NOAA Technical Memorandum NMFS-NE-159

This report series represents a secondary level of scientifiic publishing. All issues employ thorough

internal scientific review; some issues employ external scientific review. By design, reviews are

transparent collegial reviews, not anonymous peer reviews. All issues may be cited in formal

scientific communications.

U. S. DEPARTMENT OF COMMERCE

Norman Y. Mineta, Secretary

National Oceanic and Atmospheric Administration

D. James Baker, Administrator

National Marine Fisheries Service

Penelope D. Dalton, Assistant Administrator for Fisheries

Northeast Region

Northeast Fisheries Science Center

Woods Hole, Massachusetts

October 2000

An Overview and History

of the Food Web Dynamics Program

of the Northeast Fisheries Science Center,

Woods Hole, Massachusetts

National Marine Fisheries Serv., 166 Water St., Woods Hole, MA 02543-1026

Jason S. Link and Frank P. Almeida
Editorial Notes

Species Names: The NEFSC Editorial Office’s policy on the use of species names in all technical communications

is generally to follow the American Fisheries Society’s lists of scientific and common names for fishes (i.e., Robins et

al. 1991a

), mollusks (i.e., Turgeon et al. 1998b), and decapod crustaceans (i.e., Williams et al. 1989c), and to follow the

Society for Marine Mammalogy's guidance on scientific and common names for marine mammals (i.e., Rice 1998d

).

Exceptions to this policy occur when there are subsequent compelling revisions in the classifications of species, resulting

in changes in the names of species (e.g., Cooper and Chapleau 1998e

, McEachran and Dunn 1998f).

Statistical Terms: The NEFSC Editorial Office’s policy on the use of statistical terms in all technical

communications is generally to follow the International Standards Organization’s handbook of statistical methods (i.e.,

ISO 1981g

).

Internet Availability: This issue of the NOAA Technical Memorandum NMFS-NE series is being copublished,

i.e., both as a paper copy and as a Web posting. The Web posting is available at: http://www.nefsc.nmfs.gov/nefsc/

publications/index.htm. Also, additional information associated with this issue can be accessed at: http://www.

nefsc.nmfs.gov/pbio/fwdp/FWDP.htm.

a

Robins, C.R. (chair); Bailey, R.M.; Bond, C.E.; Brooker, J.R.; Lachner, E.A.; Lea, R.N.; Scott, W.B. 1991. Common and scientific names of fishes

from the United States and Canada. 5th ed. Amer. Fish. Soc. Spec. Publ. 20; 183 p.

b

Turgeon, D.D. (chair); Quinn, J.F., Jr.; Bogan, A.E.; Coan, E.V.; Hochberg, F.G.; Lyons, W.G.; Mikkelsen, P.M.; Neves, R.J.; Roper, C.F.E.;

Rosenberg, G.; Roth, B.; Scheltema, A.; Thompson, F.G.; Vecchione, M.; Williams, J.D. 1998. Common and scientific names of aquatic

invertebrates from the United States and Canada: mollusks. 2nd ed. Amer. Fish. Soc. Spec. Publ. 26; 526 p.

c

Williams, A.B. (chair); Abele, L.G.; Felder, D.L.; Hobbs, H.H., Jr.; Manning, R.B.; McLaughlin, P.A.; Pérez Farfante, I. 1989. Common and

scientific names of aquatic invertebrates from the United States and Canada: decapod crustaceans. Amer. Fish. Soc. Spec. Publ. 17; 77 p.

d

Rice, D.W. 1998. Marine mammals of the world: systematics and distribution. Soc. Mar. Mammal. Spec. Publ. 4; 231 p.

e

Cooper, J.A.; Chapleau, F. 1998. Monophyly and interrelationships of the family Pleuronectidae (Pleuronectiformes), with a revised classification.

Fish. Bull. (U.S.) 96:686-726.

f

McEachran, J.D.; Dunn, K.A. 1998. Phylogenetic analysis of skates, a morphologically conservative clade of elasmobranchs (Chondrichthyes:

Rajidae). Copeia 1998(2):271-290.

g

ISO [International Organization for Standardization]. 1981. ISO standards handbook 3: statistical methods. 2nd ed. Geneva, Switzerland: ISO.
Page iii

Contents

Abstract ............................................................................................................................................................................... 1

Introduction ......................................................................................................................................................................... 1

Program History ......................................................................................................................................................... 1

Methods............................................................................................................................................................................... 2

Databases .................................................................................................................................................................... 2

The Surveys ................................................................................................................................................................. 2

Data Processing .......................................................................................................................................................... 4

Data Continuity Across the Time Series............................................................................................................................. 4

Prey Taxonomic Resolution ....................................................................................................................................... 4

Weight-Volume Conversion ....................................................................................................................................... 4

Summary Statistics .............................................................................................................................................................. 4

Stomach Sampling Effort Coverage ........................................................................................................................... 4

Data Overview ............................................................................................................................................................. 4

Diet Summaries .......................................................................................................................................................... 5

Discussion ........................................................................................................................................................................... 7

Diet Overview ............................................................................................................................................................. 7

Historical and Current Relevance .............................................................................................................................. 8

Acknowledgments ............................................................................................................................................................... 8

References Cited................................................................................................................................................................. 9

Tables

Table 1. Timeline of research emphasized and hypotheses studied by the Food Web Dynamics Program and

 its predecessors ............................................................................................................................................. 12

Table 2a. Stomach sampling requests made to the NEFSC Bottom Trawl Survey Program during 1973-86............... 13

Table 2b. Stomach sampling requests made to the NEFSC Bottom Trawl Survey Program during 1987-99............... 15

Table 3. Levels of taxonomic resolution for selected prey items used in Food Web Dynamics Program

analyses and summaries .................................................................................................................................. 17

Table 4. Weight-to-volume regression statistics for all species combined and for selected species ........................ 18

Table 5. Summary parameters for predators examined by the Food Web Dynamics Program during 1973-98 ........ 19

Figures

Figure 1. Map of the Northeast U.S. Continental Shelf Ecosystem depicting the area covered by the NEFSC

Bottom Trawl Survey Program .................................................................................................................... 24

Figure 2. The number of stomachs examined versus the number of prey items observed for spiny dogfish, silver

hake, Atlantic cod, white hake, pollock, and yellowtail flounder ............................................................... 25

Figure 3. The number of stomachs examined versus the number of prey items observed for winter skate, smooth

skate, witch flounder, Atlantic halibut, bluefish, and alewife ..................................................................... 26

Figure 4. The number of stomachs examined versus the number of prey items observed for Atlantic herring,

Atlantic mackerel, and thorny skate ............................................................................................................ 27

Figure 5. Percent frequency of occurrence of major prey items, excluding well digested prey and empty

stomachs, for all predators in the database ................................................................................................. 28

Figure 6. Percent diet composition by weight of major prey items for spiny dogfish and smooth dogfish ............ 29

Figure 7. Percent diet composition by weight of major prey items for little skate, winter skate, and thorny

skate ............................................................................................................................................................. 30

Figure 8. Percent diet composition by weight of major prey items for smooth skate and clearnose skate ............. 31

Figure 9. Percent diet composition by weight of major prey items for Atlantic herring, Atlantic mackerel, and

alewife ......................................................................................................................................................... 32

Figure 10. Percent diet composition by weight of major prey items for northern sand lance and butterfish ............ 33

Figure 11. Percent diet composition by weight of major prey items for northern shortfin squid and longfin

inshore squid ................................................................................................................................................ 34
Page iv

Figure 12. Percent diet composition by weight of major prey items for Atlantic cod, haddock, and pollock ........... 35

Figure 13. Percent diet composition by weight of major prey items for silver hake and white hake ......................... 36

Figure 14. Percent diet composition by weight of major prey items for red hake and spotted hake.......................... 37

Figure 15. Percent diet composition by weight of major prey items for Atlantic halibut, American plaice, and

yellowtail flounder ...................................................................................................................................... 38

Figure 16. Percent diet composition by weight of major prey items for fourspot flounder, summer flounder, and

winter flounder ............................................................................................................................................ 39

Figure 17. Percent diet composition by weight of major prey items for windowpane and witch flounder ................ 40

Figure 18. Percent diet composition by weight of major prey items for bluefish, weakfish, and goosefish ............. 41

Figure 19. Percent diet composition by weight of major prey items for scup, black sea bass, and Acadian

redfish .......................................................................................................................................................... 42

Figure 20. Percent diet composition by weight of major prey items for sea raven, longhorn sculpin, and ocean

pout .............................................................................................................................................................. 43

Appendix

Appendix A. Stomach Sampling Protocols Used during NEFSC Bottom Trawl Surveys, 1963-99 ........................... 44

Appendix A Tables

Table A1. Species to be sampled, and maximum lengths for sampling YOY, for the five regions during

1973-76 ....................................................................................................................................................... 49

Table A2. Examples of stomach and jar cap labels, and codes for sex and maturity stage, during 1973-76 ............. 50

Table A3. Offshore species to be sampled, and maximum lengths for sampling juveniles, for the five regions

during 1977-80 ............................................................................................................................................ 51

Table A4. Species to be sampled for inshore strata north and south of Cape Cod during 1977-80 .......................... 52

Table A5. Miscellaneous species to be sampled from specific areas or from any area during 1977-80 .................. 53

Table A6. Examples of stomach and jar cap labels, and codes for sex and maturity stage, during 1977-80 ............. 54

Table A7. Order of sampling priority for species from which stomach contents will be sampled for the Feeding

Ecology Project during 1981-84 ................................................................................................................ 55

Table A8. Priority species to be sampled for stomach contents analyses at sea during 1985-91 ............................. 56

Table A9. Secondary species to be sampled for stomach contents analyses at sea during 1985-91 ......................... 57

Table A10. Species to be sampled, sampling ranges, and maximum stomach sampling levels for 1992-93 bottom

trawl surveys ................................................................................................................................................ 58

Table A11. Species to be sampled, sampling ranges, and designated priorities for stomach sampling for 1994-98

bottom trawl surveys ................................................................................................................................... 59

Table A12. Species to be sampled, sampling ranges, and designated priorities for stomach sampling for 1999

bottom trawl surveys ................................................................................................................................... 60

Acronyms

BEP = Benthic Ecology Program (predecessor to the FEP)

EMI = Ecosystem Modeling Investigation

FCDI = Food Chain Dynamics Investigation (predecessor to the FWDP)

FEP = Feeding Ecology Project (predecessor to the FCDI)

FWDP = Food Web Dynamics Program

GLOBEC = (U.S.) Global Ocean Ecosystems Dynamics Program

NEFC = Northeast Fisheries Center (predecessor to the NEFSC)

NEFSC = Northeast Fisheries Science Center

NMFS = National Marine Fisheries Service

YOY = young of the year
Page 1

Abstract

We provide an overview of the National Marine Fisheries Service (NMFS), Northeast Fisheries Science Center (NEFSC), Food Web Dynamics Program (FWDP). The FWDP’s food habits database is

one of the largest in the world and extends from 1973 to present. This database covers the entire

Northeast U.S. Continental Shelf Ecosystem and has over 250,000 stomachs from more than 120 predators, with more than 1,200 different types of prey collected. We discuss the differences in sampling

protocols and priorities over the history of the program, and address issues of time-series continuity.

For most species, diet can be adequately characterized with an examination of 500-1,000 stomachs.

The basic diet composition for 38 predators, including economically and ecologically important species, demonstrates that most members of the fish community of this ecosystem are generalists, exhibiting a broad diet as either a benthivore, planktivore, or piscivore. Many major ecosystem and multispecies

issues in fisheries management can only be addressed with a knowledge derived from food habits data

such as those described in this document.

INTRODUCTION

As the history of the fishes themselves would not be complete without a thorough knowledge of their associates

in the sea, especially such as prey upon them or in turn

constitute their food, it was considered necessary to prosecute searching inquiries on these points....

Spencer Baird (1873)

In his seminal report to Congress published in 1873,

Baird called for a research program to explore five potential causes of declines in fish stocks in Southern New England waters, and thereby established the precursors to the

Woods Hole scientific community and NMFS. Two of the

five major causes proposed by Baird consider trophic dynamics.

The research objectives of the FWDP are to: 1) assess predation mortality relative to fishing mortality for

commercially important fishes; 2) mechanistically and predictively model species interactions that impact the status

of these stocks, particularly critical life stages; 3) relate

changes in diet to changes in population level growth rates;

and 4) better understand the Northeast U.S. Continental Shelf

Ecosystem. In this document, we provide a history of food

web dynamics research, review the food habits data collection and analytical methods, and give an overview of the

FWDP food habits database at the NEFSC.

PROGRAM HISTORY

Baird’s (1873) report was in direct response to declining fish populations in nearshore Southern New England waters. In contrast, there were consistently productive offshore fisheries for Atlantic halibut, haddock, Atlantic cod, and similar species for the next seven or eight

decades. However, by the 1950s, after the halibut fishery

had effectively collapsed, there were indications that haddock populations were also declining. Specific surveys

were initiated in the late 1950s and were expanded in the

1960s to track these trends. Additionally, collection of

basic biological information on haddock had begun in 1953

to determine the relationship between the distribution and

abundance of this species and the availability of benthic

fauna (USFWS 1954). Since there was already an active

Benthic Ecology Program (BEP) at the Woods Hole Laboratory (Steimle et al. 1995) from Baird’s inclusive interest in all aspects of the ecosystem, and since haddock are

principally benthivores, the BEP undertook examination

of haddock stomachs (Table 1). From the BEP perspective, the examination of stomachs was an alternative sampling method to categorize the benthic fauna of the region.

In 1963, a standardized bottom trawl survey was initiated

(see “Methods” section), designed to provide quantitative

abundance indices for virtually all finfish species and to

concurrently collect selected biological data as was feasible. Opportunistic stomach sampling continued on these

surveys until 1966.

By the late 1960s, there was a clear, documented decline in the gadid-flatfish species complex of fish. In addition, Atlantic herring began a rapid decline in the late

1960s, followed by Atlantic mackerel in the early 1970s.

Given this ubiquitous decline, a multispecies management

scheme was formalized in 1974 to include a two-tiered

quota system; the first tier placed single species total allowable catch limits on the international fleet prosecuting

fisheries in the Northwest Atlantic, while the second placed

a limit on the overall multispecies catch (Hennemuth and

Rockwell 1987). This approach reaffirmed the need for

broad biological information from as many species as possible.

Protocols for stomach sampling during 1969-72 varied and were generally categorical due to a lack of resources. The efforts during this period identified the major trophic interactions during a time of precipitous change

in the fish community, and characterized the diets of major

groundfish species (Maurer 1975; Maurer and Bowman

1975; Bowman et al. 1976; Edwards and Bowman 1979;

Langton and Bowman 1980; Bowman 1981).

In 1973, the Feeding Ecology Project (FEP) was

formed to initiate more systematic stomach collections.

In the mid- to late 1970s, the issue of recruitment became
Page 2

increasingly important due to a massive decline in fish biomass. At this time, Atlantic herring and Atlantic mackerel

were added to the stomach sampling protocol due to their

potential as larval fish predators (Jossi and Marak 1983).

Two new programs were formed in response to the change

in focus toward factors affecting recruitment. The Food

Chain Dynamics Investigation (FCDI) was formed to extend the work of the FEP, while an Ecosystem Modeling

Investigation (EMI) primarily studied the mortality of

prerecruits. The need to quantify species interactions was

also recognized as an important issue, and reports detailing refined and quantified characterizations of the diet for

many major species were produced as a first step to address this issue (Michaels and Bowman 1982; Bowman and

Michaels 1984).

In the late 1970s and early 1980s, the focus of the

programs remained on attempting to link recruitment variability with predation, particularly to match predator consumption rates to observed larval fish mortalities (Grosslein

et al. 1980; Sissenwine 1984; GLOBEC 1991). Additionally, attempts to model the energy and production budgets

of the region, especially Georges Bank, were initiated. The

emphasis on the importance of predation was extended to

all life stages for more species throughout the 1980s, with

continual effort given to refining estimators of diet and

consumption. As the fish community continued to undergo

drastic changes, studies to evaluate these patterns were also

undertaken.

Through the early 1990s, an emphasis continued on

the importance of predation, particularly larval mortality

(Almeida et al. 1999). In the mid-1990s, the FWDP was

formed to extend efforts of the FCDI and EMI, with a focus on the fish community as an entity. Trophodynamic,

aggregate biomass, and multispecies modeling efforts were

initiated to continue exploring the causal mechanisms responsible for the observed changes in the fish community.

The current, broad focus of the FWDP is to examine all

trophic aspects of ecosystem dynamics in the U.S. waters

of the Northwest Atlantic.

METHODS

DATABASES

The FWDP has two major sources of data. Both

sources provide primarily stomach content information,

i.e., diet composition, total and individual prey weights or

volumes, and prey length. The more extensive source is

the standard, multispecies, NEFSC Bottom Trawl Survey

Program. These surveys were designed to monitor trends

in abundance and distribution and to provide data and

samples to study the biology and ecology of the fishes and

invertebrates inhabiting the Northeast U.S. Continental Shelf

Ecosystem. During the surveys, food habits data are collected for a variety of species.

Additionally, “process-oriented” cruises are conducted periodically to address specific questions related

to the trophic dynamics of the fishes in the ecosystem.

While an important component of the overall trophic dynamics research program, the data from these cruises are

not included in this report. Other databases, not described

in this document, encompass the prey fields of these fishes

and include zooplankton, ichthyoplankton, and benthos.

THE SURVEYS

The series of standardized bottom trawl surveys conducted in the Northwest Atlantic from Cape Hatteras, NC,

to Nova Scotia (approximately 85,300 nm2

, or 293,000

km2

) is the central element in a broadscale ecological and

fishery research program at the NEFSC (Figure 1). Surveys have been conducted continuously in the fall since

1963, and in the spring since 1968; seasonal surveys have

also been conducted in summer and winter on an intermittent basis.

Trawl stations are selected using a stratified random

design that provides unbiased estimates of a species availability to the trawl gear in relation to distribution. Strata

were defined based on water depth, latitude, and historical

fishing patterns. Within each stratum, stations are assigned

randomly. The number of stations allotted to a stratum are

in proportion to its area (approximately one station per 200

nm2

, or 690 km2); however, a minimum of two stations are

assigned to small strata in order to calculate their means.

The surveys are conducted in depths of approximately 27-

366 m; however, greater depths are occasionally sampled

in the deep canyons along the continental shelf break. Once

onboard, the catch is sorted and weighed (to the nearest

0.1 kg) by species, with individuals measured (to the nearest 1.0 cm) and categorized by sex and maturity stage.

Subsamples of key species are eviscerated for feeding ecology and other studies. Geographic location, depth, and

hydrographic data are also collected at each station. A complete description and evaluation of the Bottom Trawl Survey Program can be found in Grosslein (1969), Azarovitz

(1981), and SWG/NEFC (1988).

Processing the Catch

From 1963 to 1992, all species were weighed and

measured prior to biological sampling. If a species was

also destined to be sampled for other biological studies

(e.g., feeding ecology, age and growth, maturity staging),

each individual fish processed was measured a second time.

This “double measuring” invariably resulted in some inconsistent, mismatched fish lengths between the overall

length frequency records for the species and the individual

lengths recorded for biological samples. In addition, routine biological samples were generally collected using
Page 3

length categories (usually 10 cm), with sampling targets

based on a 6-hr watch schedule. For example, the scientific crew were required to process 10 silver hake ranging

in length from 0-10 cm, 10 ranging in length from 11-20

cm, etc., for special sampling per watch.

Beginning with the 1992 winter survey, the ondeck

processing protocols were modified to: 1) eliminate

“double measuring”, 2) give individual identification numbers to each fish sampled for biological studies, 3) sample

on a one-individual-per-one-centimeter basis, and 4) require that samples be collected at every station.

Food Habits Sampling

During 1963-66, the food habits sampling protocol

required examination of a random selection of fish species from each station for at-sea prey identification and a

qualitative estimate of diet composition. No criteria were

set for numbers of samples to collect; the number of stomachs examined was determined by the length of time available between trawl stations and the expertise of the onboard

staff (Langton et al. 1980). From 1969 to 1972, samples

were collected from up to 20 (but not less than 5) stomachs from each species caught at each station. Each stomach sample was preserved by size class at sea in 10% buffered Formalin for later processing in the laboratory. Because these data have not undergone standard audit procedures and are currently unavailable in digital format, they

were not used in these analyses.

Beginning in 1973, a systematic approach to collecting stomachs was initiated. The 1973-80 period was divided into two 4-yr blocks with different groups of primary demersal and pelagic species sampled during each

block. (See Table 2 for an overview of stomach samples

requested by species during the 1973-99 time series. Appendix A contains detailed sampling protocols and lists of

species.) The survey area was divided into five broad geographic regions, and a maximum of 100 stomachs per species per cruise, with no more than 10 per station, were requested (Langton et al. 1980). In addition, from 1977 to

1980, samples from 42 other, less commonly encountered

species were also requested. Individual samples were preserved at sea in 10% buffered Formalin for further processing. Prey composition (percentage), weight (0.01 g),

number, total stomach weight (0.01g), and lengths (millimeters) of fish prey were determined upon examination in

the laboratory. Prey identification was to the lowest taxon

feasible.

In 1981, a significant change to the at-sea sampling

protocol was made. While the stomachs of major species

such as Atlantic cod, haddock, silver hake, yellowtail flounder, winter flounder, Atlantic herring, and Atlantic mackerel continued to be individually preserved, all other species had prey examined and identified at sea. In addition, a

volumetric measurement of stomach contents (0.1 cm3

)

was initiated. The protocol also required sampling a specific number of fish for priority species per length class at

every station (see Appendix A). Shipboard stomach processing also included percent diet composition, prey number, and prey lengths. These changes were implemented

because laboratory processing of large numbers of samples

proved too costly, and fish prey identification is assumed

to be more accurate when stomach contents are fresh. This

change in protocol placed an additional burden on seagoing staff to identify both fish and invertebrate prey while

onboard ship. Many workshops were and are still conducted,

and a variety of identification aids have been placed onboard

ship to educate staff in the identification of prey species.

Since 1985, all stomach samples have been processed,

and prey identified, at sea. Because of the time limitation

at each station, from 1985 to 1991, systematic sampling

focused on eight principal species: white hake, red hake,

pollock, Atlantic herring, Atlantic mackerel, Atlantic cod,

silver hake, and spiny dogfish (with the latter three receiving the highest priority). Eighteen other species were processed as time permitted (see Appendix A). Each of the

eight principal species had target sampling levels per 6-hr

watch, with an overall cap of 50 stomachs per station.

In 1992, with the implementation of new ondeck

sample processing protocols (described earlier), the focus shifted from per-watch targets to per-station, lengthbased sampling. During 1992-93, stomach samples from

23 species were requested with maximum levels set by

species and station. First priority was assigned to Atlantic

cod, silver hake, spiny dogfish, and skates. In 1994, after

concerns were eliminated that the per-station protocols

would overwhelm the at-sea technical staff, the maxima

were removed.

From 1995 to 1998, the primary objective of sampling continued to be to provide data to estimate predation

on larval and juvenile stages of fish, particularly gadids,

and sampling priorities were given to Atlantic cod, spiny

dogfish, silver hake, Atlantic herring, and fourspot flounder, with the addition of little, winter, and thorny skates

during the spring surveys.

In 1999, after an examination of data obtained during

the previous surveys to determine an adequate sample size

for characterizing predator diets (see “Stomach Sampling

Effort Coverage” section), the sampling protocol was modified again to collect samples from a broad variety of species. While a low level of monitoring of historically priority species was maintained, the priority was shifted to

commercially or ecologically important species that appeared to be undersampled in previous schemes. The sampling focus reemphasized benthivorous fishes, and attempted to be more inclusive of the entire fish community. Sample ranges (in fish length) were set for each species, generally one stomach per 5-cm length range for most

species, and one stomach per 10-cm range for elasmobranchs. This protocol assumes that small per-station

sample sizes over a wide range of species across many hundreds of stations will allow for adequate characterization

of diets.
Page 4

DATA PROCESSING

Once collected, whether on log sheets recorded at

sea or in the laboratory, the data are entered into a computerized database (currently Oracle), audited, documented,

and archived for analysis. This database is maintained on

the NEFSC network computer system. In addition to the

data collected from the Bottom Trawl Survey Program, data

from the many special, process-oriented, cruises examining species- or life stage-specific interactions are also

online, but are not included in this analysis due to their

more focused nature.

DATA CONTINUITY ACROSS

THE TIME SERIES

PREY TAXONOMIC RESOLUTION

Taxonomic resolution was more detailed for invertebrate species during the earlier (pre-1981) period of the

database. To correct for potential differences in the resolution of prey taxonomy between in-lab and at-sea sampling, we established four prey categories. These categories span the lowest taxonomic level feasible (often genus

and species) to a very broad class- or phylum-level category (Table 3). For most analyses, invertebrate prey are

grouped into order or family level, while fish prey are maintained at the lowest level feasible. If specific time periods

or prey species are of interest, a lower taxonomic resolution is appropriate. However, for most purposes, a broader

resolution is preferable given the differences in protocol

across the time series.

WEIGHT-VOLUME CONVERSION

In order to convert from stomach volume to stomach

weight (or vice versa) to account for differences in sampling protocols across the time series, we executed a leastsquares linear regression, with no intercept, to convert

stomach-content data from volume (0.1 cm3

) to mass (0.1

g). This regression was done using all species that had simultaneous weight and volume measurements. Both a regression for all species combined and regressions for individual major species were calculated.

A conversion factor for volume to weight of 1.1:1

was determined from simple linear regression to be the

most appropriate coefficient for all predator species (Table

4). This coefficient (i.e., 1.1) is similar to those obtained

from other studies (Bowman 1982; Tanasichuk et al. 1991).

For those fishes that are piscivores and molluscivores (e.g.,

red hake and goosefish), the coefficient is slightly higher,

whereas for those that are planktivores (e.g., Atlantic mackerel) and other benthivores (e.g., windowpane and fourspot

flounder), the coefficient is slightly lower, reflecting the

different densities of different prey items. The variation

of coefficients among species does not significantly depart from the overall coefficient of 1.1.

SUMMARY STATISTICS

STOMACH SAMPLING EFFORT COVERAGE

We plotted the number of stomachs sampled versus

the number of prey species observed in the diet for each

species. The stomach sample size at which an asymptote

was reached indicated adequate information to characterize the diet of that predator. Similar to species-area curves

(Preston 1962), an asymptote indicates a low probability

of revealing novel prey items with examination of additional stomachs.

The number of stomachs examined versus the number of prey items observed generally indicated that an asymptote was reached between 500 and 1,000 stomachs.

Figures 2-4 show the relationships graphically. For example, we can categorize the general diets of spiny dogfish, silver hake, Atlantic cod, white hake, pollock, yellowtail flounder, winter skate, and bluefish without expecting

many more additional prey items in new stomach observations (Figures 2A-F, and 3A,E). Conversely, the plots indicate that we do not have adequate sample sizes for such

species as smooth skate, witch flounder, Atlantic halibut,

and alewife (Figures 3B-D,F). The species that are specialists such as the planktivorous Atlantic herring and Atlantic mackerel and the benthivorous thorny skate (Figures

4A-C) generally reach an asymptote at a lower number of

stomachs than do more omnivorous species such as spiny

dogfish, Atlantic cod, and silver hake.

DATA OVERVIEW

Predators

There are over 250,000 stomach records currently

in the database. Predator sizes range from 1 cm to 2.5 m

(Table 5). More than 120 species have been sampled, with

27 species having more than 2,000 stomachs sampled, and

42 species having more than 200 stomachs sampled. Approximately 30-40% of the stomachs examined are empty,

varying across species.

Mean stomach contents generally reflect the diet

composition (discussed later) and maximum size of the

predator (Table 5). As a group, elasmobranchs are the largest fishes we sample, are generally piscivorous, and subsequently have the largest mean stomach contents. Exceptions include some of the skates and rays that feed primarily on benthos. Many pelagic piscivores also have large

mean stomach contents. Goosefish, Atlantic cod, white

hake, pollock, lumpfish, Atlantic halibut, Atlantic sturgeon,
Page 5

and groupers all have large mean lengths and mean stomach weights. Other than Atlantic sturgeon, most of these

species are noted piscivores, particularly at the larger sizes.

Conversely, the planktivores have the smallest mean stomach weights, reflecting their smaller size and zooplankton

diet. Most other species have intermediate stomach

weights.

Prey

There are over 500,000 prey records in the database.

Prey sizes range from 0.1 mm to 1 m. There are 1,304

distinct prey items comprising 10 major taxa: arthropods,

mollusks, fishes, polychaetes, echinoderms, cnidarians,

poriferans, ctenophores, bryozoans, and urochords. The

top 10 prey items by percentage occurrence for all predators include decapod crustaceans (principally shrimps),

gammarids and other amphipods, unidentified and miscellaneous fishes (“other fishes”), unidentified and miscellaneous crustaceans (“other crustaceans”), euphausiids, polychaetes, ctenophores, cephalopods (principally squids),

bivalves, and copepods (Figure 5).

Tracking the abundance of these groups can indicate

major changes in ecosystem dynamics and foreshadow

changes to upper trophic levels, particularly commercially

valuable fishes (Christensen 1996; Jennings and Kaiser

1998). Major fish prey include northern sand lance, gadids

(principally silver hake), clupeids, anchovies, and Atlantic

mackerel. In addition to the large number of empty stomachs, unidentified fish, unclassified crustaceans, and well

digested prey were observed most frequently in the stomachs, indicating that much of the observed prey is highly

digested and difficult to identify.

DIET SUMMARIES

Statistical Estimators

Various information can be obtained from stomach

content examination (Hyslop 1980; Bowen 1996; Cortes

1997) depending upon the question being addressed. Although sampling priorities shifted between species across

the history of the program, most of the major species were

sampled continuously over the time series (Table 2). Given

the slightly different sampling protocols described previously, we treated each stomach as a random sample in one

of three possible statistical designs: unweighted random,

stratified, or two-stage clustered. From these food habits

data, percent frequency of occurrence of prey items, total

stomach contents as either volume or weight, and percent

mean diet composition of prey items can be estimated for

a given species.

The percent frequency of occurrence can be calculated as

F

n

N ij

ij

j

= EQ 1

where nij is the number of stomachs of predator j in which

prey item i occurs, and Nj

 is the total number of predator j

stomachs examined.

The simple, unweighted, percent mean diet composition (Pij) can be calculated as either weight or volume. For

weight, it can be calculated as

P

w

w

ij

ijk

k

N

jk

k

N

j

j

= =

=

∑

∑

1

1

EQ 2

where k represents an individual fish, wij is the stomach

weight of prey i in predator j, and

w w j ijk

i

n

k

N i j

= = =

∑ ∑

1 1

 EQ 3

is the total weight of all ni

 prey in the stomach of predator

j. Percent mean diet composition may also be calculated

as a ratio of means (Malvestuto 1996),

P

w

w

ij

ij

j

= EQ 4,

inclusive or exclusive of empty stomachs, where

w

w

N ij

ijk

k

N

j

j

= =

∑

1 EQ 5

and

w

w

N j

jk

k

N

j

j

= =

∑

1 EQ 6.
Page 6

Although not calculated in this document, these diet parameters can be estimated across several statistical groups

or factors (s). Examples include: 1) temporal factors such

as decade, year (or year blocks), season, month, or time of

day; 2) spatial factors such as geographic region, stratum,

or statistical area; 3) abiotic factors such as depth, sediment type, wind speed and direction, current speed and direction, temperature, or salinity; and 4) predator factors

such as length, weight, age, condition factor, or sex.

A weighted mean (wijs) to estimate mean weight of

prey i in predator j for statistical group s may be calculated

as

w

N w

N ijs

jts ijts

t

N

ts

ts

= =

∑

1 EQ 7

where t represents an individual bottom trawl tow, Njts is

the number of predator j stomachs in tow t for statistical

group s, Nts is the number of tows in statistical group s, and

w

w

N ijts

ijtsk

k

N

jts

jts

= =

∑

1 EQ 8.

If one sums across all statistical groups, the weighted mean

of prey i in predator j (w'ij) becomes

′ =

⋅

=

∑

w

w N

N ij

ijs

s

N

js

s

s

1 EQ 9

where Ns

 is the number of statistical groups and Njs is the

total number of predator j in statistical group s. Mean stomach weight of predator j for all prey combined (wjs) can

similarly be estimated for a statistical group as

w

N w

N js

jts jts

t

N

ts

ts

= =

∑

1 EQ 10

where

w

w

N jts

jtsk

k

N

jts

jts

= =

∑

1 EQ 11,

and across all statistical groups as

′ =

⋅

=

∑

w

w N

N j

js

s

N

js

s

s

1 EQ 12

which, as in our case, if one evaluates all elements in a

cluster such that Nts equals the total number of all tows

(Nt), then EQ 12 is a direct simplification of a two-stage

weighted cluster mean (Schaeffer et al. 1990). From EQ

9 and 12, a weighted mean diet composition can also be

estimated for any prey i in predator :

′ = ′

′ P

w

w

ij

ij

j

 EQ 13.

We principally report the simple arithmetic

(unweighted mean ratio inclusive of empty stomachs, i.e.,

EQ 3 with statistical grouping across all factors) mean diet

composition for these predators in this document. Variance estimators for each of these estimators can also be

calculated, with caveats from normal, Poisson, negative

binomial, gamma, lognormal, delta, or similar statistical

distributions (e.g., Zar 1984; Pennington 1996; Tirasin and

Jorgensen 1999). Given the central limit theorem and generally large sample sizes, we presume underlying normal

distributions of the data, although a delta or delta-gamma

approach is appropriate given the large number of zero values in the database.

Diet of Major Species

The two sharks regularly sampled for food habits have

dissimilar diets. Spiny dogfish (Figure 6A) consume

mostly pelagic prey, with clupeids, squids, scombrids,
Page 7

ctenophores, shrimps, and other fishes being major prey

items. Smooth dogfish is a benthivore, feeding principally

on decapod crabs (Figure 6B).

The skates are principally benthivores (Figures 7 and

8), with amphipods, polychaetes, bivalves, and various decapods (crabs and shrimp) being major prey items. Winter

skate is more piscivorous than the other skates, consuming high proportions of northern sand lance and Atlantic

herring in its diet. Smooth skate is more pelagic than the

other skates, consuming higher proportions of euphausiids and decapod shrimps than other prey in its diet. All

skates have a relatively catholic diet.

The planktivores (e.g., Atlantic herring, Atlantic mackerel, alewife, northern sand lance, butterfish) have diets

dominated by well digested prey, reflecting both their faster

digestion and our difficulty in identifying smaller prey (Figures 9 and 10). Copepods, euphausiids, amphipods (primarily hyperiids), mysids, and northern sand lance are the

other major prey items of these fishes. Well digested prey

were likely one or more of these zooplankton or small fish

prey items.

Similarly, the squids have a diet that is also dominated by well digested prey, probably a result of prey

mastication from the beak of these predators (Figure 11).

Squids are highly cannibalistic and piscivorous.

The principal gadids Atlantic cod, haddock, and pollock are dietary generalists (Figure 12). These three species’ diets form a continuum from benthic to pelagic prey,

with the haddock diet more benthic (e.g., brittle stars, polychaetes, amphipods), the cod diet in between, and pollock

diet more pelagic (e.g., euphausiids, northern sand lance,

decapod shrimps). Clupeids, northern sand lance, and other

gadids (mainly silver hake, although there is some cannibalism) are the major fish prey of these species.

The hakes are primarily pelagic predators, consuming mainly euphausiids, clupeids, squids, decapods, and other

gadids (Figures 13 and 14). These species exhibit a broad

diet that is principally fish and/or shrimp in composition.

The flatfishes can be largely categorized as either

squid-and-fish eaters (i.e., Atlantic halibut and fourspot and

summer flounders) or worm-and-amphipod eaters (i.e.,

windowpane and yellowtail, winter, and witch flounders)

(Figures 15-17). The notable exception is American plaice which primarily consumes echinoderms (Figure 15B)

-- more similar to haddock (Figure 12B) than to other flatfishes. Windowpane and fourspot flounder exhibit a broad

diet. The morphology of these flatfishes suggests benthic

feeding, thus the high degree of piscivory exhibited by

some species is noteworthy.

The other major piscivores (e.g., goosefish, weakfish, and bluefish) consume a broad variety of fishes and

squids (Figure 18). Pelagic prey such as anchovies, clupeids, northern sand lance, longfin inshore squid, and gadids

(principally silver hake) are the major dietary items of these

predators, with weakfish consuming prey whose ranges are

centered further to the south (e.g., sciaenids, butterfish),

and with goosefish consuming more benthic prey (e.g., sea

robins, bothids, pleuronectids, skates) than bluefish.

Scup are primarily benthivores, whereas black sea bass

and Acadian redfish consume shrimp and other fishes (Figure 19). Black sea bass and scup both have a broad range of

prey represented in their diets, but specialize on decapods

and polychaetes, respectively.

Sea raven are benthic piscivores, consuming several

different fish prey (Figure 20). Longhorn sculpin are also

benthic and piscivorous, but primarily consume a broader

mix of benthic invertebrates (i.e., decapod crabs, amphipods). Similar to American plaice, the ocean pout diet

consists of a high proportion of echinoderms. All three of

these fish exhibit a relatively broad, benthic diet.

DISCUSSION

DIET OVERVIEW

The diet summaries presented here extend previous

documentation for many of these fish species (e.g., Wigley

1956; Sherman et al. 1978; Edwards and Bowman 1979;

Grosslein et al. 1980; Bowman 1981, 1983; Cohen et al.

1981, 1982; Langton 1982, 1983; Durbin et al. 1983; Bowman and Michaels 1984; Bowman et al. 1984; Hahm and

Langton 1984; Overholtz et al. 1991). For further details

on a particular species or species group, we refer the reader

to these more specific documents. In general, we can categorize the diets of most species with more than 1,000

stomachs examined. For example, we know that Atlantic

cod typically consume a wide mix of benthic invertebrates,

herrings, silver hake, shrimps, and northern sand lance (Figure 12A), and that spiny dogfish typically consume ctenophores, shrimps, and smaller pelagic fishes (Figure 6A).

How the diets of these species alter across seasons, location, size classes, or decades is described elsewhere, although the major diet compositions are generally consistent (Garrison and Link 2000).

Many of the species over the period of this time series have been undersampled (Table 5, Figure 3B-D,F) due

to logistical constraints and changing priorities. One of

the challenges is to focus on species we know little about

despite their limited commercial value. For example, it

would have been difficult to predict 30 yr ago that goosefish

would currently be the most valuable finfish in the NMFS
Page 8

Northeast Region (Clark 1998), yet, fortunately, information was collected for this species. These data demonstrated the importance of this species as a piscivore. These

undersampled species, as well as protocols to better address the frequency of empty stomachs and well digested

prey, merit further examination.

Most species in this fish community are generalists,

with a few pelagic or benthic specialists. Garrison and Link

(2000) have categorized six major feeding groups, including benthivores (e.g., Figures 7, 8, 15B-C, and 16C),

planktivores (e.g., Figures 9 and 10), piscivores (e.g., Figure 18), pelagic (small fish and shrimp) feeders (e.g., Figures 13 and 14), demersal invertebrate feeders (e.g., Figure 12), and crab specialists (e.g., Figure 6B). Given the

broad diets, high degree of omnivory (Link 1999), and generalist feeding nature of most species in this community,

most predator-prey interaction strengths are mild in this

ecosystem (Link 1999; Sissenwine et al. 1982). Thus, the

population-level impacts of changes in prey (potentially

impacting growth) or predators (potentially impacting survivability) are likely less significant than if this were an

ecosystem of specialists with strong interactions.

HISTORICAL AND CURRENT RELEVANCE

We have documented the changing priorities and protocols of the food habits sampling over the history of this

program (Tables 1 and 2; Appendix A). Despite these caveats, this is a unique data set to assist with understanding

the ecosystem dynamics of the Northwest Atlantic. To our

knowledge, there are no other data sets that span 25 yr for

more than 120 species over an entire continental shelf.

The importance of the food-habits time series is enhanced given its potential role in at least partially explaining the notable dynamic nature of the Northwest Atlantic

fish community (Mayo et al. 1992; Boreman et al. 1997;

Clark 1998; Fogarty and Murawski 1998). Briefly, in the

past 30-40 yr, the abundance of commercially desirable

gadids (e.g., Atlantic cod and haddock) and flatfishes (e.g.,

yellowtail flounder) has declined, with a concurrent increase in the abundance of less desirable elasmobranchs

(e.g., spiny dogfish and skates) and small pelagic species

(e.g., Atlantic herring and Atlantic mackerel). These

changes were caused primarily by a significant increase in

fishing pressure exerted on gadids and flatfishes beginning

in the early 1960s with the arrival of distant-water fleets.

Even with the foreign fleets largely displaced from the U.S.

Exclusive Economic Zone in 1977, effective effort on the

fish stocks has remained high, and for many species, stock

biomass dropped to historically low levels in the 1990s

due to the increased capacity and efficiency of the domestic fleet (Clark 1998; Fogarty and Murawski 1998). These

phenomena are not limited to just this ecosystem; other

ecosystems around the world exhibit similar patterns (NRC

1999). There is high heuristic value in exploring from a

trophic ecology perspective why the multispecies trajectory proceeded as it did in this ecosystem, particularly to

assess how the multispecies trajectory may proceed in the

future.

Professor Baird’s (1873) concerns remain appropriate, and are still relevant to ongoing ecosystem investigations (e.g., Sherman 1991; Sherman et al. 1993;

Christensen et al. 1996; Larkin 1996; Jennings and Kaiser

1998; NRC 1999). Central to ecosystem considerations

are species interactions. In many food webs, predation can

be a major ecological process affecting fish populations

(Sissenwine 1984; Bax 1991, 1998; Christensen 1996) and

the major source of mortality for fish (e.g., Sissenwine et

al. 1984; Keast 1985; Mittelbach and Persson 1998).

Multispecies, trophodynamic, food web, and ecosystem

models are tools to give insights into fish communities

where classical fisheries methods are unable to do so (e.g.,

Steele 1974; Andersen and Ursin 1977; Helgason and

Gislason 1979; May et al. 1979; Mercer 1982; Kerr and

Ryder 1989; Daan and Sissenwine 1991). For example,

how important is natural mortality to a given fish stock

(Sissenwine 1984), what are the system-level emergent

properties from a fish community and how are they altered

with overfishing (Jennings and Kaiser 1998), or what levels of biomass tradeoff are we willing to accept among a

given species mix? Quantifying the food habits of these

species is at the heart of these and similar questions.

ACKNOWLEDGMENTS

We thank the hundreds of individuals who have collected food habits data over the course of the Bottom Trawl

Survey Program. We thank past and present NEFSC staff associated with the FWDP for their foresight in creating,

auditing, maintaining, and supporting this database of unprecedented scale and scope, especially (listed alphabetically):

R. Bowman, E. Broughton, R. Edwards, M. Fogarty, R. Fritz, B. Griswold, M. Grosslein, J. Hauser, M. Hill, B. Kaminer R.

Langton, R. Maurer, N. McHugh, C. Milliken, T. Morris, R. Rountree, R. Theroux, and R. Wigley. We particularly thank

M. Grosslein, M. Fogarty, and W. Michaels for their discussions to clarify earlier portions of the history of this program.

We thank M. Fogarty, M. Grosslein, C. Milliken, J. Gibson, and W. Gabriel for their constructive comments on earlier

versions of the manuscript.
Page 9

REFERENCES CITED

Almeida, F.; Fogarty, M.; Grosslein, M.; Kaminer, B.; Link,

J.; Michaels, W.; Rountree, R. 1999. Georges Bank predation study: report of the 1994-96 field seasons. Northeast Fish. Sci. Cent. Ref. Doc. 99-06; 58 p. Available

from: National Marine Fisheries Service, Woods Hole,

MA 02543.

Andersen, K.P.; Ursin, E. 1977. A multispecies extension to

the Beverton and Holt theory, with accounts of phosphorus circulation and primary production. Medd. Dan.

Fisk.-Havunders. 7:319-435.

Azarovitz, T.R. 1981. A brief historical review of the Woods

Hole Laboratory trawl survey time series. In: Doubleday,

W.G.; Rivard, D., eds. Bottom trawl surveys. Can. Spec.

Publ. Fish. Aquat. Sci. 58:62-67.

Baird, S.F. 1873. Report on the condition of the sea fisheries of the south coast of New England in 1871 and 1872.

Part I. Washington, DC: U.S. Commission of Fish and

Fisheries; 852 p. Available from: National Marine Fisheries Service, Woods Hole, MA 02543.

Bax, N.J. 1998. The significance and prediction of predation in marine fisheries. ICES [Int. Counc. Explor. Sea]

J. Mar. Sci. 55:997-1030.

Bax, N.J. 1991. A comparison of the fish biomass flow to

fish, fisheries, and mammals on six marine ecosystems.

ICES [Int. Counc. Explor. Sea] Mar. Sci. Symp. 193:217-

224.

Boreman, J.; Nakashima, B.S.; Wilson, J.A.; Kendall, R.L.,

editors. 1997. Northwest Atlantic groundfish: perspectives on a fishery collapse. Bethesda, MD: American

Fisheries Society; 242 p.

Bowen, S.H. 1996. Quantitative description of the diet. In:

Murphy, B.R.; Willis, D.W., eds. Fisheries techniques.

Bethesda, MD: American Fisheries Society; p. 513-532.

Bowman, R.E. 1981. Food of ten species of Northwest Atlantic juvenile groundfish. Fish. Bull. (U.S.) 79(1):220-

226.

Bowman, R.E. 1982. Preliminary evaluation of the results

of analysis of the stomach contents of silver hake

(Merluccius bilinearis) aboard ship and in the laboratory ashore. Woods Hole Lab. Ref. Doc. 82-25; 13 p.

Available from: National Marine Fisheries Service,

Woods Hole, MA 02543.

Bowman, R.E. 1983. Food of silver hake, Merluccius

bilinearis. Fish. Bull. (U.S.) 82:21-35.

Bowman, R.E.; Michaels, W.L. 1984. Food of seventeen

species of Northwest Atlantic fish. NOAA Tech. Memo.

NMFS-F/NEC-28; 183 p.

Bowman, R.E.; Eppi, R.; Grosslein, M. 1984. Diet and consumption of spiny dogfish in the Northwest Atlantic.

ICES [Int. Counc. Explor. Sea] C.M. 1984/G:27; 16 p.

Bowman, R.E.; Maurer, R.; Murphy, J. 1976. Stomach contents of twenty-nine fish species from five regions in

the Northwest Atlantic. Northeast Fish. Sci. Cent. Ref.

Doc. 76-10; 37 p. Available from: National Marine Fisheries Service, Woods Hole, MA 02543.

Christensen, V. 1996. Managing fisheries involving predator and prey species. Rev. Fish Biol. Fish. 6:417-442.

Christensen, N.L.; Bartuska, A.M.; Brown, J.H.; Carpenter,

S.; D’Antonio, C.; Francis, R.; Franklin, J.F.; MacMahon,

J.A.; Noss, R.F.; Parsons, D.J.; Peterson, C.H.; Turner,

M.G.; Woodmansee, R.G. 1996. The report of the Ecological Society of America Committee on the Scientific Basis for Ecosystem Management. Ecol. Appl.

6:665-691.

Clark, S.H., editor. 1998. Status of fishery resources off the

northeastern United States for 1998. NOAA Tech. Memo.

NMFS-NE-115; 149 p.

Cohen, E.; Grosslein, M.; Sissenwine, M.; Serchuk, F.; Bowman, R. 1981. Stomach content studies in relation to

multispecies fisheries analysis and modeling for the

Northwest Atlantic. ICES [Int. Counc. Explor. Sea] C.M.

1981/G:66; 14 p.

Cohen, E.; Grosslein, M.D.; Sissenwine, M.P.; Steimle, F.;

Wright, W.R. 1982. Energy budget of Georges Bank.

In: Mercer, M.C., ed. Multispecies approaches to fisheries management advice. Can. Spec. Publ. Fish. Aquat.

Sci. 59:95-107.

Cortes, E. 1997. A critical review of methods of studying

fish feeding based on analysis of stomach contents: application to elasmobranch fishes. Can. J. Fish. Aquat.

Sci. 54:726-738.

Daan, N.; Sissenwine, M.P., editors. 1991. Multispecies

models relevant to management of living resources.

ICES [Int. Counc. Explor. Sea] Mar. Sci. Symp. 193; 358

p.

Durbin, E.R.; Durbin, A.G.; Langton, R.W.; Bowman, R.E.

1983. Analysis of stomach contents of Atlantic cod

(Gadus morhua) and silver hake (Merluccius

bilinearis) for the estimation of daily rations. Fish. Bull.

(U.S.) 81(3):437-454.

Edwards, R.L.; Bowman, R.E. 1979. Food consumed by continental shelf fishes. In: Clepper, H., ed. Predator-prey

systems in fish communities and their role in fisheries

management. Washington, DC: Sports Fishing Institute;

p. 337-406.

Fogarty, M.J.; Murawski, S.A. 1998. Large-scale disturbance

and the structure of marine systems: fishery impacts on

Georges Bank. Ecol. Appl. 8(S1):S6-S22.

Garrison, L.P.; Link, J.S. 200. Fishing effects on spatial distribution and trophic guild structure in the Georges Bank

fish community. ICES [Int. Counc. Explor. Sea] J. Mar.

Sci. 57:723-730.

GLOBEC [U.S. Global Ocean Ecosystems Dynamics Program]. 1991. GLOBEC Northwest Atlantic Program:

GLOBEC Canada/U.S. Meeting on N.W. Atlantic Fisheries and Climate. U.S. Global Ecosyst. Dyn. Program

Rep. 2; 87 p. Available from: U.S. GLOBEC Scientific

Steering Committee Coordinating Office, c/o Woods

Hole Oceanographic Institution, Woods Hole, MA

02543.

Grosslein, M.D. 1969. Groundfish survey program of BCF

Woods Hole. Comm. Fish. Rev. 31(8-9):22-25.
Page 10

Grosslein, M.D.; Langton, R.W.; Sissenwine, M.P. 1980.

Recent fluctuations in pelagic fish stocks in the Northwest Atlantic Georges Bank region, in relation to species interactions. In: Saville, A., ed. The assessment

and management of pelagic fish stocks. Rapp. P.-V. Reun.

Cons. Int. Explor. Mer 177:374-404.

Hahm, W.; Langton, R.W. 1984. Prey selection based on

predator/prey weight ratios for some Northwest Atlantic fish. Mar. Ecol Prog. Ser. 19(1-2):1-5.

Helgason, T.; Gislason, H. 1979. VPA-analysis with species

interaction due to predation. ICES [Int. Counc. Explor.

Sea] C.M. 1979/G:52; 10 p.

Hennemuth, R.C.; Rockwell, S. 1987. History of fisheries

management and conservation. In: Backus, R. ed.

Georges Bank. Cambridge, MA: MIT Press; p. 430-446.

Hyslop, E.J. 1980. Stomach contents analysis — a review

of methods and their application. J. Fish Biol. 17:411-

429.

Jennings, S.; Kaiser, M.J. 1998. The effects of fishing on

marine ecosystems. Adv. Mar. Biol. 34:201-352.

Jossi, J.W.; Marak, R.R. 1983. MARMAP plankton survey

manual. NOAA Tech. Memo. NMFS-F/NEC-21; 258 p.

Keast, A. 1985. The piscivore feeding guild of fishes in

small freshwater ecosystems. Environ. Biol. Fish.

12:119-129.

Kerr, S.R.; Ryder, R.A. 1989. Current approaches to

multispecies analysis of marine fisheries. Can. J. Fish.

Aquat. Sci. 46:528-534.

Langton, R.W. 1982. Diet overlap between Atlantic cod,

Gadus morhua, silver hake, Merluccius bilinearis, and

fifteen other Northwest Atlantic finfish. Fish. Bull. (U.S.)

80:745-759.

Langton, R.W. 1983. Food of yellowtail flounder, Limanda

ferruginea (Storer), from off the northeastern United

States. Fish. Bull. (U.S.) 81(1):15-22.

Langton, R.W.; Bowman, R.E. 1980. Food of fifteen Northwest Atlantic gadiform fishes. NOAA [Natl. Ocean.

Atmos. Admin.] Tech. Rep. NMFS [Natl. Mar. Fish. Serv.]

SSRF [Spec. Sci. Rep. Fish.] 740; 23 p.

Langton, R.W.; North, B.M.; Hayden, B.P.; Bowman, R.E.

1980. Fish food habits studies — sampling procedures

and data processing methods utilized by the Northeast

Fisheries Center, Woods Hole Laboratory, U.S.A. ICES

[Int. Counc. Explor. Sea] C.M. 1980/L:61; 16 p.

Larkin, P.A. 1996. Concepts and issues in marine ecosystem management. Rev. Fish Biol. Fish. 6:139-164.

Link, J. 1999. Reconstructing food webs and managing fisheries. In: Baxter, B., ed. Ecosystem approaches for fisheries management: proceedings of the Symposium on

Ecosystem Considerations in Fisheries Management,

September 30 - October 3, 1998, Anchorage, Alaska.

Alaska Sea Grant Rep. AK-SG-99-01:571-588. Available from: University of Alaska Sea Grant, Fairbanks,

AK 99775.

Malvestuto, S.P. 1996. Sampling the recreational creel. In:

Murphy, B.R.; Willis, D.W., eds. Fisheries techniques.

Bethesda, MD: American Fisheries Society; p. 591-624.

Maurer, R.O. 1975. A preliminary description of some important feeding relationships. Int. Comm. Northw. Atl.

Fish. Res. Doc. 75/IX/130; 15 p.

Maurer, R.O.; Bowman, R.E. 1975. Food habits of marine

fishes of the Northwest Atlantic. Woods Hole Lab. Ref.

Doc. 75-03; 90 p. Available from: National Marine Fisheries Service, Woods Hole, MA 02543.

May, R.M.; Beddington, J.R.; Clark, C.W.; Holt, S.J.; Laws,

R.M. 1979. Management of multispecies fisheries.

Science 205:267-277.

Mayo, R.K.; Fogarty, M.J.; Serchuk, F.M. 1992. Aggregate

fish biomass and yield on Georges Bank, 1960-87. J.

Northw. Atl. Fish. Sci. 14:59-78.

Mercer, M.C., editor. 1982. Multispecies approaches to fisheries management advice. Can. Spec. Publ. Fish. Aquat.

Sci. 59; 169 p.

Michaels, W.L.; Bowman, R.E. 1982. Food of seventeen

species of Northwest Atlantic fish. Part II. Examination

by year and listing of prey species. Woods Hole Lab.

Ref. Doc. 82-17; 117 p. Available from: National Marine Fisheries Service, Woods Hole, MA 02543.

Mittelbach, G.G.; Persson, L. 1998. The ontogeny of

piscivory and its ecological consequences. Can. J. Fish.

Aquat. Sci. 55:1454-1465.

NRC [National Research Council]. 1999. Sustaining marine

fisheries. Washington, DC: National Academy Press;

164 p.

Overholtz, W.J.; Murawski, S.A.; Foster, K.L. 1991. Impact

of predatory fish, marine mammals, and seabirds on the

pelagic fish ecosystem of the northeastern USA. ICES

[Int. Counc. Explor. Sea] Mar. Sci. Symp. 193:198-208.

Pennington, M. 1996. Estimating the mean and variance from

highly skewed marine data. Fish. Bull. (U.S.) 94:498-

505.

Preston, F.W. 1962. The canonical distribution of commonness and rarity. Ecology 43:185-215, 431-432.

Schaeffer, R.L.; Mendenhall, W.; Ott, L. 1990. Elementary

survey sampling. Boston, MA: PWS-Kent; 390 p.

Sherman, K. 1991. The large marine ecosystem concept:

research and management strategy for living marine resources. Ecol. Appl. 1:349-360.

Sherman, K.; Alexander, L.M.; Gold, B.D., editors. 1993.

Large marine ecosystems: stress, mitigation and

sustainability. Washington, DC: AAAS Press; 376 p.

Sherman, K.; Cohen, E.; Sissenwine, M.; Grosslein, M.;

Langton, R.; Green, J. 1978. Food requirements of fish

stocks of the Gulf of Maine, Georges Bank, and adjacent waters. ICES [Int. Counc. Explor. Sea] C.M. 1978/

Gen:8 (Symp.); 14 p.

Sissenwine, M.P.; Brown, B.E.; Palmer, J.E.; Essig, R.J.;

Smith, W. 1982. Empirical examination of population
Page 11

interactions for the fishery resources off the northeastern USA. In: Mercer, M.C., ed. Multispecies approaches

to fisheries management advice. Can. Spec. Publ. Fish.

Aquat. Sci. 59:82-94.

Sissenwine, M.P. 1984. Why do fish populations vary? In:

May, R.M., ed. Exploitation of marine communities.

New York, NY: Springer-Verlag; p. 59-94.

Sissenwine, M.P.; Cohen, E.B.; Grosslein, M.D. 1984. Structure of the Georges Bank ecosystem. Rapp. P.-V. Reun.

Cons. Int. Explor. Mer 183:243-254.

Steele, J.H. 1974. The structure of marine ecosystems.

Oxford, England: Blackwell Scientific; 128 p.

Steimle, F.W.; Burnett, J.M.; Theroux, R.B. 1995. A history

of benthic research in the NMFS Northeast Fisheries

Science Center. Mar. Fish. Rev. 57(2):1-13.

SWG/NEFC [Survey Working Group/Northeast Fisheries

Center]. 1988. An evaluation of the bottom trawl survey program of the Northeast Fisheries Center. NOAA

Tech. Memo. NMFS-F/NEC-52; 83 p.

Tanasichuk, R.W.; Ware, D.M.; Shaw, W.; McFarlane, G.A.

1991. Variations in diet, daily ration, and feeding periodicity of Pacific hake (Merluccius productus) and spiny

dogfish (Squalus acanthias) off the lower west coast

of Vancouver Island. Can. J. Fish. Aquat. Sci. 48:2118-

2128.

Tirasin, E.M.; Jorgensen, T. 1999. An evaluation of the precision of diet description. Mar. Ecol. Prog. Ser.

182:243-252.

USFWS [U.S. Fish and Wildlife Service]. 1954. Annual report of the Woods Hole Laboratory for the year ending

June 30, 1954. Washington, DC: U.S. Fish and Wildlife

Service; 14 p.

Wigley, R.L. 1956. Food habits of Georges Bank haddock.

U.S. Fish Wildl. Serv. Spec. Sci. Rep. Fish. 165; 26 p.

Zar, J.H. 1984. Biostatistical analysis. Englewood Cliffs,

NJ: Prentice-Hall; 718 p.
Page 12

Table 1. Timeline of research emphasized and hypotheses studied by the Food Web Dynamics Program and its predecessors

 

Time Period Research Emphasis and Hypotheses

 

1950s - 1960s Exploring possible causes of haddock declines

Hypothesized relationship of diet and growth

Transition from benthic research program to using fish as benthic samplers

Emphasis on haddock, other gadids

mid-1960s Ad hoc diet studies as part of bottom trawl surveys

Emphasis extended to major (commercially valuable) groundfish

late 1960s - early 1970s Continued ad hoc sampling

Other species added to sampling priority

Multispecies considerations first formalized

through 1970s Emphasis on characterizing the diets of major fish species

Systematic stud ies of diet (food habits) adopted as p art of bottom trawl surveys

Herring studies with foreign fisheries

late 1970s - early 1980s Energy budgets

Systemwide production mode ls

Qualitative ecosystem mo dels

Hypothesized recruitment limitation via predation on larval fish

Emphasis on ichthyoplanktivores

mid-1980s Hypothesized extension of pred ation on all fish as a significant source of mortality

Emphasis on piscivores

First attempts to quantify predator-prey relationships

Consumption rates, species interactions, larval mortality estimated

late 1980s - early 1990s Detailed consumption rates and refined diet estimators

Mechanisms for historical changes in fish community composition from overfishing

Refined attempts to assess pred ation on larval fish

Multispecies models and simulations

mid-1990s - late 1990s Fish community metrics and properties

Community as an entity

Trophodynamic, aggregate b iomass, food web mo dels

Ecosystem considerations more explicitly considered

Emphasis on less understood (lower economic value) species

 
Page 13

Table 2a. Stomach sampling requests made to the NEFSC Bottom Trawl Survey Program during 1973-86 (Sp = spring; Fa =

fall; 1 = priority species; 2 = second-level species collected as time allowed)

 

1973 1974 1975 1976 1977 1978 1979 1980 1981 1982 1983 1984 1985 1986

Common Name Sp Fa Sp Fa Sp Fa Sp Fa Sp Fa Sp Fa Sp Fa Sp Fa Sp Fa Sp Fa Sp Fa Sp Fa Sp Fa Sp Fa

 

Alewife -------- 22222222 -------- 2222

Argentines -------- 22222222 ------------

Bass, black sea -------- 11111111 ------------

Bass, striped -------- 22222222 -------- 2222

Bluefish -------- 22222222 -------- 2222

Butterfish 1111111122222222 ------------

Cod, Atlantic 1111111111111111111111111111

Croaker, Atlantic - - - - - - - -22 222222 ------------

Cunner -------- 22222222 ------------

Cusk -------- 22222222 ------------

Cusk-eel, fawn -------- 22222222 ------------

Dogfish, smooth -------- 11111111 -------- 2222

Dogfish, spiny -------- 11111111111111111111

Dory, American John -------- 22222222 ------------

Eel, American -------- 22222222 ------------

Eel, conger -------- 22222222 ------------

(Flounder) American plaice 1111111122222222 ------------

Flounder, fourspot 1111111122222222 -------- 2222

Flounder, Gulf Stream -------- 22222222 ------------

Flounder, summer -------- 22222222 -------- 2222

(Flounder) windowpane -------- 11111111 -------- 2222

Flounder, winter -------- 1111111111111111 - - - -

Flounder, witch 1111111122222222 - -----------

Flounder, yellowtail 11111111 -------- 11111111 ----

Goosefish -------- 11111111111111112222

Grenadiers -------- 22222222 ------------

Haddock 111111111111111111111111 ----

Hake, longfin -------- 22222222 ------------

Hake, offshore -------- 22222222 ------------

Hake, red 1111111111111111111111111111

Hake, silver 1111111111111111111111111111

Hake, spotted 11111111 ---------------- 2222

Hake, white 1111111122222222111111111111

Halibut, Atlantic -------- 22222222 -------- 2222

Herring, Atlantic -------- 11111111111111111111

Herring, blueback ----------------------------

Herring, round -------- 22222222 ------------

Kingfish, northern -------- 22222222 ------------

Kingfish, southern -------- 22222222 ------------

Macke rel, Atlantic -------- 11111111111111111111

Mackerels, snake -------- 22222222 ------------

Needlefish, Atlantic -------- 22222222 ------------

Pout, ocean 11111111 --------------------

Pollock 11111111 -------- 111111111111

Rays -------- 22222222 ------------
Page 14

Table 2a. (Cont.)

 

1973 1974 1975 1976 1977 1978 1979 1980 1981 1982 1983 1984 1985 1986

Common Name Sp Fa Sp Fa Sp Fa Sp Fa Sp Fa Sp Fa Sp Fa Sp Fa Sp Fa Sp Fa Sp Fa Sp Fa Sp Fa Sp Fa

 

Redfish, Acadian 1111111111111111 -------- 2222

Rosefish, blackbelly ----------------------------

Salmon, A tlantic ----------------------------

Sand Lance, northern -------- 22222222 ------------

Sculpin, longhorn 11111111 ---------------- 2222

Scup 1111111122222222 -------- 2222

Sea raven -------- 22222222 -------- 2222

Searobin, armored -------- 22222222 - - - ---------

Searobin, northern - - - - - - - -2 2222222 ------------

Searobin, striped -------- 22222222 ------------

Shad, American -------- 22222222 ------------

Shad, hickory ----------------------------

Sharks -------- 22222222 ------------

Skate, little ------------------------ 2222

Skate, rosette ----------------------------

Skate, smooth ----------------------------

Skate, thorny -------- 22222222 -------- 2222

Skate, winter -------- 11111111 -------- 2222

Spot -------- 22222222 ------------

Squid, longfin inshore -------- 11111111 ------------

Squid, northern shortfin -------- 11111111 ------------

Tautog ----------------------------

Tilefish -------- 22222222 ------------

Weakfish -------- 22222222 - ------- 2222

Wolffish, Atlantic - - ------ 22222222 ------------

Wrymouth -------- 22222222 ------------

 
Page 15

Table 2b. Stomach sampling requests made to the NEFSC Bottom Trawl Survey Program during 1987-99 (Sp = spring; Fa =

fall; 1 = priority species; 2 = second-level species collected as time allowed)

 

1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999

Common Name Sp Fa Sp Fa Sp Fa Sp Fa Sp Fa Sp Fa Sp Fa Sp Fa Sp Fa Sp Fa Sp Fa Sp Fa Sp Fa

 

Alewife 2222222222 ----------------

Argentines --------------------------

Bass, black sea - - - - - - - - - - - - - - - - - - - - - - - -22

Bass, striped 22222222222222222222222222

Bluefish 22222222222222222222222222

Butterfish - - - - - - - - - - - - - - - - - - - - - - - -22

Cod, Atlantic 11111111111111111111111122

Croaker, Atlantic --------------------------

Cunner - - - - - - - - - - - - - - - - - - - - - - - -22

Cusk - - - - - - - - - - - - - - - - - - - - - - - -22

Cusk-eel, fawn - - - - - - - - - - - - - - - - - - - - - - - -22

Dogfish, smooth 22222222222222222222222222

Dogfish, spiny 11111111111111111111111122

Dory, American John --------------------------

Eel, American --------------------------

Eel, conger --------------------------

(Flounder) American plaice - - - - - - - - - - - - - - - - - - - - - - - -22

Flounder, fourspot 22222222222222221111111122

Flounder, Gulf Stream --------------------------

Flounder, summer 22222222222222222222222211

(Flounder) windowpane 22222222222222222222222222

Flounder, winter - - - - - - - - - - - - - - - - - - - - - - - -22

Flounder, witch - - - - - - - - - - - - - - - - - - - - - - - -22

Flounder, yellowtail - - - - - - - - - - - - - - - - - - - - - - - -11

Goosefish 22222222222222222222222222

Grenadiers --------------------------

Haddock - - - - - - - - - - - - - - - - - - - - - - - -11

Hake, longfin --------------------------

Hake, offshore - - - - - - - - - - - - - - - - - - - - - - - -22

Hake, red 11111111112222222222222222

Hake, silver 11111111111111111111111122

Hake, spotted 22222222222222222222222222

Hake, white 11111111112222222222222222

Halibut, Atlantic 22222222222222222222222222

Herring, Atlantic 11111111112222221121212111

Herring, blueback - - - - - - - - - - - - - - - - - - - - - - - -22

Herring, round --------------------------

Kingfish, northern --------------------------

Kingfish, southern --------------------------

Macke rel, Atlantic 11111111112222222222222111

Mackerels, snake --------------------------

Needlefish, Atlantic --------------------------

Pout, ocean - - - - - - - - - - - - - - - - - - - - - - - -11

Pollock 11111111112222222222222222

Rays --------------------------
Page 16

Table 2b. (Cont.)

 

1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999

Common Name Sp Fa Sp Fa Sp Fa Sp Fa Sp Fa Sp Fa Sp Fa Sp Fa Sp Fa Sp Fa Sp Fa Sp Fa Sp Fa

 

Redfish, Acadian 2222222222 - - - - - - - - - - - - - -22

Rosefish, blackbelly - - - - - - - - - - - - - - - - - - - - - - - -22

Salmon, A tlantic - - - - - - - - - - - - - - - - - - - - - - - -22

Sand lance, northern --------------------------

Sculpin, longhorn 22222222222222222212121211

Scup 2222222222 - - - - - - - - - - - - - -22

Sea raven 22222222222222222212121222

Searobin, armored --------------------------

Searobin, northern --------------------------

Searobin, striped --------------------------

Shad, American - - - - - - - - - - - - - - - - - - - - - - - -22

Shad, hickory - - - - - - - - - - - - - - - - - - - - - - - -22

Sharks --------------------------

Skate, little 22222222221111222212121222

Skate, rosette - - - - - - - - - - - - - - - - - - - - - - - -22

Skate, smooth - - - - - - - - - - - - - - - - - - - - - - - -22

Skate, thorny 22222222221111222222222222

Skate, winter 22222222221111222212121222

Spot - - - - - - - - - - - - - - - - - - - - - - - -22

Squid, longfin inshore --------------------------

Squid, northern shortfin --------------------------

Tautog - - - - - - - - - - - - - - - - - - - - - - - -22

Tilefish --------------------------

Weakfish 22222222222222222222222222

Wolffish, Atlantic - - - - - - - - - - - - - - - - - - - - - - - -11

Wrymouth --------------------------

 
Page 17

Table 3. Levels of taxonomic resolution for selected prey items used in Food Web Dynamics Program analyses and summaries.

("Collection Category" is the minimum level of taxonomic resolution at which these data are sampled, with some

grouping of invertebrates and fish prey at the species level. This category and the actual prey name represent the lowest

taxonomic resolution, and are used in analyses for specific prey items or a single or small group of predators. "Analytical

Category" is a broader taxonomic level that groups invertebrates to a higher level and fish to family. This category is

used for many of our multispecies analyses and less-detailed diet summaries. "General Category" groups prey at the

phylum or class level, and is used for more cursory diet summaries.)

 

Category 

Common Name Scientific Name Collection Analytical General

 

Atlantic cod Gadus morhua GADMOR Gadid fam. Fish

Fourspot flounder Paralichthys oblongus PAROBL Bothid fam. Fish

Atlantic herring Clupea harengus CLUHAR Clupeid fam. Fish

Atlantic herring eggs Clupea harengus eggs CLUHAR Clupeid fam. Fish

Atlantic herring larvae Clupea harengus larvae Fish larvae Fish larvae Fish

Longfin insho re squid Loligo pealeii LOLPEA Cephalapod Mollusk

Northern shortfin squid Illex illecebrosus ILLILL Cephalapod Mollusk

Sea scallop Placopecten magellanicus Pectinid fam. Bivalve Mollusk

Naked sea butterfly Clione limacina Pteropod Gastropod Mollusk

Brittle stars & basket stars Ophiuroidea OPHIU1 OPHIU1 Echinoderm

Comb jellies or sea walnuts Ctenophora CTENOP CTENOP CTENOP

Atlantic rock crab Cancer irroratus Cancer fam. Decapod Arthropod

Northern shrimp Pandalus borealis Pandalid fam. Decapod Arthropod

Mysids Mysidacea Mysida Mysida Arthropod

Krill Euphausiidae Euphasiid fam. Euphasiid fam. Arthropod

Calanoid copepods Calanoida Copepod Copepod Arthropod

Gammarid Gammaridea Gammar Amphipod Arthropod

 
Page 18

Table 4. Weight-to-volume regression statistics for all species combined and for selected species (N = sample size; R2 = amount

of variance explained; F = F statistic for the regression; P = probability that the slope is significantly different than 0;

= slope parameter; s = standard error of )

 

Species N R2 F P s

 

Species combined 10,806 90.6 99,999.99 0.0001 1.093 0.00338

Spiny dogfish 1,440 89.5 12,272.25 0.0001 1.040 0.00938

Winter skate 889 85.8 5,367.93 0.0001 1.105 0.01508

Little skate 213 94.9 3,945.33 0.0001 1.087 0.01730

Thorny skate 176 23.5 53.73 0.0001 1.228 0.16754

Silver hake 1,375 94.3 22,920.82 0.0001 1.042 0.00688

Atlantic cod 836 95.1 16,154.51 0.0001 1.090 0.00857

Pollock 216 95.6 4,666.91 0.0001 0.958 0.01402

White hake 105 91.3 1,097.99 0.0001 1.061 0.03201

Red hake 273 96.2 6,929.55 0.0001 1.364 0.01639

Fourspot flounder 649 87.9 4,704.09 0.0001 0.679 0.00989

Witch flounder 200 94.4 3,327.02 0.0001 1.025 0.01778

Windowpane 482 94.3 7,948.93 0.0001 0.967 0.01085

Atlantic herring 601 93.6 8716.15 0.0001 1.102 0.01088

Atlantic mackerel 369 86.9 2,444.78 0.0001 0.939 0.01899

Longhorn sculpin 1,844 86.5 11,852.49 0.0001 0.809 0.00743

Sea raven 469 94.6 8,243.01 0.0001 1.157 0.01274

Ocean pout 151 96.5 4,083.91 0.0001 0.921 0.01441

Goosefish 133 95.7 2,927.13 0.0001 1.236 0.02285

Northern shortfin squid 170 80.2 685.62 0.0001 1.157 0.04417

Longfin insho re squid 116 90.6 1,114.49 0.0001 1.476 0.04422

 
Page 19

Table 5. Summary parameters for predators examined by the Food Web D ynamics Program during 1973-98 (units of weight =

g; units of length = cm; s = standard error of the mean of stomach weight)

 

 Stomach W eights Predator Length Predator Weights

Species No. Mean s Mean Min. Max. No. Mean

 

Gadids & Macrourids

Silver hake 36,756 2.69 0.060 25.44 3 76 15,733 121.10

Atlantic cod 15,146 30.20 0.704 53.74 1 150 4,870 2,058.77

Red hake 12,994 3.41 0.097 30.88 4 72 5,036 209.23

White hake 11,740 16.93 0.520 42.72 7 136 4,832 771.45

Spotted hake 7,481 2.17 0.067 23.74 5 43 4,731 136.67

Pollock 4,200 18.03 0.876 50.86 10 120 1,561 1,381.05

Haddock 3,618 5.46 0.220 44.77 8 88 167 671.66

Cusk 141 0.84 0.284 66.67 14 104 17 2,357.59

Offshore hake 99 3.94 2.421 33.23 13 52 14 217.71

Longfin hake 25 0.62 0.259 21.56 16 35 0 -

Longnose grenadier 18 0.20 0.056 15.78 10 23 0 -

Fourbeard rockling 10 0.05 0.018 22.20 15 32 0 -

Marlin-spike 10 0.26 0.052 20.10 15 26 0 -

Ling unclassified 4 0.08 0.028 12.75 11 14 0 -

Grenadier unclassified 3 0.14 0.031 26.00 26 26 0 -

Carolina hake 1 11.00 - 28.00 28 28 0 -

Flounders

Fourspot flounder 10,040 1.10 0.038 27.08 5 49 6,799 162.19

Windowpane 8,982 1.51 0.053 25.69 3 41 5,451 211.55

Summer flounder 8,937 2.23 0.108 36.12 13 82 6,027 582.83

Winter flounder 2,733 2.84 0.117 31.25 8 65 73 430.97

Yellowtail flounder 2,015 1.08 0.049 30.64 3 58 74 326.82

American plaice 1,786 1.03 0.105 29.93 4 70 16 450.00

Witch flounder 1,014 0.62 0.042 41.72 5 65 108 196.16

Atlantic halibut 229 21.16 3.766 58.28 27 134 35 2,660.51

Gulf Stream flounder 219 0.02 0.002 10.26 4 18 0 -

Southern flounder 5 3.30 3.300 26.00 21 33 0 -

Dusky flounder 3 0.06 0.061 20.67 17 23 2 69.50

Greenland halibut 1 0.33 - 15.00 15 15 1 22.00

Pelagic Piscivores

Bluefish 3,208 21.47 1.237 35.19 8 88 829 978.51

Weakfish 3,102 3.04 0.171 25.95 7 79 1,774 238.75

Striped bass 204 52.48 9.633 56.27 23 118 188 2,787.82

Cobia 22 112.28 26.738 94.91 58 122 12 12,900.83

King mackerel 17 17.20 5.667 81.94 56 117 2 8,710.00

Atlantic bonito 11 29.31 24.674 50.36 23 57 3 2,018.00

Greater amberjack 9 105.65 83.863 59.00 21 114 0 -

Blue runner 2 0.06 0.055 15.00 15 15 0 -

Striped bonito 2 35.75 8.250 56.00 55 57 2 3,130.00

Atlantic salmon 1 2.61 - 34.00 34 34 0 -
Page 20

Table 5. (Cont.)

 

 Stomach W eights Predator Length Predator Weights

Species No. Mean s Mean Min. Max. No. Mean

 

Elasmobranchs

Spiny dogfish 41,896 14.82 0.227 69.40 13 117 15,082 1,469.64

Smooth dogfish 3,809 43.41 0.946 86.82 36 150 1,216 2,392.67

Atlantic sharpnose shark 199 18.96 2.334 81.54 34 154 10 3,020.00

Dusky shark 68 36.62 7.631 97.56 49 212 0 -

Sandbar shark 64 78.03 30.213 110.73 60 204 0 -

Chain dogfish 40 2.03 0.693 29.35 15 45 4 323.75

Sand tiger 7 224.29 149.086 196.29 105 246 0 -

Scalloped hammerhead shark 4 20.31 13.098 84.25 54 112 0 -

Shortfin mako 1 141.10 - 146.00 146 146 0 -

Thresher shark 1 33.00 - 169.00 169 169 0 -

Blacknose shark 1 8.80 - 104.00 104 104 0 -

Smooth hammerhead shark 1 2.09 - 92.00 92 92 0 -

Blacktip shark 1 - - 138.00 138 138 0 -

Little skate 19,063 4.18 0.042 39.71 6 63 11,719 432.71

Winter skate 12,122 10.77 0.226 60.41 13 135 6,444 1,620.10

Thorny skate 2,604 11.72 0.606 49.12 12 108 1,096 1,584.89

Smooth skate 286 4.63 0.388 44.44 11 66 82 451.37

Clearnose skate 244 7.09 0.670 57.38 22 73 72 1,101.04

Rosette skate 34 1.32 0.251 35.18 19 43 10 229.00

Barndo or skate 15 30.33 8.778 74.93 25 114 8 3,631.75

Bullnose say 80 20.60 4.871 56.78 29 119 7 1,108.14

Bluntnose stingray 71 31.62 6.114 54.94 21 118 3 1,928.00

Spiny butterfly ray 51 2.56 1.205 93.77 52 199 0 -

Atlantic torpedo 15 17.96 13.012 70.60 25 125 1 17,500.00

Roughtail stingray 13 84.01 31.269 98.62 74 129 0 -

Cownose ray 11 1.42 1.187 48.73 46 53 0 -

Southern stingray 1 17.22 - 84.00 84 84 0 -

Atlantic stingray 1 - - 77.00 77 77 0 -

Squids

Longfin insho re squid 3,002 0.53 0.027 13.07 1 39 0 -

Northern shortfin squid 2,946 1.59 0.162 20.06 3 32 0 -

Pelagic Planktivores

Atlantic herring 11,576 0.59 0.016 23.49 8 46 10,163 125.49

Atlantic mackerel 4,001 1.43 0.057 28.19 12 47 3,170 235.72

Butterfish 2,048 0.16 0.009 12.95 2 24 17 50.00

Northern sand lance 1,339 0.07 0.005 14.37 4 27 0 -

Alewife 362 0.95 0.077 23.11 7 34 1 68.00

Atlantic argentine 185 0.17 0.055 31.09 9 44 0 -

Round herring 104 0.28 0.061 12.05 10 18 0 -
Page 21

Table 5. (Cont.)

 

 Stomach W eights Predator Length Predator Weights

Species No. Mean s Mean Min. Max. No. Mean

 

Blueback herring 85 0.73 0.136 21.51 9 28 0 -

American shad 52 7.06 1.844 28.83 10 52 11 1,087.45

Spanish mackerel 43 3.51 1.331 34.63 16 62 3 984.33

Inshore lizardfish 42 2.13 0.571 24.10 16 35 1 87.00

Chub mackerel 35 0.44 0.123 19.31 14 23 0 -

Atlantic menhaden 34 0.08 0.022 20.82 12 28 0 -

Striped anchovy 15 0.07 0.036 11.87 10 13 0 -

Round scad 15 <0.01 0.002 16.33 14 18 0 -

Rough scad 11 0.03 0.004 13.64 12 15 0 -

Lanternfish unclassified 10 0.06 0.021 8.30 8 10 0 -

Bigeye scad 10 0.02 0.004 13.70 13 15 0 -

Hygophum taaningi 9 0.02 0.007 6.67 6 7 0 -

Offshore lizardfish 9 0.98 0.560 14.22 7 23 3 78.67

Spanish sardine 8 - - 5.25 5 6 0 -

Shortnose greeneye 6 0.04 0.020 12.50 11 14 0 -

Atlantic saury 1 - - 32.00 32 32 0 -

Striated argentine 1 - - 8.00 8 8 0 -

Rockfishes

Acadian redfish 1,244 1.24 0.116 30.89 8 45 2 38.50

Blackbelly rosefish 98 0.44 0.160 16.95 6 36 0 -

Bigeye 9 1.64 0.604 27.67 15 39 0 -

Armored Fishes

Longhorn sculpin 8,029 2.63 - 25.12 3 38 5,072 181.11

Sea raven 4,486 14.60 0.717 31.19 7 67 2,554 802.62

Northern searobin 110 0.71 0.124 22.69 13 34 17 217.53

Armored searobin 33 0.09 0.046 25.91 7 32 0 -

Moustache sculpin 28 0.07 0.021 10.57 7 15 0 -

Striped searobin 23 2.80 0.773 27.00 19 39 0 -

Hookear sculpin 22 0.01 0.008 6.41 4 8 0 -

Searobin unclassified 8 <0.01 0.001 8.63 5 11 0 -

Shorthorn sculpin 1 0.04 - 33.00 33 33 0 -

Horned searobin 1 - - 5.00 5 5 0 -

Bluespo tted searob in 1 - - 16.00 16 16 0 -

Bighead searobin 1 - - 20.00 20 20 0 -

Eel-like Fishes

Ocean pout 673 6.20 0.503 48.54 13 95 43 551.86

Fawn cusk-eel 146 0.03 0.004 21.64 14 30 0 -

Atlantic wolffish 89 10.50 2.214 47.64 3 137 12 3,397.08

Northern pipefish 38 <0.01 0.001 18.87 14 24 0 -

Snakefish 25 1.66 0.757 17.84 13 23 0 -

Conger eel 14 10.70 4.736 65.50 39 109 1 3,280.00
Page 22

Table 5. (Cont.)

 

 Stomach W eights Predator Length Predator Weights

Species No. Mean s Mean Min. Max. No. Mean

 

Atlantic cutlassfish 11 0.08 0.033 48.36 44 53 0 -

Striped cusk-eel 11 0.03 0.017 20.91 16 30 0 -

Red cornetfish 5 6.33 4.066 83.60 43 103 0 -

Atlantic hagfish 4 0.01 0.005 42.75 33 55 0 -

Margined snake eel 3 0.12 0.055 39.00 36 42 0 -

Daubed shanny 3 0.01 0.002 11.67 11 13 0 -

Radiated shanny 3 0.04 0.019 13.00 12 14 0 -

Wrymouth 3 0.40 0.202 34.67 23 41 0 -

Atlantic soft pout 3 <0.01 0.001 11.00 11 11 0 -

Snubnose eel 1 - - 11.00 11 11 0 -

Wolf eelpout 1 - - 12.00 12 12 0 -

Unaesthetic Fishes

Goosefish 5,600 38.99 2.253 44.24 6 124 3,039 1,410.41

Atlantic midshipman 10 0.11 0.050 14.00 14 14 0 -

Lumpfish 2 27.87 7.386 35.50 31 40 0 -

Northern stargazer 2 10.45 1.650 21.00 19 23 0 -

Alligatorfish 1 0.01 - 9.00 9 9 0 -

Southern stargazer 1 2.12 - 22.00 22 22 0 -

Miscellaneous Mid-Atlantic Species

Scup 1,500 0.33 0.024 15.93 6 37 2 169.50

Black sea bass 838 1.31 0.118 21.91 5 55 11 155.00

Spot 488 0.12 0.014 17.03 10 26 10 108.90

Atlantic croaker 377 0.95 0.096 24.48 11 45 10 98.30

Buckler dory 112 4.29 1.514 22.14 11 53 1 2,160.00

Northern kingfish 79 0.53 0.079 23.37 10 30 6 173.50

Cunner 60 0.75 0.239 26.25 5 47 1 734.00

Pigfish 10 0.40 0.194 18.40 16 24 0 -

Tilefish 10 0.71 0.309 42.00 25 61 0 -

Tautog 5 0.22 0.220 35.40 24 64 0 -

Atlantic sturgeon 3 119.17 9.167 97.00 84 120 0 -

Sharksucker 1 6.60 - 43.00 43 43 0 -

Miscellaneous Southern Species

Southern kingfish 119 1.43 0.316 23.84 15 32 12 163.08

Whitebone porgy 24 1.03 0.656 27.79 20 34 0 -

Tomtate 23 0.07 0.050 15.83 11 19 0 -

Deepbody boarfish 15 1.08 0.195 15.40 12 19 0 -

Vermilion snapper 15 0.69 0.436 19.07 12 24 0 -

Sheepshead 15 13.64 3.435 46.87 31 55 0 -

Banded rud derfish 13 1.44 0.478 23.23 18 27 0 -

White grunt 13 1.49 0.469 29.23 24 35 0 -

Saucereye porgy 12 0.92 0.354 21.50 12 30 0 -
Page 23

Table 5. (Cont.)

 

 Stomach W eights Predator Length Predator Weights

Species No. Mean s Mean Min. Max. No. Mean

 

Banded drum 11 0.02 0.006 15.09 14 20 0 -

Spottail pinfish 9 0.25 0.124 20.44 12 29 0 -

Pinfish 9 0.17 0.076 16.44 15 18 0 -

Red porgy 9 1.47 0.750 29.89 21 40 0 -

Snowy grouper 8 23.24 13.444 69.38 46 90 0 -

Planehead filefish 7 <0.01 0.001 6.43 5 8 0 -

Yellowfin bass 7 0.27 0.150 23.57 20 27 0 -

Scamp 6 7.10 6.745 68.17 51 99 0 -

Silver perch 5 <0.01 0.001 19.00 18 20 0 -

Atlantic spadefish 4 2.75 0.710 41.50 38 45 0 -

Sand perch 3 0.41 0.399 20.33 18 24 0 -

Hogchoker 2 0.06 0.055 17.50 17 18 0 -

Warsaw grouper 2 203.50 126.500 104.50 84 125 0 -

Hogfish 2 4.49 1.186 57.00 55 59 0 -

Gray triggerfish 2 - - 33.50 10 57 0 -

Longspine snipefish 2 - - 12.50 12 13 0 -

Almaco jack 1 209.00 - 94.00 94 94 0 -

Black drum 1 165.00 - 108.00 108 108 0 -

Blueline tilefish 1 13.20 - 50.00 50 50 0 -

Conejo 1 - - 25.00 25 25 0 -

Striped burrfish 1 - - 14.00 14 14 0 -

Beardfish 1 - - 16.00 16 16 0 -

Yellowmouth grouper 1 - - 76.00 76 76 0 -

Gag 1 - - 108.00 108 108 0 -

Atlantic bumper 1 - - 16.00 16 16 0 -

Spotted seatrout 1 - - 56.00 56 56 0 -

 
80.0 78.0 76.0 74.0 72.0 70.0 68.0 66.0

33.0

35.0

37.0

39.0

41.0

43.0

45.0

Latitude (degrees N)

Longitude (degrees W)

Figure 1. Map of the Northeast U.S. Continental Shelf Ecosystem depicting the area 

covered by the NEFSC Bottom Trawl Survey Program.
Spiny Dogfish

0

100

200

300

400

0 5000 10000 15000 20000

Stomachs Examined

Prey Items

Silver Hake

0

50

100

150

200

250

300

0 5000 10000 15000

Stomachs Examined

 Prey Items

Atlantic Cod

0

100

200

300

400

500

0 2000 4000 6000 8000 10000

Stomachs Examined

 Prey Items

Pollock

0

50

100

150

0 1000 2000 3000

Stomachs Examined

 Prey Items

White Hake

0

50

100

150

200

250

0 2000 4000 6000

Stomachs Examined

 Prey Items

Yellowtail Flounder

0

50

100

150

200

0 500 1000 1500

Stomachs Examined

 Prey Items

A B

C D

F E

Figure 2. The number of stomachs examined versus the number of prey items observed for

spiny dogfish, silver hake, Atlantic cod, white hake, pollock, and yellowtail flounder. 
Winter Skate

0

100

200

300

400

0 1000 2000 3000 4000 5000 6000

Stomachs Examined

Prey Items

Smooth Skate

0

10

20

30

40

50

0 50 100 150 200 250

Stomachs Examined

Prey Items

Atlantic Halibut

0

20

40

60

80

0 50 100 150

Stomachs Examined

 Prey Items

Witch Flounder

0

50

100

150

0 200 400 600 800

Stomachs Examined

 Prey Items

Alewife

0

20

40

60

0 100 200 300

Stomachs Examined

 Prey Items

Bluefish

0

50

100

150

0 500 1000 1500 2000

Stomachs Examined

 Prey Items

F

E

C D

A B

Figure 3. The number of stomachs examined versus the number of prey items observed for

winter skate, smooth skate, witch flounder, Atlantic halibut, bluefish, and alewife.
Atlantic Mackerel

0

20

40

60

80

100

0 500 1000 1500

Stomachs Examined

 Prey Items

Atlantic Herring

0

20

40

60

80

100

0 1000 2000 3000 4000

Stomachs Examined

Prey Items

Thorny Skate

0

50

100

150

200

250

0 500 1000 1500 2000

Stomachs Examined

Prey Items

C

A

B

Figure 4. The number of stomachs examined versus the number of prey items observed for

Atlantic herring, Atlantic mackerel, and thorny skate.
Figure 5. Percent frequency of occurrence of major prey items, excluding well digested prey

and empty stomachs, for all predators in the database.

0% 2% 4% 6% 8% 10% 12%

Gastropods

Scombrids

Other Molluscs

Ophiuroids

Cnidarians

Isopods

Engraulids

Clupeids

Mysids

Gadids

Copepods

Northern Sand Lance

Bivalves

Cephalopods

Ctenophores

Polychaetes

Euphausiids

Other Crustaceans

Other Fish

Amphipods

Decapods
Figure 6. Percent diet composition by weight of major prey items for spiny dogfish and smooth

dogfish. ThroughoutWDP is well digested prey.

Spiny Dogfish

0

10

20

30

Clupeids

Anchovies

Gadids

Sand Lance

Sciaenids

Scombrids

Eel pouts

Tonguefishes

Other Fish

Ctenophores

Bivalves

Cephalopods

Euphausiids

Decapods

WDP

% Composition

Smooth Dogfish

0

20

40

60

80

100

Other Fish

Polychaetes

Bivalves

Cephalopods

Molluscs

Decapods

Other

Arthropods

WDP

% Composition

B

A
Figure 7. Percent diet composition by weight of major prey items for little skate, winter skate,

and thorny skate.

Little Skate

0

10

20

30

40

Sand Lance

Cusk eels

Other Fish

Polychaetes

Bivalves

Molluscs

Decapods

Amphipods

Isopods

Other

Crustaceans

WDP

% Composition

Winter Skate

0

10

20

30

Clupeids

Gadids

Sand Lance

Cusk eels

Other Fish

Polychaetes

Bivalves

Cephalopods

Molluscs

Decapods

Amphipods

Isopods

WDP

% Composition

Thorny Skate

0

10

20

30

Hagfishes

Clupeids

Gadids

Eel pouts

Other Fish

Polychaetes

Cephalopods

Euphausiids

Decapods

Amphipods

Other

Crustaceans

WDP

% Composition

A

B

C
Figure 8. Percent diet composition by weight of major prey items for smooth skate and

clearnose skate.

Smooth Skate

0

10

20

30

40

50

Gadids

Other Fish

Polychaetes

Euphausiids

Decapods

Amphipods

Other

Crustaceans

WDP

% Composition

Clearnose Skate

0

20

40

60

Anchovies

Sand Lance

Wrasses

Cusk eels

Sciaenids

Tonguefishes

Other Fish

Bivalves

Decapods

Other

Crustaceans

WDP

% Composition

B

A
Figure 9. Percent diet composition by weight of major prey items for Atlantic herring,

Atlantic mackerel, and alewife.

Atlantic Herring

0

10

20

30

Anchovies

Sand Lance

Fish Larvae

Other Fish

Copepods

Euphausiids

Decapods

Mysids

Amphipods

Other

Crustaceans

Larvaceans

Chaetognaths

WDP

% Composition

Atlantic Mackerel

0

10

20

30

Anchovies

Gadids

Sand Lance

Other Fish

Gastropods

Cephalopods

Copepods

Euphausiids

Decapods

Mysids

Amphipods

Other

Crustaceans

Larvaceans

Chaetognaths

WDP

% Composition

Alewife

0

10

20

30

40

Sand Lance

Other Fish

Copepods

Euphausiids

Decapods

Mysids

Amphipods

Isopods

Other

Crustaceans

WDP

% Composition

C

B

A
Figure 10. Percent diet composition by weight of major prey items for northern sand lance and

butterfish.

Northern Sand Lance

0

20

40

60

80

100

Copepods

Mysids

Amphipods

Urochordates

Chaetognaths

WDP

% Composition

Butterfish

0

20

40

60

80

Other Fish

Cnidarians

Polychaetes

Gastropods

Cephalopods

Copepods

Amphipods

Sea squirts

Larvaceans

Urochordates

WDP

Miscellaneous

% Composition

B

A
Figure 11. Percent diet composition by weight of major prey items for northern shortfin squid

and longfin inshore squid.

Northern Shortfin Squid

0

20

40

60

80

Other Fish

Cephalopods

Euphausiids

Other

Crustaceans

WDP

% Composition

Longfin Inshore Squid

0

20

40

60

80

Other Fish

Cephalopods

Euphausiids

Other

Crustaceans

WDP

% Composition

A

B
Figure 12. Percent diet composition by weight of major prey items for Atlantic cod, haddock,

and pollock.

Atlantic Cod

0

5

10

15

20

25

Clupeids

Gadids

Sand Lance

Scombrids

Other Fish

Polychaetes

Gastropods

Bivalves

Cephalopods

Molluscs

Decapods

Amphipods

Other

Crustaceans

Brittle Stars

WDP

% Composition

Haddock

0

10

20

30

40

Clupeids

Sand Lance

Fish Eggs

Polychaetes

Bivalves

Molluscs

Euphausiids

Decapods

Amphipods

Other

Crustaceans

Brittle Stars

Sand Dollars

WDP

Miscellaneous

% Composition

Pollock

0

10

20

30

Clupeids

Gadids

Sand Lance

Butterfish

Other Fish

Cephalopods

Euphausiids

Decapods

Amphipods

Other

Crustaceans

WDP

% Composition

C

B

A
Figure 13. Percent diet composition by weight of major prey items for silver hake and white

hake.

Silver Hake

0

10

20

30

Clupeids

Gadids

Sand Lance

ScombridsButterfish

Other Fish

Cephalopods

Euphausiids

Decapods

Amphipods

Other

Crustaceans

WDP

% Composition

White Hake

0

10

20

30

40

Argentines

Clupeids

Gadids

Other Fish

Cephalopods

Euphausiids

Decapods

Other

Crustaceans

WDP

% Composition

B

A
Red Hake

0

10

20

30

Clupeids

Gadids

Sand Lance

Other Fish

Polychaetes

Bivalves

Cephalopods

Euphausiids

Decapods

Amphipods

Other

Crustaceans

WDP

% Composition

Figure 14. Percent diet composition by weight of major prey items for red hake and spotted hake.

A

Spotted Hake

0

10

20

30

Anchovies

Gadids

Sand Lance

Cusk eels

Butterfish

Bothids

Other Fish

Bivalves

Cephalopods

Euphausiids

Decapods

Amphipods

Isopods

Other

Crustaceans

WDP

% Composition

B
Figure 15. Percent diet composition by weight of major prey items for Atlantic halibut, American

plaice, and yellowtail flounder.

Atlantic Halibut

0

20

40

60

80

Clupeids

Gadids

Sand Lance

Sculpins

Eel pouts

Pleuronectids

Other Fish

Cephalopods

Decapods

% Composition

American Plaice

0

20

40

60

80

Fish Eggs

Polychaetes

Bivalves

Euphausiids

Decapods

Other

Crustaceans

Starfish

Brittle Stars

Sand Dollars

Other

Echinoderms

WDP

Miscellaneous

% Composition

Yellowtail Flounder

0

20

40

60

80

Cnidarians

Polychaetes

Bivalves

Decapods

Mysids

Amphipods

Other

Crustaceans

WDP

Miscellaneous

% Composition

A

B

C
Figure 16. Percent diet composition by weight of major prey items for fourspot flounder,

summer flounder, and winter flounder.

Fourspot Flounder

0

10

20

30

40

SkatesGadids

Sand Lance

Other Fish

Polychaetes

Cephalopods

Euphausiids

Decapods

Amphipods

Other

Crustaceans

WDP

% Composition

Summer Flounder

0

10

20

30

40

Clupeids

Anchovies

Gadids

Sand Lance

Cusk eels

Sciaenids

Scombrids

Sparids

Butterfish

Other Fish

Cephalopods

Decapods

Mysids

WDP

% Composition

Winter Flounder

0

20

40

60

Bothids

Cnidarians

Polychaetes

Other Worms

Bivalves

Amphipods

Isopods

Bryozoans

WDP

Miscellaneous

% Composition

C

B

A
Figure 17. Percent diet composition by weight of major prey items for windowpane flounder

and witch flounder.

Windowpane

0

5

10

15

20

25

30

Anchovies

Gadids

Sand Lance

Bothids

Fish Larvae

Other Fish

Euphausiids

Decapods

Mysids

Amphipods

Other

Crustaceans

Larvaceans

WDP

% Composition

Witch Flounder

0

20

40

60

80

100

Cnidarians

Polychaetes

Bivalves

EuphausiidsAmphipods

Isopods

Sea

Cucumbers

WDP

% Composition

A

B
Figure 18. Percent diet composition by weight of major prey items for goosefish, weakfish,

and bluefish.

Bluefish

0

10

20

30

Clupeids

Anchovies

Gadids

Sand Lance

Bluefish

Butterfish

Eel pouts

Bothids

Other Fish

Cephalopods

% Composition

Weakfish

0

20

40

60

Clupeids

Anchovies

Gadids

Sand Lance

Mullets

Sciaenids

Butterfish

Other Fish

Cephalopods

Decapods

Mysids

Amphipods

Other

Crustaceans

WDP

% Composition

Goosefish

0

10

20

30

40

50

Skates

Clupeids

Gadids

Goosefish

Sand Lance

Scombrids

Sparids

Searobins

Bothids

Pleuronectids

Other Fish

Cephalopods

% Composition

C

B

A
Figure 19. Percent diet composition by weight of major prey items for scup, black sea bass, and redfish.

Scup

0

20

40

60

Sand Lance

Fish Larvae

Other Fish

Cnidarians

Polychaetes

Bivalves

Cephalopods

Molluscs

Decapods

Amphipods

Other

Crustaceans

Brittle Stars

WDP

% Composition

Black Sea Bass

0

20

40

60

80

Anchovies

Seahorses

Lanternfishes

Sand Lance

Sparids

Other Fish

Cnidarians

Polychaetes

Gastropods

Bivalves

Cephalopods

Euphausiids

Decapods

Amphipods

WDP

% Composition

Acadian Redfish

0

20

40

60

Gadids

Other Fish

Euphausiids

Decapods

Amphipods

Other

Crustaceans

WDP

% Composition

A

B

C
Figure 20. Percent diet composition by weight of major prey items for sea raven, longhorn

sculpin, and ocean pout.

Sea Raven

0

10

20

30

40

Skates

Clupeids

Gadids

Wolffish

Sculpins

Cusk eels

Eel pouts

Bothids

Pleuronectids

Other Fish

Cephalopods

Decapods

% Composition

Longhorn Sculpin

0

20

40

60

80

Gadids

Sand Lance

Other Fish

Polychaetes

Bivalves

Decapods

Mysids

Amphipods

Isopods

Other

Crustaceans

WDP

% Composition

Ocean Pout

0

20

40

60

80

Polychaetes

Bivalves

Decapods

Amphipods

Starfish

Brittle Stars

Sand

Dollars

Sea Urchins

WDP

% Composition

C

B

A
Page 44

APPENDIX A

Stomach Sampling Protocols Used during NEFSC Bottom Trawl Surveys, 1963-99

STOMACH SAMPLING PROTOCOL

DURING 1963-66

General procedures are as follows:

1. After completion of other duties, randomly select fish

from baskets for stomach content examination.

2. Record cruise number, station number, and species

sampled at top of log. Record length (cm), sex, and

maturity stage of each fish examined.

3. Dissect out stomach and empty contents onto measuring board. Sort, identify, and record prey items

(record as empty when applicable).

4. Measure all fish and crab prey (total or fork length for

fish and carapace width for crabs).

STOMACH SAMPLING PROTOCOL

DURING 1967-72

Preserve in 10% neutral buffered Formalin up to 20

(but not less than 5) stomachs per species per catch, selecting individuals at random (i.e., without regard to size)

from the sorted catch. If time does not permit sampling all

those species with >5 individuals in each catch (usually

there are 4-6 species with >5 individuals), then give first

priority to the most abundant species, but seek to obtain

some samples of all but the rare species for the entire

cruise. Note that certain species (e.g., Atlantic herring,

silver hake) may yield only small or occasional catches

but they should get high priority because they represent a

large biomass.

In a few cases when there is a very wide range in size

for a given species (e.g., “small” versus “whale” size category of Atlantic cod), random selection will not be suitable, and separate samples from each size category will be

desirable.

Label jar tops with cruise number, station number, species, and number of stomachs, and repeat data on label inside jar. Do not overfill jars; allow about 2-inch air space

at top.

STOMACH SAMPLING PROTOCOL

DURING 1973-76

Stomachs will be collected only from species listed

in Table A1. Fifty stomachs should be collected for each

species in each strata set per cruise. No more than 10

stomachs per species should be collected for any one station, and the same species should not be sampled at two

consecutive stations.

When the catch of a species is large, the stomach

samples should be taken randomly with respect to fish

length. When fish are small, they should be preserved whole

after puncturing the gut cavity. Only one species shall be

placed in any one jar. After removing the stomach from a

large fish, make a label showing cruise number, station number, maturity stage, species, sex, and length (cm). Wrap

the stomach and the label in cheesecloth, and secure with a

cable tie. Stomachs from the same species collected at

the same station may be preserved together in one jar.

NEVER PUT MORE THAN ONE SPECIES OR FISH

FROM DIFFERENT STATIONS IN THE SAME JAR. Label the jar cap with cruise number, station number, species,

and the number of stomachs in the jar. See Table A2 for

examples of stomach and jar cap labels. Use 10% Formalin as a preservative.

Collect 50 young of the year (YOY) of the species

listed in Table A1 for each strata set. They should be preserved whole, and the jar cap labeled as aforementioned.

The lengths which are less than or equal to those listed in

Table A1 signify YOY. Be sure to slit the gut cavity.

If it appears that the necessary stomachs from each

strata set will not be collected as the cruise progresses,

disregard the above directions and take all stomachs possible until 50 have been collected for each species, then

collect using the normal procedure.

STOMACH SAMPLING PROTOCOL

DURING 1977-80

SAMPLING ROUTINE

Fish and squid stomachs will be collected from the

species listed in Tables A3-A5. The collection is based on

three separate needs as follows: 1) offshore priority species, 2) inshore priority species, and 3) miscellaneous species. Stomach sampling takes priority over any other nonNEFC sampling.

On all groundfish cruises sampling inshore strata, the

inshore priority species listed in Table A4 will be sampled

for food habits studies. Collect 150 fish representing the

entire size range of each species listed.

The species chosen for the miscellaneous collection

were selected because little or no food habit data have pre-
Page 45

viously been collected, or additional information about

their food habits is needed. Table A5 is a guide to those

miscellaneous species needed from specific areas, and to

those miscellaneous species needed from any area. Many

of the fish included in this collection are not very abundant, and few will probably be encountered.

SAMPLING METHODS

Stomach samples should be taken from fish representing the length range of a given species caught at any station. It is important that the largest and smallest fish be

included in the collection, along with the predominant size

group (i.e., stratified by length). No more than 10 stomachs per given species need to be collected at any one station, and the same species should not be sampled at two

consecutive stations. If it appears that the necessary number of stomachs will not be collected as the cruise

progresses, disregard the above directions and take all

stomachs necessary to complete the collection, then sample

normally.

Stomachs from large fish will be excised, and a label

indicating cruise number, station number, species, length

(cm), sex, and maturity stage will be completed (see Table

A6), and together they shall be wrapped in cheesecloth and

secured with a cable tie. Smaller fish may be preserved

whole after puncturing the gut cavity and completing a label denoting cruise number, station number, and species.

Stomachs of the same species collected at the same station may be preserved together in one jar. NEVER PUT

STOMACHS OF MORE THAN ONE SPECIES OR ONE

STATION IN THE SAME JAR. Use 10% Formalin as a

preservative. Label the jar cap with cruise number, station

number, species, and number of stomachs in the jar (see

Table A6). List stomachs collected on the tally sheet provided by the Food Habits Project for your convenience.

Juvenile fish may be identified by utilizing the lengths

listed with each species in Table A3. The lengths of fish

less than or equal to those indicated signify juvenile fish.

Additional samples may be collected if time permits.

STOMACH SAMPLING PROTOCOL

DURING 1981-84

The Feeding Ecology Project requires stomach content samples from the species listed in Table A7 whenever

they occur in trawl catches. It is especially important that

we document the size and species of fish prey being consumed by piscivorous predators in the Georges Bank - Nantucket Shoals area (Strata 9-25). Predators of immediate

concern are silver hake, Atlantic cod, and spiny dogfish.

Sampling of these and other species, which are listed in

their order of priority in Table A7, should be conducted as

follows.

PRESERVED SAMPLES

Stomach contents (and stomach tissue) of silver hake,

Atlantic cod, yellowtail flounder, haddock, winter flounder, Atlantic mackerel, and Atlantic herring are to be preserved according to the length categories and numbers given

in Table A7, throughout the entire survey area. Stomachs

from different species, length categories, or stations should

never be put in the same jar. Small fish may be preserved

whole. All jars shall be labeled on the inside and outside

(jar cap) to indicate ship, cruise number, station number,

species, number of fish, and length category. Samples will

be preserved in 10% Formalin.

STOMACH CONTENTS EXAMINED AT SEA

Stomach contents of spiny dogfish, pollock, white

hake, red hake, and goosefish are to be examined at sea.

Details are given in the “Procedure for Examining Stomach Contents at Sea [1981-84]” section. If time permits,

the examination of nonpriority species such as large sharks,

skates, rays, summer flounder, bluefish (i.e., fish eating

species) or predominant species in the catch, other than

those listed in Table A7, will be useful to personnel in the

Feeding Ecology Project. Any additional samples received

will be appreciated.

NUMBER OF SAMPLES

If sampling time becomes critical at any particular station, only five randomly chosen individual fish of the three

top priority species (i.e., silver hake, Atlantic cod, and spiny

dogfish) need be sampled. No more than 40 individual fish,

in total, need be sampled at any one station under any circumstances.

PROCEDURE FOR EXAMINING STOMACH

CONTENTS AT SEA [1981-84]

1. Record pertinent information such as vessel, cruise

number, station number, and predator species in the

space provided at the top lefthand corner of the log.

2. Inspect the buccal cavity (inside of mouth) for signs

of regurgitated food and the esophageal area (via the

body cavity) for inversion. Also check the gills to be

sure the fish was freshly caught (white or pink gills

indicate the fish was probably from a previous station).

If any of the above conditions exist, discard the fish.
Page 46

3. Determine the length (cm), sex, and maturity stage of

the fish, and record this information on the appropriate line of the log (simply circle the sex and maturity

stage; i.e., F = female, M = male, I = immature, D =

developing, R = ripe [or spawning], S = spent, and Rt

 =

resting).

4. Excise the stomach and empty the contents onto a tray

or sieve. The fullness measurement is recorded on

the “Fullness” line of the log as the estimated volume

(in cubic centimeters) made up by the stomach contents. If the stomach is empty, record the fullness

measurement as “0” and proceed to the next fish. The

volume may be estimated to the nearest 0.5 cm3

 by

comparing the appropriately sized, premeasured piece

of wood to the volume made up by the stomach contents.

5. It will be helpful if the relative state of digestion of

the prey items is recorded. If the stomach contents

(as a whole) appear relatively fresh (“FR”), partly digested (“PD”), or well digested (“WD”), they should

be recorded as such in the “State of Digestion” column of the log.

6. The stomach contents may now be spread apart and

separated into prey groups. An estimate of the percentage that each prey group makes up of the total

stomach content volume should be written on the line

of the log corresponding to the particular prey. If prey

can readily be identified to species, the name may be

written into one of the open spaces, and the percentage recorded as indicated earlier. The number and size

(or mean size) of organisms may also be recorded,

either along with the percentage, or in the “Comments”

section of the log. A small number of prey species

(or groups) usually account for a large percentage of a

fish’s food. Some organisms are common food for

many species of fish. Organisms repeatedly noted in

the stomachs of a particular species (or in the stomachs of several species), and not identified to species,

should be preserved in 10% Formalin and brought back

to the laboratory for identification. The stomach contents of all fish recorded on a particular log should be

saved in the same jar when returning material to the

laboratory for identification. The “Pisces” (i.e., fish)

column of the log should never be used if the fish found

in the stomach can be identified to any lower classification. The length(s) and number of fish prey should

always be recorded (the total length at time of ingestion may be estimated if fish prey are in pieces or partially digested).

7. Space for pathological information is provided at the

bottom of the log. Simply circle the abbreviation for

the affected organ and/or record additional information in the “Comments” section of the log.

STOMACH SAMPLING PROTOCOL

DURING 1985-91

The Northeast Fisheries Center seeks stomach content data for the priority species listed in Table A8 whenever they occur in trawl catches. It is especially important

to document the size and species of fish prey being consumed by piscivorous predators in the Georges Bank -

Southern New England area (Strata 1-25). The stomach

contents of all fish are to be examined at sea (see “Procedure for Examining Stomach Contents at Sea [1985-91].”).

If time permits, the sampling of species not listed in Table

A8 such as large sharks and rays (i.e., fish-eating species)

or any other predominant species in the catch will also be

desirable. Table A9 lists 18 secondary species for which a

random sample of 10 fish should be taken for each watch.

If sampling time is inadequate to achieve target numbers of priority species, then try to obtain at least five individual fish (randomly chosen) of each of the top three priority species in the catch. However, if possible, it is desirable to sample about 50 fish in total at each station to provide large enough samples to detect spatial and temporal

shifts in diet.

PROCEDURE FOR EXAMINING STOMACH

CONTENTS AT SEA [1985-91]

1. Record pertinent information such as vessel, cruise

number, station number, and predator species in the

spaces provided at the top of the log. Please use entire common name of predator (and prey) fishes when

completing the log.

2. Inspect the buccal cavity (inside of mouth) for regurgitated food and the esophageal area (via the body cavity if necessary) for signs of stomach inversion. Also

inspect the gills to be sure the fish was freshly caught

(white or pink gills indicate the fish is probably from a

previous station). If any of the above conditions exist,

discard the fish.

3. Determine the length (cm) (as per standard survey

measurements), sex, and maturity stage of the fish, and

record that information in the appropriate spaces of

the log (see codes for sex and maturity stage at the top

of log).

4. Excise the stomach and empty the contents onto a clean

measuring board. Determine and record the stomach

fullness (volume to the nearest 0.5 cm3

) by comparing

the appropriately sized volumetric gauge to the entire

volume of the bolus. If the stomach is empty, record

stomach fullness as “0.0” and proceed to the next fish.

5. Separate the stomach contents into prey groups and

record each group to the lowest taxon practical (see
Page 47

Watch Chief if necessary). Estimate the percentage

that each prey group makes up of the total stomach

content volume and write it on the corresponding line

of the log. For each prey category, record the number

(you may estimate for small organisms), individual

sizes as per survey standards (or minimum, maximum,

and average size in millimeters if more than 10 organisms are present), and state of digestion (see codes at

top of log). It is only necessary to measure organisms

>15 mm in length (e.g., fish, squid, crabs, and decapod

shrimp). The length(s) and number of fish prey should

be estimated to reflect the number and size at time of

ingestion if only pieces or partly digested fish are

present. Larvae and juvenile fish which can’t be identified should be preserved (with pertinent station information) for microscopic examination at the Woods

Hole Laboratory. Organisms repeatedly observed as

prey, but not identified to species, may occasionally

be preserved (10% Formalin) and brought to the laboratory for positive identification.

STOMACH SAMPLING PROTOCOL

DURING 1992-99

Information on predator-prey interactions among

fishes is critical for recruitment and multispecies models.

Routine stomach sampling on groundfish surveys provides

an extremely valuable time series of gut-content data which

is needed for evaluating major changes in the diets of fishes

in relation to composition and abundance of their prey. The

primary objective is to estimate predation on fish (particularly larval and juvenile stages). The current focus is on

piscivorous species representing major components of the

finfish biomass along the continental shelf off the northeastern United States.

First priority is assigned to silver hake, Atlantic cod,

spiny dogfish, and skates. Sampling guidelines for these

and other species are outlined in the accompanying Tables

A10-A12. Any unusual or interesting species not included

in Tables A10-A12 can be sampled as time permits.

PROCEDURE FOR VOLUMETRIC EXAMINATION

OF FISH STOMACHS AT SEA

1. Select fish according to priorities in Tables A10-A12.

2. Inspect gills to be sure fish was freshly caught (pale

pink or white gills means fish is probably from an earlier station).

3. For each species sampled, use a separate log sheet.

Print complete name of species. Abbreviations can

be confused (e.g., “s. hake” could be silver hake or

spotted hake).

4. Record each predator length to nearest centimeter following standard NEFSC survey methods. Record individual fish weight to the nearest gram. Record sex

and maturity stage. Fill in “F” block with an “E” to

show that the stomach was examined at sea. Excise

stomach and empty stomach contents onto a clean

measuring board or into a sorting tray.

5. If stomach is everted (blown) or shows signs of regurgitation (food in mouth), leave the “F” block and the

“Fullness” section of the log blank. Record “BLOWN”

as the prey name. Continue on to next fish.

6. If stomach is empty, record “0.0” in the “Fullness” section and record “EMPTY” as the prey name. Continue

on to next fish.

7. If stomach contains food, estimate total volume of

bolus using the volumetric gauges (i.e., “wind chimes”).

Record volume to nearest 0.1 cm3

. Trace amounts

<0.1cm3

 in volume should be recorded as 0.1cm3.

ALWAYS USE GAUGE.

8. Sort stomach contents into separate piles of prey

groups whenever possible. Prey should be identified

to the lowest taxon practical. Fish prey should be identified to species as much as possible. Unidentified

larval fish should be measured, recorded as “larval fish,”

and preserved in the provided vials. Label vial lid with

cruise number, station number, predator, and identification number. Invertebrate prey should at least be

recorded to major taxonomic group (e.g., crab, polychaete, gammarid, bivalve) Use the illustrated prey

sheet to aid identification and spelling, or ask the food

habits representative on your watch. Unidentifiable

remains should be recorded as “AR.”

9. Estimate and record percentage of total volume represented by each prey group. Record the average digestion for each group.

10. All fish, crabs, and squid should be measured using

standard NEFSC survey methods. ALL species should

be counted or have the count estimated by volume if

possible. It is of critical importance to record the number and individual lengths of all fish prey. A MAXIMUM of 10 individuals should be measured to the

nearest millimeter. If over 10 animals are present select a random subsample of 10 individuals and record

their lengths to the nearest mm. For partly digested

prey remains or large fragments of prey that cannot be

accurately measured, estimate the length of the animal to nearest 10 mm at time of ingestion. Record

these estimated lengths, followed by an “E” (e.g., 250E,

110E). Be sure to record the total number of prey

present, not the number of prey measured. RECORD

ALL PREY LENGTHS IN MILLIMETERS.

11. Use the “Remarks” section to note larval fish preserved

for further identification, comments on prey, or general comments on feeding (i.e., net feeding or scallop

draggers in vicinity). Remember to check “R” block

if “Remarks” section is used.

IF YOU HAVE ANY QUESTIONS, ASK THE FOOD HABITS REPRESENTATIVE ON YOUR WATCH.
Page 48

CRITERIA FOR ASSESSING DIGESTION STAGE

FRESH = No obvious sign of digestion. No skin

discoloration. Crustacean carapace is

hard. Prey are easily identifiable to family or species, but do not have to be identified to this level to fit category.

PARTIAL = Some recognizable external characteristics remain. Crustacean carapace is

intact but soft. Prey can frequently be

identified to family or species, but do

not have to be identified to this level to

fit category.

WELL = No external characteristics remaining.

Prey cannot be identified to family or

species using external features. Prey

may sometimes be identified using

otoliths or other remaining hard internal structures.

STOMACH SAMPLE PROCESSING

During 1992-93 surveys, sampling ranges (i.e., number of fish per range of length) and maximum stomach sampling levels were set by species and station. Refer to Table

A10. Maxima were removed in 1994, and priority species

were designated for each survey beginning in 1995. Refer

to Table A11. In 1999, the composition of species to be

sampled, sampling ranges, and sampling priorities changed.

Refer to Table A12.

An effort should be made to complete all food habits

sampling requested. If catches become overwhelming,

complete stomach analyses in order of priority. At the

Watch Chief’s discretion, a cap of five randomly selected

fish may be placed on the number of stomachs examined,

excluding empty or blown stomachs.
Page 49

Table A1. Species to be sampled, and maximum lengths for sampling YOY, for the five regions (strata sets) during 1973-76

ı

Middle Atlantic Southern New England Georges Bank Gulf of Maine Scotian Shelf

 (Strata 61-76) (Strata 1-12) (Strata 13-23, 25) (Strata 24, 26-30, 36-40) (Strata 31-35, 41-49)

Max. YOY Max. YOY Max. YOY Max. YOY Max. YOY

Species Length (cm) Species Length (cm) Species Length (cm) Species Length (cm) Species Length (cm)

ı

Silver hake 20 Yellowtail flounder 12 Yellowtail flounder 12 Acadian redfish 7 Atlantic cod 20Spotted hake 13 Silver hake 20 Atlantic cod 20 Atlantic cod 20 Haddock 20Fourspot flounder 7 Red hake 20 Haddock 20 Pollock 20 Pollock 20

Butterfish 13 Ocean pout 13 Ocean pout 13 White hake 20 Witch flounder 7Scup 13 Little skate 20 Little skate 20 Witch flounder 7 American plaice 7

Butterfish 13 Silver hake 20 American plaice 7Scup 13 Longhorn sculpin 7 Haddock 20
Page 50

Table A2. Examples of stomach and jar cap labels, and codes for sex and maturity stage, during 1973-76

 Label Code

 Stomach Jar Cap Sex Maturity Stage

Alb IV 73-1 Alb IV 73-1 M = male I = immature

Sta 149 Sta 149 F = female R1

 = ripening 1

Silver hake Silver hake U = unknown R2 = ripening 2

45 cm, M, S1 10 stomachs R3 = ripening 3

S1 = spawning 1

S2

 = spawning 2

Rc = spent-recovering

Rt = resting
Page 51

Table A3. Offshore species to be sampled, and maximum lengths for sampling juveniles, for the five regions (strata sets) during 1977-80

Middle Atlantic Southern New England Georges Bank Gulf of Maine Scotian Shelf

 (Strata 61-76) (Strata 1-12) (Strata 13-23, 25) (Strata 24, 26-30, 36-40) (Strata 31-35, 41-49)

Max. Juv. Max. Juv. Max. Juv. Max. Juv. Max. Juv.

Species Length (cm) Species Length (cm) Species Length (cm) Species Length (cm) Species Length (cm)

Spiny dogfish 60 Spiny dogfish 60 Spiny dogfish 60 Spiny dogfish 60 Spiny dogfish 60Smooth dogfish 60 Smooth dogfish 60 Winter skate 50 Red hake 20 Red hake 20Black sea bass 15 Atlantic cod 20 Red hake 20 Haddock 20 Silver hake 20Windowpane 10 Goosefish 40 Goosefish 40 Silver hake 20 Goosefish 40Longfin inshore squid 15 Winter flounder 15 Winter flounder 15 Goosefish 40 Acadian redfish 7Northern shortfin squid 15 Longfin inshore squid 15 Atlantic mackerel 25 Atlantic herring 15 Northern shortfin squid 15

Northern shortfin squid 15 Longfin inshore squid 15 Northern shortfin squid 15

Northern shortfin squid 15
Page 52

Table A4. Species to be sampled for inshore strata north and south of Cape Cod during 1977-80

 South of Cape Cod North of Cape Cod

All sharks, skates, and rays Weakfish All sharks, skates, and rays Cunner

Smooth dogfish Black sea bass Spiny dogfish Alewife

Summer flounder Spot Thorny skate Atlantic cod

Winter flounder Atlantic croaker Atlantic wolffish Silver hake

Windowpane Striped bass Winter flounder Haddock

Butterfish Northern kingfish Witch flounder Red hake

Scup Southern kingfish Atlantic halibut White hake

Bluefish Longfin inshore squid American plaice Northern shortfin squid
Page 53

Table A5. Miscellaneous species to be sampled from specific areas or from any area during 1977-80 Middle Atlantic Southern New England Georges Bank Gulf of Maine Western Nova Scotia Any AreaSharks Sharks Sharks Sharks Sharks Conger eelSkates Skates Skates Skates Skates American eelRays Rays Rays Rays Rays TilefishSpot Atlantic mackerel Sea raven Cusk Cusk BluefishWeakfish Summer flounder Gulf Stream flounder Sea raven Atlantic halibut

Summer flounder Gulf Stream flounder Windowpane Atlantic mackerel Offshore hake

Windowpane Fourspot flounder Argentines American John DoryFourspot flounder White hake Winter flounder Alewife

Butterfish American shadAtlantic wolffish Atlantic croakerThorny skate Snake mackerelsNorthern sand lance WrymouthPollock Round herringSummer flounder Longfin hakeWitch flounder Fawn cusk-eel

All grenadiersAtlantic needlefishAmerican sand lanceNorthern sea robinStriped sea robinArmored sea robinAny other unusual fish obtained
Page 54

Table A6. Examples of stomach and jar cap labels, and codes for sex and maturity stage, during 1977-80

 Label Code

 Stomach Jar Cap Sex Maturity Stage

Alb IV 77-1 Alb IV 77-1 M = male I = immature

Sta 149 Sta 149 F = female D = developing

Silver hake Silver hake U = unknown R = ripe

45 cm, M, S 10 stomachs S = spent

Rt

,T = resting
Page 55

Table A7. Order of sampling priority for species from which stomach contents will be sampled for the Feeding Ecology Project during 1981-84. (Shown are the

number of fish to be sampled per watch in each length category, and the method of sampling.)

 Length No. to Sampling Length No. to Sampling Category Sample/ Method Category Sample/ Method Species (cm)a Watch to Use Species (cm)a Watch to UseSilver hake 0-10 10 Preserve samples White hake 0-20 5 Examine at sea

11-20 10 21-40 5

21-30 20 >40 531-35 20

>35 20 Red hake 0-10 5 Examine at sea

11-20 5

Atlantic cod 0-10 5 Preserve samples 21-30 5

11-30 20 31-35 5

31-50 20 >3551-70 2071-90 30 Goosefish All 5 Examine at sea

>90 All

Spiny dogfish 0-65 20 Examine at sea Winter flounder 0-15 5 Preserve samples

66-85 20 16-30 5

>85 20 31-50 5

>50 5

Yellowtail flounder 0-10 5 Preserve samples

11-20 5 Atlantic mackerel 0-20 5 Preserve samples

21-30 5 21-25 531-40 5 26-30 5

>40 5 >30 5

Haddock 0-25 5 Preserve samples Atlantic herring 0-15 5 Preserve samples

26-50 5 16-25 5

>50 5 26-30 5

>30 5

Pollock 0-15 5 Examine at sea

16-25 526-50 551-80 5

>80 5

aLength categories are to be consistent with those of the Age and Growth Project.
Page 56

Table A8. Priority species to be sampled for stomach contents analyses at sea during 1985-91. (Given for each

species are the minimum target numbers to be sampled per watch.)

 Length Minimum Length Minimum

 Category No. to Category No. to

 Species (cm) Sample Species (cm) Sample

Silver hakea 1-20 5 Pollock 1-25 5

21-25 5 26-50 5

26-30 10 51-80 5

31-35 10 >80 5

>35 10

Red hake 1-20 5

Atlantic coda 1-30 5 21-25 5

31-50 10 26-30 5

51-70 15 31-35 5

71-90 15 >35 5

>90 All

Atlantic mackerel 1-25 5

Spiny dogfisha 1-65 20 26-30 5

66-85 25 >30 10

>85 25

Atlantic herring 1-25 5

White hake 1-20 5 26-30 5

21-40 5 >30 10

>40 5

a

Highest priority species.
Page 57

Table A9. Secondary species to be sampled for stomach contents analyses at sea during 1985-91. (A random sample

of 10 of each species should be taken for each watch.)

Acadian redfish Alewife Atlantic halibut Bluefish Fourspot flounder Goosefish

Little skate Longhorn sculpin Scup Sea raven Smooth dogfish Spotted hake

Striped bass Summer flounder Thorny skate Weakfish Windowpane Winter skate
Page 58

Table A10. Species to be sampled, sampling ranges, and maximum stomach sampling levels per station for 1992-93

bottom trawl surveys

 Bottom Trawl Survey

 Sampling 1992 1993

 Common Name Range (cm) Spring Fall Spring Fall

Bass, striped 1 per 1 All All All All

Bluefish 1 per 1 10 10 10 10

Cod, Atlantic 3 per 3 25 25 25 25

Dogfish, smooth 1 per 3 10 10 10 10

Dogfish, spiny 1 per 3 30 30 30 30

Flounder, fourspot 1 per 1 10 10 10 10

Flounder, summer 1 per 1 10 10 10 10

(Flounder) windowpane 1 per 1 10 10 10 10

Goosefish 1 per 1 All All All All

Hake, red 1 per 1 10 10 10 10

Hake, silver 1 per 1 10 10 10 10

Hake, spotted 1 per 1 10 10 10 10

Hake, white 3 per 3 10 10 10 10

Halibut, Atlantic 1 per 1 All All All All

Herring, Atlantic 1 per 1 10 10 10 10

Mackerel, Atlantic 1 per 1 10 10 10 10

Pollock 1 per 1 20 20 20 20

Sculpin, longhorn 1 per 1 10 10 10 10

Sea raven 1 per 1 10 10 10 10

Skate, little 1 per 2 10 10 10 10

Skate, thorny 1 per 2 10 10 10 10

Skate, winter 1 per 2 10 10 10 10

Weakfish 1 per 1 10 10 10 10
Page 59

Table A11. Species to be sampled, sampling ranges, and designated priorities for stomach sampling per station for 1994-98

bottom trawl surveys. (A “” indicates that samples were requested with no particular priority ranking.)

 Sampling Bottom Trawl Survey

 Range 1994 1995 1996 1997 1998

 Common Name (cm) Spring Fall Spring Fall Spring Fall Spring Fall Spring Fall

Bass, striped 1 per 1 

Bluefish 1 per 1 

Cod, Atlantic 3 per 3 11111115

Dogfish, smooth 1 per 3 

Dogfish, spiny 1 per 3 2222222 

Flounder, fourspot 1 per 1 55656564

Flounder, summer 1 per 1 

(Flounder) windowpane 1 per 1 

Goosefish 1 per 1 

Hake, red 1 per 1 

Hake, silver 1 per 1 33333331

Hake, spotted 1 per 1 

Hake, white 3 per 3 

Halibut, Atlantic 1 per 1 

Herring, Atlantic 1 per 1 4 4 4 4 2

Mackerel, Atlantic 1 per 1 3

Pollock 1 per 1 

Sculpin, longhorn 1 per 1 8 8 8 

Sea raven 1 per 1 7 7 7 

Skate, little 1 per 2 4 4 4 

Skate, thorny 1 per 2 

Skate, winter 1 per 2 5 5 5 

Weakfish 1 per 1 Page 60

Table A12. Species to be sampled, sampling ranges, and designated priorities for stomach sampling for 1999 bottom

trawl surveys.

 Sampling

 Common Name Range (cm) Priority

Bass, black Sea 1 per 5 -

Bass, striped 1 per 5 -

Bluefish 1 per 5 -

Butterfish 1 per 5 -

Cod, Atlantic 1 per 5 -

Cunner 1 per 5 -

Cusk 1 per 5 -

Cusk-eel, fawn 1 per 5 -

Dogfish, smooth 1 per 10 (by sex) -

Dogfish, spiny 1 per 10 (by sex) -

(Flounder) American plaice 1 per 5 -

Flounder, fourspot 1 per 5 -

Flounder, summer 1 per 5 3

(Flounder) windowpane 1 per 5 -

Flounder, winter 1 per 5 -

Flounder, witch 1 per 5 -

Flounder, yellowtaila 1 per 5 2

Goosefish 1 per 5 -

Haddock 1 per 5 1

Hake, offshore 1 per 5 -

Hake, red 1 per 5 -

Hake, silver 1 per 5 -

Hake, spotted 1 per 5 -

Hake, white 1 per 5 -

 Sampling

 Common Name Range (cm) Priority

Halibut, Atlantic 1 per 5 -

Herring, Atlantic 1 per 5 7

Herring, blueback 1 per 5 -

Mackerel, Atlantic 1 per 5 8

Ocean pout 1 per 5 5

Pollock 1 per 5 -

Redfish, Acadian 1 per 5 -

Rosefish, blackbelly 1 per 5 -

Salmon, Atlantic 1 per 5 -

Sculpin, longhorn 1 per 5 4

Scup 1 per 5 -

Sea raven 1 per 5 -

Shad, American 1 per 5 -

Shad, hickory 1 per 5 -

Skate, little 1 per 10 -

Skate, rosette 1 per 10 -

Skate, smooth 1 per 10 -

Skate, thorny 1 per 10 -

Skate, winter 1 per 10 -

Spot 1 per 5 -

Tautog 1 per 5 -

Weakfish 1 per 5 -

Wolffish, Atlantic 1 per 5 6

a

Sample ALL yellowtail flounder from Strata 5, 6, 9, and 10. Continue to sample one fish per 5-cm length interval in

all other strata.