mounted on the headrope ofthe trawl.

The headrope sensor was calibrated with independent

XBT observations and proved to be accurate. In 1977, a

minimum temperature recording headrope thermometer was used during most hauls. The data collected

from the headrope thermometers exhibited so much

variation that meaningful trends in distribution were

obscured. Because of this imprecision and the absence

of measurements north of lat. 44°N, we excluded the

1977 bottom temperature data from the analysis.

Relative population densities of target species based

on survey CPUE data are presented in charts by year,

depth zone, and OS latitudinal blocks. The chart for

each species was constructed by calculating the mean

CPUE in each latitude/depth block in each year. The

mean CPUE values for 1977 were then ranked in descending order, and the top 10% of the nonzero values

were assigned to represent the highest density category.

The next highest 30% of the values represent the moderate density category, and the remaining 60% represent the lowest density category. Blocks without catch

or samples are also indicated. These CPUE categories

were used for all subsequent years; therefore, all density values are relative to 1977.

Biomass estimates for each depth and geographic

stratum were derived using the following standard

area-swept equation:

B·. =-'A.(- CPUE x-IJ , t'

a; q

where B; = estimated biomass in the zth area/depth

stratum, A. = total area in the zth stratum, a· = area swept , --- , during a standard trawl haul, CPUE; = mean CPUE

(kg/km) in the zth area or depth stratum, and q = the

catchability coefficient of the sampling trawl (assumed

q = 1). The variance about biomass estimates was estimated by

var(B) = I(~; rvar(CPUE;)

where

var(CPUE) = 1 L (CPUE.. - CPUE)2 . , n; (n; -1) 'l t

Ninety percent confidence intervals were calculated

using

B ± t(.90,n,) ~var(B)

where ne = effective degrees of freedom.

Although trawl catches tend to be non-normally distributed, in most cases our sample sizes were sufficiently large that we could reasonably assume that our

estimator, CPUE;, behaved according to the Central

Limit Theorem (Fisher, 1921) and was, for practical purposes, normally distributed. Therefore, the assumption of

normality underlying the use of the variance and confidence interval formulae above was considered satisfied.

The length composition of a population within a

stratum was estimated by weighting sample length frequencies from each haul by the CPUE of that haul,

summing the weighted length frequencies over all hauls

in a stratum, and then applying that weighted stratum

length frequency to the estimated population numbers

in the stratum. Stratum length compositions were converted to estimated stratum age compositions by using

age-length keys constructed for each International North

Pacific Fisheries Commission (INPFC) area (Fig. 2).

Our use of distinct age-length keys minimized any bias

that might be introduced by different age-length relationships among INPFC areas.

Several data limitations affected the analysis of the

survey data. Because research objectives in 1977 differed somewhat from those established in subsequent

years, some data from the four surveys were not exactly

comparable. As previously mentioned, bottom trawl

sampling in 1977 occurred between 91 and 457 m (50

and 250 fm), whereas in later surveys sampling was

conducted between 55 and 366 m (30 and 200 fm).

Therefore, we excluded samples collected deeper than

366 min 1977 from these analyses. Samples collected at

55-91 m in 1980, 1983, and 1986 could have been

excluded to achieve consistency, but we included them

rather than sacrifice a large amount of information.

Extrapolation of 1977 abundance estimates to the 55-

91 m (30-50 fm) interval based on proportions found

in that interval in 1980-86 was unacceptable because

that would have required assumptions that probably

are not valid. Alternatively, results of the four surveys

were compared with the caveat that 1977 absolute abundance estimates are conservative relative to those from

later years for species that occur mainly in the shallower

portions of the survey area (e.g. Pacific hake; English

sole, Pleuronectes vetulus; lingcod, Ophiodon elongatus; canary rockfish; and yellowtail rockfish). The 55-91 m

zone represents 34, 32, 26, and 15% of the area between 55 and 366 m in the Monterey, Eureka, Columbia, and U.S. portion ofthe Vancouver (U.S.-Vancouver)

INPFC areas, respectively. As noted previously, depth

strata employed in the designs of the four surveys differed as research objectives changed. Depth strata were

combined to allow the best interannual comparability

of results for this analysis. Two common depth zones

(55-183 m and 184-366 m) were ultimately used for

abundance analysis of all species except shelf (canary
6 NOAA Technical Report NMFS 117

and yellowtail) rockfish. Three common depth zones (55-

183 m, 184-219 m, and 220-366 m) were used for these

two species. Because of the different depth stratification

in 1977, common depth zones for that survey year were

91-183 m, 184-274 m, and 275-366 m for shelf rockfish

and 91-183 m and 184-366 m for all other species.

We present biomass estimates to provide insight on

the relative magnitude of various groundfish populations, but a caution is warranted. A catchability coefficient of unity (i.e. all fish in the trawl path are caught)

was assumed in the estimation of biomass. Actual

catchability coefficients are unknown, but they are certain to vary within and among species. Biomass estiVancouver

(US portion)

Columbia

Eureka

Monterey

mates generated from bottom trawl surveys also reflect

an assumption that the trawl is capable ofsampling the

entire habitat of the target species. The Noreastern

trawl rigged with rollers was selected as our standard

sampling gear in 1977 because it could be fished over a

wide range of seabed types and was considered at that

time to be an effective rockfish trawl. We have elected

to continue using this trawl, even though trawls that

appear to be more efficient at catching rockfish are

now available. This decision was made to preserve data

comparability and because the Noreastern trawl as

equipped has suited the multispecies aspects of the

survey. However, the trawl is a compromise and is prob50 OON

l

(

45 00

Cape Blanco

Cape Mendocino

40 00

135 OOW 129 00 123 00 117 00

Figure 2

Distribution of successful bottom trawl hauls during 1977, 1980, 1983, and 1986 National Marine Fisheries

Service surveys.
Dark and Wilkins: Groundfish off Washington, Oregon, and California 7

ably inefficient for some species. For instance, Demory

et al.2 reported that a few comparisons between a trawl

rigged with discs and another rigged with rollers on the

footrope indicated that the roller-equipped trawl was

only 25% as efficient in capturing Dover sole, Microstomus

pacificus. Also, some rockfishes and sablefish, Anaplopoma

fimbria, range into midwater areas and are not completely available even to this relatively high opening

bottom trawl. Herding by trawl components located

outside the wing tips of the net (e.g. bridles, doors, and

warps; Carrothers, 1981; Main and Sangster, 1983) will

tend to compensate for the effects of unavailability and

escapement. Lacking information on herding in species

of concern and assuming that escapement and unavailability can be significant, we view our biomass estimates as

conservatively biased. Biomass estimates probably bestserve

as indicators of changes in relative abundance and are

used in this study to examine trends in population size.

Finally, procedural changes could account for some

of the interannual variability in age compositions observed during the study period. Age determination methods at the Alaska Fisheries Science Center (AFSC) have

evolved slowly since 1977 as new techniques have been

studied and accepted. During 1977-80, groundfish species treated in this report were aged using otolith surfaces. Otoliths were only sectioned or broken and

burned to meet special requests or to resolve specific

questions about ages derived from surface readings.

Since 1983, greater and more systematic use of the

break-and-burn technique has been employed, because

surface ageing methods were shown to underestimate

the age of older fish (Beamish, 1979 a and b; Chilton

and Beamish, 1982). All Pacific ocean perch, Sebastes

alutus, ages are now determined from broken-andburned otoliths. All other species are aged using whole

(surface) or broken-and-burned otoliths. The specific

method applied is left to the discretion of the otolith

reader, although most otolithsfrom olderspecimens were

subjected to both techniques. Within- and between-reader

variability is continuously monitored and maintained at

the lowest possible levels. The extent ofage-determination

bias will be discussed species by species.

Results _

Samples Collected

Survey areas encompassed 28,529 km2 (8,318 nmi2) in

1977 and 39,463 km2 (11,506 nmi2) in each ofthe other

2 Demory, R. L.,J. T. Golden, and E. K. Pikitch. 1984. Status of

Dover sole (Microstomus pacificus) in INPFC Columbia and

Vancouver areas in 1984. In Pacific Fisheries Management Council, Status of the Pacific coast groundfish fishery and recommendations for management in 1985, Appendix 11, 33 p. Pacific Fisheries Management Council, Metro Center, Suite 420,

2000 S.W. First Avenue, Portland, OR 97201.

years. The 1977 survey area was smaller because a narrower depth interval was sampled. The 1980 and 1986

survey areas were slightly smaller than planned because

adverse weather precluded sampling between lat. 42°00'

and 42°50'N in 1980 and between lat. 42°07' and 42°50'N

in 1986. A total of 485 to 515 bottom trawl hauls were

successfully completed each year in the four INPFC

statistical areas combined (Table 1, Fig. 2). INPFC areas (Fig. 2) are commonly used by the PFMC in the

management of groundfish resources. Sampling was

emphasized in the Monterey area in 1977 to estimate

bocaccio, Sebastes paucispinis, and chilipepper, S. goodei,

abundance. The shift of additional sampling effort to

more northern areas in 1980, 1983, and 1986 reflected

our desire to more precisely estimate canary and yellowtail rockfish abundance in that region.

Length data were collected for 12 species (Table 2)

and age data for nine species (Table 3). Length and age

data were collected on a priority basis and therefore

more data are available for key species. Only a portion

of the age structures collected have been processed to

obtain ages. For example, age determinations were only

available for Pacific hake and canary rockfish in 1983

and for Pacific hake only in 1986 because of the lack of

reader expertise in ageing some species and because of

incomplete validation of ageing methods for others.

Groundfish Distribution, Abundance, and

Biological Parameters

General Distribution and Abundance - The importance of each INPFC area in terms of the relative abundance of groundfish present during the survey periods

was examined by using mean CPUE as an index of

density (Table 4). On average, density of all groundfish

species combined was greatest in the U.S.-Vancouver

area (lat. 4T30'N to U.S.-Canada border) followed by

the Monterey, Eureka, and Columbia areas (Table 4).

Mean CPUE in the U.S.-Vancouver area was 1.9 times

greater than that ofthe Columbia area. Average groundfish density in the Monterey area, nearly as great as that

in the U.S.-Vancouver area, was 1.7 times greater than

that observed in the Columbia area. Overall, density in

the shallow depth zone (55-183 m) was slightly greater

than in the deep zone (184-366 m), and the density in

1977 was greater than in later survey years. The considerable interannual and bathymetric variability in CPUE

among areas was due mainly to the distribution of Pacific hake, a large and dynamic component of the west

coast groundfish complex.

An examination of the catch rates of predominant

species by INPFC area (Table 5) revealed latitudinal

patterns of distribution that have persisted through the

years. Spiny dogfish, Squalus acanthias, Pacific hake,
8 NOAA Technical Report NMFS 117

Table 1

Numbers of successful bottom trawl hauls and areas surveyed in groundfish surveys off Washington, Oregon, and

California during 1977, 1980, 1983, and 1986.

International North Pacific Fisheries Commission area ------

U.S.-Vancouver Columbia Eureka Monterey Total ---._---

Depth zone Area surveyed Area surveyed Area surveyed Area surveyed Area surveyed

(m) (km2) Hauls (km2 ) Hauls (km2) Hauls (km2) Hauls (km2 ) Hauls ------

1977 91-183 2,840 32 10,536 106 2,408 19 5,134 82 20,915 239

184-366 1,187 38 3,996 122 1,080 36 1,554 128 7,820 324

Total 4,027 70 14,532 228 3,488 55 6,688 210 28,735 563

1980 55-183 3,537 17 15,642 288 2,717 24 8,543 56 30,436 385

184-366 1,200 9 4,018 62 1,076 9 1,626 20 7,923 100

Total 4,737 26 19,660 350 3,793 33 10,169 76 38,359 485

1983 55-183 3,537 46 15,642 237 4,089 40 8,543 55 31,811 378

184-366 1,200 24 4,052 73 1,076 20 1,626 20 7,954 137

Total 4,737 70 19,694 310 5.165 60 10,169 75 39,765 515

1986 55-183 3,546 171 15,665 187 4,089 27 8,437 60 31,739 445

184-366 1,125 18 3,542 28 1,076 4 1,615 12 7,360 62

Total 4,671 189 19,207 215 5,165 31 10,053 72 39,100 507

and Pacific ocean perch were consistently important

species in the U.S.-Vancouver area. Pacific hake and

Pacific ocean perch continued to dominate in the Columbia area, but sablefish and Dover sole began to

assume a higher rank in the species composition. Although Pacific ocean perch was prominent in the Columbia area in 1977 and 1980, its importance fell noticeably in later years. Canary and yellowtail rockfish

were relatively abundant in the two northern areas, but

their CPUE declined noticeably in the Eureka and

Monterey areas, where they were not among the important components. In the Eureka area, Pacific hake

ranked high, reflecting its coastwide dominance. Dover

sole became relatively more important there. Splitnose

rockfish, Sebastes diploproa, and stripetail rockfish, S.

saxicola, emerged as important components in the Eu·

reka area. Finally, stripetail rockfish became a major

component of the groundfish community in the

Monterey area, as did splitnose rockfish, chilipepper,

and bocaccio.

In the survey area as a whole, Pacific hake was the

dominant species in all years. Spiny dogfish CPUE also

ranked high each year, but annual variability in CPUE

was evident among other species. Sablefish was among

the four most abundant species in 1980, 1983, and 1986

but ranked 13th in 1977. Shortbelly rockfish, S. jordani,

was prominent in 1977 and 1986 but was not among the

species composing 80% of the total groundfish CPUE

in 1980 and 1983. Likewise, splitnose rockfish was relatively abundant in 1977, 1980, and 1986 but was not

among the most abundant species in 1983.

Trends in Species of Major Commercial Importance

Pacific hake - Pacific hake is the largest single

groundfish resource found off Washington, Oregon,

and California. Biomass estimates have usually been in

excess of one million metric tons (t) (Stauffer, 1985).

The species first became the subject offoreign fisheries

in the mid-1960's, and since 1978 it has supported a

substantialjoint venture fishery. Domestic fisheries have

existed since the early 1960's but, except for the first

2-3 years of operation, have only accounted for a small

portion of the total catch. Total catches from 1980 to

1987 have ranged from 73,151 to 160,448 t, and only

recently have approached optimum yield levels of

175.000 to 195,000 t (PacFIN 1986-883).

Pacific hake were usually present in all depth strata

throughout the survey area but were most densely distributed on the continental shelf between 55 and 183

m; intermediate densities occurred in the 184-366 m

zone (Fig. 3). From 1977 to 1986, Pacific hake CPUE

decreased from south to north. Averaged over all years,

mean CPUE was 93.2 kg/km ill the Monterey area, 76.2

kg/km in the Eureka area, 33.4 kg/km in the Columbia

area, and 32.2 kg/km in the U.S.-Vancouver area. The

greater densities in the southern areas reflect the presence of abundant prerecruit and recruiting stock components. High densities (l12.3 to more than 453 kg/

km) occurred over larger regions in 1983 and 1986. In

3 Pacific Fisheries Information Network (PacFIN). 1981-88. U.S.

catches 1981-88. PacFI ,Pacific States Marine Fisheries Commission, Metro Center, Suite 170, 200ll S.W. first Avenue, Portland, OR 97201.
Dark and Wilkins: Groundfish off Washington, Oregon, and California 9

Table 2

Number of length samples taken from bottom trawl catches in 1977, 1980, 1983, and 1986 by species, depth zone, and

International North Pacific Fisheries Commission statistical area. See text for scientific names.

U.S.-Vancouver

1977 1980 1983 1986

Columbia

1977 1980 1983 1986

Eureka

1977 1980 1983 1986

Monterey

1977 1980 1983 1986

Pacific hake Sf 615 977

D2 167 248

977 7,425

551 1,096

5,594 6,495 18,416 10,843

1,561 648 4,913 663

1,188

760

946 5,493 2,977

336 1,497 539

3,649 4,744 3,604 10,399

3,834 1,138 894 924

Sablefish S

D

243 189 1,721

360 155

732 890 1,860 1,820

852 414 1,649 694

86 211

12

372

855

40 1,121 457

580

245 570

303

Yellowtail

rockfish S 488 500 820 1,318

D

1,195 1,544 2,306 1,585

178 68 83 42

106 100 207 178 321 28 159 271

Canary rockfish S

D

348 1,007 1,676

104

186 819 1,644 1,344

58 52

813 130

126

63 25 83 407 67

Bocaccio

Chilipepper

S

D

S

D

7

141 66 34

28

63 29

23

50

4

35

24

26

12

67

12

37

20

42 575 345 19 149

374 201 410 19

2,543 581 894 1,720

2,553 697 562 127

Pacific

ocean perch S 69 184 274

D 1,765 1,566 1,286

212

732

307 27 17

3,728 1,609 1,365 257 213 41 187 37

Lingcod

English sale

S

D

S

D

35

I

177 204 3,487

70 186

6

379 740 3,322

38

127 34

33

90 179 321

Dover sale

Rex sale

S

D

S

D

63 48 1,927

318 115 740

179 3,076

97 564

743 1,452 2,962

219 516 882

411 1,182 3,080

13 182 346

379 250

396 377

39

105

81 1,038

272 363 701

265

72 275

Arrowtooth

flounder S

D

607 127 5,287

61 36 739

155

106

1,048

125

19

J Shallow (91-183 m in 1977; 55-183 min 1980-1986).

2 Deep (184-366 m).

1983, the highest densities (>453 kg/km) ofjuveniles

were found off the extreme northern portion of California and southern Oregon. In 1977, 1980, and 1986,

the CPUE in the Monterey area was 74,747, and 104%,

respectively, of the CPUE in the Eureka area, whereas

in 1983 it was only 40%. This northward displacement

in 1983 may have been a response to unusually warm

water in the central California region. Bottom temperatures in the Monterey area (Jat. 36'30'-39'30'N) averaged about 1.5'C warmer in 1983 than the average

combined temperatures from other survey years; temperatures similar to the mean from other survey years

were not encountered until sampling proceeded north

of about lat. 41 'OO'N. A large concentration of young

Pacific hake was found in 1983 between lat. 40'00' and

42'30'N. This suggests that young fish departed from

areas where they normally reside and migrated northward until they encountered more suitable cooler temperatures.

Estimated biomass was generally least in the U.S.-

Vancouver area because of the small size of the area

and the lower densities observed there (Fig. 4). Bio-
10 NOAA Technical Report NMFS 117

Table 3

Number of age samples taken from bottom trawl catches in 1977, 1980, 1983, and 1986 by species, depth zone and

International North Pacific Fisheries Commission statistical area. See text for scientific names.

U.S.-Vancouver Columbia Eureka Monterey

1977 1980 1983 1986 1977 1980 1983 1986 1977 1980 1983 1986 1977 1980 1983 1986

Pacific hake SI 263 348 377 73 1,216 1,784 1,306 669 503 289 477 252 684 1,101 689 359

D2 75 120 208 120 648 314 773 169 102 587 173 228 490 103 260

Sablefish S 75 459 68 85 94

D 126 520 351 78

Yellowtail

rockfish S 437 305 465 135 722 872 1,154 197 65 87 141 87

D 96

Canary

rockfish S 177 301 281 234 509 647 1,070 365 90 78 296

D 104 34 20 126

Bocaccio S 126 66 14 4 132 116

D 25 136 66 326

Chilipepper S 67 1,147 196 386

D 50 775 324 317

Pacific ocean

perch S 294 88 161 591

D 149 214 429 92 283 500

I Shallow (91-183 m in 1977; 55-183 min 1980-1986).

2 Deep (184-366 m),

mass estimates were generally larger in the Columbia

area, usually because of the greater habitat area there.

The greatest biomass was often found in the Monterey

area where estimates were also most variable. For instance, in 1980, 77% of the biomass was found in the

Monterey area, but in 1977, only 27% was found there.

These latitudinal shifts in distribution were probably

related to oceanographic changes, food availability, and

population age composition. Pacific hake populations

are stratified latitudinally by age and size; the youngest,

smallest fish inhabit the southern portion ofthe species

range (Nelson and Larkins, 1970; Dark, 1975). In years

when strong year classes are recruited, the distribution

usually shifts southward, as in 1980 and 1986. As expected, 90% confidence intervals (Table 6, Fig. 4) were

relatively narrow but increased as estimated biomass

increased. Standard normal variates (Z.statistics) were

calculated to compare INPFC area and total survey area

biomass estimates for all possible pairs of years. These

were tested for significance at the 98% level. (A

Bonferroni inequality (Miller, 1981) must be assumed

due to the multiple nature of the tests; therefore, the

actual probability is equal to (n X p) = 6 x 0.02 = 0.12.

Thus the tests used will be conservative in the rejection

of the null hypotheses.) Significant differences in total

biomass estimates were found between 1977 and all

other years and between 1983 and 1986 (Table 7).

Major changes i,n Pacific hake abundance occur because of wide variations in year-class strength (Stauffer,

1985). Such fluctuations were observed during the period of the four surveys. Biomass estimates based on

bottom trawl catches (a small portion of the total biomass estimate) ranged from 65,983 tin 1977 to 239,153 t

in 1986, almost a fourfold increase (Table 6). This

resource is commonly dominated by only a few year

classes (Bailey and Francis, 1985). The variability of

recruitment to the stock, therefore, has a large impact

on overall biomass estimates. Sampling variability can

also be a significant source of variation in abundance

estimation. Pacific hake are more uniformly distributed

than many other species so variances of biomass estimates tend to be smaller. Coefficients of variation (CV)

for biomass estimates in the entire survey area ranged

from about 12 to 22% over the four surveys (Table 6),

which represents some of the smallest values observed

among the species considered in this study.
Dark and Wilkins: Groundfish off Washington, Oregon, and California 11

Table 4

Mean catch per unit of effort of all groundfish species combined (kg/km

trawled) by year, International North Pacific Fisheries Commission (INPFC)

statistical area, and depth stratum.

INPFC area Depth (m) 1977 1 1980 1983 1986

U.S.-Vancouver 55-183 429 230 182 165

184-366 181 150 191 122

55-366 305 190 187 144

Columbia 55-183 137 64 104 138

184-366 128 74 134 99

55-366 133 69 122 118

Eureka 55-183 77 91 192 372

184-366 42 66 105 207

55-366 59 76 142 289

Monterey 55-183 175 314 108 204

184-366 188 116 258 121

55-366 181 215 183 163

Mean of all areas 55-183 200 115 143 176

184-366 166 82 146 144

55-366 183 97 145 161

I The shallow stratum in 1977 was 91-193 m.

Larger Pacific hake tend to be found over the continental shelf in waters less than 184 m deep. However,

the size to depth relationship is not strong and considerable variability exists. Interannual variability is the

most notable feature of the length data. The length

composition in 1977 was generally unimodal and characteristic of a mature population, with little evidence of

abundant, newly recruited hake (Fig. 5). Length distributions in subsequent years were dominated by large

numbers of fish between 32 and 43 cm, representing

strong year classesjust recruiting to the fishable population. In 1983, this mode of small hake predominated

in the Columbia area, and small fish were even found in

the Vancouver area. This unusual presence ofsmall hake

in the northern part ofthe survey area may have been due

to a broader distribution typical of extraordinarily large

year classes or may have been related to major oceanographic changes resulting from the 1982-83 El Nino.

The population age compositions (Fig. 6) have the

following characteristics suggested by the length data.

Females generally reach older ages and the interannual

variability of the age composition can be dramatic. The

1977 age composition consisted of individuals ranging

from 1 to 15 years old; 4- and 7-year-old fish of the 1973

and 1970 year classes, respectively, prevailed (Fig. 6).

The 1977 year class emerged prominently in 1980 when

large numbers of age-3 fish in the Monterey and Eureka

areas accounted for about 67% of the estimated population that year (Nelson and Dark, 1985) (i.e. their

latitudinal distribution may overlap the southern portion of the survey area to a different extent in different

years). The age composition in 1983 was also characterized by a large age-3;component (1980 year class) that

overwhelmed all other age groups. While the 1977 and

1980 year classes appear to be of similar magnitude

based on bottom trawl data, the 1980 and 1983

hydroacoustic surveys indicated that the 1980 year class

at age 3 was about 1.9 times larger than the 1977 year

class at the same age. 4 This may partIy account for its

presence in northern areas in 1983 where the 1977 year

class did not occur. The 1986 age composition shows

the 1984 year class, though large, to be smaller than

either the 1977 or 1980 year classes. However, the availability of 2- and 3-year-olds may differ enough due to

incomplete recruitment to preclude a meaningful comparison. Assessmen t ofsurvey and fishery data confirms

the high abundance of both the 1984 and 1980 year

classes (Hollowed et aI., 1988).

Changes in the age composition of the population

introduced major changes in the distribution of the

resource. Much of this variation can be explained by

the recruitment of a succession of weak or average year

classes punctuated occasionally by strong year classes,

4 Williamson, N., Alaska Fisheries Science Center, National Marine Fisheries Service, NOAA, 7600 Sand Point Way NE, Seattle, WA 98115. Personal commun., April 1984.
12 NOAA Technical Report NMFS 117

Table 5

Dominant groundfish species composing approximately 80% of the total catch per unit of effort (CPUE) in each

International North Pacific Fisheries Commission statistical area by year.

U.S.-Vancouver Columbia Eureka

CPUE Cumulative CPUE Cumulative CPUE Cumulative

Year Species (kg/km) percentage Species (kg/km) percentage Species (kg/km) percentage

1977 Spiny dogfish 59.2 19.4 Pacific hake 22.4 16.8 Pacific hake 30.6 51.6

Canary rockfish 31.2 29.6 Lingcod 17.0 29.6 Dover sole 6.4 62.4

Pacific hake 25.7 38.0 Pacific ocean perch 14.2 40.4 Splitnose rockfish 3.3 68.0

Pacific ocean perch 25.3 46.3 Yellowtail rockfish 12.1 49.5 Darkblotched rockfish} 2.9 73.0

Pacific herring} 24.9 54.5 Sablefish 10.5 57.4 Sablefish 2.3 76.8

Arrowtooth flounder 24.4 62.5 Arrowtooth flounder 10.2 65.1 Spiny dogfish 2.0 80.2

Silvergray rockfish} 22.4 69.8 Dover sole 10.0 72.6

Yellowtail rockfish 20.8 76.7 Canary rockfish 5.3 76.6

Lingcod 9.8 79.9 Sharpchin rockfish} 3.7 79.4

Monterey Total survey area

Species CPUE (kg/km) Cumulative percentage Species CPUE (kg/km) Cumulative percentage

Shortbelly rockfish 38.8 21.3 Pacific hake 25.5 13.9

Splitnose rockfish 23.5 34.3 Shortbelly rockfish 22.6 26.2

Pacific hake 22.8 46.9 Spiny dogfish 17.1 35.5

Chilipepper 17.1 56.4 Splitnose rockfish 14.8 43.6

Dover sole 12.9 63.5 Chilipepper 10.0 49.0

Spiny dogfish 12.5 70.3 Dover sole 9.7 54.3

Bocaccio 10.1 75.9 Pacific ocean perch 7.9 58.6

Stripetail rockfish 9.3 81.0 Yellowtail rockfish 7.4 62.6

Lingcod 7.1 66.5

Canary rockfish 6.9 70.2

Arrowtooth flounder 6.8 73.9

Bocaccio 6.6 77.5

Sablefish 5.8 80.7

U.s.-Vancouver Columbia Eureka

CPUE Cumulative CPUE Cumulative CPUE Cumulative

Year Species (kg/km) percentage Species (kg/km) percentage Species (kg/km) percentage

1980 Spiny dogfish 61.8 32.6 Sablefish 10.6 15.3 Splitnose rockfish 22.0 29.0

Pacific hake 24.1 45.3 Pacific ocean perch 8.8 27.9 Pacific hake 15.9 49.9

Pacific ocean perch 15.6 53.5 Pacific hake 8.6 40.4 Sablefish 10.2 63.4

Arrowtooth flounder 10.8 59.2 Splitnose rockfish 4.6 47.0 Dover sole 5.2 70.3

Dover sole 9.9 64.4 Dover sole 4.4 53.3 Darkblotched rockfish} 4.5 76.3

Yellowtail rockfish 9.5 69.4 Arrowtooth flounder 4.4 59.6 Stripetail rockfish 4.1 81.8

Sablefish 7.3 73.3 Lingcod 4.4 65.9

Splitnose rockfish 7.1 77.0 Sharpchin rockfish J 3.5 70.9

Redslripe rockfish} 7.1 80.8 Yellowtail rockfish 2.6 74.7

Darkblotched rockfish} 2.1 77.7

Yellowmouth rockfish} 1.8 80.2

Monterey Total survey area

Species

Pacific hake

Sablefish

Stripetail rockfish

Chilipepper

Bank rockfish}

CPUE (kg/km) Cumulative percentage

118.8 55.3

14.0 61.8

13.9 68.3

12.6 74.1

11.0 79.2

Species CPUE (kg/km) Cumulative percentage

Pacific hake 21.1 18.6

Sablefish 11.0 28.4

Splitnose rockfish 9.8 44.5

Spiny dogfish 6.7 51.5

Pacific ocean perch 6.5 58.2

Dover sole 5.3 63.7

Arrowlooth flounder 3.4 67.2

Lingcod 3.0 70.3

Stripelail rockfish 2.7 73.2

Darkblolched rockfish} 2.7 75.9

Yellowtail rockfish 2.6 78.6

Sharpchin rockfish J 2.0 80.1
Dark and Wilkins: Groundfish off Washington, Oregon, and California 13

Table 5 (Continued)

U.S.-Vancouver Columbia Eureka

CPUE Cumulative CPUE Cumulative CPUE Cumulative

Year Species (kg/km) percentage Species (kg/km) percentage Species (kg/km) percentage

1983 Spiny dogfish 33.5 17.9 Pacific hake 23.1 19.0 Pacific hake 52.1 36.6

Pacific ocean perch 17.4 27.1 Dover sole 16.1 32.2 Spiny dogfish 29.8 57.5

Redstripe rockfish I 16.5 35.9 Sablefish 15.4 44.9 Dover sale 18.2 70.3

Pacific hake 16.3 44.6 Darkblotched rockfish I 9.3 52.5 Sablefish 10.1 77.4

Silvergray rockfish I 15.5 52.9 Sharpchin rockfish I 6.3 57.7 Rex sole 4.2 80.3

Canary rockfish 14.8 60.8 Arrowtooth flounder 6.2 62.8

Arrowtooth flounder 10.7 66.5 Pacific ocean perch 5.9 67.7

Sharpchin rockfish I 9.8 71.7 Rex sale 5.8 72.4

Sablefish 7.9 76.0 Splitnose rockfish 2.8 74.8

Dover sale 7.5 80.0 Lingcod 2.6 76.9

Yellowtail rockfish 2.5 79.0

Monterey Total survey area

Species

Stripetail rockfish

Bocaccio

Pacific hake

Chilipepper

Dover sole

Spiny dogfish

Splitnose rockfish

Sablefish

Shortbelly rockfish

CPUE (kg/km)

30.5

23.7

20.9

15.9

15.0

13.4

10.8

9.3

8.6

Cumulative percentage

16.6

29.6

41.0

49.6

57.8

65.1

71.0

76.1

80.8

Species

Pacific hake

Spiny dogfish

Dover sole

Sablefish

Pacific ocean perch

Darkblotched rockfish I

Sharpchin rockfish I

Arrowtooth flounder

Canary rockfish

Rex sole

Yellowtail rockfish

Redstripe rockfish I

Silvergray rockfish I

CPUE (kg/km)

29.4

16.0

14.9

12.1

6.5

5.8

5.3

5.1

4.6

4.4

4.1

3.8

3.3

Cumulative percentage

20.4

31.4

41.7

50.1

54.5

586

62.2

65.8

69.0

72.0

74.9

77.6

79.9

U.s.-Vancouver Columbia Eureka

Year

1986

CPUE Cumulative CPUE Cumulative CPUE Cumulative

Species (kg/km) percentage Species (kg/km) percentage Species (kg/km) percentage

Pacific hake 39.7 27.6 Pacific hake 44.4 37.6 Pacific hake 140.0 48.4

Spiny dogfish 19.7 41.4 Sablefish 9.4 45.6 Dover sale 19.6 55.2

Arrowtooth flounder 13.4 50.7 Dover sole 7.5 51.9 Darkblotched rockfish I 17.3 61.1

Darkblotched rockfish I 8.8 56.8 Splitnose rockfish 6.8 57.7 Shortbelly rockfish 16.0 66.6

Pacific ocean perch 7.5 62.1 Darkblotched rockfish I 5.3 62.2 Sablefish 12.9 71.1

Sablefish 7.0 67.0 Pacific ocean perch 4.9 66.3 Bank rockfish I 10.7 74.8

Walleye pollockI 6.3 71.3 Rex sale 4.3 69.9 Bocaccio 9.3 78.0

Dover sole 6.3 75.7 Pacific sanddabl 4.0 73.3 Splitnose rockfish 7.5 80.6

Canary rockfish 5.1 79.2 Arrowtooth flounder 3.5 76.3

Sharpchin rockfish I 3.5 79.2

Monterey Total survey area

I Scientific names not mentioned in text: Pacific herring, Clupea pallasi; silvergray rockfish, Sebasles brevispinis; sharpchin rockfish, S. zacenlrus; darkblotched

rockfish, S. cramm; redstripe rockfish, S. pronger; yellowmouth rockfish, S. reedi; bank rockfish, S. rufus; walleye pollock, Theragra chalcogramma; Pacific sanddab,

Cilhanchlhys sordidus.

Species

Pacific hake

Dover sale

Sablefish

Chilipepper

Stripetail rockfish

Spiny dogfish

Rex sole

Bank rockfish I

CPUE (kg/km)

71.1

15.5

10.2

9.1

7.8

7.3

5.4

4.4

Cumulative percentage

43.6

53.1

59.4

65.0

70.0

74.2

77.5

80.2

Species

Pacific hake

Dover sole

Sablefish

Darkblotched rockfish I

Spiny dogfish

Rex sole

Splitnose rockfish

Arrowtooth flounder

Pacific ocean perch

Shortbelly rockfish

Bank rockfish I

Bocaccio

Stripetail rockfish

CPUE (kg/km)

73.8

12.2

9.9

8.7

7.3

4.6

4.5

4.3

4.3

4.2

3.8

3.3

3.1

Cumulative percentage

41.3

48.2

53.7

58.6

62.7

65.2

67.7

70.1

72.5

74.9

77.0

78.8

80.6
14 NOAA Technical Report NMFS 117

.;-.....--..........----....o~~ ....""l'oloo!~- ..........--.........Io-......._ SOO OO'N

[i] Area not sampled

D Nocatch

[2J < 112.3 kglkm

• 112.3-452.9 kglkm

• > 452.9 kglkm

~::::;;;;;;;;;;;;;;::;:~-..._-.....,-,....,...._.......,.--_J- 30° 00'

)'6>,.. 05>)'

\l ')''''- ~6l v,,>

Pacific Hake '?)

Mean CPUE

1977

135° OO'W

1980 1983

c

o

L

U

M

B

I

A

5,cape Blanco

E

R 'r-------,-----+

K

A

-",Cape Mendocino

11roo'

45° 00'

40° 00'

Figure 3

Distribution of Pacific hake, Merluccius productus, during 1977, 1980, 1983, and

1986 National Marine Fisheries Service bottom trawl surveys.

such as those appearing in 1977, 1980, and 1984. The

1980 year class at age 3, for example, was estimated to

be more than 15 times as large as the 1983 year class at

age 3. The recruitment of the very large 1980 and 1984

year classes resulted in high catch rates over larger

regions in 1983 and 1986 than in years without strong

recruiting year classes. Young Pacific hake are usually

most concentrated off northern California, but this

pattern changed in 1983 when the population normally

found off California was found farther to the north in

the vicinity ofthe Oregon-California border. More typical distributions associated with populations having

strong recruiting year classes were seen in 1980 and

1986 when large numbers of juvenile Pacific hake of

the 1977 and 1984 year classes, respectively, occupied

the Monterey, Eureka, and southern Columbia areas

(Coleman, 1986 and 1988).

Survey results support historical data that indicate

strong year classes tend to occur in a 3-4 year cycle.

Francis5 applied a variety ofindices to chart the relative'

abundance ofthe 1960-84 year classes. The 1970, 1973,

5 Francis, R. C. 1985. Status of the Pacific hake resource and

recommendations for managemen t in 1986. In Pacific Fisheries

Management Council, Status of the Pacific coast groundfish

fishery through 1985 and recommended acceptable biological

catches for 1986, 22 p. Pacific Fisheries Management Council,

Metro Center, Suite 420, 2000 S.W. First Avenue, Portland, OR

97201.
Dark and Wilkins: Groundfish off Washington, Oregon, and California 15

250 T;.:===:.:;-······

o ..L.c:i1ilil::::EL..-l.:JiliL...E3.-L..JjjJL...l_...L.:J~=--------'-~~ l US Vancouver Columbia Eureka Monterey Total

50

OJ] 1977

Iiliilil 1980

200-- 0 1983

1986

if)

100

E

o

iii

o

o

o

...= 150 x

INPFC Area

J

t t

+ + 77808386

US Vancouver

t1 oJ..:!~---L_-----_.L--'-------------- + + ++ + 778083~ 77808386 77808386 77808386

Columbia Eureka Monterey Total

Year and INPFC Area

50

x

150 if)

if)

E'"

o 100

iii

250

300

Figure 4

Estimates of Pacific hake, Merluccius productus, biomass and associated

90% confidence intervals by International North Pacific Fisheries Commission area and year.

1977, and 1980 year classes were identified as strong by

all indices. Survey results are consistent with these observations (Fig. 6). Bailey and Francis (1985) related

year-class strength to oceanographic features present

subsequent to spawning and postulated that warm water years associated with relatively weak upwelling are

important to the production of large year classes.

Mean lengths at age tend to decrease over time (Fig.

7). The cause ofthis trend is uncertain, but two circumstances may have affected growth. Estimated total biomass (including estimates from hydroacoustic surveys)

in 1980, 1983, and 1986 were 1.28, 1.11, and 1.78 times

larger, respectively, than in 1977. These population

increases may have increased competitIOn for food,

which resulted in a decreased growth rate for all age

groups. Another factor is the 1982-83 El Nino, which

possibly created an adverse environment for good

growth. Francis5 observed smaller mean weight at age

in 1983 and 1984 in an analysis based on fishery samples

and suggested that the El Nino played an important

role in retarding growth. More recently, Canadian and

U.S. scientists have observed continuing reductions in

mean length at age throughout the commercial range

of Pacific hake; these reductions cannot be readily explained by intensive exploitation or the factors cited

above (Hollowed et aI., 1988).
16 NOAA Technical Report NMFS 117

Table 6

Pacific hake, Merluccius productus - Mean catch per unit of effort (CPUE) (kg/km trawled), biomass estimates

(metric tons), 90% confidence intervals (CI), and coefficients of variation (CV in %) of biomass estimates by

International North Pacific Fisheries Commission statistical area, depth stratum, and year.

U.S.-Vancouver Columbia

Depth Mean CV Mean CV

Year stratum (m) CPUE Biomass CI (%) CPUE Biomass CI (%)

1977 91-183 23.4 4,949 21-9,877 37.2 29,130 18,623-39,637

184-366 9.5 841 512-1,171 8.1 2,418 717-4,120

91-366 19.3 5,791 848-10,734 42.4 29.2 31,549 20,998-42,099 20.0

1980 55-183 42.9 11,293 1,687-20,899 16.3 18,999 11,908-26,09I

184-366 5.3 477 190-765 2.9 859 438-1,280

55-366 33.4 11,770 2,160-21,380 46.8 13.6 19,858 12,756-26,961 21.4

1983 55-183 28.0 7,381 0-15,647 44.7 52,042 36,920-67,165

184-366 7.7 687 213-1,162 15.3 4,623 3,104-6,141

55-366 22.9 8,068 0-16,347 57.9 38.7 56,665 41,474-71,856 16.0

1986 55-183 65.1 18,068 8,155-27,982 62.9 77,147 50,585-103,710

184-366 15.1 1,335 750-1,919 5.1 1,421 957-1,885

55-366 53.1 19,403 9,559-29,247 28.2 52.3 78,568 52,002-105,134 19.9

Eureka Monterey Total

Depth Mean CV Mean CV Mean CV

Year stratum (m) CPUE Biomass C1 (%) CP E Biomass CI (%) CPUE Biomass Cl (%)

1977 91-183 53.1 9,508 978-18,038 43.6 15,875 6,855-24,895 38.6 59,463 43,062-75,864

184-366 8.0 645 370-921 25.1 2,filti 0-7,250 J1.4 6,520 1,530-11,510

91-366 39.1 10,153 1,6I9-I8,688 48.5 39.4 18,4YI 9,105-27,877 29.6 31.2 65,983 49,344-82,622 15.2

1980 55-183 52.2 10,536 694-20,379 218.0 138,575 70,787-206,363 79.2 179,403 I10,139-248,667

184-366 10.0 802 0-1,827 19.6 2,373 1,112-3,634 7.6 4,51 I 2,893-6,I29

55-366 40.2 11,338 1,451-21,226 49.Y 18n.3 140,941:l 73, I76-208,720 28.7 64.4 183,915 114,634-253,196 22.5

1983 55-183 138.0 41,998 17,247-66,748 27.-1 17,438 10,567-24,310 50.2 118,859 88,628-149,090

184-366 19.5 1,561 933-2,189 14.3 1,727 844-2,609 14.5 8,598 6,723-10,472

55-366 113.3 43,559 18,800-68,317 32.7 25.3 19,165 12,243-26,087 21.6 43.1 127,457 97,167-157,747 14.1

1986 55-183 132.2 42,321 29,682-54,959 138.0 91,128 63,619-11R,637 92.1 228,666 179,217-278,115

184-366 34.5 2,903 550-5,256 38.~ 4,829 828-8,830 18.1 10,487 4,140-16,834

55-366 1I1.9 45,224 32,4 I6-58,032 16.8 122.0 95,957 68,218-123,696 17.1 78.2 239,153 189,367-288,940 12.5

Yellowtail rockfish - Yellowtail rockfish is among

the most important rockfish species off the west coast,

and in recent years landings have been second only to

widow rockfish, S. enlomelas. Landings from 1980 to

1987 ranged from 3,214 to 8,718 t and averaged about

13% of the total rockfish landings (PacFI 3). Because

of the species' historical commercial importance and

concern about the status of the resource, it was designated as a target species for the triennial assessment

surveys.

Many rockfishes display a strong tendency to school,

which results in contagious or "clumped" distributions.

This seriously degrades the precision of area-swept abundance estimates and places high demands on the sampling design. In spite of intensive sampling in important rockfish areas, abundance estimates are often accompanied by relatively large variances. Also, biases

associated with trawl sampling of rockfish probably result in conservative estimates of abundance. The precision and accuracy of rockfish abundance estimates will

be more fully discussed later in this paper.

In all survey years yellowtail rockfish densities were

greatest off Washington and central Oregon (Table 8,

Fig. 8). Density tended to decrease from north to south.

Mean CPUE over all the surveys was 32.2 kg/km in the

U.S.-Vancouver area, 5.7 kg/km in the Columbia area,
Dark and Wilkins: Groundfish off Washington, Oregon, and California 17

Table 7

Values used to test the significance of observed differences between pairs of biomass estimates for 1977, 1980, 1983,

and 1986. Asterisks denote significance at P = 0.02 1. See text for scientific names.

Pacific hake Canary rockfish Yellowtail rockfish Bocaccio Chilipepper Pacific ocean perch

U.S.-Vancouver 1977

1980

1983

0.992 0.431 2.267 0.880 0.778 0.845 0.870 0.866 1.037 1.011 0.891 1.036

0.513 0.983 0.684 0.293 0.058 0.643 0.933 0.314

1.573 0.556 0.457 1.276

0.859 0.743 1.291

0.299 1.099

1.716

Columbia

Eureka

Monterey

Total

1977

1980

1983

1977

1980

1983

1977

1980

1983

1977

1980

1983

1.534 2.268 2.785*1.517 0.050 0.211 1.130 0.959 1.208 0.994 0.861 0.646 1.537 1.2510.986 1.738 1.883 2.726

3.667* 3.619* 1.364 0.906 0.412 0.063 0.176 0.168 1.011 0.800 0.226 1.086

1.210 0.239 0.491 0.050 0.199 0.807

0.158 2.219 3.878* 1.054 3.262* 2.140 0.263 0.021 0.657 2.593* 2.027 1.315 0.800 0.846 3.163* 0.701 0736 0.698

2.104 3.579* 0.765 0.379 0.320 0951 1.318 0.869 0.967 2.355 0.246 1.334

0.103 1.165 0.679 1.127 3.269* 1.116

2.998* 0.098 4.472*0.983 1.392 0.855 1.156 0.567 1.077 0.602 0.299 0.012 0132 0.0680.455 1.272 0.822 1.522

2.993* 1.030 1.476 1.463 1.087 1.610 0.627 0.336 0.059 0.394 0.000 1.488

4.532* 1.234 0.408 0.227 0.364 1.487

2.765* 2.985* 5.503*0.998 0.387 0.791 1.454 1.158 1.490 0.892 0.019 0.087 0.231 0.0550.444 1.386 1.340 2.136

1.249 1.081 1.856 0.937 0.406 0.126 0.574 0.502 0.1520.081 0.114 1.505

3.206* 1.185 0.459 0.063 0.275 1.717

Sablefish Lingcod English sole Dover sole Rex sole Arrowtooth llounder

U.S.-Vancouver 1977

1980

1983

Columbia 1977

1980

1983

Eureka 1977

1980

1983

Monterey 1977

1980

1983

Total 1977

1980

1983

0.052 0.985 0.075 0.572 0.304 0.840 1.494 3.209* 7.772* 0.454 0.498 1.146 0.762 0.052 0.794 0.911 1.393 0.822

1.230 0.165 0.635 0.528 0.248 1.290 0.80 I 1.272 0.802 0.490 0.696 0.375

1.760 1.990 1.650 0.566 1.030 3.185*

1.803 1.761 1.416 0.299 0.751 0.942 1.392 4.951* 5.484* 3.651* 0.662 1.530 0.144 6.549*9.053* 2.768* 3.185* 1.703

0.893 1.050 0.726 1.069 3.116* 3.862* 3.919* 4.846* 6.438*8.799* 0.607 2527

1.439 2.507* 1.123 0.795 0.917 4.579*

0.996 2.324 1.883 0.583 1.033 0.413 2.582 4.698* 8.796* 0.344 2.783* 4.986* 0.134 4.150*7.007* 1.330 0.707 1.096

0.778 0.452 0.252 0.362 3.965* 7.647* 3.597* 5.897* 4.187*7.084* 1.151 0.594

1.072 0.786 1.702 2.388* 2.500* 0.722

1.210 1.501 1.828 1.440 0.056 1.611 1.0104.035* 4.151* 1.408 2.309 4.530* 0.153 3.406*5.572* 2.430* 1.776 0.000

1.008 0.422 1.137 0.244 4.612* 5.472* 3.075* 5.040* 3.388* 5.538* 0.868 2.009

1.298 1.269 1.599 2.487* 2.456* 1.490

1.964 2.031 2.1340.416 0.767 1.112 1.4987.376* 9.128* 3.141*2.539* 4.588*0.370 8.113*10.182*1.905 2.541* 1.442

0.621 0.804 0.520 1.139 5.672* 6.776* 5.145* 6.458* 7.217*9.372* 0.818 1.258

0.218 3.320* 0.156 2.474* 2.727* 4.950*

I In fact P < 0.12 due to multiple testing of pairs (Bonferroni's inequality).

2.3 kg/km in the Eureka area, and 1.5 kg/km in the

Monterey area. Density in the waters off Washington

was relatively higher and more uniform in 1977 than in

later years. In that year and area, yellowtail rockfish

densities were also higher on the upper continental

slope between 184 and 366 m (Table 8). Conversely, in

1986 the species was almost completely confined to the

continental shelf (depths <184 m), which is more characteristic of its typical distribution.

Biomass estimates for the entire area ranged from

10,978 t in 1980 to 24,725 tin 1977 (Table 8) . Almost all

of the estimated biomass occurred on the continental

shelf in waters less than 183 m. Only 1-5% of the total

biomass occurred in deeper waters. Biomass consistently decreased in the U.S.-Vancouver area between

1977 and 1986 (Fig. 9); the 1986 biomass estimate was

only about 24% ofthe 1977 estimate. Biomass estimates

in the Columbia area decreased by 55% (from 11,801
18 NOAA Technical Report NMFS 117

By Sex By Depth

70

60

/ • SaKes Combined

9 Females

o Mates

..-;;;.

70

60

50

'0

30

20

'0

/ • Tolal (91-.366 m)

m Slope (164-366 ml

OShell (91-183 m)

.-.

• Total 166-366 ml

Slope 1184-366 ml

D Shelf 165-183 ml

o

20 30 40 50 60

Length (em)

o 70 20

1977 30

30

40 50 60

Length (em)

40 50 60

Length (em)

70

70

/ 70

30 40 60 60

Length (em)

70

60

2

~ro

1,,0

30

z 20

10

0

70 20 30

1983

---IHl- - -- - _.--- -

40 60 60

Length (em)

70

70

60

e

~50

1 ..0

30

z 20

10

0

20 30 40 50 60

Length (em)

70

30 40 50 60

Length (em)

70

Figure 5

Pacific hake, Merluccius productus, length compositions by year, depth, and sex.

to 5,276 t) between 1977 and 1980 but have remained

rather constant since. The estimated biomass in the

Eureka and Monterey areas was very low, but there is an

indication of recent increases in both areas. As typical

for most rockfishes, sampling variability was large. Coefficients ofvariation for total biomass estimates ranged

from about 24 to 48%, but were as high as 90% in some

INPFC areas (Table 8). Confidence intervals for total

biomass estimates are relatively large and overlap in all

years even though estimates often differed by more

than a factor of two (Fig. 9). Biomass estimates did not

differ significantly among years (Table 7).
Dark and Wilkins: Groundfish off Washington, Oregon, and California 19

By Sex By Depth

250 1 ------------;::::=====:;1

'0 ---------70-------

g, 0

SEX

.,200

:§. 150 ~._- .-------.-.---

&

f

l00f---·-- -----------

I

z

Males

Females

250,---------;=======::::;.,

DEPTH STRATUM

m Shell (91-i83 mj

o Slope (184 -366 ml

6 8 10

Age (years)

12 " 16

1977 e 8 10

Age (years)

12 16

250r----r'-'-'"7'"7--------------' 250,---------;=========n

1

200

g 150---

!,00-

z 501----

1----------------

n 2001------

g

1160 ---

,

i 100 ----

§

%50---

OEPT~STRATUM

o Slope (184-300 m)

Shelt (55-183 ml

------ -

,--------------

04--r-+ o 2 6 e 10

Age (yeers)

12

04---r--t- 16 0 2

1980 e e 10

Age (years)

12

" 16

2.0,--------------------,

16 " 6 e 10 12

Age (years)

----------_._--/

roor----r,---------------

I 160

.

IIt 100

z 50

16

1983 6 e 10 12 ,. Age (years)

80

f----

r---

r--

4---.--+-

250

-.;200

1160

,

t 100

z 50

250,--------------------, 2.0,----------------------,

Figure 6

Pacific hake, Merluccius productus, age compositions by year, depth, and sex. Numerals at top

of bars identify prominent year classes.

16

" 6 8 10 12

Age (years)

16

1986 12

77

8 B 10

Age (years)

114 _

II 100

I

z 50

1

200

§. 150
20 NOAA Technical Report NMFS 117

60············ .

E

u

-.c

~40 -1977

+1980

"*"1983

-0-1986

20 L..-.L..-.L..-.L..-J.-J.-J.-.L-.L-...l.-...l.---'----'----'----....l-....l-....l-LL--l.---l.--l

1 2 3 4 5 6 7 8 9 1011 12131415161718192021

Age (yrs)

Figure 7

Pacific hake, Merluccius productus, mean length-at-age by year.

Length compositions for 1977 and 1980 were similarly unimodal; most lengths ranged between 40 and 54

cm (Fig. 10). The 1983 distribution was also unimodal

but the numbers of fish smaller than 40 cm increased,

suggesting improved recruitment. The length distribution in 1986 was clearly bimodal with modes at about 33

and 43 em. This provides further evidence of good

recruitment in recent years. Few fish less than about 40

cm were found to inhabit the deep zone.

Yellowtail rockfish ages were available only for 1977

and 1980 (Fig. 11). Ages were determined from reading otolith surfaces in both years, but evidence that

sectioned otoliths yield older ages may have influenced

readers to assign older ages to some 1980 samples.6

This may explain why there appeared to be relatively

more fish older than about age 17 in 1980. The variability in year-class strength in 1977 was not so extreme in

1980, when only ages 4-15 are compared. The proportion of females aged 10 or older decreased steadily,

with very few remaining in the population by age 15;

this is contrary to the usual situation where females

dominate the older age groups because oftheir greater

longevity. In all years males predominated in catches by

as much as 6:1, especially in the northern part of the

survey area (i.e. Columbia and Vancouver areas). A

similar disproportionate abundance of males has been

observed in commercial landings in Washington

(Tagart7). As yet there is no sound explanation for this,

6 Tagart, J. V., Washington Department of Fisheries, Natural

Resources Building, Olympia, WA 98504. Personal commun.,

June 1988.

but it could be a matter of differential availability to

trawls or a higher rate of natural mortality for females.

Canary rockfish - Canary rockfish is also one of the

more commercially important rockfish species in the

survey area. Between 1980 and 1987, landings varied from

1,819 to 4,297 t. In 1987 total landings of 2,493 t ranked

the species third among rockfish, behind widow and yellowtail rockfish. Most of the catch was made in the U.S.-

Vancouver and Columbia areas. In 1987 the two areas

accounted for 89% of the total landings (PacFIN, 19883).

Canary rockfish densities showed a latitudinal cline

similar to that of yellowtail rockfish (Fig. 12, Table 9).

The mean CPUE of canary rockfish was usually greatest

in the U.S.-Vancouver area (7.3-66.0 kg/km) and decreased southward to the Monterey area (0.3-9.9 kg/

km). However, there was some interannual variability

in canary rockfish distribution. In 1977 densities were

higher (>50 kg/km) in the northern Columbia area in

both the 91-183 m and 184-366 m depth zones than

throughout the remainder of the survey area (mostly

<12 kg/km; Table 9). In 1980 canary rockfish were

concentrated more in the southern Columbia area. An

exception to the usual pattern of distribution occurred

in 1983 when high densities were found between Point

Arena and Cape Mendocino, California, as well as the

7 Tagart,J. V. 1988. Status of the yellowtail rockfish stocks in the

International North Pacific Fishery Commission Vancouver and

Columbia areas. In Pacific Fisheries Management Council, Status of the Pacific coast groundfish fishery through 1988 and

recommended acceptable biological catches for 1989, 112 p.

Pacific Fisheries Management Council, Metro Center, Suite

420,2000 S.W. First Avenue, Portland, OR 97201.
Dark and Wilkins: Groundfish off Washington, Oregon, and California 21

..............._ ..........__..........Io~':-.....~~ ......__..........._ ......... 50° OO'N

)'c9,r. $)' )'c9,r. .tor

,~'» '\'%

Yellowtail Rockfish

Mean CPUE

R

45° 00'

/Cape Mendocino

40° 00'

'Monterey Bay

35° 00'

Area not sampled

D No catch

ttl < 13.5 kglkm

.13.5-39.2 kglkm

• > 39.2 kglkm

~.:::;;:::;:::;::::;::::.,. .............._.....,-,....,....__.,....-_..J- 30° 00'

135° DOW 129°00' 123°00' 117°00'

Figure 8

Distribution of yellowtail rockfish, Sebastes flavidus, during 1977, 1980, 1983, and

1986 National Marine Fisheries Service bottom trawl surveys.

area north of lat. 45"30'N. Finally, higher mean densities were found on Heceta Bank, offsouthern Oregon,

in 1986 than in previous surveys.

Estimates of canary rockfish biomass varied widely

from 26,732 tin 1977,6,965 tin 1980, 18,821 tin 1983,

down to 10,998 tin 1986 (Table 9, Fig. 13). Generally

lower, variable population levels have been observed

since 1977. In every year most of the biomass occurred

in the U.S.-Vancouver and Columbia areas. Almost all

the estimated biomass was in the 55-183 m depth interval. The single exception was in the U.S.-Vancouver

area in 1983, when about one-third of the biomass was

present in the 184-219 m depth interval. However, only

5% of the total biomass over all areas and years was

found on the continental slope (i.e. deeper than 183

m). As in yellowtail rockfish, abundance estimates of

canary rockfish were also highly variable. Because this

species schools, overall CV's ranged from about 30 to

73%; values for individual strata reached as high as 98%

(Table 9). Confidence intervals were large and overlapped extensively (Fig. 13). Only the relatively small

biomass estimates in the Eureka area in 1977 and 1983

were significantly different (Table 7); estimates were

higher in 1983 than in 1977.

Canary rockfish length distributions in 1977 and 1980

were generally unimodal, with modes at about 50 em,

but in 1983 a second mode of smaller fish appeared at

about 30 cm (Fig. 14). The latter group was composed
22 NOAA Technical Report NMFS 117

Table 8

Yellowtail rockfish, Sebastes flavidus - Mean catch per unit of effort (CPUE) (kg/km trawled), biomass estimates

(metric tons), 90% confidence intervals (CI), and coefficients of variation (CV in %) of biomass estimates by

International North Pacific Fisheries Commission statistical area, depth stratum, and year.

U.S.-Vancouver Columbia

Depth Mean CV Mean CV

Year stratum (m) CPUE Biomass CI (%) CPUE Biomass CI (%)

1977 91-183 53.4 11,277 0-22,585 14.5 11 ,325 2,793-19,858

184-274 2.9 172 0-359 2.7 465 217-713

275-366 2.0 I 0-3 4.6 10 0-22

91-366 38.2 11,450 140-22,759 57.8 10.9 !l,801 3,265-20,337 41.9

1980 55-183 18.9 4,965 0-10,927 4.5 5,177 151-10,203

184-219 0.3 11 0-37 0.7 58 0-118

220-366 0.0 0 0.2 42 0-108

55-366 14.1 4,976 0-10,914 68.4 3.6 5,276 250-10,303 56.5

1983 55-183 17.6 4,640 0-11,700 5.6 6,559 3,457-9,661

184-219 0.8 25 ~50 0.7 64 17-112

220-366 0.0 0 5.0 102 2-201

55-366 13.2 4,665 0-11 ,725 89.7 4.6 6,725 3,622-9,829 27.8

1986 55-183 9.7 2,689 1,079-4,299 4.3 5,312 2,478--8,146

184-219 0.4 12 0-34 1.9 178 0-1,280

220-366 0.0 0 0.0 0

55-366 7.4 2,701 1,091-4,311 36.0 3.6 5,490 2,643--8,337 30.6

Eureka Monterey Total

Depth Mean CV Mean CV Mean CV

Year stratum (m) CPUE Biomass CI (%) CPUE Biomass CI (%) CPUE Biomass CI (%)

1977 91-183 3.6 649 0-1,407 1.0 813 0-1,762 15.5 24,064 10,123-38,006

184-274 0.3 12 0-34 0.0 0 1.9 649 345-954

275-366 0.0 0 0.0 0 1.2 11 0-23

91-366 2.6 661 0-1,419 66.1 0.7 813 0-1,762 62.8 11.6 24,725 10,780-38,670 33.5

1980 55-183 2.6 522 9-1,035 0.3 205 0-416 4.8 10,868 3,234-18,502

184-219 0.0 0 0.0 0 0.4 69 7-131

220-366 0.0 0 0.0 0 0.1 42 0-108

55-366 2.0 522 9-1,035 57.1 0.3 205 0-416 61.5 3.9 10,978 3,344-18,613 41.3

1983 55-183 2.2 671 38-1,304 2.5 1,579 0-3,700 5.7 13,450 5,482-21,418

184-219 0.1 2 (one sample) 0.0 0 0.5 92 39-144

220-366 0.0 0 0.1 7 0-16 02 109 7-209

55-366 1.8 673 42-1,306 54.3 2.1 1,587 0-3,706 79.7 4.6 13,650 5,682-21,619 34.9

1986 55-183 3.5 1,128 178-2,077 3.5 2,326 121-4,531 4.6 !l ,455 6,718-16,192

184-219 0.0 0 0.0 0 1.0 190 0-1,299

220-366 0.1 3 0-10 0.1 6 0-17 0.7 9 0-27

55-366 2.8 1,131 182-2,081 50.1 3.0 2,332 127-4,537 56.4 3.8 !l ,655 6,909-16,400 24.5

mainly of 4- and 5-year-olds of the 1978 and 1979 year

classes (Fig. 15). In 1986 the length distribution was

again unimodal but flattened as the 1978 and 1979 year

classes grew into the 35-45 cm length interval. New

recruitment was not evident in the 1986 samples. Females predominated at lengths greater than 55 cm.

Although sample sizes from the deep zone were small,

individuals in those samples were generally larger on

average than those from the shallow zone.

Canary rockfish age compositions for 1977, 1980,

and 1983 are presented in Figure 15. Ages were determined from reading otolith surfaces in 1977 and 1980.
Dark and Wilkins: Groundfish off Washington, Oregon, and California 23

US Vancouver Columbia Eureka Monterey Total o

5

25

:::. 15 + . (/)

(/)

8'" 10-1·+ (:l ·····1<+· . .' . iIi

x

o

020

3

INPFC Area

40 -'" . .. ' . _._ .

30

oo

Cl.

x

:::.20

t +

10

(/)

(/)

E'"

o

iIi

O...L.J.----'---'---~'-----'---=J::.....-'--"---.J........~-'--'-------

77 80 83 86 77 80 83 86 77 80 83 86 77 80 83 86 77 80 83 86

US Vancouver Columbia Eureka Monterey Total

Year and INPFC Area

Figure 9

Estimates of yellowtail rockfish, Sebastes flavidus, biomass and associated

90% confidence intervals by International North Pacific Fisheries Commission (INPFC) area and year.

Adoption ofsectioning and break-and-burn techniques

with the 1983 samples resulted in the detection of older

fish. Whereas 20- to 25-year-olds were the oldest aged in

1977 and 1980, maximum ages read in 1983 were about

twice as old. Discrepancies between canary rockfish

ages read from whole and sectioned otoliths appear to

arise at about ages 10 to 12 years, or at the age of

maturity (Gunderson et aI., 1980; Wyllie Echeverria,

1987), and increase linearly with age (Boehlert and

Yoklavich, 1984). However, some observations and comparisons can be made, assuming that differences between the ageing techniques resulted in minor differences in age composition for ages less than 15 years old.

Canary rockfish ages ranged from 2 to 40 years; samples

were typically dominated by specimens of age 7-15

years. Younger fish took on special prominence in 1983

when large numbers of age 4 and 5 fish of the 1978 and

1979 year classes appeared. Goldens reported a similar

trend in samples from commercial landings in the Co8 Golden, J. T. 1987. Progress report on the status of canary

rockfish (Sebastes pinniger) in the INPFC Columbia area and

recommended ABC for 1988. Unpub\. manuscr., 25 p. Oregon

Department of Fish and Wildlife, Hatfield Marine Science Cen·

ter, Newport, OR 97365.
24 NOAA Technical Report NMFS 117

By Sex By Depth

• Sexes Combined

m Females

D Males

• Total (91-366 ml

m Slope (184-366 rn)

D Shell (91-183 m)

40 50 60

Length (em)

30

1000

2000

1500

1977 40 50 60

Length (em)

30

2000

1

1500

;:

§. 1000

2000 2000

_ Totel (66-366 m)

m Slope (184 -366 m)

OShell (65-183 m)

30 40 50

Length (em)

60

1

1500

1000

1980 30 40 60

Length (em)

60

2000

1500

;: 1000

30 40 60

Length (em)

60

1983 30 40 60

Length (em)

60

---- 2000 2000

..i 1500 1

1500

;: §. 1000 §. 1000

I D

E, 600 600 z z

0 0

20 30 40 60 60 20 30 40 60 60

Length (em) 1986 Length (em)

Figure 10

Yellowtail rockfish, Sebastes flavidus, length compositions by year, depth, and sex.

lumbia area. He found that fish less than 13 years of age

accounted for 26.8% of the 1980-82 population, but

the same age groups composed 51.3% of the 1983-86

population. The 1968 year class appeared large in both

1977 and 1980 survey samples, but the prominent 1961-

64 year classes observed in 1977 were much smaller by

1980. The 1965 and 1966 year classes seemed relatively

weak. The 1976-79 year classes, which first appeared in

significant numbers as age 4-7 fish in 1983, were unusually large when compared with the numbers of age

4-7 fish in 1977 and 1980.
Dark and Wilkins: Groundfish off Washington, Oregon, and California 25

By Sex By Depth 2600.---------------,r=======]l DEPTH STRATUM

D Slope (184-219 m)

m Shelt (91-183 m)

10 15 20 :30 35

Age (years)

1

2000

! 1500 -

; lOOO

a

} 600

SEX

o Females

Males

o 10 16 ro 25 :30 35 0

Age (years) 19 7 7

250°1--------;====:::;1

2600r-----------------, 2600,------,========j1

.

i 1000 ------- - -

E

:i. 6001-----

DEPTH STRATUM I 2000 ----~----~---,- D Slope (184-219 m)

11m Shell (55-'83 mJ

1'600 - ------~======_1

_2000----

i 1500 -

I: 1000~---------

i 500 -

z

o4-n,......,._"" 0 4-r.-r"l"!'W1' o 10 15 20 25 :30 35 0 10 15 20 25 :30 35

Age (years) 19 8 0 Age (years)

Figure 11

Yellowtail rockfish, Sebastes flavidus, age compositions by year, depth, and sex.

Bocaccio - This rockfish species is a common component of commercial and recreational groundfish

catches throughout the survey area, but it is most important in California fisheries, particularly those in the

Monterey area. The 1987 coastwide catch was 1,218 t

and 57% of that was landed in the Monterey area. The

1980-87 landings ranged from 669 to 4,237 t.

Survey data showed bocaccio was distributed over a

broader bathymetric range than the rockfish previously

discussed (Fig. 16). The CPUE in the deep stratum

(184-366 m) often equaled or exceeded the CPUE in

the shallow stratum (55-183 m) (Table 10). Highest

densities were in the southern portion of the survey

region in the Monterey and Eureka areas. Some annual

changes in distribution were observed (Fig. 16). Bocaccio rarely occurred in samples taken from about Cape

Mendocino, California, to Cape Blanco, Oregon, (lat.

41 'OO'-42'30'N) in 1977 and 1986. Although the species

did occur in that region during the 1980 and 1983

surveys, densities were never high. In 1980 and 1983

the general distribution of bocaccio throughout the

survey area was similar. The distribution in 1986 was

discontinuous and patchy, but the estimated biomass was

relatively large. Such widely scattered but dense aggregations were not as prevalent during previous surveys. In

general, densities offCalifornia were much lower in 1986.

Total biomass estimates varied little during the study

period (7,620-8,162 t), with the exception ofl980when

the estimate dropped to 5,186 t (Table 10, Fig. 17).

Biomass was by far the highest in the Monterey area

where, on average, 71 % of the total occurred. There is

an indication that stock reductions have occurred in

the U.S.-Vancouver and Columbia areas since 1977.

The greatest reduction occurred in the U.S.-Vancouver

area, where a decline of 92% was estimated. An apparent population increase was noted in the Monterey

area in 1983, which may have resulted from recruitment of a large 1977 year class (Thomas9 ). Abundance

was most variable in the Eureka area, where the precision ofbocaccio biomass estimates was among the worst

in the study. The 90% confidence intervals were plus or

minus 54, 42, 94, and 119% of the 1977, 1980, 1983,

and 1986 total biomass estimates, respectively. Coefficients of variation were 32, 53, 55, and 71 % for the

same years. This large variability affected the sensitivity

of the surveys and our ability to detect changes in

9 Thomas, D. H. 1985. Status of California's bocaccio stock. In

Pacific Fisheries Management Council, Status of the Pacific

coast groundfish fishery through 1985 and recommended acceptable biological catches for 1986, 9 p. Pacific Fisheries Management Council, Metro Center, Suite 420, 2000 S.W. First

Avenue, Portland, OR 97201.
26 NOAA Technical Report NMFS 117

............._ .................._l.-~....."""I"'~ ........... .....__ SOO OO'N

,,~.p)' "~'ts:

~"~ i?."~ ~~ "<S'~

Canary Rockfish

Mean CPUE

19n 1980 1983

c

o

L

U

M

B

I

A

R

--- Monterey Bay

45° 00'

40° 00'

35° 00'

Area not sampled

D Nocatch

til < 11.8kglkm

• 11.8-50.8 kglkm

• > 50.8 kglkm

+=:;:::;:::;:::;:~_~__.,.......- .......,..__-J- 30° 00'

135° OOW 123°00'

Figure 12

Distribution of canary rockfish, Sebastes pinniger, during 1977, 1980, 1983, and 1986

National Marine Fisheries Service bottom trawl surveys.

population size. Only the 1977 and 1980 biomass estimates in the Eureka area were found to be significantly

different (Table 7), even though in some areas interannual

differences in estimated abundance were relatively large.

Most of the length data was collected from the

Monterey area in 1977, 1980, and 1983, but sampling

was more evenly distributed among INPFC areas in

1986. Samples were relatively small in all years. Lengths

in the samples ranged from about 23 to 79 cm (Fig. 18).

Two prominent modes noted in 1977 and 1986 reflected the presence of substantial numbers of relatively new recruits (32-45 cm) and much older fish

(50-65 cm). The 1980 length composition is distinct

because the population was so strongly dominated by

fish in the 37-47 cm interval; few fish were longer than

47 cm. This group was observed in the 1983 length

composition (46-54 cm), but probably because of

under-sampling it was not as abundant as we would

have expected given its abundance in 1980. Contrary to

observations in other survey years, no fish were less

than 33 cm in 1983 samples.

Age data were available only for 1977 and only for the

Monterey area (Fig. 19). Ages based on otolith surface

readings ranged from 2 to 13 years but ages from 4 to 9

years prevailed. Males dominated most age groups. As

bocaccio became older they were less abundant on the

shelf and were more likely to occur above the upper

continental slope.
Dark and Wilkins: Groundfish off Washington, Oregon, and California 27

Table 9

Canary rockfish, Sebastes pinniger - Mean catch per unit of effort (CPUE) (kg/km trawled), biomass estimates

(metric tons), 90% confidence intervals (CI), and coefficients of variation (CV in %) of biomass estimates by

International North Pacific Fisheries Commission statistical area, depth stratum, and year.

U.S.-Vancouver Columbia

Depth Mean CV Mean CV

Year stratum (m) CPUE Biomass CI (%) CPUE Biomass CI (%)

1977 91-183 94.1 19,804 0-53,217 7.3 5,687 2,558-8,817

184-274 0.1 5 (one sample) 2.9 495 0-993

275-366 0.0 0 1.7 10 0-33

91-366 66.0 19,809 0-53,222 98.1 5.7 6,193 3,040-9,345 30.5

1980 55-183 9.8 2,579 0-6,667 2.4 2,835 1,101-4,570

184-219 0.2 7 0-28 0.8 71 0-164

220-366 0.0 0 0.1 13 0-31

55-366 7.3 2,586 0-6,658 90.2 2.0 2,920 1,184-4,655 35.7

1983 55-183 11.8 3,093 1,208-4,977 5.1 5,893 2,092-9,694

184-219 46.9 1,544 0-4,293 4.5 406 0-828

220-366 0.0 0 0.2 43 11-75

55-366 13.2 4,636 1,401-7,872 40.6 4.3 6,342 2,528-10,155 36.0

1986 55-183 12.1 3,356 1,218-5,495 4.4 5,432 992-9,873

184-219 0.3 II 2-20 0.4 40 0-91

220-366 0.0 0 0.2 32 0-73

55-366 9.2 3,367 1,229-5,506 38.3 3.7 5,504 1,064-9,945 48.3

Eureka Monterey Total

Depth Mean CV Mean CV Mean CV

Year stratum (m) CPUE Biomass CI (%) CPUE Biomass CI (%) CPUE Biomass CI (%)

1977 91-183 0.2 38 7-69 1.4 525 0-2,879 17.2 26,134 0-59,627

184-274 0.0 0 1.4 88 0-264 1.8 587 88-1,087

275-366 0.0 0 0.0 0 1.1 10 0-33

91-366 0.2 38 7-69 47.2 1.3 612 0-3,024 62.4 12.8 26,732 0-60,227 73.4

1980 55-183 6.11 1,235 0-3,237 0.3 200 0-430 3.0 6,850 2,098-11,602

184-219 0.2 6 (one sample) 0.4 12 0-29 0.5 97 1-192

220-366 0.1 5 0-12 0.0 0 <0.1 18 0-36

55-366 4.8 1,246 0-3,247 92.0 0.3 213 0-443 64.5 2.4 6,965 2,212-11,717 40.2

1983 55-183 1.2 365 196-533 11.7 7,432 0-15,674 7.1 16,782 7,560-26,003

184-219 0.0 0 0.0 0 9.6 1,949 0-4,718

220-366 <0.1 2 0-5 0.5 45 0-117 0.2 90 12-168

55-366 1.0 366 198-535 27.0 9.9 7,476 0-15,716 65.8 6.4 18,821 9,265-28,376 30.5

1986 55-183 2.4 784 197-1,371 2.0 1,326 62-2,591 4.4 10,899 5,477-16,322

184-219 0.2 6 0-16 0.2 9 0-29 0.4 65 17-114

220-366 2.3 2 0-4 0.0 0 0.1 33 0-77

55-366 2.0 792 204-1,379 44.4 1.7 1,335 70-2,599 56.5 3.6 10,998 5,575-16,421 29.7

Chilipepper - Chilipepper is of minor importance

to rockfish communities in the U.S.-Vancouver, Columbia, and Eureka areas but is a predominant species in

commercial and recreational catches from the Monterey

and Conception areas offCalifornia (HenrylO). Between

1980 and 1987 landings tended to decrease, averaging

10 Henry, F. D. 1985. A progress report on the status of chili pepper

(Sebastes goodei) off California. In Pacific Fisheries Managemen t

Council, Status of the Pacific coast groundfish fishery through

1985 and recommended acceptable biological catches for 1986,

16 p. Pacific Fisheries Management Council, Metro Center,

Suite 420, 2000 S.W. First Avenue, Portland, OR 97201.
28 NOAA Technical Report NMFS 117

30

25

o

020

3

lED 1977

IiliiliI 1980

01983

--L- 1986 -J-.-..--...,-----

)(

15 (J)

(J)

<Xl

E

o 10

CD

5

o US Vancouver Columbia Eureka Monterey Total

INPFC Area

70

60

77 8083 86

Total

77 8083 86

US Vancouver

-+

o ..LL----L~~ ++ __++tt .:.._~'________'+:J=....",____=J-+-=_____~l±___L....:l=________'_ t _

t 77 80 83 86 77 80 83 86 77 80 83 86

ColumDia Eureka Monterey

Year and INPFC Area

10

30 co

E

o

CD 20

0 50

o

o

:: 40 --

Figure 13

Estimates of canary rockfish, Sebastes pinniger, biomass and associated

90% confidence intervals by International North Pacific Fisheries Commission (INPFC) area and year.

about 1,493 t and ranging from 669 to 2,427 t (PacFIN,

1980-873).

The distribution and relative abundance of chilipepper during the survey years showed no significant

concentrations north oflat. 41 'OO'N and relatively high

CPUE values in the Monterey area (Fig. 20). High or

moderate densities occurred in both depth zones, except in 1986 when chilipepper were either absent or

scarce in waters deeper than 183 m. In some years

densities on the upper continental slope substantially

exceeded those on the shelf. Distributions differed little

annually until 1986, when the deep zone contained a

smaller proportion of the population.

Biomass estimates derived from the trawl surveys indicate that this resource was largely confined to the

Monterey area (Fig. 21). The species was absent in the

U.S.-Vancouver area. Low densities of chilipepper were

found in the Columbia area, and only in 1986 did

significant densities occur in the Eureka area. The

Monterey area CPUE averaged about 13.3 kg/km over

the four years, which was 266 and 5 times greater than

mean CPUE's in the Columbia and Eureka areas, re-
Dark and Wilkins: Groundfish off Washington, Oregon, and California 29

By Sex By Depth

_ Tolal (91-368 m)

Slope (184-366 ml

D Shell (9'·184 ml

1600

1200

BOO

• Sexes Comblned

. m Females

o Males

1600

1

1200

i5 800

2. 36 45 615

Length (em)

65

35 45 55

Length (em)

2.

• Total {55-3Be ml

," - Slope (184-366 ml -_.

o Shelf (55-183 ml

lBOO

1980

'BOO

I1200 ~-'-- - 11200

2 g

i 800 BOO

5

z 40:~~~~~~E~ 4~~~~~~~~r 15 25 35 46 65 15

Length (em)

lBOO / ----------------- / (No 'on,'" del. (,am slopo) 1600 ------- - ----

1986

2. 35 45 55

Length (em)

6.

Figure 14

Canary rockfish, Sebastes pinniger, length compositions by year, depth, and sex.

spectively. Biomass estimates in the Monterey area and

over all areas were remarkably consistent for the 4

years; values ranged from 7,567 to 9,799 t in the

Monterey area and from 9,152 to 10,945 t in all other

areas, suggesting that population sizes were relatively

stable. Most of the biomass in the Monterey area was

found on the continental shelf, but from 6% (1986) to

47% (1977) occurred in waters 184-366 m over the

upper continental slope (Table 11). The precision of

biomass estimates for this species was also relatively

poor. Ninety percent confidence intervals ranged from

42 to 82% of the total estimates and CV's overall were
30 NOAA Technical Report NMFS 117

By Sex

2500 2500

SEX

';; 2000 o Females 2000

i Ii!!l!J "ale. i ! 1500 1500

!

f 1000 ~1000

:; .~ .00 500 z z

0 0

0 10 ,. 20 2. 30 3. <0 0

Age (years) 1977

By Depth

DEPTH STRATUM

o Slope (184-219 m)

Sh~1f (91-183 mj

10 10 20 26 30 36 40

Age (years)

DEPTH STRATUM

o Slope (184-219 m)

liii!l! Shall (55-,e3 m)

2000

2800,------,=========;l

!1600

.

~,oao --

500 -

z

-- --

04-,-,-,-Ti_1'I'

10 15 20 25 30 35 40 0 10 15 W 25 30 35 40

Age (years) 19 80 Age (years)

UOO,------------~-_____,

r

ooo

! 1600

1000 -

i .00 z

2000,--------------_____, 2.00,------------------,

16 20 215 30 38 <0

Age (years)

.....--=----------_..

10

1

2000

i 1000

8

! 'ooo~_ml-----------·-------

i 800 z

1983 16 20 26 30 35 <0

Age (years)

10

1

2000

i 1600

1000

f

I 600 z

Figure 15

Canary rockfish, Sebastes pinniger, age compositions by year, depth, and sex.

from 25 to 49%. However, in some INPFC areas and

years CV's approached or exceeded 100%, reflecting

the extremely contagious distribution of the species.

Significant differences in biomass were only detected

between 1977 and 1986 and between 1983 and 1986 in

the Eureka area (Table 7).

Chilipepper length compositions consisted ofseveral

distinct length modes and demonstrated considerable

interannual variability (Fig. 22). The smallest size group

(20-28 cm) was present in 1977 and prominent in

1986. The 28-38 cm category was present in all survey

years. A third group, ranging from 38 to 53 cm, also

occurred in all years to a greater or lesser extent. Length

distributions revealed some aspects of male and female

growth and survival histories. The right-hand mode

consisted almost entirely of large females. Males seldom reach lengths greater than 40 cm, whereas females

commonly attain lengths of 50 cm or greater (Wilkins,

1980). Approximately equal numbers of males and females were present in the group ofsmallest fish. Fish in

the lower portion (28-33 cm) ofthe middle group were

mostly males, while those in the upper portion of the

group were mostly females. This is probably a result of

the differential growth rates between the sexes of this

species noted by Wilkins (1980). The persistent low

incidence of females in that length interval, however,
Dark and Wilkins: Groundfish off Washington, Oregon, and California 31

..-.................---1_...................~.....Io~~i-......."""-..................10_-... SOO OO'N

1977

Bocacclo

Mean CPUE

1980 1983

'-Monterey Bay

40° 00'

[i] Area not sampled

D Nocatch

LI < 6.1 kglkm

• 6.1 - 35.5 kglkm

• > 35.5 kglkm

-l.:=~;;;:;;;;:;:;;;;:;;;;;:..__......_...,............. ~,..._........J- 30° 00'

135° OOw 11]000'

Figure 16

Distribution of bocaccio, Sebastes paucispinis, during 1977, 1980, 1983, and 1986

National Marine Fisheries Service bottom trawl surveys.

could also imply less availability to the trawl during

certain life history stages. In all years except 1977 most

fish were found on the continental shelf. Small fish less

than about 30 em were prevalent in the shallow zone

and seldom seen in samples from the upper continental slope. This observation is similar to that noted in

length compositions for other rockfish species and provides evidence that young rockfish generally first recruit

to fishable populations in shallow water and migrate into

deeper waters only after attaining larger sizes (Moser,

1967; Carlson and Haight, 1976; Boehlert, 1977 and 1980;

Lenarz, 1980; Wilkins, 1980). Samples from the continental slope mainly contained fish larger than 30 em.

In 1977 and 1980, chilipepper ranged from 2 to 22

years old (based on otolith surface readings), but few

specimens older than 13 years were present (Fig. 23).

Age compositions were similar for the two years except

that 2- and 3-year-old fish, observed in 1977, were not

seen in 1980. Following the pattern observed previously

in the depth distribution offish smaller than 30 em, the

age 2-3 fish present in 1977 occurred almost exclusively in the shallow (91-183 m) zone. In each year, age5 fish were dominant and apparently fully recruited to

the sampling trawl. The shape of the age compositions

indicates that variation in year-class strength has not

been extreme, although the 1977 and 1978 year classes
32 NOAA Technical Report NMFS 117

Table 10

Bocaccio, Sebastes paucispinis - Mean catch per unit of effort (CPUE) (kg/km trawled), biomass estimates (metric

tons), 90% confidence intervals (CI), and coefficients of variation (CV in %) of biomass estimates by International

North Pacific Fisheries Commission statistical area, depth stratum, and year.

U.S.-Vancouver Columbia

Depth Mean cr Mean CV

Year stratum (m) CPUE Biomass CI {o/c} CPUE Biomass CI (%)

1977 91-]83 7.4 ],569 0-4,019 0.7 566 55-],078

184-366 0.8 49 3-95 1.1 340 166-515

91-366 5.4 1,618 0-4,068 88.7 0.8 907 369-],444 35.6

]980 55-183 0.5 130 0-291 0.4 475 197-754

184-366 0.4 34 0-98 0.2 68 0-137

55-366 0.5 ]64 0-333 59.6 0.4 544 259-829 31.5

]983 55-]83 1.2 3]3 59-567 0.4 462 ]65-760

184-366 0.2 19 1-37 0.4 ]26 70-]81

55-366 0.9 332 77-587 45.6 0.4 588 286-891 31.0

1986 55-183 0.4 12] 45-198 0.2 240 64--4]6

184-366 0.1 9 0-24 1.3 367 0-1,1]3

55-366 0.4 130 52-208 36.0 0.4 607 0-1,393 55.]

Eureka Monterey Total

Depth Mean CV Mean CV Mean CV

Year stratum (m) CPUE Biomass CI (%) CPUE Biomass Cl (%) CPUE Biomass CI (%)

]977 91-183 0.1 ]3 0-34 5.6 2,159 385-3,933 2.7 4,306 ],3]6-7,297

184-366 0.2 ]0 0-27 28.2 2,914 0-6,344 5.8 3,313 65-6,561

91-366 0.1 22 0-49 72.1 ]0.7 5,073 J,600-8,547 37.4 3.5 7,620 3,482-]1,758 31.5

]980 55-183 3.3 668 ]7]-1,166 4.6 2,956 966-4,946 1.9 4,230 2,164--6,296

184--366 1.3 ]05 12-197 6.2 749 52-],445 1.6 956 253-],659

55-366 2.7 773 270-1,277 37.4 4.9 3,705 1,610-5,799 33.9 1.8 5,186 3,014-7,358 25.1

1983 55-183 0.5 ]42 31-253 1.4 892 400-1,383 0.8 ],809 1,178-2,440

184-366 2.5 ]98 0-468 46.0 5,558 0-]2,786 9.3 5,901 0-13,]34

55-366 0.9 340 57-623 45.9 8.5 6,450 0-]3,696 65.0 3.3 7,710 447-14,972 54.5

1986 55-183 6.4 2,049 0-4,944 7.2 4,756 0-]1,517 2.9 7,166 0-]6,825

184-366 3.0 250 8-492 2.9 371 0-780 1.7 995 80-1,910

55-366 5.7 2,299 0-5,202 75.3 6.5 5,127 0-]],898 78.8 2.7 8,162 0-17,856 70.9

seem to be very much underrepresented in 1980 and

may be unusually weak or unavailable.

Pacific ocean perch - Pacific ocean perch was once

an important rockfish in Washington and Oregon trawl

landings. Landings increased slowly until the early 1960's

when U.S. and Canadian landings from the Vancouver

and Columbia areas peaked at about 8,5001. Intensive

foreign fishing during the late 1960's seriously depleted

stocks, and U.S. and Canadian landings from these

areas plummeted to about 400 tin 1974 (Gunderson et

al. 1977). Since 1978 the U.S. Pacific ocean perch fishery has been managed under a program to rebuild

stock size using annual catch quotas and trip limits to

discourage targeting by the fishery. Optimum yields

and landings for the U.S.-Vancouver and Columbia

areas combined have be~n about 1,300 t since 1987.

From 1977 to 1986, population densities were greatest in the northern portion of the survey area and

generally decreased from north to south, with very low

densities south of Cape Mendocino (Fig. 24). Average

CPUE in the U.S.-Vancouver area (12.0 kg/km) was

considerably larger than in the Columbia area (3.0 kg/

km), the Eureka area (1.0 kg/km), and the Monterey

area «0.1 kg/km). Relatively high densities occurred
Dark and Wilkins: Groundfish off Washington, Oregon, and California 33

10

8

o

o

o

.-: 6 x

(f)

(f)

'" 4 E

o

m

2

01977

mTITIl 1980

01983

1986

US Vancouver Columbia Eureka Monterey Total

20 ,-

15

o

o

q

x

::::.10 1--

(f)

(f)

E'"

o

m

5 -

INPFC Area

h 77 80 83 86 77 80 83 86 77 80 83 86 77 80 83 86 77 80 83 86

US V8ncouver Columbia Eureka Monterey Total

Year and INPFC Area

Figure 17

Estimates of bocaccio, Sebastes paucispinis, biomass and associated 90%

confidence intervals by International North Pacific Fisheries Commission (INPFC) area and year.

in the deep zone throughout the area off Washington

and Oregon in 1977, but in 1980 densities off Oregon

decreased. There was little change in 1983, but by 1986

densities were relatively low everywhere except offWashington. Densities were consistently low in the shallow

depth zone.

Our biomass estimates were based on samples from

waters less than 366 m deep, which did not cover the

full bathymetric range ofthis species. However, in 1977

sampling did occur deeper than 366 m, and results

showed that the average CPUE in the 366-475 m zone

was about 6% of the Pacific ocean perch CPUE in

waters less than 366 m deep (Gunderson and Sample,

1980). So, although our biomass estimates are certain

to be conservative, the failure to sample deeper waters

should not seriously distort our estimates. Almost all of

the estimated biomass occurred in the Vancouver and

Columbia areas, with only small amounts appearing in

the Eureka and Monterey areas (Table 12, Fig. 25).

Biomass was approximately equally divided between

the U.S.-Vancouver area and the Columbia area, even

though the U.S.-Vancouver area is only about 25% as

large as the Columbia area. Major reductions in stock

size apparently occurred in both the U.S.-Vancouver
34 NOAA Technical Report NMFS 117

o

20

1977 70

By Depth

40 60 60

Length (em)

30

/ • Totel (9H366 m)

Slope (184-366 m)

OShell (91-183 ml

200

400

600

800

'000

70

By Sex

_ Sexes Combined

m Females

D Males

/ 1000

_800

g

1

600

;400 ~~-

z~~_~ 20 30 40 60 eo Length (em)

40 60 60 70

Length (em)

30

/ ---It _ Totel (55-366 m)

Slope (184-366 ml

_ 0 Shell (66-'84 m)

-~ 1- - --- -_.- ,

AJ l1. \ ....

o

20

'000

';;)800

!600

iii 400

z 200

1980 70

./

~~~~ 20 30 .co 60 eo

Length (em)

400

BOO

600

1000

o

20 70

(NO 19n9th dtJts from SfOPfJ)

---------------

'000/

n BOO

!600

:D 400

.....

Z2~~~~.~W' 20 30 40 60 80

Length (em) 1983 40 60 eo 70

Length (em)

30

/

--

L/

/

.......... 200

400

600

BOO

'000

'000 1------------- '000

70

e 800

i 600

! "00

Z2~~~~W 20 30 40 50 60

Length (em) 1986 40 50 60 70

Length (em)

30

200

400

BOO

BOO

Figure 18

Bocaccio, Sebastes paucispinis, length compositions by year, depth, and sex.

and Columbia areas between 1977 and 1980. Little

change was observed between 1980 and 1983; the total

estimated biomass in these years was approximately

48% of that in 1977. Another notable reduction in

biomass (a 54% decrease) followed in 1986. Pacific

ocean perch primarily inhabit waters of the upper continental slope; over the four surveys, an average of91 %

of the estimated biomass was found there. The precision of Pacific ocean perch biomass estimates varied

considerably among strata, as was observed in other
Dark and Wilkins: Groundfish off Washington, Oregon, and California 35

By Sex

5OOi---------,=====Jl

By Depth

500,----------,========;]

.00

300

200

100

SEX

Males

D Females

DEPTH STRATUM

Shell (9H83 ml

o Slope (184-366 m)

Figure 19

Bocaccio, Sebastes paucispinis, age compositions by

year, depth, and sex.

o , 2 3 .. 6 e 7 8 9 10 11 12 13 '4 15 0 1 2 3 .. 5 e 7 e 9 10 11 12 13 14 10

Age (years) Age (yeers)

1977

........_-'--.....................""""'I::-:-....~~--"-....._-...........- ... SOO OO'N

?c9,r.l'?

~)'~ ~~ Chlllpepper

Mean CPUE

1977 1980 1983

c

o

L

U

M

B

I

A

R

-Cape Blanco

'Monterey Bay

45° 00'

40° 00'

35° 00'

[i] Area not sampled

D No catch

• < 34.1 kglkm

.34.1-131.9 kglkm

• > 131.9 kglkm

~=~;;;;;;;;;;;;;;::;;;;~----~---,....,....,....-_J- 30° 00'

Figure 20

Distribution of chilipepper, Sebastesgoodei, during 1977,1980,1983,

and 1986 National Marine Fisheries Service bottom trawl surveys.

135° OO'W 129°00' 123°00' 117°00'
36 NOAA Technical Report NMFS 117

12

EEJ 1977

10 IiliiliI 1980

01983

8' 8 a 1988

o

x

<J)

<J)

'" 4

iIi

2

US Vancouver Columbia Eureka Monterey

20----

INPFC Area

15

<3

o

q

x

::::- 10 -

'"

<J)

E'"

o

ii5 5 .. ---._-.----- .- -----...--.-.--- .-- -

t j j ..T---- ----- - ----

77 8083 88

US Vancouver

0.L-----~~--~--L-----------

77 80 83 86 77 80 83 88 77 80 83 86 77 80 83 86

Columbia Eureka Monterey Total

Year and INPFC Area

Figure 21

Estimates of chilipepper, Sebastes goodei, biomass and associated 90%

confidence intervals by International North Pacific Fisheries Commission (INPFC) area and year.

rockfishes, but preCIsiOn was relatively high in most

instances. Confidence limits for total biomass ranged

from 46 to 252% of the point estimates. Coefficients of

variation for total estimates ranged from 27 to 40%. No

significantly different biomass estimates were found for

this species (Table 7).

Pacific ocean perch ranged in length from 11 to 50

cm, but most were between 30 and 48 cm (Fig. 26). As

noted in other species discussed in this study, females

were generally longer than males. Few males were longer

than 45 cm, while fish of 42-49 cm were often the most

abundant female length group sampled. Several modes

were often present due to sexual dimorphism and variable year-class strength. In 1977, 1980, and 1986, a

mode occurred at about 32 cm marking the entry of

substantial numbers of young fish. That was not the

case in 1983 when the population was dominated by

relatively old fish greater than 34 cm and there was

little in the way of new recruitment. This could at least

partly explain the much reduced estimate of biomass in

1986. Only a very small portion of the resource occurred in the shallow zone and our samples showed no

particular trend in size with depth. The use of more

depth strata across the slope would likely have revealed
Dark and Wilkins: Groundfish off Washington, Oregon, and California 37

Table 11

Chilipepper, Sebastes goodei - Mean catch per unit of effort (CPUE) (kg/km trawled), biomass estimates (metric

tons), 90% confidence intervals (CI), and coefficients of variation (CV in %) of biomass estimates by International

North Pacific Fisheries Commission statistical area, depth stratum, and year.

U.s.-Vancouver Columbia

Depth Mean CV Mean CV

Year stratum (m) CPUE Biomass C[ (%) CPUE Biomass CI (%)

1977 9[-183 0.0 0 0.0 0

184-366 0.0 0 0.0 0

91-366 0.0 0 0.0 0

1980

55-183 0.0 0 0.1 87 0-181

184-366 0.0 0 0.0 0

55-366 0.0 0 0.1 87 0-181 65.1

1983 55-183 0.0 0 0.0 0

184-366 0.0 0 0.1 26 0-62

55-366 0.0 0 0.0 26 0-62 79.9

1986 55-183 0.0 0 0.0 0

184-366 0.0 0 0.1 34 0-135

55-366 0.0 0 <0.1 34 0-135 101.4

Eureka Monterey Total

Depth Mean CV Mean CV Mean CV

Year stratum (m) CPUE Biomass C1 (%) CPUE Biomass CI (%) CPUE Biomass CI (%)

1977 91-183 0.6 109 0-293 13.4 4,854 1,828-7,879 3.1 4,962 1,932-7,993

184-366 0.0 0 40.6 4,189 1,581-6,797 7.3 4,189 1,581-6,797

91-366 0.4 109 0-293 96.9 19.6 9,043 5,217-12,868 25.0 4.3 9,152 5,322-12,981 24.7

1980 55-183 2.9 583 0-1,601 13.1 8,316 0-16,805 4.0 8,986 447-17,525

184-366 0.0 0 12.1 1,463 423-2,504 2.5 1,463 422-2,504

55-366 2.1 583 0-1,601 100.0 12.9 9,779 1,238-18,321 52.2 3.7 10,449 1,854-19,044 49.2

1983 55-183 0.1 9 0-26 10.8 6,849 0-13,921 2.9 6,858 0-13,928

184-366 0.1 9 0-23 20.9 2,531 378-4,684 4.3 2,566 413-4,719

55-366 0.1 19 0-39 62.5 12.4 9,380 2,030-16,729 46.9 3.2 9,424 2,075-16,774 46.7

1986 55-183 9.6 3,083 1,408-4,758 10.8 7,126 3,262-10,990 4.1 10,209 4,671-15,748

184-366 3.1 261 0-580 3.5 441 0-989 1.3 736 0-1,605

55-366 8.3 3,344 1,647-5,041 30.4 8.3 7,567 3,675-11,459 30.8 3.6 10,945 5,358-16,533 30.6

a positive relationship between size and depth (Wilkins

and Golden, 1983; Wilkins and Weinberg, 1987).

Ages of Pacific ocean perch were based on otolith

surface readings. Age composition data were available

only for 1977 and 1980 (Fig. 27), from which two features should be noted. In 1977, the 1970 year class

(7-year-olds) was extremely strong. The unusual strength

of that year class was also reported by Wilkins and

Golden (1983) based on a 1979 Pacific ocean perch

survey. They also observed that the 1970 year class was

particularly strong in the Columbia area. Surprisingly,

the 1970 year class was insignificant in the 1980 age

composition. The reason for this discontinuity is unexplained, but sampling error, age determination error,

and heavy commercial exploitation of that specific year

class]] are possible causes. In 1980 more fish younger

than 7 years and fewer fish older than 18 years were

present. Age 4-6 fish occurred in greater numbers in

1980 than in 1977, suggesting improved recruitment

since 1977.

II Demory, R. L., Oregon Department ofFish and Wildlife, Hatfield

Marine Science Center, Newport, OR 97365. Personal commun.,

September 1988.
38 NOAA Technical Report NMFS 117

By Sex By Depth

3000

_ $8JC8$ Combined

Em Females

o Male,

3500 3000 _ TOISI (91-366 rnJ

Slope (l84-366 m)

o Sholf 191-183 ml

30 40 60 60

Length (em)

20

i

2500

22000

1600

l000k~~~IIi!~~ 500o

10

1977 30 ..0 60 60

Length (em)

20

•

i 2500

~2000

'500L~~i"'i---l"iii~ z

§1000 ~~

500

o

10

30 40 50 60

Length (em)

20

_ Total (66-366 mI

.m Slope (184-366 m)

o Shelf 15~H83 mJ

3500

3000

•

~2500

~2000 'i 1500

'~kg~~~~~i~I~~;i~~r? 10

1980

-

30 40 50 00

Length (em)

20

3.00 /1------- ~---_ __ _

.3000

a2500 I ~2000 ,

1500 "'(\J

'OOOL~~~iJlil1~IAlJi!l"'~~e"'\...~-w~ 500

o

'0

30 40 60 eo

Length (em)

----i1--\ 11'---__.--------

20

3500 n 3000

l'

: 2600

5

2. 2000

1roo E /

'~~/~_~~~~~i5;ii~r~ '0

1983 30 40 60 eo

Length (em)

20

3500

~3000

:2600

!2000

i 1500

~,ooo~~~ 500 -

o 10

30 40 50 60

Length (em)

20

3600

co 3000

2500

~2000

g 1500

E

l000~~~~~~~~ 500o

10

1986 30 40 50 60

Length (em)

20

/ -- -

•

I ---- ---

, ----- -

- - --- ... -- r:....

I\.. __ -

Iii ~A \.4 A....~ -- -

500

o 10

'000

1500

2000

3000

2500

3500

Figure 22

Chilipepper, Sebastes goodei, length compositions by year, depth, and sex.

SableHsh - Sablefish has a long history as an important species for the west coast groundfish industry. Annuallandings were less than 6,000 t until the late 1970's

when a peak catch of about 24,000 t was recorded

(Francis12). Sablefish commands a higher price than

12 Francis, R. C. 1985. Status of the sablefish resource of the west

coast and recommendations for management in 1986. Unpub!.

manuscr., 30 p. Northwest and Alaska Fisheries Science Center,

National Marine Fisheries Service, NOAA, 7600 Sand Point

Way NE, Seattle, WA 98115.
Dark and Wilkins: Groundfish off Washington, Oregon, and California 39

By Sex By Depth

SEX -----_._- fIii!il Males

._. . 0 Females

DEPTH STRATUM

Shell (91-183 m)

o Slope (184 -366 m)

'0 IS 20

Age (years) 1977 '0 IS 20Age (years)

10 IS 20

Age (years)

DEPTH STRATUM

~=g • f-----li!iD--------1 0 SloPe (184-366 mJ

- Ill!lI Shelf (55-'83 mJ

~3f----

f2

f

z,

1980

'0 20

Age (years)

f-----------

Figure 23

Chilipepper, Sebastes goodei, age compositions by year, depth, and sex.

most other groundfish species, which enhances its value

to the industry. Volatile markets and prices have resulted in variable landings more recently, but landings

have averaged about 13,123 t during 1980-87 (PacFIN

1980-19873). Landings since 1986 have been limited by

the optimum yield levels set by the Pacific Fishery Management Council.

Sablefish densities were greatest north of Cape

Mendocino, California, in all survey years (Fig. 28).

Densities tended to be greater in the deep zone, but

occasionally high densities were found in small areas

within the shallow stratum. There were annual,

small-scale variations in density distributions, but major

changes over large areas were not noted.

Biomass estimates are probably minimal because significant quantities of sablefish occur in depths greater

than those surveyed (Low et al. 13). A trawl survey ofthe

upper continental slope off Oregon in late summer of

1984 showed that only about 50% of the sablefish biomass in the 110-914 m zone occurred between 110 and

13 Low, L. L., G. K. Tanonaka, and H. H. Shippen. 1976. Sablefish

of the northeastern Pacific Ocean and Bering Sea. Northwest

and Alaska Fisheries Science Center, National Marine Fisheries

Service, NOAA, 7600 Sand Point Way NE, Seattle, WA 98115.

NWAFC Processed Rep., 115 p.

366 m (Raymore and Weinberg, 1990). This would

suggest that the 1977, 1980, and 1983 surveys accounted

for, at most, only about half of the total biomass. Another factor that would contribute to underestimated

biomass is the relatively low vulnerability of at least

some population components to capture by trawl. Large

sablefish may have a lower vulnerability to trawls than

small sablefish (Parks, 1973). Therefore, survey biomass estimates presented herein may be used as indices

of population size (especially for the younger component of the population); however, we caution against

interpreting them as estimates oftotal population abundance. Sablefish population trends varied among INPFC

areas (Table 13, Fig. 29). Biomass levels remained rather

constant in the U.S-Vancouver area. However, in the

Columbia area, biomass increased markedly between

1977 and 1983, only to fall by 57% in 1986. The biomass

peak that occurred in the Columbia area in 1983 was

not observed in other INPFC areas. Instead, 1983 abundance estimates were lower in those areas than in either

1980 or 1986. Trends in the Eureka and Monterey area

were nearly identical. Over all areas, biomass estimates

increased markedly between 1977 and 1980 only to decline thereafter. However, because of the imprecision of

the total biomass estimates, the reality of this decline
40 NOAA Technical Report NMFS 117

.;------............--.... ......."""'l"'~"f_ .............- .....--.................... SOO OO'N

1977 1980 1983

c

o

L

U

M

B

I

A

R

'-Monterey Bay

45° 00'

40° 00'

[±] Area not sampled

D Nocalch

it! < 6.3 kglkm

.6.3-188.3 kglkm

• >188.3kg1km

-\-~::;:::;::::;:::::;::::..,~-P-- ..... __..,-.....""""'..,..__-J- 30° 00'

135° OOw 123°00' 117"00'

Figure 24

Distribution of Pacific ocean perch, Sebastes alutus, during 1977, 1980, 1983, and

1986 National Marine Fisheries Service bottom trawl surveys.

remains in question. Biomass estimates did not differ

significantly between any years in any area (Table 7).

Sablefish caught in trawl samples ranged in length

from 22 to 70 cm; most were between 35 and 55 cm

long (Fig. 30). Because ofsize selection by the trawl and

the absence ofsamples from the deeper portions ofthis

species' bathymetric range, actual mean population

lengths were probably greater than sample mean

lengths. Parks (1973), for instance, found that trawls

failed to sample sablefish longer than 68 cm in the

same proportion as did traps. The use of small mesh

(32 mm) liners in codends probably resulted in the

trawls sampling small sablefish in proportion to their

true abundance. Klein H found that the minimum retention length for 32-mm mesh was 25 cm. Very few

sablefish less than 27 cm occurred in our surveys. Most

sablefish in survey trawl samples are less than 52 cm,

which until recently was considered an unmarketable

size by the industry. Except in 1986, length compositions were bimodal in all years, with modes at about 38

and 46 cm; in 1986, only the ~ode at 38 cm was noted.

14 Klein, S.]. 1986. Selectivity of trawl, trap, longline and set-net

gears to sablefish, Anoplopoma fimlrria. Northwest and Alaska

Fisheries Science Center, National Marine Fisheries Service,

NOAA, 7600 Sand Point Way NE, Seattle, WA 98115. NWAFC

Processed Rep. 86-06, 84 p.
Dark and Wilkins: Groundfish off Washington, Oregon, and California 41

Table 12

Pacific ocean perch, Sebastes alutus - Mean catch per unit of effort (CPUE) (kg/km trawled), biomass estimates

(metric tons), 90% confidence intervals (CI), and coefficients of variation (CV in %) of biomass estimates by

International North Pacific Fisheries Commission statistical area, depth stratum, and year.

U.s.-Vancouver Columbia

Depth Mean CV Mean CV

Year stratum (m) CPUE Biomass CI (%) CPUE Biomass CI (%)

1977 91-183 0.8 165 0-446 1.0 802 42-1,562

184-366 84.1 7,424 0-16,037 19.7 5,854 3,081-8,627

91-366 25.3 7,589 0-16,207 64.8 6.2 6,656 3,870-9,442 22.5

1980 55-183 2.0 525 0-1,294 0.1 96 13-178

184-366 29.1 2,602 0-5,673 10.8 3,245 1,167-5,322

55-366 8.9 3,128 50-6,205 53.7 2.3 3,340 1,260-5,420 35.4

1983 55-183 4.2 1,093 0-3,183 0.0 58 1-114

184-366 30.1 2,693 980-4,407 9.6 2,889 594-5,184

55-366 10.7 3,786 1,262-6,310 37.6 2.0 2,947 651-5,243 43.4

1986 55-183 0.3 73 30-117 <0.1 24 10-37

184-366 12.9 1,141 314-1,968 5.6 1,559 0-8,534

55-366 3.3 1,214 386-2,043 38.3 1.0 1,583 0-8,558 69.8

Eureka Monterey Total

Depth Mean CV Mean CV Mean CV

Year stratum (m) CPUE Biomass CI (%) CPUE Biomass CI (%) CPUE Biomass CI (%)

1977 91-183 0.1 10 0-26 0.0 0 0.6 977 170-1,783

184-366 2.7 220 64-375 <0.1 I 0-2 23.7 13,499 4,595-22,402

91-366 0.9 229 73-385 39.3 <0.1 I 0-2 50.3 6.9 14,475 5,532-23,419 35.5

1980 55-183 0.4 90 0-232 0.0 0 0.3 710 0-1,492

184-366 3.0 238 101-375 <0.1 6 0-12 10.3 6,090 2,587-9,593

55-366 1.2 328 140-515 33.2 <0.1 6 0-12 65.0 2.4 6,801 3,225-10,377 30.2

1983 55-183 0.1 28 0-67 <0.1 6 0-16 0.5 1,184 0-3,276

184-366 4.4 354 4-704 0.0 0 10.0 5,937 3,193-8,680

55-366 1.0 381 29-734 48.8 <0.1 6 0-17 101.0 2.4 7,121 3,835-10,406 27.0

1986 55-183 <0.1 <I 0-1 <0.1 <I 0-1 <0.1 98 52-144

184-366 1.7 141 0-297 1.8 230 0-497 5.3 3,072 0-11,058

55-366 0.4 141 0-298 62.6 0.3 230 0-497 65.4 1.0 3,169 0-11,149 39.9

Data from other studies (Chilton and Beamish, 1982;

Parks and Shaw, 1987; Methot and Hightower15) indicate that fish in the 38 cm mode were primarily age-l

fish and most ofthose in the 46 cm mode were probably

age 2-4 fish. In all years, few fish less than 45 cm were

15 Methot, R., and J. Hightower. 1988. The status of the

Washington-Oregon-California sablefish stock in 1988. In Pacific Fisheries Management Council, Status of the Pacific Coast

groundfish fishery through 1988 and recommended acceptable biological catches for 1989. Appendix B. Pacific Fisheries

Management Council, Metro Center, Suite 420, 2000 S.W. First

Avenue, Portland, OR, 97201.

found in the deep stratum, but those of 45-55 cm were

somewhat more equally distributed between the two

zones. These data and the results of other studies

(McFarlane and Beamish, 1983; Sasaki, 1985) provide

good evidence that sablefish first occur in bays, inlets,

and on the continental shelf at age 1, move off the shelf

and onto the upper slope as they grow older, and move

deeper with increasing age.

Lingcod - Lingcod has always been an important

component of west coast trawl landings, but landings

have recently been less than those of commercially

important rockfish and flatfish species. Landings in-
42 NOAA Technical Report NMFS 117

16

14

12

0

0

3 10

x

::. 8

'"

'"ro

E 6 0

i:i3 4

2

E3J 1977

liliilil 1980

01983

1986

US Vancouver Columbia Eureka Monterey Total

25

20

o

o

0.

-;; 15

'"E'" 10 o

iii

5

INPFC Area

H

77808386 77808386 77808386 77808386 77808386

US Vancouver Columbia Eureka Monterey Total

Year and INPFC Area

Figure 25

Estimates of Pacific ocean perch, Sebastes alutus, biomass and associated

90% confidence intervals by International North Pacific Fisheries Commission (INPFC) area and year.

creased constantly from 806 t in 1963 to 4,146 t in 1983,

but decreased to 2,561 tin 1987 (Pacific Fishery Management Council16; PacFIN, 1983 and 19883). The species is sought by recreational as well as commercial

fishermen.

t6 Pacific Fishery Management Council. 1982. Fishery management plan and supplemental environmental impact statement

for the Washington, Oregon, and California groundfish fishery. Pacific Fisheries Management Council, Metro Center, Suite

420, 2000 S.W. First Avenue, Portland, OR 97201. 320 p.

Based on survey CPUE observations, lingcod densities were always relatively high in the U.S.-Vancouver

and northern Columbia areas (Fig. 31). Elsewhere, high

densities occurred sporadically with little consistency

among years, but abundance dropped notably south of

the Columbia area. Average CPUE for the four surveys

combined was 4.8 kg/km in the U.S.-Vancouver area,

5.4 kg/km in the Columbia area, 1.2 kg/km in the

Eureka area, and 1.7 kg/km in the Monterey area.

Densities were noticeably higher in the shallow zone,

although in some areas, particularly in the U.S.-Van-
Dark and Wilkins: Groundfish off Washington, Oregon, and California 43

By Sex By Depth

_ Sexes Combined -

D Females

o Males

30 40

Length (em)

20

_ Totar 191-365 ml

m Slope 1184-366 ml

OShell 191-183 m} 1400

_'200

iu)oo

~800

z

i800~'/ 200

400

o

/ ~~

10 1977 30 40 60

Length (em)

20

1400

1200

1000

800

30 40 00

Length (em)

20

• Total 166-366 ml

rm Stope (18-4-366 ml

D Shell (65-183 ml ,·tL --------'-----_.-.__. 1200

/

c1QOO

1600

i6OO~~tt 400 Z

200

o

10

1980 30 40

Length (em)

20

-------------1

'400

1200

1000

800 j'/

000

400

200

0

10

/ /

..&.

I

"" / / ... , / /

- ...d.IU~

l/

o 10

/. /

..&~

--1 ""

, - /I ,~

r>

1400

'200

1000

800

800

400

200

o 10 20 30 40

Length (em)

60

1400

m1200

'i!

·'000

!800

li800

z 400

200

1983 20 30 40

Length (em)

30 40

Length (em)

20

~------------_.-

-------

l% -- - --

- ,TAo. 'A l'"

1//, --

'400

«; 1200

'i!

: 1000 l 800

Ii 800

Z 400

200

o 10

1986 30 .co

Length (em)

- - --~------I

20

2004oo~~§!F o 10

800

600

1400

1200

1000

Figure 26

Pacific ocean perch, Sebastes alutus, length compositions by year, depth, and sex.

couver area in 1980 and 1983, lingcod were also quite

abundant in the deep zone. The distribution of biomass in 1986 was clearly more patchy than in earlier

survey years, particularly in the deep zone.

Most of the lingcod biomass occurred in the Columbia area (Fig. 32, Table 14). The major proportion of

the biomass was found in the 55-183 m depth interval

in all areas. Overall, slightly more than 8% of the bio-
44 NOAA Technical Report NMFS 117

By Depth

DEPTH STRATUM

- 0 Slope (184-366 m)

Shell (91-183 m)

By Sex 3000 3000

SEX ;;; 2500 2500

D Females i 2000 Males 2000

! 1500 1500

1000 1000

.00 .00

0 0

0 '0 10 20 2. 30 0

Age (years) 1977

10 15 20

Age (years)

2. 30

3000,-----------------, 3000,----------r=======;l

10 15 20 25 30

Age (years)

DEPTH STRATUM

.------ _.. 0 Slope (184-366 m)

Il!i!il Shell 155-1aa mJ

.,2500

1

2000

1500 -

1000 --

Z 500

1980

_._------

O~~~~~~~~~+'?,~+-r''?'-r-,...J 04-r.,.y.,..L;J.,J,.L,J~,....,..,p.,.i+........c,J,_+'?,~+-r''?-r-r+J o 10 15 25 30 0

Age (years)

n 2600

2000

&. 1600

:; 1000 --

Z 500

Figure 27

Pacific ocean perch, Sebastes alutus, age compositions by year, depth, and sex.

mass was estimated to be deeper than 183 m, but in

certain areas (e.g. the U.S.-Vancouver area in 1983) as

much as 62% occurred in the deep zone. A declining

trend in biomass over time was observed in the U.S.-

Vancouver area, but the most dramatic reduction occurred in the Columbia area, where estimates fell from

12,650 tin 1977 to 1,849 tin 1986. Biomass estimates in

the Eureka and Monterey areas were relatively small

and variable, without a discernable temporal trend.

The dominating influence of the trend in the Columbia area was reflected in the estimates of coastwide

biomass, which also show a steady and precipitous decline of 77% since 1977. However, because of the relatively large confidence intervals around some of the

point estimates, this trend may not be valid. For instance, in 1977 the 90% confidence interval for the

total biomass was ±126% of the point estimate. The CV

in that year was about 70%, but it then decreased steadily

from 47% in 1980 to 12% in 1986. Lingcod densities in

1986 were lower than in other years throughout the

survey area (Fig. 31), suggesting a declining population. The total biomass and Columbia area estimates

for 1986 were significantly smaller than the corresponding 1983 estimates, but Z values for all other paired

comparisons were not significant (Table 7).

English sole - English sole has long been a mainstay

In trawl fisheries of the west coast, but landings have

decreased in the past eight years from 3,242 t in 1980 to

2,474 t in 1987 (PacFIN, 1981 and 19883). Even so,

English sole usually ranked second among flatfish only

to Dover sole in tonnage landed Uow and GeibeI17).

English sole were distributed more evenly throughout the survey area than many other species. Somewhat

higher densities of English sole were often found off

California, south of Cape Mendocino (Fig. 33). The

CPUE averaged over the four surveys ranged from 1.3

(Eureka) to 2.4 (Monterey) kg/km trawled (Table 15).

Densities were lower throughout the survey area in

1977 and 1980, with only scattered pockets of high

densities. In contrast, higher overall abundance in 1983

and 1986 resulted in more uniform distributions; densities were moderate to high over much of the continental shelf. The species was much less densely distributed

in depths greater than 183 m.

Estimates of English sole biomass steadily increased

between 1977 and 1986 in all areas except Monterey,

17 Jow, T., and].]. Geibel. 1985. Progress report on the status of

English sole in California Conception, Monterey, and Eureka

areas. In Pacific Fisheries Management Council, Status of the

Pacific Coast groundfish fishery through 1985 and recommended acceptable biological catches for 1986, 7 p. Pacific

Fisheries Management Council, Metro Center, Suite 420, 2000

S.W. First Avenue, Portland, OR 97201.
Dark and Wilkins: Groundfish off Washington, Oregon, and California 45

.............__...........""""" ~.....Io_~+ ......-""-............-""-.... SOO OO'N

1977 1980 1983

'-Monterey Bay

45° 00'

40° 00'

35° 00'

5ablefish

Mean CPUE

[i] Area not sampled

D No catch

IJ < 38.0 kgJkm

.38.0'110.2kglkm

• > 110.2kglkm

~~;;;;;;;;;;;;;;;;;;;;;;;:;;;;;;:"'--__"'I""""_-.- ...,.-_-J- 30° 00'

135° OOw 129°00' 123°00' 117°00'

Figure 28

Distribution of sablefish, Anoplopoma fimbria, during 1977, 1980, 1983, and 1986

National Marine Fisheries Service bottom trawl surveys.

where biomass decreased 31% between 1983 and 1986

(Table 15, Fig. 34). Estimates derived for the entire

survey area showed continuous increases (1,785 in 1977,

2,598 in 1980, 7,180 in 1983, and 7,313 tin 1986). Only

5% of the estimated biomass occurred in the deep

stratum. English sole, and flatfishes in general, are much

more uniformly distributed than non-flatfishes. Consequently, the precision offlatfish biomass estimates tends

to be much higher. Therefore, trawl surveys are capable of detecting smaller changes in population sizes.

Confidence intervals of biomass estimates were clearly

compressed (Fig. 34), and CV's for the total biomass

estimates were less than 20% (Table 15). More than

half of the biomass estimate pairs that were compared

by Ztests were significantly different (Table 7). Significant changes in abundance took place in all INPFC

areas and the survey area as a whole, giving more validity to the observed trends. Total biomass estimates for

1983 and 1986 were significantly greater than estimates

for 1977 and 1980, lending support to the conclusion

that a major increase in abundance has occurred since

1980. English sole biomass estimates were low, given

the magnitude of commercial landings. Relatively low

vulnerability to the sampling gear and the absence of
46 NOAA Technical Report NMFS 117

50 ------------- --------

[[ill] 1977

mITITI 1980

0 1983

a 1986

40

0-

o

o

.-= 30 x

10

:::::

._._.._-------- :::::

:.'\1

O--'---'''-''''iiiL..E3e..-J=iiliL---'=''L-=iiiliL----E''--'''"''''"''-----'''''- ---=..liiii'----'''"'--

rn

rn

20 o

CD

US Vancouver Columbia Eureka Monterey Total

INPFC Area

70

60

0-50 - o

0.

1 t

++ +t

10 + t

x 40

o ..L+-"--+-'------"+~+ ~±-L.....:=------=_ __=___"______'___ _

77 80 83 86 77 80 83 86 77 80 83 86 77 80 83 86 77 80 83 86

US Vancouver Columbia Eureka Monterey Total

Year and INPFC Area

Figure 29

Estimates of sablefish, Anoplopoma fimbria, biomass and associated 90%

confidence intervals by International North Pacific Fisheries Commission (INPFC) area and year.

sampling throughout the species' bathymetric range

were probably major factors leading to underestimation. The trawl equipment employed in our groundfish

sUIveys was selected to sample rockfish and Pacific hake,

and the roller gear on the footrope may have caused it

to be less efficient for capturing flatfish. Flatfish biomass estimates were derived for the purpose ofidentifying population changes and should be viewed as minimal estimates of abundance.

Lengths of English sole collected in the 1980, 1983,

and 1986 surveys ranged from about 14 to 50 cm with

females predominating at lengths longer than about 29

cm (Fig. 35). Almost all individuals larger than 40 cm

were females. The vast majority of the resource was

located in waters over the continental shelf, so few

observations were available from the deep zone. However, a small sample obtained in 1986 was composed of

fish larger than 32 cm. Little interannual variation in

the length distribution occurred during the three years

of record. The most abundant length classes in 1986

were more broadly distributed than in previous years,

possibly because of the presence of several strong
Dark and Wilkins: Groundfish off Washington, Oregon, and California 47

Table 13

Sablefish, Anoplopoma fimbria - Mean catch per unit of effort (CPUE) (kg/km trawled), biomass estimates (metric

tons), 90% confidence intervals (CI), and coefficients of variation (CV in %) of biomass estimates by International

North Pacific Fisheries Commission statistical area, depth stratum, and year.

U.S.-Vancouver Columbia

Depth Mean CV Mean CV

Year stratum (m) CPUE Biomass CI (%) CPUE Biomass CI (%)

1977 91-183 4.0 848 283-1,413 4.5 3,513 1,955-5,072

184-366 18.9 1,667 0-3,587 12.1 3,605 2,720-4,490

91-366 8.4 2,515 531-4,499 45.2 6.6 7,119 5,385-8,852 14.3

1980 55-183 6.5 1,711 384-3,039 8.1 9,470 3,759-15,182

184-366 8.2 731 136-1,325 16.7 4,988 1,556-8,420

55-366 6.9 2,442 1,023-3,860 33.7 9.9 14,458 7,894-21,022 27.3

1983 55-183 1.6 431 0-938 14.3 16,647 1,375-31,920

184-366 10.2 914 488-1,341 22.3 6,723 3,696-9,751

55-366 3.8 1,345 734-1,956 25.6 16.0 23,371 7,862-38,879 39.3

1986 55-183 6.3 1,740 934-2,547 5.1 6,269 3,529-9,009

184-366 9.9 873 87-1,658 13.3 3,675 2,478-4,873

55-366 7.2 2,613 1,542-3,684 24.2 6.6 9,944 7,009-12,879 17.2

Eureka Monterey Total

Depth Mean CV Mean CV Mean CV

Year stratum (m) CPUE Biomass CI (%) CPUE Biomass CI (%) CPUE Biomass CI (%)

1977 91-183 3.1 548 16-1,079 1.1 389 203-575 3.5 5,298 3,580-7,016

184-366 1.5 117 48-187 5.8 623 400-845 10.5 6,012 3,948-8,076

91-366 2.6 665 131-1,199 46.3 2.2 1,012 728-1,295 16.6 5.4 11,310 8,676-13,944 13.8

1980 55-183 41.2 8,324 0-2,234 24.9 15,815 0-36,808 15.6 35,321 9,824-60,818

184-366 4.3 347 0-708 3.0 366 128-604 10.9 6,431 2,946-9,916

55-366 30.7 8,671 0-22,694 92.6 21.4 16,181 0-37,167 77.5 14.6 41,752 16,047-67,457 36.9

1983 55-183 2.7 832 0-1,669 2.3 1,475 455-2,496 8.2 19,385 4,062-34,708

184-366 19.6 1,571 669-2,472 16.2 1,963 0-4,535 18.9 11,171 7,230-15,113

55-366 6.2 2,403 1,233-3,573 28.4 4.5 3,438 693-6,183 46.7 10.3 30,557 14,783-46,330 30.6

1986 55-183 13.2 4,211 507-7,916 14.4 9,515 899-18,132 8.8 21,736 9,124-34,348

184-366 8.2 693 140-1,246 7.5 948 7-1,890 10.8 6,189 4,317-8,061

55-366 12.1 4,904 1,178-8,631 45.5 13.3 10,464 1,819-19,108 49.4 9.1 27,925 15,190-40,660 27.3

year classes; however, no age data were available to

confirm this.

Dover sole - Dover sole is another species that always has been a key component of trawl landings. In

recent years, Dover sole and arrowtooth flounder,

Atheresthes stomias, were the only two flatfishes that have

contributed to major increases in landings. From 1963

to 1968, Dover sole landings averaged about 6,400 t,

but in 1969 landings rose to 8,643 t and continued to

increase, reaching 20,719 tin 1983 before declining to

18,391 t in 1987 (Pacific Fishery Management Counci116; PacFIN, 1984 and 19883). Much of this increase

was due to the expansion of the Dover sole fishery to

new grounds in deep waters, especially off northern

California. Presently, Dover sole landings are exceeded

only by Pacific hake landings.

Most of the Dover sole resource occurred on the

upper continental slope in the deeper portions of the

survey area (Fig. 36). There were notable interannual

variations in distribution and density. Higher densities

were found in the deep stratum throughout much of

the survey area in 1977 but densities at all depths were

uniformly low in 1980. By 1983 densities were higher

and even more uniform than in 1977. Overall density
48 NOAA Technical Report NMFS 117

By Sex By Depth

70

• Total (91-366 m)

Slope (184-366 ml

0 .. Shell (91-183 rnJ

-10 50 60

Length (em)

o~;i-~F 20 30

1977 40 60 60 70

Length (em)

30

/ _ Selles Combined

m Females

D Males

f-

-- -- - -

o

20

• Tolal (55-366 mj

Iii Slope t184 -366 ml

OShell (55-183 m)

30 40 50 60

Length (em)

70 30 40 50 60

Length (em)

70

1------------- ---- --

o -

40 60 60

Length (em)

70 30 40 50 60

Length (em)

70

30 40 50 60

Length (em)

70 30 40 50 BO

Length (em)

70

Figure 30

Sablefish, Anoplopoma fimbria, length compositions by year, depth, and sex.

rose again in 1986, with much ofthe increase occurring

south ofWashington. In all years, higher densities were

observed in the Monterey area.

These values should be considered minimal estimates

as for English sole. A bottom trawl survey of the upper

continental slope conducted in the Columbia area in

1984 between DO and 914 m (Raymore and Weinberg,

1990) indicated that 51% of the estimated Dover sole

biomass occurred between 366 and 914 m, a depth

interval not sampled by the coastwide triennial surveys.
Dark and Wilkins: Groundfish off Washington, Oregon, and California 49

....--......_ ..........--...........l...-..:~ ....."'T"'l~_....--....._-_....,.. SOO OO'N

40° 00'

45° 00'

35° 00'

Gt cape Blanco

R ... ---.- ---+

~M ~c.pe M"~;,, o , N "

T', "" E ' ""

\~\ Monterey Bay

c

o

L

U

M

B

I

A

1980 1983

Lingcod

Mean CPUE

1977

[i] Area not sampled

D No catch

• < 7.2 kglkm

• 7.2·33.5 kglkm

• > 33.5 kglkm

~=:;:::;::::;::::;:~_......_--"!~~~ __,....-_J. 30° 00'

135° OO'W 129°00' 123°00' 117°00'

Figure 31

Distribution of lingcod, Ophiodon elongatus, during 1977, 1980, 1983, and 1986

National Marine Fisheries Service bottom trawl surveys.

This suggests that our biomass estimates are only about

half the level they would be had sampling occurred as

deep as 914 m. In all years most of the biomass was in

the Columbia area (Table 16, Fig. 37), more because of

the area's size than higher fish density. As with English

sole, the population size of Dover sole increased during

the survey period in all areas except the U.S.-Vancouver

area. The 29% decrease in estimated biomass (from

15,054 to 10,698 t) observed between 1977 and 1980

was reversed in 1983 and 1986 when total biomass estimates increased to 19,241 and 25,121 t, respectively.

Thus, estimated total stock size increased between 1980

and 1986. The relatively uniform distribution of Dover

sole led to low estimates of variance (overall CV's were

less than 10%) and narrow confidence limits (15% or

less of the total biomas,s estimates). Biomass estimates

for this species were the most precise in this study. The

total biomass estimates for all years were significantly

different from one another, giving credibility to the major

biomass increases observed since 1980 (Table 7). Many

significant interannual differences in biomass were observed in all INPFC areas except the U.S.-Vancouver

area. Thus, the increasing trend in biomass was nearly

coastwide during the study period.

Dover sole ranged in length from 15 to 64 cm, with

most fish between 25 and 45 cm (Fig. 38). Females were
50 NOAA Technical Report NMFS 117

20

15

o

o

Cl.

E:ZJ 1977

Iilillil 1980

01983

1986

x

.::: 10 (J)

(J)

E'"

o

en

5

O..LLl.lliill~L12lliiliLE3.....-=:==--£lliliL.=-__------Lill

us Vancouver Columbia Eureka Monterey Total

INPFC Area

40

30

o

o

Cl.

x

.::: 20 (J)

(J)

E'"

o

en

10

+

77 8083 86

US Vancouver

+

o-LL_+L-+----=::-+-=-----.LJ--+--o...-±--"'=.--=o<---'-----=-T-"-..~+--<-=--~'------"-- 77 8083 85 77 8083 85 77 8083 85 77 8083 86

Columbia EureKa Monterey Total

Year and INPFC Area

Figure 32

Estimates of lingcod, Ophiodon etonga/us, biomass and associated 90%

confidence intervals by International North Pacific Fisheries Commission (INPFC) area and year.

larger than males on average, and they predominated

at lengths greater than about 38 cm. Males tended to

predominate in the 25-35 cm length range, which may

be a result of differential growth rates or perhaps unequal vulnerability to the sampling gear. The length

distribution shifted somewhat toward larger sizes when

samples from the deep zone were isolated, displaying a

tendency for length to increase with depth. The population was composed of a greater proportion of small

fish «28 cm) in 1983 and 1986 than in 1980, but

otherwise few interannual differences in size composition were observed.

Rex sole - Landings of rex sole, Errex zachirus, have

varied between 1,200 and 1,745 t from 1981 to 1987

(PacFIN, 1982-19883). Although the species is common in mixed species trawl catches, it usually ranks

only fourth or fifth among flatfish landings. This remained true in 1987, when the ex-vessel price was about

$0.38 per pound, which was higher than that paid for

Dover sole or arrowtooth flounder-the two most abundant species in the landings (PacFIN, 19883).

Rex sole densities displayed notable interannual variability (Fig. 39). Densities in 1977 and 1980 were lower

in all INPFC areas than in subsequent years. However,
Dark and Wilkins: Groundfish off Washington, Oregon, and California 51

Table 14

Lingcod, Ophiodon elongatus - Mean catch per unit of effort (CPUE) (kg/km trawled), biomass estimates (metric

tons), 90% confidence intervals (CI), and coefficients of variation (CV in %) of biomass estimates by International

North Pacific Fisheries Commission statistical area, depth stratum, and year.

U.S.-Vancouver Columbia

Depth Mean CV Mean CV

Year stratum (m) CPUE Biomass CI (%) CPUE Biomass CI (%)

1977 91-183 0.7 2,260 0-5,298 15.8 12,343 0-33,121

184-366 0.2 17 0-38 1.0 307 85-529

91-366 7.6 2,277 0-5,315 66.2 11.7 12,650 0-33,429 90.7

1980 55-183 3.6 951 47-1,854 7.4 8,548 0-19,450

184-366 4.4 393 0-1,059 0.6 167 41-292

55-366 3.8 1,343 274-2,413 46.5 6.0 8,715 0-19,617 73.6

1983 55-183 4.4 1,152 689-1,615 2.9 3,419 2,096-4,741

184-366 7.3 652 194-1,110 2.0 597 333-862

55-366 5.1 1,805 1,172-2,438 20.8 2.7 4,016 2,669-5,363 20.2

1986 55-183 3.5 974 735-1,213 1.4 1,698 1,227-2,169

184-366 0.4 31 0-64 0.5 151 0-334

55-366 2.8 1,005 764-1,246 14.5 1.2 1,849 1,355-2,343 16.0

Eureka Monterey Total

Depth Mean CV Mean CV Mean CV

Year stratum (m) CPUE Biomass CI (%) CPUE Biomass CI (%) CPUE Biomass CI (%)

1977 91-183 1.4 242 63-420 3.3 1,234 0-4,203 10.5 16,080 0-37,055

184-366 0.4 32 0-71 2.7 279 0-675 l.l 635 214-1,055

91-366 l.l 274 93-455 38.3 3.2 1,513 0-4,705 33.4 8.0 16,714 0-37,693 69.3

1980 55-183 1.8 356 0-752 0.8 504 176-832 4.6 10,359 0-21,308

184-366 0.8 67 0-168 1.7 210 7-413 1.4 836 151-1,521

55-366 1.5 423 19-827 55.1 0.9 714 332-1,095 32.0 3.9 11,195 227-22,163 57.7

1983 55-183 1.3 391 47-735 2.3 1,442 399-2,485 2.7 6,404 4,639-8,169

184-366 1.4 108 18-197 0.2 26 0-62 2.3 1,384 862-1,905

55-366 1.3 499 149-848 38.2 1.9 1,468 425-2,511 42.4 2.6 7,788 5,953-9,622 14.2

1986 55-183 0.8 253 136-371 0.8 516 245-787 1.4 3,441 2,772-4,110

184-366 0.9 79 0-210 1.0 124 0-349 0.7 385 10-761

55-366 0.8 332 170-494 28.1 0.8 641 313-968 30.2 1.2 3,826 3,083-4,569 11.7

in all years the Monterey area was the most important

region for rex sole. In contrast, the U.S.-Vancouver

area always contained lower densities. As overall biomass increased in 1983 and 1986 (Fig. 40), densities in

the Monterey, Eureka, and Columbia areas increased

markedly. Increases in biomass resulted in the same

types of distributional changes that have been noted

for other flatfishes; the distribution became more homogeneous and young fish were more abundant in the

55-183 m depth zone.

Rex sole biomass followed the pattern observed in

other flatfish species, with major increases occurring in

1983 and 1986 (Fig. 40, Table 17). Little change was

observed in the U.S.-Vancouver area, but significant

increases in abundance occurred in all areas to the

south (Table 7). The greatest percentage change took

place in the Eureka area, where the 1986 biomass was

about ten times greater than the 1977 and 1980 estimates. The overall rex sole biomass estimate increased

by 254% between 1980 and 1986. Variances were relatively small; CV's for total biomass estimates were less

than 12%.

Rex sole ranged in length from 10 to 48 cm; most

occurred in a single mode between 20 and 33 cm (Fig.
52 NOAA Technical Report NMFS 117

........----............- ...........~-.....,~+ ......- .....----.......... 50000'N

1977

English Sole

Mean CPUE

1980 1983

~~VANCOUV R

Pk mb• R;,,, ~-----f-

~)Gt cape Blanco

R . --,..-----t-

~c,P' M"dodoo

N' T(

E "

\1

\ Monterey Bay

"

40° 00'

35° 00'

[i] Area not sampled

D Nocatch

[ill < 5.7 kglkm

.5.7-13.9 kglkm

• > 13.9 kglkm -+_-_...._-.,...__-.,............,_.,....... ---~ 30° 00'

135°00'W 117"00'

Figure 33

Distribution of English sole, Pleuronectes vetulus, during 1977, 1980, 1983, and 1986

National Marine Fisheries Service bottom trawl surveys.

41). Differential growth between sexes was similar to

that found in other flatfishes; females were generally

larger than males and dominated at sizes greater than

28 em. Again, little interannual variation in length composition was apparent.

Arrowtooth Flounder - Historically, arrowtooth

flounder has been considered a low value species and

typically was used in the reduction industry. Landings

have been small, amounting to only a few hundred tons

annually. However, landings began to increase in the

early 1980s and in 1987 they were more than triple

historical levels at 2,831 t (PacFIN, 19883; Coleman and

Raymore18). Although that was still a relatively low utilization rate, an expanding market would lead one to

anticipate continued increases in landings.

Arrowtooth flounder occurs mainly in the Gulf of

Alaska. The area covered by these surveys is at the

southern extreme of its range. A distinct latitudinal

cline in arrowtooth flounder density was observed off

the west coast from 1977 to 1986 (Fig. 42). On average,

18 Coleman, B. A., and P. A. RaymoreJr. 1990. An investigation of

the history and population trends for the Pacific west coast

arrowtooth flounder (Atheresthes stomias) resource from 1975-

1986. Unpubl. manuscr., 72 p. Alaska Fisheries Science Center,

National Marine Fisheries Service, NOAA, 7600 Sand Point

Way NE. Seattle, WA 98115.
Dark and Wilkins: Groundfish off Washington, Oregon, and California 53

Table 15

English sole, Pleuronectes vetulus - Mean catch per unit of effort (CPUE) (kg/km trawled), biomass estimates (metric

tons), 90% confidence intervals (CI), and coefficients of variation (CV in %) of biomass estimates by International

North Pacific Fisheries Commission statistical area, depth stratum, and year.

U.S.-Vancouver Columbia

Depth Mean CV Mean CV

Year stratum (m) CPUE Biomass C[ (%) CPUE Biomass C[ (%)

1977 91-183 0.3 63 26-99 0.8 612 300-924

184-366 0.1 8 1-14 0.8 238 75-400

91-366 0.2 71 34-108 30.5 0.8 849 501-1,198 24.4

1980 55-183 2.1 556 0-1,149 1.1 1,262 777-1,747

184-366 0.2 23 0-51 0.2 53 0-JJ2

55-366 1.6 578 0-1,170 58.6 0.9 1,315 826-1,804 20.0

1983 55-183 2.4 634 322-945 2.0 2,271 1,882-2,660

184-366 0.5 41 0-114 0.5 158 39-278

55-366 1.9 674 360-988 27.7 J.7 2,430 2,025-2,834 10.0

1986 55-183 3.7 1,022 808-1,235 2.2 2,733 2,235-3,232

184-366 0.2 21 3-39 0.5 134 33-235

55-366 2.8 1,043 828-1,257 11.8 1.9 2,867 2,360-3,374 10.6

Eureka Monterey Total

Depth Mean CV Mean CV Mean CV

Year stratum (m) CPUE Biomass Cl (%) CPUE Biomass CI (%) CPUE Biomass C[ (%)

1977 91-183 <0.1 3 0-8 2.0 829 378-1,280 0.9 1,507 1,005-2,008

184-366 0.0 0 0.3 33 0-73 0.5 278 113-443

91-366 <0.1 3 0-8 96.2 1.6 862 409-1,314 24.6 0.8 1,785 1,261-2,308 16.7

1980 55-183 0.5 98 27-169 0.9 558 320-796 1.1 2,474 1,708-3,240

184-366 0.1 5 0-9 0.4 45 5-85 0.2 125 52-198

55-366 0.4 102 31-174 37.5 0.8 603 362-844 23.9 0.9 2,598 1,827-3,369 17.5

1983 55-183 2.4 739 469-1,008 5.0 3,168 2,224-4,111 2.9 6,811 5,718-7,903

184-366 0.2 13 1-26 1.3 156 0-331 0.6 369 158-579

55-366 2.0 752 482-1,022 21.2 4.4 3',324 2,366-4,281 17.2 2.4 7,180 6,069-8,291 9.3

1986 55-[83 3.4 1,078 871-1,285 3.5 2,285 1,824-2,746 2.9 7,118 6,250-7,987

184-366 0.2 18 6-29 0.2 23 3-42 0.3 195 87-303

55-366 2.7 1,096 888-1,303 11.3 2.9 2,308 1,846-2,769 12.0 2.4 7,313 6,439-8,188 7.2

densities in the U.S.-Vancouver area (14.5 kg/km) were

much greater than in the Columbia (3.5 kg/km), Eureka (0.5 kg/km), or Monterey (0.1 kg/km) areas.

Highest densities were found north of the Columbia

River in all years, and low densities occurred south of

Cape Blanco, Oregon; the species was absent in survey

samples from south of San Francisco Bay (lat. 37°30'N).

We concluded that both depth zones provided important habitat because densities in the shallow ZOne were

usually commensurate with densities in adjacent sections ofthe deep zone. Densities and distributions were

similar throughout the study period.

The biomass estimates (Fig. 43, Table 18) of this

study are conservative. The aforementioned survey of

the continental slope in 1984 (Raymore and Weinberg,

1990) indicates that over one third of the arrowtooth

flounder biomass could occur between 366 and 549 m,

a depth interval not covered in this study. Almost all of

the estimated arrowtooth flounder biomass occurred in

the U.S.-Vancouver and northern Columbia areas (Fig.

43). In all four years, biomass estimates were similar in

the U.S.-Vancouver area and the Columbia area.

Declines in biomass occurred in these two areas between 1977 and 1983; the 1983 biomass estimates were
54 NOAA Technical Report NMFS 117

10

c:J 1977

lliiliil 1980 8 D 1983

0

0 1986 0

.-: 6 x

::::.

(J)

(J)

'" 4 E

g

ill

2

US Vancouver Columbia

INPFC Area

10

8

o

o

o

-- 6 x

(J)

(J)

'" 4 E

o

iIi

2

o.k-~------------=''=--------------- 77 80 83 86 77 80 83 86 77 80 83 86 77 80 83 86 77 80 83 86

US Vancouver Columbia Eureka Monterey Total

Year and INPFC Area

Figure 34

Estimates of English sole, Pleuronecles velulus, biomass and associated

90% confidence intervals by International North Pacific Fisheries Commission (INPFC) area and year.

less than 30% of the 1977 estimates. That trend was

contrary to what was observed for other flatfishes. Increased fishing mortality may have played a role in

reducing population size, or the conditions which favored high production in English, Dover, and rex soles

during those years may not have benefitted arrowtooth

flounder populations in this region. Another possibility

is that the apparent reduction in stock size in 1983 was,

instead, a northward displacement of this more northerly distributed species brought on by the unusually

warm water temperatures of that year. The latter hypothesis appears weak based on the analysis of flatfish

distribution and water temperatures discussed in the

following section.

The total biomass estimate rose in 1986 to 9,812 t,

representing an 86% increase from the 1983 level, but

that was still only 62% of the 1977 estimated abundance. Variances associated with the total biomass estimates tended to be larger than for the other flatfishes,

with CV's ranging from about 7 to 30%. Confidence

intervals also were generally wider and fewer pairs of

biomass estimates generated significant Zvalues (Table
Dark and Wilkins: Groundfish off Washington, Oregon, and California 55

By Sex By Depth

• Tolel 155-366 ml

m Slope (18. -366 m)

OShell 155-183 m)

• Se~u ComblneCl

W Femetes

o Males

10 20 30 40

Length (em)

fiO 10

1980 20 30 .0

Length (em)

00

30 40

Length (em)

20

.4

a

!3

z

j2~~~ 1

o 00

1983 30 .0 '0

Length (em)

10 20

30 40

Length (em)

20

·--A._----- - .4

g

~3

!2

o~~~ 10 20 30 40 50~~~w 10

Length (em) 19 8 6

Figure 35

English sole, Pleuronectes vetulus, length compositions by year, depth, and sex.

7). The total biomass estimate for 1983 was significantly

smaller than both the 1977 and 1986 estimates. Thus,

the indicated major decline in total abundance between 1977 and 1983 and subsequent recovery in 1986

can be accepted.

Length data, available only for 1980 and 1986, showed

considerable variability because of small sample sizes

(Fig. 44). Arrowtooth flounder ranged in length from

11 to 80 cm, but most were between 15 and 60 cm.

Several length modes were present in both years. Small

arrowtooth flounder of 18-22 cm, which were absent in

1980, were abundant in 1986 and probably represent

the recruitment of a relatively strong year class. Strong

modes between 28 and 55 cm suggest that highly variable recruitment is common. Almost all specimens

greater than 50 cm were females. As with most other

groundfish species, length and bottom depth are

strongly associated. Virtually all specimens less than 25

cm and most less than 40 cm were found on the continental shelf. Although some of the largest specimens

were captured in the shallow stratum, most ofthe larger

fish inhabited the upper continental slope.
56 NOAA Technical Report NMFS 117

.........-""-.................._-......'r':'......"""'r'~t--............- ......................... SOO OO'N

[!] Are. not sampled

o Nocalch

WI <39.4kgl1<m

.39.4-92.1 kgl1<m

• > 92.1 kgl1<rn

19n 1980 1983

40° 00'

35° 00'

+ ...,........ ...._-po-_..........-,..."'I"""__...-I~ 30° 00'

135° DOW

Figure 36

Distribution of Dover sole, Microstomus pacificus, during 1977, 1980, 1983, and 1986

National Marine Fisheries Service bottom trawl surveys.

Sea Temperatures and Groundfish Distribution

We examined the relationship between bottom temperature and fish distribution as a factor that might

explain some of the observed interannual variability in

distribution. The period spanned by this study was of

particular interest because a strong £1 Nino phenomenon occurred in 1983, resulting in an environmental

anomaly that could have stimulated observable changes

in distribution.

Unfortunately, bottom temperature data are sparse

and were not always collected in a way that adequately

represented the full range of latitudes and depths surveyed. As previously mentioned, bottom temperature

data collected during the 1977 survey were excluded

from this analysis. Bottom temperatures were collected

from 62 of 586 hauls (11 %) in 1980, 92 of 596 hauls

(15%) in 1983, and 202 of 569 hauls (36%) in 1986.

Temperatures were averaged by 0.5° latitudinal intervals for each year (Fig. 45). Surface temperatures generally decreased from lat. 3TOO' to 39°30'N, remained

relatively constant from lat. 39°30'N to 44°00'N, and

increased northward before they decreased again at the

northern limit of the survey area. The area off Califor-
Dark and Wilkins: Groundfish off Washington, Oregon, and California 57

E2l 1977

25 !iliilil 1980

0 1983

1986

x

:::. 15

<fJ

<fJ

E'"

o 10 iii

5

o

US Vancouver Columbia Eureka Monterey Total

INPFC Area

30

25

0

g 20 ~.

x

:::. 15 <fJ

UJ

'" tt E

0 10 iii + 5 +

+t++

0 77 8083 86 77 8083 86

us Vancouver Columbia

77 8083 86

Eureka

t

+ +

+

77 8083 86

Monterey

t

t

t

77 80 83 86

Total

Year and INPFC Area

Figure 37

Estimates of Dover sole, Microstomus pacificus, biomass and associated

90% confidence intervals by International North Pacific Fisheries Commission (INPFC) area and year.

nia is known for strong upwelling during the summer,

which depresses surface temperatures (Ingraham and

Love, 1978). Upwelling weakens off northern Oregon

and Washington. Reduced temperatures in the extreme

northern portion of the survey area may have resulted

from mixing from strong tidal flows in the vicinity of

the Strait ofJuan de Fuca. Bottom temperatures, on the

other hand, usually decreased steadily with increasing

latitude. Both surface and bottom temperatures were

generally warmer coastwide in 1983 than in the other

survey years, as a result of the El Nino event. Surface

temperatures off Oregon and Washington were unusually warm in 1983; means ranged from 2 to 6°C higher

than those observed in previous surveys.

The temperature regime preferred by each species

was examined by plotting CPUE against bottom temperatures. During 1980, 1983, and 1986, bottom temperatures usually ranged from 5.5 to 1l.0°C. The flatfishes were most dense where temperatures were

mid-range, with highest CPUE observations occurring

between 6.5" and 8.0°C in the "normal" years of 1980

and 1986 (Fig. 46). However, in 1983 all flatfish species

were most densely distributed at about 9.0°C, suggesting that those species did not avoid unusually warm
58 NOAA Technical Report NMFS 117

Table 16

Dover sole, Microstomus pacificus - Mean catch per unit of effort (CPUE) (kg/km trawled), biomass estimates

(metric tons), 90% confidence intervals (CI), and coefficients of variation (CV in %) of biomass estimates by

International North Pacific Fisheries Commission statistical area, depth stratum, and year.

U.S.-Vancouver Columbia

Depth Mean CV Mean CV

Year stratum (m) CPUE Biomass CI (%) CPUE Biomass CI (%)

1977 91-183 2.7 576 220-933 6.2 4,895 3,878-5,911

184-366 15.1 1,330 982-1,678 12.1 3,592 2,824-4,359

91-366 6.4 1,907 1,419-2,395 15.2 7.9 8,486 7,221-9,752 9.0

1980 55-183 2.3 595 108-1,082 2.9 3,326 2,613-4,038

184-366 17.6 1,574 713-2,436 5.2 1,565 748-2,381

55-366 6.2 2,170 1,213-3,126 23.1 3.3 4,890 3,839-5,942 12.7

1983 55-183 2.7 715 225-1,206 4.2 4,911 3,817-6,006

184-366 10.8 967 594-1,340 14.5 4,372 3,218-5,525

55-366 4.8 1,682 1,088-2,276 20.6 6.3 9,283 7,722-10,843 10.0

1986 55-183 2.3 650 509-791 6.2 7,616 6,347-8,885

184-366 8.7 768 227-1,308 9.8 2,716 1,753-3,679

55-366 3.9 1,418 864-1,971 22.0 6.9 10,332 8,772-11,892 9.0

Eureka Monterey Total

Depth Mean CV Mean CV Mean CV

Year stratum (m) CPUE Biomass CI (%) CP E Biomass CI (%) CP E Biomass C1 (%)

1977 91-183 1.9 336 78-594 3.5 1,238 947-1,528 4.6 7,045 5,909-8,180

184-366 10.9 875 260-1,489 18.8 2,213 1,677-2,750 13.6 8,010 6,866-9,154

91-366 4.7 1,211 554-1,868 32.0 7.0 3,451 2,849-4,052 10.3 7.1 15,054 13,445-16,664 6.4

1980 55-183 2.1 430 171-689 2.2 1,375 797-1,952 2.5 5,725 4,672-6,778

184-366 7.9 630 364-897 10.0 1,203 557-1,850 8.4 4,973 3,684-6,262

55-366 3.8 1,060 705-1,416 19.5 3.4 2,578 1,725-3,431 19.7 3.7 10,698 9,047-12,349 9.3

1983 55-183 3.0 911 503-1,320 3.4 2,155 1,251-3,059 3.7 8,692 7,157-10,228

184-366 24.9 1,991 1,277-2,704 26.6 3,220 2,309-4,130 17.8 10,549 8,938-12,160

55-366 7.6 2,902 2,098-3,706 16.1 7.1 5,375 4,113-6,636 14.0 6.5 19,241 17,032-21,451 6.9

1986 55-183 7.6 2,433 1,896-2,970 7.7 5,504 3.812-6,295 6.3 15,752 13,536-17,968

184-366 26.6 2,244 1,383-3,106 28.8 3,641 2,178-5,104 16.3 9,370 6,855-11,886

55-366 11.6 4,677 3,687-5,667 12.3 11.0 8,695 6,829-10,560 12.7 8.2 25,121 21,824-28,418 7.8

temperatures by migrating to deeper or more northern

waters. Water temperatures in 1983, though higher,

may still have been within the comfort range for flatfishes and thus failed to trigger major avoidance movements.

Sablefish seemed to demonstrate stronger temperature preferences than flatfishes during the three years.

While some sablefish clearly inhabited waters warmer

than 9'e in 1983, highest densities generally occurred

in waters colder than 8.0'e, which was consistent with

the other two years (Fig. 47). In 1983, 37% of the

estimated biomass occurred in the 184-366 m depth

zone compared to only 15% in 1980 and 22% in 1986

(Table 13). This information suggests that sablefish

responded to the £1 Nino conditions in 1983 by moving

down the continental slope to cooler habitats. Because

only a portion of the sablefish population was sampled

by the triennial surveys, it is uncertain how the population as a whole reacted to the warmer conditions.

The greatest densities oflingcod were found at slightly

different temperatures each year (Fig. 47). Highest

epu£ values were observed between 7' and 8° in 1980,

8° and 10' in 1983, and 6.5° and 7.5°e in 1986. The

depth and latitudinal distribution of lingcod was similar in all years, suggesting that it also did not seek

different habitat in response to warming in 1983. Ling-
Dark and Wilkins: Groundfish off Washington, Oregon, and California 59

By Sex By Depth

• Total (55-366 m)

m Slope (184-366 rnJ

o SheH 15~H84 ml '0

• Sexes Combined

riiJ Famale.

o Male.

5

Ie

o~----_o--~~EoE---~---~- l:~'~=~

16 26 ~6 66 60 26 35 45 00 M

Length (em) 198 0 Length (em)

10 '0 o _

_ 8-

g

i e

Io~~~ 10 26 30 46 60 o~~~ 16 26 U 40 65 M

Length (em) 1983 Length (em)

35 45 55 t15

Length (em)

_I-~ -0 --

'0 10

.. 8

6

• 4

z

0 0

'6 26 36 -. 66 06 16 26

Length (em) 1986

Figure 38

Dover sole, Microstomus pacificus, length compositions by year, depth, and sex.

cod are relatively sedentary and, like flatfishes, are closely

associated with a particular substrate (generally hard

bottom). A strong substrate preference could have inhibited movement in response to the range oftemperatures observed during the study period.

We could not clearly demonstrate that Pacific hake

avoided the warmer temperatures of 1983. This species

occurred over a broad temperature range in 1983, and

its highest densities that year were found in water warmer

than in 1980 and 1986 (Fig. 47). Latitudinal shifts in

densities or biomass are, to a large extent, related to

population age composition, which would tend to confound any attempt to relate distribution and temperatures. While we noted that three-year-old hake, which

are not normally found in the northern portion of the

survey area, were clearly more prominent there in 1983,

an explanation is elusive. The temperature regime could

have played a role, as could have the unusually large

size of the 1980 year class. We have observed that large

year classes often occupy a greater latitudinal range

than do less abundant ones.

The five rockfish species examined also failed to

show any pronounced changes in density that might be

considered a response to changes in the temperature

regime. The 1983 distributions of each of the five rockfishes were spread over a broader range of tempera-
60 NOAA Technical Report NMFS 117

.,...--..........._ ...........--......~::-..... ................._ ....................-- SOO OO'N

)'<2 .9)'

"~;~ Rex Sole

Mean CPUE

[.!J Area not sampled

D No catch

• < 12.3·20.4 kglkm

.12.3-20.4 kgikm

• > 20.4 kgikm

1977 1980 1983

c

o

L

U

M

B

I

A

-~

40° 00'

35° 00'

~_~__"""'''''' '''''''_-__'''''''''''''-_''I'''""__-~ 30° 00'

135° OOW 129°00' 123°00' 117°00'

Figure 39

Distribution of rex sole, Errex zachirus, during 1977, 1980, 1983, and 1986 National

Marine Fisheries Service bottom trawl surveys.

tures, and highest CPUE tended to be associated with

slightly warmer water than was observed in the other

two years (Fig. 48). Coupled with the lack of any indication of depth or latitudinal shifts in their distribution,

this would indicate that these rockfishes remained on

their usual grounds in 1983 and endured the influx of

warmer water.

From this examination, only sablefish exhibited a

clear response to warmer conditions brought on by the

1982-83 El Nino. Sablefish is a relatively mobile species

that commonly undergoes seasonal bathymetric migrations (Heyamoto and Alton, 1965; Alton, 1972; Tuponogov and Kodolov, 1983) and moves considerably

within the water column. Although its sensltlVlty to

temperature may prevail over its responses to other

habitat parameters, the species is known to tolerate a

wide temperature range. Pacific hake shares many behavioral characteristics with sablefish, and there is some

evidence that the large 1980 year class might have sought

cooler temperatures through a general northward movement. Pacific hake data will have to be reviewed by age

group to interpret the effects of temperature on distribution. We were not able to detect an aversion to the

warm conditions present in 1983 in true demersal species (flatfishes, lingcod, and rockfishes). We surmise

that other features of their habitat exerted stronger
Dark and Wilkins: Groundfish off Washington, Oregon, and California 61

14

Total

.... _~- +---

+ ++

+ t------

77 80 83 86 77 80 83 86 77 80 83 86 77 80 83 86

Columbia Eureka Monterey Total

Year and INPFC Area

INPFC Area

[ZJ 1977

Iiliilil 1980

D 1983

1986

US Vancouver Columbia

12

x 8

16

14

12

0

010 3

x 8 ::::.

(I)

(I)

ro 6 E

0

iii 4

2

0 +++~

77 80 83 86

US Vancouver

(I)

6

E

o

iii 4

010

o

q

Figure 40

Estimates of rex sole, Errex z.achirus, biomass and associated 90% confidence intervals by International North Pacific Fisheries Commission

(INPFC) area and year.

influences over their behavior than did the differences

in temperature range.

Discussion

In summary, data collected in bottom trawl surveys

during the summers of 1977,1980,1983, and 1986 off

Washington, Oregon, and California were compared to

examine trends in groundfish population sizes. The

sampling effort was designed to provide the most precise and comprehensive information on a few key species, but CPUE and estimates of biomass were derived

for a variety of commercially important species. Canary

and yellowtail rockfish and Pacific hake were most frequently designated as "target" species, but we also focused on bocaccio and chilipepper during the 1977

survey.

The estimated abundance of Pacific hake tended to

increase, canary and yellowtail rockfish abundance estimates decreased, and bocaccio and chilipepper abundance estimates held relatively stable over the study

period. Among the secondary study species, English

sole, rex sole, and Dover sole abundance estimates
62 NOAA Technical Report NMFS 117

Table 17

Rex sole, Errex zachirus - Mean catch per unit of effort (CPUE) (kg/km trawled), biomass estimates (metric tons),

90% confidence intervals (CI), and coefficients of variation (CV in %) of biomass estimates by International North

Pacific Fisheries Commission statistical area, depth stratum, and year.

U.S.-Yancouver Columbia

Depth Mean CV Mean CY

Year stratum (m) CPUE Biomass CI (%) CPUE Biomass C1 (%)

1977 91-183 0.9 185 66-305 1.5 1,153 863-1,443

184-366 3.7 323 190-456 1.9 573 419-728

91-366 1.7 508 332-684 20.7 1.6 1,726 1,400-2,052 11.3

1980 55-183 1.7 449 0-921 1.2 1,347 997-1,696

184-366 3.3 297 57-536 1.2 345 149-541

55-366 2.1 746 234-1,258 39.4 1.2 1,691 1,295-2,088 14.1

1983 55-183 l.l 293 185-401 3.7 4,264 3,419-5,109

184-366 2.3 208 115-300 4.5 1,286 930-1,642

55-366 1.4 501 362-640 16.5 3.8 5,550 4,638-6,462 9.9

1986 55-183 1.8 486 423-548 4.1 5,064 4,369-5,760

184-366 1.3 114 58-170 4.1 1,140 821-1,459

55-366 1.6 600 518-682 8.2 4.1 6,204 5,448-6,960 7.3

Eureka Monterey Total

Depth Mean CY Mean CY Mean CY

Year stratum (m) CPUE Biomass CI (%) CPUE Biomass C1 (%) CPUE Biomass CI (%)

1977 91-183 0.1 21 6-36 1.1 401 201-600 1.2 1,759 1,394-2,124

184-366 1.9 153 41-266 3.9 454 353-554 2.6 1,503 1,256-1,750

91-366 0.7 174 61-288 38.0 1.8 854 634-1,074 15.0 1.5 3,263 2,823-3,702 8.1

1980 55-183 0.4 73 34-111 0.8 527 334-719 l.l 2,395 1,789-3,001

184-366 1.4 112 30-195 2.5 297 111-482 1.8 1,050 703-1,397

55-366 0.7 185 97-273 26.5 l.l 823 561-1,086 19.1 1.2 3,445 2,752-4,138 12.1

1983 55-183 1.4 420 239-600 2.5 1,559 1,019-2,099 2.8 6,536 5,516-7,556

184-366 8.2 658 325-991 4.6 555 333-778 4.6 2,707 2,189-3,224

55-366 2.8 1,078 714-1,442 19.3 2.8 2,114 1,534-2,693 16.4 3.1 9,242 8,102-10,382 7.4

1986 55-183 7.6 1,144 858-1,429 3.6 2,385 1,745-3,024 3.7 9,078 7,915-10,241

184-366 8.4 710 433-986 9.1 1,154 683-1,624 5.4 3,117 2,318-3,915

55-366 4.6 1,853 1,466-2,240 12.4 4.5 3,538 2,763-4,314 13.1 4.0 12,195 10,807-13,584 6.9

increased. Estimates of sablefish abundance increased

between 1977 and 1980 and then decreased steadily.

Pacific ocean perch, lingcod, and, to a lesser extent,

arrowtooth flounder abundance estimatesshowed rather

precipitous decreases. However, none ofthe interannual

differences in estimated abundance for sablefish or any

of the rockfishes were statistically significant.

Population trends within INPFC areas tended to parallel the overall coastwide trend for each species, but

frequent exceptions did occur. For instance, almost all

of the decline in canary rockfish abundance took place

in the U.S.-Vancouver area. Likewise, yellowtail rockfish abundance estimates decreased in the U.S.-

Vancouver and Columbia areas but were stable or increased elsewhere. Changes in flatfish abundance

seemed to be more uniform among INPFC areas. This

may be due to dissimilarities between non-flatfish and

flatfish responses to small-scale environmental changes

and to their distinctly different recruitment mechanisms, or it may be an artifact of sampling variability

(i.e. because flatfish distributions are generally more uniform, estimates of their biomass are usually less variable).

Precision has long been a concern to researchers

estimating population abundance. Fishery research lit-
Dark and Wilkins: Groundfish off Washington, Oregon, and California 63

By Sex

_ Sexss Combined

m Females

o Males

50

By Depth

• Total (55-366 mj

Slope (184-366 m)

D Shelf (55-183 ml

30 40

Length (em)

20

1980 30 40 50

Length (em)

20

"/

50

50

30 40

Length (em)

30 40

Length (em)

--()..)rll---tIIr-------------

20

20

----11----'.------ '4

1------------------- 10 1... '.-- _

I~tl/~~~i~.J~;'~'i""lllllllll..i~~~~ 10

12

!? 10

g B

t

z •

6~~~~~iiiif~-~-~r---- o

10

1986

1983

50

50

30 40

Length (em)

30 40

Length (em)

20

20

o~~F 10

'4

12

10

o~~w 10

"

10

12

Figure 41

Rex sole, Errex zachirus, length compositions by year, depth, and sex.

erature contains a multitude ofstudies directed at controlling the variance of abundance estimates using a

variety ofsurvey designs and data manipulations (Byrne

et al., 1981; Pennington and Brown, 1981; Wilkins and

Golden, 1983; Smith and Gavaris, 1993). Trawl sampling is time consuming and costly; thus survey designs

that seek to increase precision are often compromised

by operational and fiscal realities. Hydroacoustic surveys, to a large extent, can overcome the problem with

their inherent capability ofsampling at very high rates.

Ourstudy utilized sampling designs that were molded

by the need to obtain relatively precise abundance estimates for the target species without sacrificing the important multispecies aspects of the triennial surveys.

The first priority was to preserve the multispecies time

series by providing a minimum level of sampling

throughout the survey area; the second priority was to

allocate all remaining samples to areas where target

species were expected to be most abundant and sampling

variability the highest. Much of the sampling effort was

therefore assigned to important rockfish areas because it

is well known that most rockfish species exhibit extremely

contagious distributions, requiring intensive sampling or

effective stratification to gain control ofvariance.

Coefficients of variation can give some insight into

species' schooling or aggregating behavior. As expected,
64 NOAA Technical Report NMFS 117

.;-.....----..........----~......~~!_.............---........ SOO OO'N

1977 1980 1983

c

o

L

U

M

B

I

A

R

...... Monterey Bay

45° 00'

40° 00'

35° 00'

liJ Area not sampled

D Nocatch

IE] < 9.0 kglkm

.9.0-51.2 kglkm

• > 51.2kglkm

~~;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;".,... ............_ .....,...__-I- 30° 00'

135° OOW 129°00' 123°00' 117°00'

Figure 42

Distribution of arrowtooth flounder, Atheresthes stomias, during 1977, 1980, 1983,

and 1986 National Marine Fisheries Service bottom trawl surveys.

the magnitude of the CV's varied markedly among

species. Mean CV's were calculated using total biomass

estimates and variance of the biomass for the four surveys. Average CV's were highest for bocaccio, canary

rockfish, lingcod, chilipepper, yellowtail rockfish, Pacific ocean perch, and sablefish, averaging 46, 43, 38,

38, 34, 33, and 27%, respectively. This would suggest

that these species have the most nonuniform or contagious distributions. Arrowtooth flounder and Pacific

hake biomass estimates displayed intermediate variability with CV's averaging 18 and 16%, respectively. Smallest CV's were indicative of the most uniformly distributed species and belonged to the flatfish group comprised of Dover, rex, and English soles. Those three

species had CV's of 8,9, and 13%, respectively.

The variances associated with biomass estimates were

determined largely by each species' distribution and

characteristics ofthe experimental design. The extreme

patchiness of rockfish distribution and the relatively

uniform and ubiquitous flatfish distributions were influential in fixing the precision levels for the two groups.

Canary and yellowtail rockfish were principal survey

species that received special sampling considerations

aimed at reducing variance. Even so, abundance esti-
Dark and Wilkins: Groundfish off Washington, Oregon, and California 65

25 --

,-----,

20

x

(J)

10

E

o

iIi

5

o

lZII 1977

IiliiliI 1980

D 1983

§ 1986

US Vancouver Columbia Eureka Monterey Total

25

20

<5

o

3- 15

(J)

(J)

10

E'"

0

iii

5

INPFC Area

~~_1~---

Tt t+ o--'----------------~-----~-----

77 80 83 86 77 80 83 86 77 80 83 86 77 80 83 86 77 80 83 86

US Vancouver Columbia Eureka Monterey Total

Year and INPFC area

Figure 43

Estimates of arrowtooth flounder, Atheresthes stomias, biomass and associated 90% confidence intervals by International North Pacific Fisheries

Commission (INPFC) area and year.

mates for those species were relatively imprecise. The

survey design was modified in 1980 in an effort to

improve precision, particularly in the Columbia area,

through more accurate delineation of canary and yellowtail rockfish distribution (based on commercial fishery data) and reallocation ofsampling effort. Although

this resulted in more precise estimates in the Columbia

area, no clear improvement in the precision ofthe total

estimates was noted for either species. While the same

design was employed in 1983 to provide information on

the stability ofvariances, additional time at the completion of the survey was used to sample an additional 44

stations in the U.S-Vancouver area. The 1980 CV for

canary rockfish in that area was reduced by more than

half, but the yellowtail rockfish CV actually increased.

Clearly, interannual variation in distribution or behavior can confound efforts to develop a sampling strategy

based on historical data. This was further demonstrated

in 1986 when the sampling design was based on a much

more rigorous analysis of historical fishery and survey

data. Results were mixed: precision improved in some

strata but remained unchanged or deteriorated in other
66 NOAA Technical Report NMFS 117

Table 18

Arrowtooth flounder, Atheresthes stomias- Mean catch per unit of effort (CPUE) (kg/km trawled), biomass estimates

(metric tons), 90% confidence intervals (CI), and coefficients of variation (CV in %) of biomass estimates by

International North Pacific Fisheries Commission statistical area, depth stratum, and year.

U.S.-Vancouver Columbia

Depth Mean CV Mean CV

Year stratum (m) CPUE Biomass CI (%) CPUE Biomass CI (%)

1977 91-183 12.2 2,575 846-4,304 6.2 4,818 2,456-7,181

184-366 60.2 5,319 0-11,743 9.4 2,806 1,376-4,236

91-366 26.4 7,894 1,283-14,505 48.0 7.1 7,624 4,928-10,321 20.7

1980 55-183 11.9 3,121 0-6,541 1.5 1,779 484-3,074

184-366 9.8 877 175-1,579 3.9 1,164 696-1,631

55-366 11.3 3,998 542-7,453 49.7 2.0 2,943 1,751-4,135 20.8

1983 55-183 3.9 1,026 357-1,695 1.3 1,482 1,161-1,803

184-366 17.2 1,540 867-2,214 3.5 1,058 767-1,350

55-366 7.3 2,567 1,658-3,475 20.7 1.7 2,540 2,115-2,966 10.0

1986 55-183 11.0 3,050 2,492-3,608 2.8 3,445 2,807-4,083

184-366 19.4 1,711 1,199-2,224 5.0 1,396 1,026-1,766

55-366 13.0 4,761 4,024-5,498 9.2 3.2 4,841 4,118-5,564 8.9

Eureka Monterey Total

Depth Mean CV Mean CV Mean CV

Year stratum (m) CPUE Biomass CI (%) CPUE Biomass CI (%) CPUE Biomass C1 (%)

1977 91-183 0.8 151 28-274 0.2 51 8-94 5.0 7,595 4,734-10,456

184-366 0.6 46 0-94 0.5 48 14-81 14.4 8,219 1,662-14,776

91-366 0.8 197 68-327 38.3 0.2 98 48-148 29.6 7.6 15,814 8,754-22,873 25.9

1980 55-183 0.3 54 14-94 <0.1 7 0-15 2.2 4,960 1,444-8,476

184-366 0.4 36 6-66 0.1 14 0-37 3.5 2,092 1,293-2,891

55-366 0.3 90 42-138 31.0 <0.1 21 0-45 61.2 4.1 7,052 3,466-10,638 29.5

1983 55-183 0.2 45 16-74' <0.1 15 0-30 l.l 2,568 1,844-3,292

184-366 1.2 94 45-143 0.2 25 1-48 4.6 2,717 1,994-3,441

55-366 0.4 139 84-194 23.1 0.1 39 12-67 41.7 1.8 5,285 4,289-6,282 11.2

1986 55-183 0.2 80 48-112 0.1 88 29-148 2.7 6,663 5,652-7,675

184-366 0.4 31 12-49 0.1 10 0-21 5.5 3,148 2,536-3,760

55-366 0.3 III 74-147 19.5 0.1 98 38-159 36.8 3.2 9,812 8,645-10,978 7.1

areas where historical data failed to predict current

distribution.

Another question contingent upon the precision of

biomass estimates is whether the observed differences

were statistically significant. Due to the large variances

associated with biomass estimates of many of these species, most differences observed between years were not

statistically significant. As expected, the surveys were

most sensitive to population changes in species with

relatively small CV's such as Pacific hake and flatfishes.

In some INPFC areas, biomass estimates for canary and

yellowtail rockfish differed by factors as great as 35 and

11, respectively, among years; however, these estimates

were not found to be significantly different. Imprecision of such magnitude causes one to question the

utility of trawl surveys for rockfish assessment. It certainly emphasizes the need to review all elements of the

experimental design and perhaps consider other assessment strategies. We used the results of the 1977-86

triennial surveys to compare projected and realized

precision levels of rockfish abundance estimates. We

concluded that we could not reasonably expect future

"area-swept" surveys to furnish adequate information to

discern rockfish abundance trends and have deleted

this objective from triennial bottom trawl surveys conducted since 1989.
Dark and Wilkins: Groundfish off Washington, Oregon, and California 67

By Sex By Depth

• Total 155-366 m}

f!l!l Slope (184 -366 m)

OShell 155-'83 m)

'400

~1200

1000

1800

~600

400

• Sexes Combined

m Females

o Males

'400

1200

~1000

1800

;p600

"00

20:~__ 2~ts~_ ill ro "0 w ro M W ro 00 40 W 70 80

Length (em) 1980 Length (em)

'400 1----11--------------------- 1400

1200

1000

!800600

z 400

1200

: 1000

800

600

Z 400

M

20:ta

ill W 30

__

40 W 00 70

w80 1986 Length (em)

Figure 44

Arrowtooth flounder, Atheresthes stomias, length compositions by year, depth, and sex.

The accuracy of population estimates based on bottom trawl surveys is a continuing concern and is not as

easily addressed as the question of precision. Typically,

evaluations of accuracy rely on comparison of survey

estimates with estimates derived independently. Resource assessments based on commercial catch-andeffort data have been unavailable for many west coast

species until recently because of the lack of adequate

fishery statistics and biological data. However, since

implementation of the groundfish management plan

in 1981, improvements have been made in the collection of commercial fisheries statistics and some new

assessments have followed.

Independent assessments that provide for comparisons with the survey results are available only for canary

rockfish, yellowtail rockfish, and sablefish (Fig. 49). A

cohort analysis was conducted on yellowtail rockfish

(Tagart7), which provides annual biomass estimates for

the INPFC Columbia area from 1977 to 1985, and a

dynamic pool model was used to project the biomass in

1986. The initial instantaneous rate offishing mortality

was unknown, so Tagart used a range of 0.05-0.30. The

estimates (Fig. 49) are the averages of estimates derived

using initial fishing mortalities of 0.10 and 0.15, which

Tagart considered to be liberal and conservative estimates respectively. The survey and cohort analysis population trends were similar, both indicating a marked

decline between 1977 and 1980 with a very slow decline

or near-stability subsequently. Estimates of absolute

abundance derived by cohort analysis are 3-5 times

larger than those from the bottom trawl surveys and

serve as an indication that the true catchability of the

survey trawl is considerably less than the assumed value

of 1.0.

Cohort analysis and catch-at-age analysis (CAGEAN)

were used by GoldenS in an assessment of canary rockfish in the INPFC Columbia area. He generated annual

exploitable biomass estimates from 1980 to 1986 using

instantaneous natural mortality rates (M) of 0.05 and

0.10. The values in Figure 49 were derived using M =

0.05. In this instance, the cohort analysis and CAGEAN

produced quite different estimates of absolute abundance, but the trends were similar. Both analyses portrayed decreasing biomass from 1980 to 1984 and subsequent increases. Survey biomass estimates, in fact,

followed the opposite trend. Canary rockfish presented

a worst case example of patchy distribution and the

greatest challenge in obtaining reasonable precision. It

may be that sampling variability was responsible for the

failure ofsurvey data to correspond to the other indices

or that the species was relatively unavailable during the

time ofthe survey in the Columbia area. Once again, we
68 NOAA Technical Report NMFS 117

Sea Surface Temperature

19 -r;:======:;--------------i

18

17

18+-'===='

2: 15

"' 14 <pr",<,\---j'I"-*

0,

~13+-~~~~

12

11

38 39 40 41 42 43 44 45 46 47 48 49 Latitude

Sea Bottom Temperature

121------------~======~

11 --------

10

7 -

+ '980 * '983

-B- '988

6 +-I-+-+-+-+-I-+-+-+-+-I-+---+---i-+-I-+-+-+-+-t-+-+-j

37 38 39 40 41 42 43 44 45 46 47 48 49 Latitude

Figure 45

Sea surface and bottom (55-366 m) temperatures averaged by

30' latitudinal intervals by year.

believe that the biomass estimates from the bottom

trawl survey were only a fraction of the estimates from

analysis of fishery data because catchability was lower

than assumed.

Sablefish biomass estimates from bottom trawl surveys in the Columbia and U.S.-Vancouver areas were

compared with indices of changes in relative abundance of sablefish obtained from AFSC trap surveys

(Parks and Shaw, 1988) in the same region (Fig. 49).

The general trends in biomass were similar. Both studies showed increasing sablefish biomass during 1980-

83 with ensuing decreases. Methot and Hightower15

also found that the abundance of age-l sablefish in the

trawl surveys (left-hand size mode in Fig. 30) was consistent with the magnitude of the population inferred

from commercial catch levels.

These limited comparisons are inconclusive but suggest that even though there may be considerable variability around survey estimates of abundance, long-term

trends can compare favorably with trends derived by

other methods. However, some species, such as canary

rockfish, may never be tracked very accurately with any

practical level ofsampling effort. More conclusive evaluations of accuracy must await additional independent

resource assessments and longer time series. It is notable That survey estimates are always considerably

smaller than those based on catch data except for age-l

sablefish. This is largely due to the probable violation of

catchability assumptions associated with the survey, resulting in an underestimation of biomass. The difference between estimates of absolute abundance from

survey and fishery-based models could be considered a
100

1201 I

60

80

6 7 8 9 10 11 12 13

oj , .....-;:... 6 • I

20

Arrowtooth Flounder

80

40

60

100"---------------,

6 8 9 10 11 12 13

5

I '.' • o ......,\ .... 5 .. ,I· I

. .'

Rex Sole

10

15

25"---------------,

20

8 9 10 11 12 13

., " .... 6

01 - .1' 'c.,I_ I 5

20

40

English Sole Dover Sole faG .

::f I 30

1

20~

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Figure 46

Relationship between flatfish catch per unit of effort (CPUE) and bottom temperature by year. See text for scientific names,

o

.,

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1983

40

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~~ I

rot

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70 NOAA Technical Report NMFS 117

6 7 8 9 ro " a

150

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...

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ol----__...,,;_--.-~_-_-.J II II

5

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10

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." 6 6

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1980

1400,--------------,

1200

1000

800

600

400

200ol-- o.!IoA-,-~ _____l

5

Pacific hake

6 7 6 9 ro " a 6 6 9 ro 11 12 13

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5

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6 6 9 ro " a

... o~~~__W""' :.. " . ~--a-J

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1983

1400,--------------,

1200

1000

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600

400

200 ••

oI----I'--"~.............Ool......... • •.........·c....-...__'_-' 5

w

::::>

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1200

1000 II II 150

.... 3..8

-I 40,--------------,

30

6 6 9 ro " a

.:

..

6 7 8 9 ro " a

. .,.,. ol--- ~.~......",""'--~_-_-.J

II

5

10

20

6 7 6 9 ro " a

50

100 600

600 .~

. 400 II 811 II:· 200 '" •

o~ lIIollod_l'_"_~-_--l

5

Bottom temperature (OC)

Figure 47

Relationship between Pacific hake, Merluccius productus, sablefish, Anoplopoma fimbria, and lingcod, Ophiodon

elongatus, catch per unit of effort (CPUE) and bottom temperature by year.

gross indication of true catchability. More comparisons

of this type, accompanied by dedicated studies of trawl

performance and fish behavior, should begin to provide some insight to real catchability values and better

estimates of absolute abundance.

Acknowledgments _

The collection of survey data at sea for research on

groundfish resources is demanding. Over the ten years

of this study period, many dedicated biologists and

technicians from the Alaska Fisheries Science Center,

the Southwest Fisheries Science Center, state fishery

agencies, and universities devoted weeks or months in

that endeavor. Their sacrifices are deeply appreciated.

Helpful statistical guidance provided by Doug Knechtel,

Peter Munro, and Susan Picquelle enabled us to substantiate the inferences made from our analyses. Production and editorial assistance was provided by the

Graphics and Publications Units at the AFSC. Finally,

many reviewers provided encouragement and constructive advice during the long preparation of this manuscript. Although we received helpful suggestions from

many colleagues, we especially thank Miles Alton, Rick

Methot, and Bill Lenarz.
Figure 48

Relationship between rockfish catch per unit of effort (CPUE) and bottom temperature by year. See text for scientific names.

III

:=

Q.

~.

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"'l

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:=

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=:

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t"'l

e:.

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Pacific Ocean Perch

I ----

0 1 • ..-

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. 01 "

5678910111213

50

50

50

150

100

100

150

100

150

'2 '3

12 13

" 10

',..

8 9

0 1 • ••

5 6 7 8 9 W " 12 13

Chilipepper

9 10 "

..

'40

120

100

80

80

40

20

01 •• ' - • 5

:::l . I 80

60

40

20

10 11 12 13

..

7 8 9

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Bocaccio

0 1 • 'Me ..... I

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40

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20

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Bottom temperature (OC)

8 9 10 11 12 13

"'au

'_31:' ~215-'

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0 1 ......._. I

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Canary

50

I

':] . _ ....'-.~. .1

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'00

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'40,-----------------,

'20

'00

80

60

40 •

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oj - ,~"';"- • 5 6 7 B 9 10 " 12 13

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o

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140

1986

• l J

1

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100

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-
72 NOAA Technical Report NMFS 117

Beamish, RJ.

1979a. Differences in the age of Pacific hake (Merluccius

productus) using whole otoliths and sections of otoliths. J.

Fish. Res. Board Can. 36:141-151.

1979b. New information on the longevity ofPacific ocean perch

(Sebastes alutus). J. Fish. Res. Board Can. 36:1395-1400.

Boehlert, C.W.

1977. Timing of the surface-to-benthic migration in juvenile

rockfish, Sebastes diploproa, off southern California. Fish.

Bull. 75:887-890.

1980. Size composition, age composition, and growth of canary rockfish, Sebastes pinniger, and splitnose rockfish, S.

diploproa, from the 1977 rockfish survey. Mar. Fish. Rev.

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Boehlert, C.W., and M. Yoklavich.

1984. Variability in age estimates in Sebastes as a function of

methodology, different readers, and different laboratories.

Calif. Fish Came 20:210-224.

Byrne, CJ., TR. Azarovitz, and M.P. Sissenwine.

1981. Factors affecting variability of research vessel trawl

surveys. In W.C. Doubleday and D. Rivard (eds.), Bottom

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Sci. 58.

Carlson, H.R., and R.E. Haight.

1976. Juvenile life of Pacific ocean perch, Sebastes alutus, in

coastal fiords of southeastern Alaska: their environment,

growth, food habits, and schooling behavior. Trans. Am.

Fish. Soc. 105:191-201.

Carrothers, Pj.C.

1981. Catch variability due to variations in groundfish otter

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procedures. In W.C. Doubleday and D. Rivard (eds.), Bottom trawl surveys: proceedings of a workshop held at Ottawa, November 12-14, 1980, p. 247-257. Can. Spec. Publ.

Fish. Aquat. Sci. 58.

Chilton, D.E., and RJ. Beamish.

1982. Age determination methods for fishes studied by the

Croundfish Program at the Pacific Biological Station. Can.

Spec. Publ. Fish. Aquat. Sci. 60, 102 p.

Coleman, B.A.

1986. The 1980 Pacific coast bottom trawl survey of groundfish resources: estimates of distribution, abundance, length

and age composition. U.S. Dep. Commer., NOAA Tech.

Memo. NMF5-F/NWC-I00, 181 p.

1988. The 1986 Pacific west coast bottom trawl survey of

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Dark, TA.

1975. Age and growth of Pacific hake, Merluccius

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Dark, TA., M.E. Wilkins, and K. Edwards.

1983. Bottom trawl survey of canary rockfish (Sebastes pinniger) ,

yellowtail rockfish (S·flavidus) , bocaccio (S. paucispinis) and

chilipepper (S. goodei) off Washington-California,

1980. U.S. Dep. Commer., OAA Tech. Memo. NMF5-F/

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Edwards, K.D., TA. Dark, R. French, R. NelsonJr., andJ. Wall.

1981. A summary offoreign Pacific whiting catches and trawl

positions in the Washington-California Region, 1977-

1980. U.S. Dep. Commer., NOAA Tech. Memo. NMF5-F/

NWC-l1, 206 p.

25 -:::-

20 i

15 J

10 I

!

--.-- -~

...- CAGEAN -0- VPA ...... Survey

o 0 HI77 1078 HI7e 1880 tsif81 1882 1083 1884 H18& 1888

V.ar

20

;;:

,. ..

j 10

(INP..C COlumlMo ••••)

Literature Cited

30,------------------,7

o L-_~__~__,__-_:_::'::_:_-'-_:_::'::_:_-:_:':=____::_:!0

1880 1S18l 1882 1883 1884 lli1KS leBfS

Y.ar

(INPf'C Coklmbl......)

25,-----------------,30

o 0 181918801881188219831884198518881887

+ Survey

Sableflsh

(INPFC Colunoblo .. U.•. V.ncou....r 0 ....0)

40

12

60,----------------------,14

Yellowtail Rockfish

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Figure 49

A comparison of abundance trends based on survey

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Sebastes flauidus, cohort analysis from Tagart, text footnote 9; canary rockfish, S. pinniger, catch-at-age analysis

(CAGEAN) and cohort analysis from Golden, text footnote 8; sablefish, Anoplopomafimbria, trap analysis from

Parks and Shaw, 1988.) VPA = virtual population analysis; INPFC = International Pacific Fisheries Commission.

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1980. Distribution and abundance of rockfish off Washington, Oregon, and California during 1977. Mar. Fish. Rev.

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Wilkins, M.E.

1980. Size composition, age composition, and growth of

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NOAA TECHNICAL REPORTS NMFS

The major responsibilities of the National Marine Fisheries Service (NMFS) are to monitor and assess the abundance

and geographic distribution of fishery resources, to understand and predict fluctuations in the quantity and distribution of

these resources, and to establish levels for their optimum use. NMFS is also charged with the development and implementation of policies for managing national fishing grounds, with the development and enforcement of domestic fisheries

regulations, with the surveillance of foreign fishing off U.S. coastal waters, and with the development and enforcement of

international fishery agreements and policies. NMFS also assists the fishing industry through marketing services and

economic analysis programs and through mortgage insurance and vessel construction subsidies. It collects, analyzes, and

publishes statistics on various phases of the industry.

Recently Published NOAA Technical Reports NMFS

107. Field guide to the searobins (Prionotus and

Bellator) in the western North Atlantic, by Mike Russell,

Mark Grace, and ElmerJ. Gutherz. March 1992, 26 p.

108. Marine debris survey manual, by Christine A.

Ribic, Trevor R. Dixon, and Ivan Vining. April 1992, 92 p.

109. Seasonal clixnatologies and variability of eastern tropical Pacific surface waters, by Paul C. Fiedler.

April 1992, 65 p.

110. The distribution of Kemp's ridley sea turtles

(Lepidochelys kem.plJ along the Texas coast: an atlas,

by Sharon A. Manzella, andJo A. Williams. May 1992,52 p.

Ill. Control of disease in aquaculture: proceedings of the nineteenth U.S.-japan meeting on aquaculture; Ise, Mie Prefecture, Japan, 29-30 October 1990,

edited by Ralph S. Svrjcek. October 1992, 143 p.

112. Variability of temperature and salinity in the

Middle Atlantic Bight and Gulf of Maine, by Robert L.

Benway, Jack W. Jossi, Kevin P. Thomas, and Julien R.

Goulet. April 1993, 108 p.

113. Maturation of nineteen species of finfish off the

northeast coast of the United States, 1985-1990, by

LJretta O'Brien,Jay Burnett, and Ralph K. Mayo. June 1993,66 p.

114. Structure and historical changes in the

groundfish complex of the eastern Bering Sea, by

Richard G. Bakkala. July 1993,91 p.

115. Conservation biology of elasmobranchs, edited

by Steven Branstetter. September 1993,99 p.

116. Description of early larvae of four northern

California species of rockfishes (Scorpaenidae:

Sebastes) from rearing studies, by Guillermo Moreno.

November 1993, 18 p.

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