NOAA Technical Memorandum NMFS-AFSC-80

U.S. DEPARTMENT OF COMMERCE

National Oceanic and Atmospheric Administration

National Marine Fisheries Service

Alaska Fisheries Science Center

September 1997

The 1995 Pacific West Coast

Upper Continental Slope Trawl Survey of

Groundfish Resources off

Southern Oregon and Northern California:

Estimates of Distribution, Abundance, and

Length Composition

by

R. R. Lauth
NOAA Technical Memorandum NMFS

The National Marine Fisheries Service's Alaska Fisheries Science Center

uses the NOAA Technical Memorandum series to issue informal scientific and

technical publications when complete formal review and editorial processing

are not appropriate or feasible. Documents within this series reflect sound

professional work and may be referenced in the formal scientific and technical

literature.

The NMFS-AFSC Technical Memorandum series of the Alaska Fisheries

Science Center continues the NMFS-F/NWC series established in 1970 by the

Northwest Fisheries Center. The new NMFS-NWFSC series will be used by

the Northwest Fisheries Science Center.

This document should be cited as follows:

Lauth, R. R. 1997. The 1995 Pacific West Coast upper continental 

slope trawl survey of groundfish resources off southern Oregon 

and northern California: Estimates of distribution, abundance, and 

length composition. U.S. Dep. Commer., NOAA Tech. Memo. NMFSAFSC-80, 110 p.

Reference in this document to trade names does not imply endorsement by

the National Marine Fisheries Service, NOAA.
NOAA Technical Memorandum NMFS-AFSC-80

The 1995 Pacific West Coast

Upper Continental Slope Trawl Survey of

Groundfish Resources off

Southern Oregon and Northern California: Estimates of Distribution, Abundance, and Length Composition

by

R. R. Lauth

Alaska Fisheries Science Center

7600 Sand Point Way N.E., BIN C-15700

Seattle, WA 98115-0070

U.S. DEPARTMENT OF COMMERCE

William M. Daley, Secretary

National Oceanic and Atmospheric Administration

D. James Baker, Under Secretary and Administrator

National Marine Fisheries Service

Rolland A. Schmitten, Assistant Administrator for Fisheries

September 1997
This document is available to the public through:

National Technical Information Service

U.S. Department of Commerce

5285 Port Royal Road

Springfield, VA 22161
Notice to Users of this Document 

This document is being made available in .PDF format for the convenience of users; however, the 

accuracy and correctness of the document can only be certified as was presented in the original hard 

copy format. 

iii

ABSTRACT

The Alaska Fisheries Science Center (AFSC) conducted a

groundfish bottom trawl survey of the West Coast upper

continental slope (WCUCS) off southern Oregon and northern

California in 1995. The survey area was between lat. 43°OO' N

(near Cape Blanco) and lat. 40°30' N (near Cape Mendocino) in

waters from 183 to 1,280 m deep. This was the eighth survey in

an ongoing series to monitor long-term trends in the distribution

and abundance of WCUCS groundfish populations. Concerns about

the performance of the fishing gear that surfaced during the 1993

WCUCS survey resulted in gear experiments in 1994, which in turn

led to changes in trawl gear and trawling methodology during this

year's survey. Sampling was conducted aboard the NOAA ship

Miller Freeman. We successfully sampled 106 of 108 established

stations. Catches included 121 different species of fishes and

68 different species of invertebrates.

The survey design and the methods used are described, the

data collected are summarized, and the results of analyses of

distribution, abundance, and biological parameters are presented.

Data on water temperature, catch composition, relative abundance,

and geographic distribution are reported. Estimates of biomass,

population abundance, and length composition are also presented.

Appendices include position and catch listings for each haul,

catch rates of fish and invertebrates, and population size

compositions.
V

CONTENTS

INTRODUCTION . . . . . . . . . . . . . . . . .

SURVEYMETHODS . . . . . . . . . . . . . . . .

Survey Period and Sampling Area . . . . .

Vessels and Sampling Gear . . . . . . . .

Trawl Station Allocation . . . . . . . . .

Trawling Procedures . . . . . . . . . . .

Revised Survey Gear and Towing Protocol .

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Catch Sampling Procedures and Biological Data Collection

Oceanographic Data Collection . . . . . . . .

Data Analysis . . . . . . . . . . . . . . . .

RESULTS.................

Haul, Catch, and Biological Data . .

Temperature Data . . . . . . . . . .

Relative Density and Distribution of

. . . . .

Species .

Biomass and Population Estimates

Size and Age Composition . .

Length-Weight Relationship .

ACKNOWLEDGMENTS

TABLES . .

FIGURES . .

CITATIONS .

APPENDIX A

APPENDIX B

APPENDIX C

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101
INTRODUCTION

Fishery-independent data obtained from the Alaska Fisheries

Science Center's (AFSC) West Coast upper continental slope

(WCUCS) groundfish trawl surveys are used by fishery managers to

assess stock condition and to establish annual harvest guidelines

for several commercially valuable WCUCS fish species including

sablefish (Anoplopoma fimbria), shortspine thornyhead

(Sebastolobus alascanus), longspine thornyhead (S. altivelis),

and Dover sole (Microstomus pacificus). The WCUCS covers habitat

183-1,280 m deep from the U.S.-Canada border to lat. 32°30'N and

is divided into five International North Pacific Fisheries

Commission (INPFC) statistical areas including the U.S.

Vancouver, Columbia, Eureka, Monterey, and Conception areas

(Fig. 1). The Resource Assessment and Conservation Engineering

(RACE) Division of the AFSC conducted groundfish assessment

surveys of the WCUCS starting in 1984 and has done so annually

from 1988 to 1993. Due to limited vessel time each year, these

trawl surveys covered different but contiguous sections of the

WCUCS. The U.S. Vancouver area was surveyed in 1993 and various

sections of the Columbia area were surveyed in 1984, 1988, 1989,

1992, and 1993 (Raymore et al. 1990, Parks and Shaw 1993,

Lauth et al. 1997). The Eureka area was last surveyed in 1990,

and the northern part of the Monterey area was surveyed down to

lat. 38°20'N in 1991. Two other groundfish bottom trawl surveys

covering parts of the Conception area between lat 34°30' N and
2

lat. 36°30' N were conducted by the Southwest Fisheries Science

Center (SWFSC) in 1987 and 1988 (Butler et al. 1989).

During the 1993 AFSC survey, concerns were also raised about

the poor performance of the slope survey trawl, and consequently,

the validity of slope survey data. As a result, vessel time

allotted for the 1994 slope survey was instead spent

experimenting with ways to stabilize the sampling trawl, learning

more about evaluating trawl performance and its effects on the

validity of survey data, and investigating alternative methods of

surveying groundfish resources using a video camera sled. When

regular survey work resumed for this year's survey, we tested and

implemented the needed improvements to the trawl gear and

trawling methodology (see Survey Methods section).

The objectives of this report are to document the survey

design and field procedures, summarize the survey data, and

present the results of the standard RACE analyses for the 1995

WCUCS survey of the Eureka area. Included are summaries of

catches, distribution, abundance, and size composition for major

components of the community, as well as analyses of age-length

and length-weight relationships of selected species.
3

SURVEY METHODS

Survey Period and Sampling Area

The INPFC Eureka area (43°00'N lat. to 40°30'N lat.) was

surveyed between 23 October and 22 November. Sampling for the

survey began near Cape Blanco (43°00'N lat.) and progressed

southward during the first leg and from Cape Mendocino (40°30'N

lat.) northward during the second leg (Fig. 2). Water depth at

survey stations ranged between 183 and 1,280 m (100-700 fm).

The NOAA ship

trawler powered by

Vessels and Sampling Gear

Miller Freeman is a 65.5 m (215 ft) stern

a 2,300 continuous horsepower engine. The

ship is equipped with dual net reels, a Rapp-Hydema warp

tensioning system, Wesmar Fish Eye net sonar system, Furuno

netsonde, EQ-50 depth sounder, and Global Positioning System

(GPS) navigational aids. A high-opening Nor'eastern trawl (Fig.

3) constructed of polyethylene mesh and equipped with mudsweep

roller gear (Fig. 4) was used to collect all samples. This

trawl, built and rigged to RACE Division gear standards, has a

27.2 m headrope and a 37.4 m footrope. The body is constructed

of 127 mm stretched-mesh polyethylene netting, 89 mm stretchedmesh web in the codend, and a 32 mm stretched-mesh codend liner.

Three 55 m dandylines made of 16 mm galvanized steel cable
4

connect each wing to a pair of 1.8 x 2.7 m steel V-doors weighing

1,000 kg each. Each door has a 4-point bridle on its backside

made with 13 mm long link chain having 33 links forward and 22

links aft in both the top and bottom. Instruments attached to

the trawl gear to monitor gear performance included SCANMAR

equipment for measuring net dimensions, a Furuno wireless

netsonde for real-time monitoring of the headrope height, a tilt

sensor on the starboard V-door, and a bottom contact sensor on

the footrope. A Wesmar net sonar was attached to the net

headrope and used to assure that the trawl gear was performing to

engineering specifications during the wire marking procedure and

during the initial gear calibration. A Richard Brancker XL-200

submersible data logger was attached to the trawl and used in

conjunction with a Trimble Global Positioning System (GPS) unit

to record data on the time, depth, water temperature, and

geodetic position during each trawl. These data were combined

with fishing dimensions of the net, producing a comprehensive set

of haul data describing gear performance in space and time.

Trawl Station Allocation

The stations targeted for this survey were the same as those

selected for the WCUCS bottom trawl survey of the Eureka area in
5

1990 (Lauth et al. 1997). There were 108 stations along 17

tracklines between 43°00'N lat. near Cape Blanco and 40°30'N lat.

near Cape Mendocino. A cross between a systematic and random

design was used for selecting the stations for the 1990 WCUCS

bottom trawl survey. Stations were located on transect lines

16.7 km apart and transect lines were positioned roughly

perpendicular to the coastline. Sampling was conducted between

183 and 1,280 m in six strata of 183 m (100 fm) depth intervals

(183-365 m, 366-547 m, 548-730 m, 731-913 m, 914-l,095 m, and

1,096-1,280 m). The number of sampling stations within each

depth stratum were allocated proportional to the trackline length

across each depth interval at the rate of one station per 13.0 km

of linear trackline length (e.g., three stations would be

allocated to a stratum with a trackline length of 30 km). To

assure even depth coverage within a stratum, the depth range of

each stratum was divided into a number of bins equal to the

number of stations scheduled to be surveyed that year.

Nominally, a bin was identified by its midpoint target depth.

Stations were then randomly assigned to tracklines by picking

target depths without replacement.
6

Trawling Procedures

Sampling was done on a 24-hour basis. Stations were located

by GPS and echosounder and then surveyed prior to towing. If the

terrain was determined to be too rough or steep to successfully

complete a tow, an alternate site was searched for and chosen

within an approximate 10 km radius of the original station. If

no favorable ground was located the station was declared

untrawlable and abandoned. If the gear was damaged during the

tow severely enough to affect catch composition, the haul was

considered unsatisfactory and the station was either repeated or

abandoned. Unsuccessful tows were not used in later analyses.

Revised Survey Gear and Towing Protocol

There were two changes made to the trawl gear and numerous

changes made in towing protocol for the 1995 WCUCS survey. These

changes were intended to stabilize trawl performance and to

better standardize trawling effort. Modifications to the trawl

gear included a change from a 2-point to a 4-point door bridle

configuration and a reduction in the number of links from 5 links

to 2 links of 9 mm chain at attachment points between the

groundgear and footrope.

More significant changes were made to various towing

protocols including target towing speed, scope ratio, tow

duration, trawl warp metering, and trawling mode of the Rapp-
7

Hydema winch system. Target towing speed was increased from

3.7 km/hr to 4.3 km/h with an acceptable range of plus or minus

0.6 km/h. Slightly higher speed improved vessel steerage and

increased power to the doors helping to improve the consistency

of net performance. Previous slope surveys used a standard scope

table but the scope ratios were excessive and the table was not

strictly followed, hence scope ratios were variable between

depths and survey years. A new standard scope table based on

empirical data from the 1994 gear experiment was used for this

survey (Table 1). Tow duration for depths greater than 732 m

was reduced from 60 to 30 minutes. Trawl metering also changed

from previous surveys. Prior to commencing survey trawling,

trawl wires were marked at 50-m intervals. Wire marks were used

exclusively for determining the amount of wire payed out during

trawl operations. Earlier surveys aboard the NOAA ship Miller

Freeman used what we later learned were inaccurate readouts from

the Rapp-Hydema counter. The Rapp-Hydema autotrawl function is

no longer used because it is uncertain how it performs under the

diverse and extreme conditions encountered on the WCUCS. As an

alternative, equal amounts of wire were payed out on both sides

and the brakes were set for the entire tow.

Several new pieces of electronic equipment were used for the

1995 slope survey to better measure and assess gear performance

and to pinpoint when the trawl gear was on the bottom. Among
8

these were an underwater video camera, a bottom contact sensor, a

door tilt sensor, and a Wesmar scanning sonar.

Catch Sampling Procedures and Biological Data Collection

Standard RACE catch sampling procedures were followed as

described by Smith and Bakkala (1982). Briefly, catches which

fit on the sampling table (about 1 t) were processed entirely,

while larger catches were weighed using an electronic load cell.

In very few 'cases, catches greater than 1 t were subsampled using

the method described by Hughes (1976). Fishes and invertebrates

were identified to species as time and expertise permitted.

After the catches were sorted by species, weighed, and

enumerated, biological and specimen data were collected. Samples

of all fish species were measured to characterize how their size

composition varied with depth. Length measurements for up to 200

specimens of each of the primary target species were collected by

sex per haul. Otoliths, used for age determination, were

collected from sablefish, Dover sole, arrowtooth flounder

(Atheresthes stomias), shortspine thornyhead, longspine

thornyhead, and giant grenadier (Albatrossia pectoralis). Three

biological sampling strata, 183-549 m, 550-914 m, and 915-1,280 m,

were established to assure that samples were taken from a full

range of depths. Sampling effort was also spread evenly over the

geographic range of the survey. Otoliths were collected from
9

stratified samples of five fish per sex/centimeter interval per

biological sampling stratum.

Additional biological collections were made in cooperation

with colleagues from National Marine Fisheries Service (NMFS) and

other outside agencies. These collections were taken for studies

involving reproductive biology, age and growth, genetics, food

habits, morphometrics, pathology, and other fish life history

parameters.

Oceanographic Data Collection

Sea surface temperatures were taken at all stations using a

bucket thermometer. Bottom temperatures were measured using a

Richard Brancker XL-200 data logger mounted on the trawl

headrope. Additional information on temperature profiles from

this cruise is available on request from the authors.

Data Analysis

Several analyses are performed routinely on RACE survey

data. These include:

1) estimation of relative abundance,

2) estimation of population biomass,

3) estimation of population numbers, and

4) estimation of the population's size composition.
10

We used the area-swept method as described by Gunderson and

Sample (1980) to estimate population biomass and numbers.

Briefly, this method entails standardizing samples from each

station into catch per unit of effort (CPUE) in terms of either

kilograms or numbers per hectare (kg/ha, no./ha) and calculating

the arithmetic mean for each sampling stratum. Length-frequency

data were weighted by CPUE (no./ha) and expanded to the total

estimated population abundance to estimate the population size

composition for each species. Selected size composition

estimates were applied to age-length keys to obtain estimated age

compositions. All analyses were computed for the INPFC Eureka

statistical area by depth stratum, and by all depth strata

combined.
11

RESULTS

Haul, Catch, and Biological Data

One-hundred and forty-seven tows were attempted during the

survey. All 17 of the east-west tracklines within the survey

area were completed. Out of 108 scheduled stations, 106 were

sampled successfully (Fig. 2). Two stations were abandoned

because the bottom was too rough or too steep. The remainder of

the attempted tows were unsuccessful due to hang-ups, rips, bad

bottom, or gear problems. SCANMAR net mensuration data were

obtained from 109 tows, submersible bathythermograph and bottom

contact sensor data from 103 tows, door tilt sensor data from

125 tows, videotape of the Wesmar net sonar video output from

65 tows, and GPS course and position data from 128 tows. Eleven

test tows were conducted with an underwater video camera attached

to the trawl in addition to the other net metering

instrumentation, to observe and assess the performance of the

modified trawl.

The trawl's horizontal opening (wingtip to wingtip) was

measured for 109 tows and mean net width was calculated for each

trawl haul. An overall mean path width of 17.15 m was calculated

for the entire survey using 87 of the 109 tows with good

performance. The range of average net widths for these 87 tows
12

was 14.66 m to 19.01 m. The relationship between mean net width

and depth, and mean net width and wire length was constant. The

overall mean path width was used in area-swept calculations for

hauls where actual net width measurements were unavailable.

Table 2 summarizes the biological data collected from fish

species. Specimen ages from collected otoliths will be

determined by researchers from the Pacific States Marine

Fisheries Commission (Dover sole and sablefish) and by a graduate

student from the Moss Landing Marine Laboratory (giant,

grenadier). We also collected data and specimens for several

special studies requested by colleagues in other agencies or

institutions, who will report the results of their studies

elswhere.

A total of 121 fish species representing 50 fish families

were identified over the course of the survey. Table 3 lists the

frequencies of occurrence, depth ranges, and the range of

distribution by latitude for all fishes identified in trawl

samples. Table 4 lists the invertebrates captured representing 9

phyla and 17 classes. Of the 140 invertebrates listed, 68 were

identified to species. Appendix A presents detailed station

information for each haul and catch weights of the major fish and

invertebrate species caught in each haul. The number of

individual fish length observations of each fish species is

reported in Table 5 by depth stratum.
13

Temperature Data

Sea surface temperatures ranged from 9.8" to 13.9°C, and

bottom temperatures ranged from 2.3° to 8.O°C. Mean sea surface

temperature was 13.O°C, and mean bottom temperature was 4.6°C.

Sea surface temperature generally increased with increasing

latitude south of lat. 41°36'N and north of lat. 42°06'N. The

area between lat. 41°36'N and 42°06'N appeared to be some sort of

transition zone where surface temperatures dropped by

approximately 3°C. This may, to some extent, be an artifact of

the sampling pattern. Bottom temperatures decreased with

increasing depth in the Eureka area (Fig. 5).

Relative Density and Distribution of species

The 20 most abundant groundfish and selected crab species in

each depth stratum are presented in Table 6. Pacific hake

(Merluccius productus), spiny dogfish (Squalus acanthias), and

Dover sole had the highest mean catch rates in Strata 1 and 2,

and longspine thornyhead, shortspine thornyhead, Dover sole, true

Tanner crab (Chionoecetes tanneri), sablefish, Pacific grenadier

(Coryphaenoides acrolepis), and giant grenadier had the highest

mean catch rates in Strata 3 to 6. The complete listings of

relative abundance of all fish and invertebrate species ranked by

mean CPUE by depth stratum and by all strata combined are

presented in Appendix B.
14

Maps of the geographical distribution of arrowtooth

flounder, darkblotched rockfish (Sebastes crameri), Dover sole,

giant grenadier, longspine thornyhead, Pacific grenadier, Pacific

hake, Pacific ocean perch (Sebastes alutus), sablefish,'

shortspine thornyhead, spiny dogfish, splitnose rockfish

(Sebastes diploproa), and true Tanner crab are presented in

Figures 6-18 in alphabetical order. These maps show the

locations of hauls with positive catches of the species. Catch

rates were categorized as: 1) greater than zero and less than or

equal to the mean; 2) greater than the mean and less than or

equal to one standard deviation from the mean; 3) between one and

two standard deviations greater than the mean; and 4) over two

standard deviations greater than the mean.

Biomass and Population Estimates

Abundance estimates (t) of biomass and associated

coefficient of variation (%) are presented for various taxa by

stratum in Table 7. Similarly, estimates of population numbers

are presented for important species groups in Table 8.

The total number of hauls and hauls with weight, number, and

length data by stratum for the various taxa are represented in

Table 9. Biomass estimates for the four commercially important

species varied by species and by stratum. The total biomass

estimates for sablefish, Dover sole, longspine thornyhead, and
15

shortspine thornyhead were 11,202 t, 17,340 t, 21,104 t, and

5,470 t, respectively. The total population estimates were

6,448,871 sablefish, 32,572,431 Dover sole, 220,124,793 longspine

thornyhead, and 11,804,231 shortspine thornyhead.

Readers should be aware that the biomass and population

estimates presented here are not absolute estimates since herding

by doors and bridles and escapement underneath the trawl's roller

gear, around the net's opening, and through the net's meshes can

affect the bottom trawl catches (Gunderson 1993). For lack of

data on species-by-species catchability, abundance calculations

are based on the assumption that all fish in front of the trawl

and between the wingtips are captured. The degree of bias

introduced by this assumption will vary among species. For

instance, the ability of a fish to avoid the net will depend on

the fish's shape, size, speed, and its reaction to the part of

the net encountered. Furthermore, the survey covers limited

portions of the depth and geographic range of some of these

species. As mentioned previously, this survey targets many.

species and provides general information where it lacks in

specific information. These surveys are the only fisheryindependent source of information on the abundance, distribution,

and length and age-composition for many of these species. Stock

assessment scientists utilize our survey results, along with

commercial catch data, in order to set the most -appropriate catch

levels.
16

Size and Age Composition

Estimated population length compositions for several

groundfish species are presented in Figures 19-25 by species and

by depth stratum. For more detail, Appendix C contains listings

of estimated length compositions for major species by sex and for

all depth strata combined. Printed or electronic files of size

composition are available by species, INPFC area, and depth

stratum upon request from the authors.

At the time this report was prepared, the only age data

available for analyses were for sablefish. Population estimates

by age group and mean length at age for the Eureka area are

presented in Table 10 using an age-length key for all depths,

sexes, and areas combined. Lengths at age were different between

the sexes and were more variable at greater depths for sablefish,

so further analyses were done using three depth and sex-specific

age-length keys. The depth strata used were the same as the

biological sampling strata. Results from these analyses are

presented in graphical format in Figure 26.

The age data from other years and species, and the results

generated by these data, including growth rates, population at

age, and biomass at age, can be obtained upon request from the

authors in either printed or electronic form.
17

Length-Weight Relationships

From the individual fish weight samples, we determined

length-weight relationships for arrowtooth flounder, Dover sole,

sablefish, shortspine thornyhead, longspine thornyhead, and giant

grenadier using a non-linear least squares regression model.

Table 11 summarizes the length-weight relationships by sex and

for all sexes combined (including unsexed fish).
18

ACKNOWLEDGMENTS

I would like to thank all the cruise participants for their

hard work during the 1995 West Coast upper continental slope

groundfish survey. Participants included (in alphabetical order)

Troy Buckley, Jim Burns, Roger Clark, Bill Flerx, Robin Harrison,

Allen Harvison, Dan Kamikawa, Dave King, Mike MacEwan, Michael

Martin, Scott McEntire, Jay Orr, Ben Page, Terry Sample, Jim

Smart and, Gary Stauffer. I would also like to express my

appreciation to Commander John Clary, the officers, the survey

department, the electronics department, and the rest of the crew

of the NOAA ship Miller Freeman. They provided a safe and

livable working environment and valuable assistance during the

1995 West Coast continental slope groundfish trawl survey.

Thanks also to Gary Mundell for data editing and Dave

Roetcisoender for help with the gear mensuration equipment.

Special thanks to Scott McEntire for his help with obtaining the

underwater video camera footage of the groundgear and V-door, and

for developing and fabricating the tilt sensors.
19

TABLES
20

Table l.-- The relationship between bottom depth and the length of trawl wire

used for bottom trawling during the West Coast upper continental

slope bottom trawl survey using mudsweep roller gear, 1 inch

die-formed trawl warps, and a towing speed of 2.3 knots.
21

Table P.--Biological data collected during the 1995 West Coast upper continental slope

bottom trawl survey of the International North Pacific Fisheries Commission

Eureka area.
22

Table 3 .--Frequency of occurrence, depth, and latitude ranges

caught during the 1995 West Coast upper continental

survey of the International North Pacific Fisheries

area.

for fish species

slope bottom trawl

Commission Eureka

24

Table 3 .--Continued.
25

Table 4: --Frequency of occurrence, depth, and latitude ranges for invertebrate

species caught during the 1995 West Coast upper continental slope bottom

trawl survey of the International North Pacific Fisheries Commission

Eureka area.
26

Table 4. --Continued.
Table 4 .--Continued.
28

Table 4 .--Continued.
29

Table 5.--Number of length frequency measurements collected by stratum for the 1995

West Coast upper continental slope bottom trawl survey of the International

North Pacific Fisheries Commission Eureka area.
30

Table 6.--Mean CPUE (kg/ha) of the 20 most abundant groundfish and selected crab species

caught during the 1995 West Coast upper continental slope bottom trawl survey

of the International North Pacific Fisheries Commission Eureka area.
31

Table 7.--Estimates of fish biomass (metric tons) and coefficient of variation (CV)

stratum for the International North Pacific Fisheries Commission Eureka

area from the 1995 West Coast upper continental slope bottom trawl survey.

Differences in totals result from rounding.
32

Table 9.--Estimates of fish population and coefficient of variation (CV) by stratum for the

International North Pacific Fisheries Commission Eureka area from the 1995 West Coast

upper continental slope bottom trawl survey. Differences in totals result from rounding.

34

Table lO.--Population estimates for sablefish by age group and mean length

at age for the International North Pacific Fisheries Commission

Eureka area for all depth strata (183-1,280 m) from the 1995

West Coast upper continental slope bottom trawl survey.
Table Il.--The length-weight relationships for selected fishes from the 1995 West Coast

upper continental slope bottom trawl survey of the International North Pacific

Fisheries Commission Eureka area using nonlinear regression fit for the equation:
37

FIGURES
Figure 1. --Map showing the boundaries for the West Coast

International North Pacific Fisheries Commission

(INPFC) statistical areas and the latitudinal ranges

of West Coast upper continental slope groundfish

bottom trawl surveys from 1989 to 1993.
Figure 2. --Map showing the location of 106 successful bottom

trawl tows sampled during the 1995 West Coast

upper continental slope groundfish survey.
Web: Chaffing strip along inside of Bottom wings and Busom. Cut 8 meshes wide.

5 mm Double Bar mesh, goring 3 meshes on each side (leaving 2 open meshes)

Secure 3 mesh of gore on inside (Bar Cut) of Bottom wings, and securing

other gore to footrope (Bolsh).

Figure 3. --The sampling trawl used during the 1995

West Coast upper continental slope bottom

traw1 survey.
41

West Coast Upper

Continental Slope

Bottom Trawl Survey

Ground Gear

Figure 4. --The groundgear used during the 1995 West Coast

upper continental slope bottom trawl survey.

Figure 6. --Arrowtooth flounder distribution and relative

abundance (kg/ha) from the 1995 West Coast upper

continental slope bottom trawl survey.
Figure 7.-- Darkblotched rockfish distribution and relative

abundance (kg/ha) from the 1995 West Coast upper

continental slope bottom trawl survey.
Figure 8.-- Dover sole distribution and relative abundance

(kg/ha) from the 1995 West Coast upper continental

slope bottom trawl survey.
Figure 9. --Giant grenadier distribution and relative

abundance (kg/ha) from the 1995 West Coast upper

continental slope bottom trawl survey.
Figure 10. --Longspine thornyhead distribution and relative

abundance (kg/ha) from the 1995 West Coast upper

continental slope bottom trawl survey.
Figure 11. --Pacific grenadier distribution and relative

abundance (kg/ha) from the 1995 West Coast upper

continental slope bottom trawl survey.
Figure 12. --Pacific hake distribution and relative

abundance (kg/ha) from the 1995 West Coast upper

continental slope bottom trawl survey.
Figure 13. --Pacific ocean perch distribution and relative

abundance (kg/ha) from the 1995 West Coast upper

continental slope bottom trawl survey.
Figure 14. --Sablefish distribution and relative

abundance (kg/ha) from the 1995 West Coast upper

continental slope bottom trawl survey.
Figure 15. --Shortspine thornyhead distribution and relative

abundance (kg/ha) from the 1995 West Coast upper

continental slope bottom trawl survey.
Figure 16. --Spiny dogfish distribution and relative

abundance (kg/ha) from the 1995 West Coast upper

continental slope bottom trawl survey.
Figure 17. --Splitnose rockfish distribution and relative

abundance (kg/ha) from the 1995 West Coast upper

continental slope bottom trawl survey.
Figure 18. --True Tanner crab distribution and relative

abundance (kg/ha) from the 1995 West Coast upper

continental slope bottom trawl survey.

Figure 20.--Estimated population size composition and mean lengths (cm) of Dover sole by stratum and

by sex for the International North Pacific Fisheries Commission Eureka area for all depths

sampled (183-1,280 m) from the 1995 West Coast upper continental slope bottom trawl survey.
Figure 21. --Estimated population size composition (snout-to-anal fin) and mean lengths (cm) of giant

grenadier by stratum and by sex for the International North Pacific Fisheries Commission Eureka

area for all depths sampled (183-1,280 m) from the 1995 West Coast upper continental slope

bottom trawl survey.
Figure 22.--Estimated population size composition and mean lengths (cm) of longspine thornyhead by stratum

and by sex for the International North Pacific Fisheries Commission Eureka area for all depths

sampled (183-1,280 m) from the 1995 West Coast upper continental slope bottom trawl survey.
Figure 23. --Estimated population size composition (snout-to-anal fin) and mean lengths (cm) of Pacific

grenadier by stratum and by sex for the International North Pacific Fisheries Commission Eureka

area for all depths sampled (183-1,280 m) from the 1995 West Coast upper continental slope

bottom trawl survey.
Figure 24.--Estimated population size composition and mean lengths (cm) of sablefish by stratum and'

by sex for the International North Pacific Fisheries Commission Eureka area for all depths

sampled (183-1,280 m) from the 1995 West Coast upper continental slope bottom trawl survey.

Figure 26. --Sablefish estimated population age composition by stratum and by sex

for the International North Pacific Fisheries Commission Eureka area

from the 1995 West Coast upper continental slope bottom trawl survey.
64

CITATIONS

Butler, J.L., C.A. Kimbrell, W.C. Flerx, and R.D. Methot. 1989.

The 1987-88 demersal fish surveys off central California

(34°30'N to 36°30'N). U.S. Dep. Commer., NOAA Tech. Memo.

NMFS-SWFC-133, 44 p.

Eschmeyer, W.N., E.S. Herald, and H. Hammann. 1983. A field

guide to Pacific Coast fishes of North America. Houghton

Mifflin Co., Boston, MA., 336 p.

Gunderson, D.R. 1993. Surveys of fisheries resources. John

Wiley and Sons, Inc., New York, NY, 248 p.

Gunderson, D.R., and T.M. Sample. 1980. Distribution and

abundance of rockfish off Washington; Oregon, and California

during 1977. Mar. Fish. Rev. 42(3-4):2-16.

Hughes, S.E. 1976. System for sampling large trawl catches of

research vessels. J. Fish. Res. Board Can. 33:833-839.

Lauth, R.R., M.E. Wilkins, and P.R. Raymore Jr. 1997. Results of

trawl surveys of groundfish resources of the West Coast

upper continental slope. U.S. Dep. Commer., NOAA Tech. Memo.

NMFS-AFSC-79, 342 p.
65

Nelson, J.S. 1984. Fishes of the world, 2nd edition. John

Wiley & Sons, New York, NY, 523 p.

Parks, N.B., F.R. Shaw, and R.L. Henry. 1993. Results of a 1988

trawl survey of groundfish resources of the upper

continental slope off Oregon. U.S. Dep. Commer., NOAA Tech.

Memo. NMFS-AFSC-23, 164 p.

Raymore, P.A., Jr., and K.L. Weinberg. 1990. 1984 spring and

autumn surveys of Pacific West Coast upper continental slope

groundfish resources. U.S. Dep. Commer., NOAA Tech. Memo.

NMFS F/NWC-179; 196 p.

Robins, C.R. 1991. Common and scientific names of fishes from

the United States and Canada, Fifth Edition, Am. Fish. Soc.,

Special Publ. 20, 183 p.

Smith, G.B., and R.G. Bakkala. 1982. Demersal fish resources of

the eastern Bering Sea: Spring 1976. U.S. Dep. Commer.,

NOAA Tech. Rep. NMFS SSRF-754, 129 p.
67

APPENDIX A

Haul and Catch Information

Appendix A contains listings of station data and catch data

for all hauls from the 1995 West Coast upper continental slope

bottom trawl survey of the International North Pacific Fisheries

Commission (INPFC) Eureka statistical area. The depths are

reported in meters, the distances fished in kilometers, and

catches are in kilograms. Only catches with a performance value

of 0 or 1 were used for further data analysis.

A-l. Station and catch data for the NOAA ship Miller Freeman

during the 1995 West Coast upper continental slope bottom

trawl survey ...............................................68
Table A-l .--Station and catch data for the NOAA ship Miller Freeman during the 1995 West Coast upper

continental slope bottom trawl survey.
Table A-l--Continued.
Table A-l--Continued.
Table A-l--Continued.
Table A-l--Cohtinued.
Table A-l--Continued.
Table A-l --Continued.
Table A-l --Continued.
Table A-l--Continued.
Table A-l --Continued.
Table A-l--Continued.
Table A-l--Continued.
Table A-l--Continued.
Table A-l--Continued.
Table A-l--Continued.
83

APPENDIX B

Relative Abundance

Appendix B contains listings of all fish and invertebrate

species encountered during the 1995 West Coast upper continental

slope bottom trawl survey, ranked in order of relative abundance

by catch per unit effort (CPUE in kg/ha). Ranks are presented by

by depth stratum and for all depth strata combined.

B-l. Rank order of relative abundance (kg/ha) of fish and

selected crab species by depth stratum for the

International North Pacific Fisheries Commission Eureka

area from the 1995 West Coast upper continental slope

bottom trawl survey ......................................84
84

 Table B-l.--Rank or&r of relative abundance (kg/ha) of fish and invertebrate species by depth stratum for

the Eureka area from the 1995 West Coast upper continental slope bottom trawl survey.

Stratum 1 = 183-366 m, Stratum 2 = 367-549 m, Stratum 3 = 550-732 m, Stratum 4 = 733 - 914 m,

Stratum 5 = 915-1,097 m, and Stratum 6 = 1,098-1,280 m.
85

Table B-l.--Continued.
86

Table B-l.--Continued.
87

Table B-l.--Continued.
88

Table B-l.--Continued.
89

Table B-l.--Continued.
90

Table B-l.--Continued.
91

Table B-l.--Continued.
92

Table B-l.--Continued.
93

Table B-l.--Continued.
94

Table B-l.--Continued.

96

Table B-l.--Continued.
97

Table B-l.--Continued.
98

Table B-l.--Continued.
99

Table B-l.--Continued.
101

APPENDIX C

Population Numbers by Sex and Size Group

Appendix C contains listings of population numbers by sex

and size group (cm) for selected species from the 1995 West Coast

upper continental slope bottom trawl surveys. For each species,

estimates are presented for all depth strata combined.

C-l. Arrowtooth flounder population estimates for all depth

strata combined by sex and centimeter interval ...........102

C-2. Dover sole population estimates for all depth strata

combined by sex and centimeter interval ..................103

C-3

C-4

. Giant grenadier population estimates for all depth strata

combined by sex and centimeter interval ..................104

Longspine thornyhead population estimates for all depth

strata combined by sex and centimeter interval ...........105

C-5. Pacific grenadier population estimates for all depth strata

combined by sex and centimeter interval ..................106

C-6. Sablefish population estimates for all depth strata combined

by sex and centimeter interval ...........................107

C-7. Shortspine thornyhead population estimates for all depth

strata combined by sex and centimeter interval ...........109
102

Table C-l .--Arrowtooth flounder population estimates for all depth strata

combined by sex and centimeter interval for the International

North Pacific Fisheries Commission Eureka area from the 1995

West Coast upper continental slope bottom trawl survey.
103

Table C-Z .--Dover sole population estimates for all depth strata combined

by sex and centimeter interval for the International North

Pacific Fisheries Commission Eureka area from the 1995 West

Coast upper continental slope bottom trawl survey.
104

Table C-3 .--Giant grenadier population estimates for all depth strata combined

by sex and centimeter interval (snout-to-anal fin) for the

International North Pacific Fisheries Commission Eureka area from.

the 1995 West Coast upper continental slope bottom trawl survey.
105 

Table C-4.--Longspine thornyhead population estimates for all depth strata

combined by sex and centimeter interval for the International North

Pacific Fisheries Commission Eureka area from the 1995 West Coast

upper continental slope bottom trawl survey.
106

Table c-5 .--Pacific grenadier population estimates for all depth strata combined

by sex and centimeter interval (snout-to-anal fin) for the International

North Pacific Fisheries Commission Eureka area from the 1995 West Coast

upper continental slope bottom trawl survey.
107

Table C-6 .--Sablefish population estimates for all depth strata combined by sex

and centimeter interval for the International North Pacific

Fisheries Commission Eureka area from the 1995 West Coast upper

continental slope bottom trawl survey.
108

Table C-6 .--Continued.
109

Table C-7 .--Shortspine thornyhead population estimates for all depth strata

combined by sex and centimeter interval for the International North

Pacific Fisheries Commission Eureka area from the 1995 West Coast

upper continental slope bottom trawl survey.
110

Table C-7.--Continued.
RECENT TECHNICAL MEMORANDUMS

Copies of this and other NOAA Technical Memorandums are available from the

National Technical Information Service, 5285 Port Royal Road, Springfield, VA 22167

(web site: www.ntis.gov). Paper and microfiche copies vary in price. 

AFSC79 LAUTH, R. R., M. E. WILKINS, and P. A. RAYMORE JR. 1997. Results of trawl surveys of groundfish

resources of the West Coast upper continental slope from 1989 to 1993, 342 p. NTIS No. PB97-208904.

78 HILL, P. S., D. P. DEMASTER, and R. J. SMALL. 1997. Alaska marine mammal stock assessments,

1996, 150 p. NTIS No. PB97-203277.

77 CHUMBLEY, K., J. SEASE, M. STRICK, and R. TOWELL. 1997. Field studies of Steller sea lions

(Eumetopias jubatus) at Marmot Island, Alaska, 1979 through 1994, 99 p. NTIS No. PB97-203376.

76 OSMEK, S., J. CALAMBOKIDIS, J. LAAKE, P. GEARIN, R. DELONG, J. SCORDINO, S. JEFFRIES, and

R. BROWN. 1997. Assessment of the status of harbor porpoise ( Phocoena phocoena) in Oregon and

Washington waters, 46 p. NTIS No. PB97-198436.

75 WING, B. L., C. W. DERRAH, and V. M. O’CONNELL. 1997. Ichthyoplankton in the eastern Gulf of

Alaska, May 1990, 42 p. NTIS No. PB97-174379.

74 WILSON, C. D., and M. A. GUTTORMSEN. 1997. Echo integration-trawl survey of Pacific whiting,

Merluccius productus, off the west coasts of the United States and Canada during July-September 1995,

70 p. NTIS No. PB97-174387.

 

73 CELEWYCZ, A. G., and A. C. WERTHEIMER. 1997. Suitability of Dry Bay, southeastern Alaska, as

rearing habitat for juvenile salmon, 19 p. NTIS No. PB97-161343.

72 KINOSHITA, R. K., A. GREIG, D. COLPO, and J.M. TERRY. 1997. Economic status of the groundfish

fisheries off Alaska, 1995, 91 p. NTIS No. PB97-161269. 

71 STRICK, J. M., L. W. FRITZ, and J. P. LEWIS. 1997. Aerial and ship-based surveys of Steller sea lions

(Eumetopias jubatus) in Southeast Alaska, the Gulf of Alaska, and Aleutian Islands during June and July

1994, 55 p. NTIS No. PB97-144026.

70 EBBERTS, B. D., and B. L. WING. 1997. Diversity and abundance of neustonic zooplankton in the north

Pacific subarctic frontal zone, 34 p. NTIS No. PB97-138218. 

69 SINCLAIR, E.H. (editor). 1996. Fur seal investigations, 1994, 144 p. NTIS No. PB97-129456.

68 MERRICK, R. L., T. R. LOUGHLIN, and D. G. CALKINS. 1996. Hot branding: A technique for long-term

marking of pinnipeds, 21 p. NTIS No. PB97-124226.

67 LANG, G M., and P. A. LIVINGSTON. 1996. Food habits of key groundfish species in the eastern Bering

Sea slope region, 111 p. NTIS No. PB97-124010.

66 KINOSHITA, R. K., and J. M. TERRY. 1996. Oregon, Washington, and Alaska exports of edible fishery

products, 1995, 48 p. NTIS No. PB96-214663.

65 HONKALEHTO T., and N. WILLIAMSON. 1996. Echo integration-trawl survey of walleye pollock

(Theragra chalcogramma) in the Southeastern Aleutian Basin during February and March 1995, 57 p. 

NTIS No. PB96-202726.

64 TYNAN, C. 1996. Characterization of oceanographic habitat of cetaceans in the Southern Indian Ocean

between 82/ - 115/ E: Cruise report from World Ocean Circulation Experiment (WOCE) I8S and I9S,