NOAA Technical Memorandum NMFS-NE-124

Essential Fish Habitat Source Document:

Atlantic Cod, Gadus morhua,

Life History and Habitat Characteristics

U. S. DEPARTMENT OF COMMERCE

National Oceanic and Atmospheric Administration

National Marine Fisheries Service

Northeast Region

Northeast Fisheries Science Center

Woods Hole, Massachusetts

September 1999
Recent Issues

105. Review of American Lobster (Homarus americanus) Habitat Requirements and Responses to Contaminant Exposures.

By Renee Mercaldo-Allen and Catherine A. Kuropat. July 1994. v + 52 p., 29 tables. NTIS Access. No. PB96-115555.

106. Selected Living Resources, Habitat Conditions, and Human Perturbations of the Gulf of Maine: Environmental and

Ecological Considerations for Fishery Management. By Richard W. Langton, John B. Pearce, and Jon A. Gibson, eds.

August 1994. iv + 70 p., 2 figs., 6 tables. NTIS Access. No. PB95-270906.

107. Invertebrate Neoplasia: Initiation and Promotion Mechanisms -- Proceedings of an International Workshop, 23 June

1992, Washington, D.C. By A. Rosenfield, F.G. Kern, and B.J. Keller, comps. & eds. September 1994. v + 31 p., 8 figs.,

3 tables. NTIS Access. No. PB96-164801.

108. Status of Fishery Resources off the Northeastern United States for 1994. By Conservation and Utilization Division,

Northeast Fisheries Science Center. January 1995. iv + 140 p., 71 figs., 75 tables. NTIS Access. No. PB95-263414.

109. Proceedings of the Symposium on the Potential for Development of Aquaculture in Massachusetts: 15-17 February 1995,

Chatham/Edgartown/Dartmouth, Massachusetts. By Carlos A. Castro and Scott J. Soares, comps. & eds. January 1996.

v + 26 p., 1 fig., 2 tables. NTIS Access. No. PB97-103782.

110. Length-Length and Length-Weight Relationships for 13 Shark Species from the Western North Atlantic. By Nancy E.

Kohler, John G. Casey, Patricia A. Turner. May 1996. iv + 22 p., 4 figs., 15 tables. NTIS Access. No. PB97-135032.

111. Review and Evaluation of the 1994 Experimental Fishery in Closed Area II on Georges Bank. By Patricia A. Gerrior,

Fredric M. Serchuk, Kathleen C. Mays, John F. Kenney, and Peter D. Colosi. October 1996. v + 52 p., 24 figs., 20 tables. NTIS

Access. No. PB98-119159.

112. Data Description and Statistical Summary of the 1983-92 Cost-Earnings Data Base for Northeast U.S. Commercial

Fishing Vessels: A Guide to Understanding and Use of the Data Base. By Amy B. Gautam and Andrew W. Kitts. December

1996. v + 21 p., 11 figs., 14 tables. NTIS Access. No. PB97-169320.

113. Individual Vessel Behavior in the Northeast Otter Trawl Fleet during 1982-92. By Barbara Pollard Rountree. August 1997.

v + 50 p., 1 fig., 40 tables. NTIS Access. No. PB99-169997.

114. U.S. Atlantic and Gulf of Mexico Marine Mammal Stock Assessments -- 1996. By Gordon T. Waring, Debra L. Palka, Keith

D. Mullin, James H.W. Hain, Larry J. Hansen, and Kathryn D. Bisack. October 1997. viii + 250 p., 42 figs., 47 tables. NTIS

Access. No. PB98-112345.

115. Status of Fishery Resources off the Northeastern United States for 1998. By Stephen H. Clark, ed. September 1998. vi

+ 149 p., 70 figs., 80 tables. NTIS Access. No. PB99-129694.

116. U.S. Atlantic Marine Mammal Stock Assessments -- 1998. By Gordon T. Waring, Debra L. Palka, Phillip J. Clapham, Steven

Swartz, Marjorie C. Rossman, Timothy V.N. Cole, Kathryn D. Bisack, and Larry J. Hansen. February 1999. vii + 182 p., 16

figs., 56 tables. NTIS Access. No. PB99-134140.

117. Review of Distribution of the Long-finned Pilot Whale (Globicephala melas) in the North Atlantic and Mediterranean.

By Alan A. Abend and Tim D. Smith. April 1999. vi + 22 p., 14 figs., 3 tables. NTIS Access. No. PB99-165029.

118. Tautog (Tautoga onitis) Life History and Habitat Requirements. By Frank W. Steimle and Patricia A. Shaheen. May 1999.

vi + 23 p., 1 fig., 1 table. NTIS Access. No. PB99-165011.

119. Data Needs for Economic Analysis of Fishery Management Regulations. By Andrew W. Kitts and Scott R. Steinback.

August 1999. iv + 48 p., 10 figs., 22 tables. NTIS Access. No. PB99-171456.

120. Marine Mammal Research Program of the Northeast Fisheries Science Center during 1990-95. By Janeen M. Quintal and

Tim D. Smith. September 1999. v + 28 p., 4 tables, 4 app. NTIS Access. No. PB2000-100809.
U. S. DEPARTMENT OF COMMERCE

William Daley, 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

September 1999

Essential Fish Habitat Source Document:

Atlantic Cod, Gadus morhua,

Life History and Habitat Characteristics

Michael P. Fahay, Peter L. Berrien, Donna L. Johnson,

and Wallace W. Morse

National Marine Fisheries Serv., James J. Howard Marine Sciences Lab., 74 Magruder Rd., Highlands, NJ 07732

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

thorough internal scientific review; some issues employ external scientific review.

Reviews are -- by design -- transparent collegial reviews, not anonymous peer reviews.

All issues may be cited in formal scientific communications.

NOAA Technical Memorandum NMFS-NE-124
Editorial Notes on Issues 122-152

in the

NOAA Technical Memorandum NMFS-NE Series

Editorial Production

For Issues 122-152, staff of the Northeast Fisheries Science Center's (NEFSC's) Ecosystems Processes Division have

largely assumed the role of staff of the NEFSC's Editorial Office for technical and copy editing, type composition, and

page layout. Other than the four covers (inside and outside, front and back) and first two preliminary pages, all preprinting

editorial production has been performed by, and all credit for such production rightfully belongs to, the authors and

acknowledgees of each issue, as well as those noted below in "Special Acknowledgments."

Special Acknowledgments

David B. Packer, Sara J. Griesbach, and Luca M. Cargnelli coordinated virtually all aspects of the preprinting editorial

production, as well as performed virtually all technical and copy editing, type composition, and page layout, of Issues

122-152. Rande R. Cross, Claire L. Steimle, and Judy D. Berrien conducted the literature searching, citation checking,

and bibliographic styling for Issues 122-152. Joseph J. Vitaliano produced all of the food habits figures in Issues 122-

152.

Internet Availability

Issues 122-152 are being copublished, i.e., both as paper copies and as web postings. All web postings are, or will soon

be, available at: www.nefsc.nmfs.gov/nefsc/habitat/efh. Also, all web postings will be in "PDF" format.

Information Updating

By federal regulation, all information specific to Issues 122-152 must be updated at least every five years. All official

updates will appear in the web postings. Paper copies will be reissued only when and if new information associated with

Issues 122-152 is significant enough to warrant a reprinting of a given issue. All updated and/or reprinted issues will retain

the original issue number, but bear a "Revised (Month Year)" label.

Species Names

The NMFS Northeast Regions policy on the use of species names in all technical communications is generally to follow

the American Fisheries Societys 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

).

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.
Page iii

FOREWORD

One of the greatest long-term threats to the viability of

commercial and recreational fisheries is the continuing

loss of marine, estuarine, and other aquatic habitats.

Magnuson-Stevens Fishery Conservation and

Management Act (October 11, 1996)

The long-term viability of living marine resources

depends on protection of their habitat.

NMFS Strategic Plan for Fisheries

Research (February 1998)

The Magnuson-Stevens Fishery Conservation and

Management Act (MSFCMA), which was reauthorized

and amended by the Sustainable Fisheries Act (1996),

requires the eight regional fishery management councils to

describe and identify essential fish habitat (EFH) in their

respective regions, to specify actions to conserve and

enhance that EFH, and to minimize the adverse effects of

fishing on EFH. Congress defined EFH as “those waters

and substrate necessary to fish for spawning, breeding,

feeding or growth to maturity.” The MSFCMA requires

NMFS to assist the regional fishery management councils

in the implementation of EFH in their respective fishery

management plans.

NMFS has taken a broad view of habitat as the area

used by fish throughout their life cycle. Fish use habitat

for spawning, feeding, nursery, migration, and shelter, but

most habitats provide only a subset of these functions.

Fish may change habitats with changes in life history

stage, seasonal and geographic distributions, abundance,

and interactions with other species. The type of habitat,

as well as its attributes and functions, are important for

sustaining the production of managed species.

The Northeast Fisheries Science Center compiled the

available information on the distribution, abundance, and

habitat requirements for each of the species managed by

the New England and Mid-Atlantic Fishery Management

Councils. That information is presented in this series of

30 EFH species reports (plus one consolidated methods

report). The EFH species reports comprise a survey of the

important literature as well as original analyses of fisheryJAMES J. HOWARD MARINE SCIENCES LABORATORY

HIGHLANDS, NEW JERSEY

SEPTEMBER 1999

independent data sets from NMFS and several coastal

states. The species reports are also the source for the

current EFH designations by the New England and MidAtlantic Fishery Management Councils, and have

understandably begun to be referred to as the “EFH source

documents.”

NMFS provided guidance to the regional fishery

management councils for identifying and describing EFH

of their managed species. Consistent with this guidance,

the species reports present information on current and

historic stock sizes, geographic range, and the period and

location of major life history stages. The habitats of

managed species are described by the physical, chemical,

and biological components of the ecosystem where the

species occur. Information on the habitat requirements is

provided for each life history stage, and it includes, where

available, habitat and environmental variables that control

or limit distribution, abundance, growth, reproduction,

mortality, and productivity.

Identifying and describing EFH are the first steps in

the process of protecting, conserving, and enhancing

essential habitats of the managed species. Ultimately,

NMFS, the regional fishery management councils, fishing

participants, Federal and state agencies, and other

organizations will have to cooperate to achieve the habitat

goals established by the MSFCMA.

A historical note: the EFH species reports effectively

recommence a series of reports published by the NMFS

Sandy Hook (New Jersey) Laboratory (now formally

known as the James J. Howard Marine Sciences

Laboratory) from 1977 to 1982. These reports, which

were formally labeled as Sandy Hook Laboratory

Technical Series Reports, but informally known as “Sandy

Hook Bluebooks,” summarized biological and fisheries

data for 18 economically important species. The fact that

the bluebooks continue to be used two decades after their

publication persuaded us to make their successors – the 30

EFH source documents – available to the public through

publication in the NOAA Technical Memorandum NMFSNE series.

JEFFREY N. CROSS, CHIEF

ECOSYSTEMS PROCESSES DIVISION

NORTHEAST FISHERIES SCIENCE CENTER
Page v

Contents

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

Life History .......................................................................................................................................................................................1

Habitat Characteristics ......................................................................................................................................................................3

Geographical Distribution.................................................................................................................................................................4

Status of the Stocks ...........................................................................................................................................................................5

Research Needs .................................................................................................................................................................................5

Acknowledgments.............................................................................................................................................................................5

References Cited ...............................................................................................................................................................................6

Tables

Table 1. Age and length at 50% maturity for two stocks of Atlantic cod, Gadus morhua. .........................................................10

Table 2. Food habits of Atlantic cod, Gadus morhua. ................................................................................................................11

Table 3. Minor diet items of Atlantic cod (Gadus morhua) based on NEFSC Food Habits Study .............................................12

Table 4. Summary of life history and habitat parameters for Atlantic cod, Gadus morhua, based on data in Appendix 1. ........13

Table 5. Distribution of life history stages of Atlantic cod in representative estuaries between Maine and Chesapeake Bay..... 14

Figures

Figure 1. The Atlantic cod, Gadus morhua (from Goode, 1884)..................................................................................................15

Figure 2. Abundance of the major prey items in the diet of Atlantic cod, based on NEFSC bottom trawl survey data................16

Figure 3. Distribution and abundance of Atlantic cod from Newfoundland to Cape Hatteras......................................................17

Figure 4. Distribution and abundance of Atlantic cod eggs collected during NEFSC MARMAP ichthyoplankton surveys........18

Figure 5. Water temperatures and depths associated with Atlantic cod eggs collected during NEFSC MARMAP surveys ........22

Figure 6. Distribution and abundance of Atlantic cod larvae collected during NEFSC MARMAP ichthyoplankton surveys .....23

Figure 7. Water temperatures and depths associated with Atlantic cod larvae collected during NEFSC MARMAP surveys......27

Figure 8. Distribution and abundance of juvenile and adult Atlantic cod from NEFSC bottom trawl surveys ............................28

Figure 9. Distribution of juvenile and adult Atlantic cod in relation to temperature and depth based on NEFSC surveys ..........30

Figure 10. Distribution and abundance of juvenile and adult Atlantic cod collected in Massachusetts inshore trawl surveys.......31

Figure 11. Distribution of juveniles and adults in relation to temperature and depth based on Massachusetts trawl surveys ........32

Figure 12. Landings and spawning stock biomass for the Gulf of Maine and Georges Bank/south stocks of Atlantic cod............33

Figure 13. Distribution and abundance of juvenile and adult Atlantic cod during relatively high and low abundance periods .....34

Appendices

Appendix 1. Table of habitat parameters for Atlantic cod, Gadus morhua, based on life history stage.........................................35
Page 1

INTRODUCTION

The Atlantic cod (Figure 1) is distributed in the

northwest Atlantic Ocean from Greenland to Cape

Hatteras, North Carolina. Within the overall distribution,

densities are highest off Newfoundland, in the Gulf of St.

Lawrence and on the Scotian Shelf, while in U.S. waters,

densities are highest on Georges Bank and the western

Gulf of Maine. Atlantic cod are managed as two stocks in

American waters: (1) Gulf of Maine and (2) Georges

Bank and southward (Mayo 1995). Little interchange

occurs between the two. It occurs from nearshore areas to

depths exceeding 400 m (rarely). The greatest

concentrations off the northeast coast of the U.S. are on

rough bottoms in waters between 10 and 150 m and at

temperatures between 0 and 10o

C.

A regular pattern of migrations, associated with

reproduction and seasonal temperature change, has been

observed in the Newfoundland stock (Rose 1993). Here,

huge schools of cod leave wintering areas in deep oceanic

waters and follow tongues of deep, relatively warm,

oceanic waters ("highways") across the shelf to summer

feeding areas nearshore. They then move northward along

the Newfoundland coast in late summer, and eventually

return to wintering areas. Spawning occurs in dense

concentrations (> 1 fish/m3

) as they begin this mass

movement, with multiple pairs of spawning fish observed

in "columns" above the mass. As this huge mass of fish

migrates inshore, it periodically encounters important prey

aggregations (e.g., capelin and shrimp) and disperses.

The mass is led by the largest size class (or "scouts") and

the smallest fish are found at the rear. The author

postulates that the youngest learn the route from the

oldest, and that loss of the largest fish (through fishery

pressure directed at them) could result in changes in this

migration pattern. Similar changes have been observed in

Norwegian herring stocks, but observations of such

migrations are lacking in the two U.S. stocks. Off New

England, Atlantic cod typically move into coastal waters

during the fall and then retreat into deeper waters during

spring. Another seasonal movement occurs in the Great

South Channel area where they move southwesterly

during autumn, spend the winter in southern New England

and the Mid-Atlantic coast, and then return in the spring.

Atlantic cod attain ages of 20 years, although most

enter fisheries at ages 2-5. They can grow to lengths of

130 cm and weights of 25-35 kg and average 26 cm by the

end of their first year. Median age at sexual maturity is

1.7-2.3 years at lengths between 32 and 41 cm (O’Brien et

al. 1993). Fecundity is high and a large female may

produce between 3 and 9 million eggs. Spawning occurs

near bottom during winter and early spring, usually in

water temperatures between 5 and 7o

C. Eggs are pelagic

and drift for 2-3 weeks before hatching. The larvae are

also pelagic until they reach 4-6 cm in about 3 months,

whence they descend to the bottom. Further details of the

life history of Atlantic cod are summarized in the Final

EIS for Amendment 5 (NEFMC 1993) for the

multispecies complex, and certain data are updated in

Amendment 7, Vol. 1 of the Multispecies FMP (NEFMC

1996). Generalizations contained in those summaries

suffice to describe most biological and life history traits of

cod occurring off the northeastern coast of the U.S. The

present document examines dietary requirements and

expands somewhat on spawning patterns, distributions and

habitat characteristics of four life history stages (eggs,

larvae, juveniles, adults).

LIFE HISTORY

EGGS

Atlantic cod eggs are pelagic, buoyant, spherical and

transparent. Their diameter ranges from 1.2-1.7 mm. The

chorion is smooth (unsculptured) and the yolk is

homogeneous. There are no oil globules and the

perivitelline space is narrow (Fahay 1983; Markle and

Frost 1985). Hatching occurs after 8 to 60 days in varying

temperatures (Hardy 1978) and averages 2-3 weeks in

average spring conditions (Lough et al. 1989).

Temperature, more than season, also exerts the most

influence on egg and hatchling sizes (Miller et al. 1995).

LARVAE AND PELAGIC-JUVENILES

Larvae hatch at sizes between 3.3 and 5.7 mm, with

pigmented eyes, but unformed mouth parts. The body is

long and tapering and the vent opens laterally on the

finfold, rather than at its margin. The preanus length is <

50% of the total length. Characteristic pigment includes

pairs of bars on the dorsal and ventral edges of the body

and individual melanophores under the notochord tip.

Pollock (Pollachius virens) larvae are similar, but have

five primary caudal rays on the superior hypural; Atlantic

cod larvae have four (Fahay 1983). Some studies have

found increased growth rates with warmer temperatures

(e.g., Laurence 1978 ); others have correlated enhanced

growth with concentrations of zooplankton prey (Suthers

et al. 1989). Several studies have described developing

larvae drifting in a clockwise pattern around Georges

Bank with high concentrations over the southern flank

between 50 and 100 m (e.g., Lough et al. 1989). Larvae

occur from near-surface to depths of 75 m, and larvae

move deeper with growth (Hardy 1978).

JUVENILES

Transformation to the juvenile stage occurs at sizes

greater than 20 mm, when all fin rays are formed (Fahay

1983). Descent from the water column to bottom habitats

occurs at sizes of 2.5-6 cm (Fahay 1983; Lough et al.
Page 2

1989) or < 7 cm (Bailey 1975). Most remain on the

bottom after this descent, and there is no evidence of a

subsequent, diel, vertical migration (Bailey 1975).

Coloration during this initial descent mimics the substrate,

reducing predation (Lough et al. 1989). After descent to

the bottom, juveniles are most dense in the following

areas: off Cape Ann, MA, Massachusetts Bay, Vineyard

Sound, Nantucket Shoals, and the Northeast Peak of

Georges Bank (present report).

ADULTS

Adults are heavy-bodied and have a large head, blunt

snout and a distinct barbel under the lower jaw tip. Color

varies, but usually includes many small spots and a pale

lateral line. Color can change depending on bottom

habitats. There are three distinct dorsal fins and two

distinct anal fins. Vertebrae number 50-59 and fin ray

counts are: D1: 13-16; D2: 19-24; D3: 18-21; A1: 20-24;

A2: 17-22. Size averages 2.3-3.6 kg and the largest

recorded was 95.9 kg (Scott and Scott 1988). They tend

to move in schools, usually on the bottom, although they

may also occur in the water column.

REPRODUCTION

Both size and age at maturity have declined in recent

decades, likely in response to the fishery harvesting older

and larger fish, or to a general decline in stock biomass

due to intense exploitation. In a Scotian Shelf study

(Beacham 1983), the median age at maturity declined

about 50% between 1959 (when age at 50% maturity was

5.4 years in males, 6.3 years in females) and 1979 (when

age at 50% maturity was 2.8 years in both sexes). Median

lengths at maturity declined from 51 to 39 cm in males, 54

to 42 cm in females. This "smaller and younger at

maturity" trend continued between 1972 and 1995 in all

zones between Georges Bank and Labrador (Trippel et al.

1997). Presently, in U.S. waters, sexual maturity is

reached at ages between 1.7 and 2.3 years (median) and

lengths between 32 and 41 cm (average) (O’Brien et al.

1993). Age and length at 50% maturity for Georges Bank

and Gulf of Maine stocks are shown in Table 1. In

preparing the distribution maps for this report, a size of 35

cm was used as the division between juveniles and adults,

based on data in Table 1 and Morse (1979).

On Georges Bank, an analysis of the Marine

Resources Monitoring, Assessment and Prediction

(MARMAP) data set indicates that 60% of spawning

occurs between February 23 and April 6, based on the

abundance of Stage III eggs, back-calculated to spawning

date. Ninety percent occurs between mid-November and

mid-May, with a median date of mid-March (Page et al.

1998; Colton et al. 1979). Spawning begins along the

southern flank of Georges Bank and progresses toward the

north and west. It ends latest in the year on the eastern

side of the bank. Egg distributions indicate that the most

intense spawning activity occurs on the Northeast Peak of

Georges Bank (Page et al. 1998). The results of the

present compilation of egg distributions indicate that most

spawning occurs not only on the Northeast Peak of

Georges Bank, but also around the perimeter of the Gulf

of Maine, and over the inner half of the continental shelf

off southern New England. It occurs year-round, with a

peak in winter and spring. Peak spawning is related to

environmental conditions. It is delayed until spring when

winters are severe and peaks in winter when they are mild

(Smith et al. 1979; Smith et al. 1981). Spawning peaks in

April on Browns Bank (Hurley and Campana 1989).

Reproduction also occurs in nearshore areas, such as

Beverly-Salem Harbor, MA, where eggs are found

November through July (with a peak in April) at

temperatures between -2 and 20o

C (Elliott et al. 1979).

FOOD HABITS

The Atlantic cod has a varied diet. Reported food

items vary by life history stage and study area (Table 2).

During Northeast Fisheries Science Center (NEFSC)

bottom trawl surveys, the most frequently observed food

items were invertebrates, with fishes comprising only a

minor component (Figure 2; Table 3). In another study,

leading fish (also known as “scouts”) at the head of

migrating shoals were larger, were more successful in

feeding on preferred prey (fishes and pelagic

invertebrates), and had a more varied diet than those

following, which tended to feed mostly on benthic

invertebrates (Deblois and Rose 1996). Although

cannibalism is not often reported to occur in this species,

recent studies suggest the importance of habitat

segregation of Age 1 cod from older year classes in order

to avoid it (Gotceitas et al. 1995, in prep.).

PREDATION

Yolk sac larvae are vulnerable to zooplankton

predators including Aurelia, Thysanoessa and Euchaeta

(Bailey 1984). Adults, because of their large size, have

few enemies other than large sharks. Young stages,

however, are preyed upon by spiny dogfish, winter skate,

silver hake, sea raven, squid (northern shortfin), Atlantic

halibut, fourspot flounder and adult cod.

MIGRATIONS

In the middle part of their range, cod are nonmigratory in the strictest sense, only undertaking minor

seasonal movements in reaction to changing temperatures.

At the extremes of their range, however, cod migrate
Page 3

annually (see Introduction). In the extreme northern

region (east coast of Labrador) cod are only present

during summer and early fall. In the Middle Atlantic

Bight as far south as Chesapeake Bay, cod only occur

during winter and spring and retreat north and east to

Nantucket Shoals as shallow waters in the southern part of

the Bight exceed 20o

C (Heyerdahl and Livingstone 1982).

STOCK STRUCTURE

Several stocks have been recognized in Canadian and

U.S. waters. In U.S. waters three (or four) stocks occur:

(1) in the Gulf of Maine, north of Provincetown; (2) on

Georges Bank; (3) in southern New England, south and

west of Nantucket Shoals; and (4) along the Middle

Atlantic Bight, although the latter three intermingle. In

U.S. waters, cod are managed as two stocks, the Gulf of

Maine, and the Georges Bank and southward stocks

(Mayo 1995).

HABITAT CHARACTERISTICS

The results of a literature review directed at habitat

requirements of four life history stages of Atlantic cod are

presented in Appendix 1 and a synthesis of those data are

presented in Table 4. These tables include data from U.S.

(and certain non-U.S.) western Atlantic stocks, but

excludes data from the eastern Atlantic. Data from

Canadian waters were included only if the results could

reasonably be applied to U.S. stocks. Specifics of some

Canadian studies (e.g., distribution relative to

temperatures within a distinct region) were not included

since they have little applicability to U.S. waters.

In general, young stages of Atlantic cod tend to have

restricted distributions near major spawning centers. With

increasing age, they tend to be more widely distributed

and occur in deeper, colder and more saline water

(Tremblay and Sinclair 1985).

EGGS

An analysis of nearly 50 years of trawl data in

Canadian waters concluded that spawning rarely occurs

beyond the continental shelf, but rather occurs near where

eggs and larvae are likely to be retained (Hutchings et al.

1993). These authors concluded that inshore spawning

populations contribute more to recruitment than those

farther offshore. In MARMAP sampling between 1979

and 1987, eggs were collected from virtually all depths

sampled, but primarily from depths < 100 m (Berrien and

Sibunka 1999). Many reports describe eggs occurring in

the upper 10 m of the water column, although spring

rainfalls can lower the salinity and they will then sink to

lower depths. Although eggs are collected in a wide range

of temperatures and salinities, several studies have found

optimum conditions for incubation, hatching and

development, depending on study site (Table 4). The

present compilation of collections indicates that most eggs

are found in water column temperatures of 4-8o

C (winter,

spring, summer) or 7-14o

C (fall). A lab study found that

egg mortality was independent of temperature, but that

mortality increased at lower salinities within the range 26-

36 ppt (Laurence and Rogers 1976).

LARVAE AND PELAGIC-JUVENILES

Several studies have found increased recruitment

success when dispersion of larvae from spawning areas by

currents is reduced (Table 4; Cong et al. 1996). Although

larvae have been collected from a wide range of

temperatures, most are found in temperatures < 8o

C,

although growth rates may be enhanced in warmer

temperatures (e.g., Lawrence 1978) and one study found

no increased mortality when larvae were exposed to

higher temperatures (Iversend and Danielssen 1984).

Larvae can survive undercooling to -1.8o

C but if in direct

contact with ice they froze at -1.36o

C (Valerio et al.

1992). When larvae are 3-8 days old, they are positively

phototactic and are reported to occur from the surface to

75 m depths, moving deeper in the water column as they

grow older (Hardy 1978).

JUVENILES

Juveniles may tolerate a wider range of temperatures

than adults (Table 4; and Bigelow and Schroeder 1953).

Several studies have stressed the importance of cobble

substrates over finer grained bottoms after settlement

(e.g., Bigelow and Schroeder 1953; Colton 1978), and

some of these studies have related this preference to

avoidance of predation by older year classes of cod (e.g.,

Gotceitas and Brown 1993 and others). Nearshore

nurseries (including grass beds) may be significantly more

important to survival of juveniles than offshore habitats

(see Table 4).

ADULTS

Adult cod are typically found on or near bottom along

rocky slopes and ledges. They prefer depths between 40

and 130 m, but are sometimes found in midwater. Cod

rarely occur deeper than 200 m. Larger individuals

remain closer to the bottom in deeper water, and many

move to offshore banks during summer (Hardy 1978;

Cohen et al. 1990). Several studies have ascertained a

preference by adult cod for coarse sediments over finer

mud and silt (Table 4; Scott 1982b). They engage in diel

vertical migrations, where they make forays off the bottom
Page 4

and into the water column at night (several studies; e.g.,

Beamish 1966). Cod can occur in temperatures from near

freezing to 20o

C, and are usually found in temperatures <

10o

C, except during fall when they can occur in warmer

temperatures. Larger fish are generally found in colder

waters (Cohen et al. 1990).

GEOGRAPHICAL DISTRIBUTION

Atlantic cod in the northwest Atlantic are distributed

from Cape Chidley, Labrador to Cape Henry, VA (Figure

3). The areas of highest abundance are in Canadian

waters and include the eastern coast of Labrador south of

Cape Harrison, off eastern Newfoundland, the Flemish

Cap, the Grand Bank, the Gulf of St. Lawrence, and the

Scotian Shelf.

The estuarine occurrences of early life history stages

between Maine and the Chesapeake Bay are shown in

Table 5. These are expressed as relative abundance

characterizations, based on the observations of biologists

working in each of the systems listed, but they are not

quantitative measurements and should be considered as

presence or absence value only. Despite these limitations,

it is apparent that no early life history stages are

commonly collected south of Buzzards Bay, and north of

there they are uncommon in systems comprised mostly of

low salinity zones.

EGGS

During MARMAP sampling between the Gulf of

Maine and Cape Hatteras, 1978-1987, eggs were

distributed throughout the study area, with centers of

abundance in western Gulf of Maine, Georges Bank and

southern New England waters (Berrien and Sibunka

1999). Although they occurred year-round, densities were

much lower during August and September. Maximum

average densities of eggs occurred during March on

Georges Bank. A downward trend in abundance was

observed between 1979 and 1987 in this study area

(Berrien and Sibunka 1999). Monthly distribution maps

presented here (Figure 4) pertain to the same MARMAP

collections. In general, eggs were most dense on the

Northeast Peak of Georges Bank and around the perimeter

of the Gulf of Maine, as well as lower densities in

southern New England waters (Figure 4). Monthly

densities reached a peak in March-April, declined through

the summer, and began to increase again in the fall. Note

the relative lack of sampling in the Gulf of Maine during

March, when densities might be expected to be high.

Eggs usually occurred at temperatures between 4 and

8o

C, although they also occurred at warmer temperatures,

especially during the fall (Figure 5). Most eggs occurred

over depths of 60-110 m, although they occurred in

shallower waters during the winter (Figure 5).

There is no information on this life history stage from

state surveys.

LARVAE AND PELAGIC-JUVENILES

Larvae also occurred in MARMAP samples yearround. They were most abundant in March-May over

Georges Bank and southern New England (Figure 6),

although sampling was light during March in the Gulf of

Maine. Few larvae were collected between August and

October. Most larvae were collected in temperatures

between 4 and 10o

C and over depths of 30-70 m (Figure

7).

There is no information on this life history stage from

state surveys.

JUVENILES

The distribution of juveniles (< 35 cm) closely

matches that of spawning activity, with centers of

abundance on Georges Bank and the western part of the

Gulf of Maine (Figure 8). [Also see the distribution of

immature Atlantic cod, < 37 cm, resulting from NEFSC

bottom trawl survey cruises, 1968-1986 in Wigley and

Gabriel (1991)]. During spring trawl surveys, densities

are highest in the area north and south of Cape Ann,

Massachusetts. During summer (presence or absence data

only) juveniles are mostly found along the western shore

of Gulf of Maine, but also occur on the Northeast Peak of

Georges Bank and on Browns Bank. Fall densities are

highest in the areas of Massachusetts Bay, Nantucket

Shoals and the Northeast Peak of Georges Bank. Winter

distributions (presence or absence data only) are similar.

During spring, juveniles are mostly found in temperatures

of 4-7o

C and depths of 25-75 m, while during fall, they

occur mostly between 7 and 12o

C, but in the same depths

(Figure 9).

Juvenile cod (< 35 cm) occur in nearshore waters of

Massachusetts during spring and fall (Figure 10). In the

spring they are most dense around Cape Ann and the tip

of Cape Cod, with scattered occurrences in Massachusetts

Bay and Nantucket Sound. In the fall they occur densely

around Cape Ann and throughout Cape Cod Bay, but are

not found in Nantucket Sound. During spring surveys,

their occurrences relative to temperature and depth closely

match those sampled, but during fall surveys, they tend to

occur at the coolest and deepest sampling stations (Figure

11).

In a trawl survey of Narragansett Bay undertaken by

the Rhode Island Division of Fish and Wildlife, 1990-

1996, very few juvenile cod were collected. They were

collected in winter, spring and summer at stations with

bottom temperatures between 5 and 22o

C and depths of

10-110 ft. Too few were collected to draw conclusions

regarding temperature or depth preferences.
Page 5

See below for cod occurrences in Long Island Sound,

and Hudson-Raritan Estuary/Sandy Hook Bay.

ADULTS

Spring densities of cod adults closely match those of

the fall, with additional collections made throughout the

central part of the Middle Atlantic Bight (Figure 8).

Temperature and depth preferences are similar to those of

juveniles except that the depth range of adults is greater

than juveniles during the fall (Figure 9). During summer

(presence or absence data only) adult cod are found

throughout the Gulf of Maine and on Georges and Browns

Banks (Figure 8). Fall densities are highest in the western

part of Gulf of Maine, Nantucket Shoals and on the

Northeast Peak of Georges Bank. Winter occurrences

(presence or absence data only) are scattered over

Georges Bank and southern New England with fewer

occurrences in the western part of Gulf of Maine.

Adults occur more frequently in spring surveys than

in fall surveys in nearshore Massachusetts. During the

spring, they occur abundantly around Cape Ann, the tip of

Cape Cod, and the western part of Cape Cod Bay (Figure

10). A few adults are found during fall surveys, and these

are restricted to the Cape Ann and Cape Cod tip areas.

Adults occur in the coolest stations sampled during spring

and fall, occur at all depths sampled during spring, but

only in the deepest stations sampled during fall (Figure

11).

Only one adult cod was collected in a survey of

Narragansett Bay by the Rhode Island Division of Fish

and Wildlife, 1990-1996. Cod do not regularly occur in

Long Island Sound. In a survey of that body of water by

the State of Connecticut, 1992-1997, only three

(unmeasured) cod were collected, all near the eastern end

of the sound, during the spring, at temperatures of 9-10o

C.

A NEFSC trawl survey of the Hudson-Raritan

Estuary/Sandy Hook Bay, 1992-1997, only collected two

cod, both during winter (D. McMillan, National Marine

Fisheries Service, Highlands, NJ, personal

communication).

STATUS OF THE STOCKS

Combined commercial landings of the Gulf of Maine

and Georges Bank stocks of cod are presently at their

lowest level in 25 years (Mayo 1995 and Figure 12).

Annual landings from the Gulf of Maine stock averaged

5,500 tons from 1960-1975; 12,000 tons from 1976-1985.

A record high 18,000 tons was landed in 1991, but

landings have declined since (Murawski et al. 1997). The

relatively strong 1987 year-class no longer dominates

catches, and recent landings are mostly comprised of

weaker year classes deriving from 1988-1991 (Mayo

1995). The most recent year-classes have been among the

weakest recorded. The Gulf of Maine stock is markedly

depressed and remains overexploited.

Annual U.S. landings from the Georges Bank stock

increased from 10,800 tons in 1960 to 40,000 tons in

1980, then declined to 18,000 in 1986 and 9,800 in 1994.

Canadian landings from the same stock peaked at 14,300

tons in 1990, but have declined sharply since. The stock

is currently dominated by the 1990 year-class.

Subsequent year-classes have been much weaker and

older fish are almost non-existent in this stock. This stock

is presently at very low abundances, compared to

historical levels (Murawski et al. 1997).

Based on landings (Gulf of Maine stock) or combined

landings and estimates of spawning stock biomass

(Georges Bank stock), 1979-1982 was selected as a period

of relatively high abundance for cod, and 1993-1996 as a

period of low abundance. The distributions of juveniles

and adults during spring bottom trawl surveys were then

plotted (Figure 13). Juveniles were relatively less dense

in all areas where they occurred during the low-abundance

period and are absent from certain areas (e.g., Long

Island, Nantucket Shoals, Browns Bank) where they

occurred during high-abundance periods. Distributions of

adults during the two periods were similar. During the

low-abundance period, densities were obviously lower

throughout their range, and they did not occur in certain

regions sampled (e.g., Browns Bank, much of southern

New England) where they occurred during highabundance periods.

RESEARCH NEEDS

Our knowledge of habitat requirements of Atlantic

cod is scant beyond the distribution and relative

abundance levels (EFH tiers 1 and 2). Scientists have

only recently begun to investigate the early settlement

stage and its associated substrate preferences (Lough et al.

1989) and the importance of certain bottom habitat types

to the survival of young-of-the-year (e.g., Tupper and

Boutilier 1995). Associated with these studies are those

equating bottom habitats with the avoidance of predation,

including cannibalism (e.g., Gotceitas et al. 1995, in

prep.) or the importance of habitat segregation between

year classes (e.g., Fraser et al. 1996). These kinds of

studies are essential to improving our understanding of the

importance of habitat at tiers 3 and 4 (effects of habitat

variables on growth and/or survival).

ACKNOWLEDGMENTS

Thanks to C. Steimle and R. Ramsey-Cross for

literature searches and bibliography preparation. A. Howe

provided data from the State of Massachusetts trawl

surveys, J. Brown allowed us to see unpublished

manuscripts, and an anonymous reviewer improved the
Page 6

manuscript by suggesting numerous changes and

additions.

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Differential selection of crab Chionoecetes opilio and

Hyas spp. as prey by sympatric cod Gadus morhua

and thorny skate Raja radiata. Fish. Bull. (U.S.) 89:

669-680.

Rose, G.A. 1993. Cod spawning on a migration highway

in the northwest Atlantic. Nature 366: 458-461.

Rose, G.A. and W.C. Leggett. 1988. Atmosphere-ocean

coupling and Atlantic cod migrations: effects of windforced variations in sea temperatures and currents on

nearshore distributions and catch rates of Gadus

morhua. Can. J. Fish. Aquat. Sci. 45: 1234-1243.

Rose, G.A. and W.C. Leggett. 1989. Interactive effects of

geophysically-forced sea temperatures and prey

abundance on mesoscale coastal distributions of a

marine predator, Atlantic cod (Gadus morhua). Can.

J. Fish. Aquat. Sci. 46: 1904-1913.

Scott, J.S. 1982a. Depth, temperature and salinity

preferences of common fishes of the Scotian Shelf. J.

Northwest Fish. Sci. 3: 29-39.

Scott, J.S. 1982b. Selection of bottom type by

groundfishes of the Scotian Shelf. Can. J. Fish.

Aquat. Sci. 39: 943-947.

Scott, W.B. and M.G. Scott. 1988. Atlantic fishes of

Canada. Can. Bull. Fish. Aquat. Sci. 219. 731 p.

Smith. W.G., P. Berrien, D.G. McMillan and A. Wells.

1981. Distribution, abundance and production of
Page 9

Atlantic cod and haddock larvae off northeastern

United States in 1978-79 and 1979-80. ICES C.M.

1981/G: 52. 16 p.

Smith, W.G., M. Pennington, P. Berrien, J. Sibunka, M.

Konieczna, M. Baranowski and E. Meller. 1979.

Annual changes in the distribution and abundance of

Atlantic cod and haddock larvae off the northeastern

United States between 1973-74 and 1977-78. ICES

C.M. 1979/6. 47 p.

Stone, S.L., T.A. Lowery, J.D. Field, C.D. Williams, D.M.

Nelson, S. H. Jury, M. E. Monaco, and L. Andreasen.

1994. Distribution and abundance of fishes and

invertebrates in Mid-Atlantic estuaries. ELMR Rep.

No. 12. NOAA/NOS Strategic Environmental

Assessments Division, Silver Sping, MD. 280 p.

Suthers, I.M., K.T. Frank and S.E. Campana. 1989.

Spatial comparison of recent growth in postlarval

Atlantic cod (Gadus morhua) off southwestern Nova

Scotia: inferior growth in a presumed nursery area.

Can. J. Fish. Aquat. Sci. 46 (Suppl. 1): 113-124.

Tatyankin, Y. 1972. The distribution of juvenile cod

(Gadus morhua), pollock (Pollachius virens) and

haddock (Melanogrammus aeglefinus) under

temperature gradient conditions. J. Ichthyol. 12:

1002-1011.

Tremblay, M.J. and M. Sinclair. 1985. Gulf of St.

Lawrence cod: Age-specific geographic distributions

and environmental occurrences from 1971 to 1981.

Can. Tech. Rep. Fish. Aquat. Sci. 1387. 47 p.

Trippel, E.A., M.J. Morgan, A. Frechet, C. Rollet, A.

Sinclair, C. Annand, D. Beanlands and L. Brown.

1997. Changes in age and length at sexual maturity of

northwest Atlantic cod, haddock and pollock stocks,

1972-1995. Can. Tech. Rep. Fish. Aquat. Sci. 2157.

132 p.

Tupper, M. and R.G. Boutilier. 1995. Effects of habitat on

settlement, growth and postsettlement survival of

Atlantic cod (Gadus morhua). Can. J. Fish. Aquat.

Sci. 52: 1834-1841.

Tyler, A.V. 1971. Periodic and resident components in

communities of Atlantic fishes. J. Fish. Res. Board

Can., 28: 935-946.

Tyler, A.V. 1972. Food resource division among northern

marine demersal fishes. J. Fish. Res. Board Can. 29:

997-1003.

Valerio, P.F., S.V. Goddard, M.H. Kao and G.L. Fletcher.

1992. Survival of northern Atlantic cod (Gadus

morhua) eggs and larvae when exposed to ice and

low temperature. Can J. Fish. Aquat. Sci. 49: 2588-

2595.

Werner, F.E., F.H. Page, D.R. Lynch, J.W. Loder, R.G.

Lough, R.I. Perry, D.A. Greenberg and N.M. Sinclair.

1993. Influences of mean advection and simple

behavior on the distribution of cod and haddock early

life stages on Georges Bank. Fish. Oceanogr. 2: 43-

64.

Whitehead, P.J.P., M.-L. Bauchot, J.-C. Hureau, J.

Nielsen, E. Tortonese eds. 1986. Fishes of the Northeastern Atlantic and the Mediterranean. Vol.2.

UNESCO, Paris, France. 1007 p.

Wigley, S.E. and W.L. Gabriel. 1991. Distribution of

sexually immature components of 10 northwest

Atlantic groundfish species based on Northeast

Fisheries Center bottom trawl surveys, 1968-86.

NOAA Tech. Mem. NMFS-F/NEC-80. 15 p.

Witman, J.D. and K.P. Sebens. 1992. Regional variation

in fish predation intensity: a historical perspective in

the Gulf of Maine. Oecologia 90: 305-315.
Page 10

Table 1. Age and length at 50% maturity for two stocks of Atlantic cod, Gadus morhua. Data are from Mayo (1995).

Similar results were obtained in a Canadian study for zones near U.S. waters (Trippel et al. 1997).

Georges Bank Georges Bank Gulf of Maine Gulf of Maine

Males Females Males Females

Age at 50%

Maturity

1.9 years 1.7 years 2.3 years 2.1 years

Length at 50%

Maturity

41 cm 39 cm 36 cm 32 cm
Page 11

Table 2. Food habits of Atlantic cod, Gadus morhua.

Source Study Area and Food Habits

Marak 1960

LARVAE

Georges Bank, Gulf of Maine: Larvae eat most abundant prey. 4-18 mm eat mostly larval copepods; 18+

mm eat mostly adult copepods.

Bainbridge and McKay

1968

Greenland: Larvae (3-10 mm) mostly eat nauplii and copepodites of the copepods Calanus and Temora.

Also euphausiids.

McLaren and Avendano

1995

Scotian Shelf (Western Bank): Larvae predominant prey: 2 species of the copepod Pseudocalanus.

Bowman 1975

JUVENILES AND ADULTS

Gulf of Maine: Primary item: herring. Also redfish, mackerel, cod, and red and rock crabs.

Hacunda 1981 Central Maine coast ; Crustaceans most important, especially amphipods, Unciola, Leptocheirus, and

decapods Crangon, Cancer.

Langton 1982 Northwest Atlantic: Initially crustaceans, switch to fishes with growth. Overlaps with white hake

(Urophycis tenuis) and, at smaller sizes, with haddock (Melanogrammus aeglefinus).

Bigelow and Schroeder

1953

Gulf of Maine: Mollusks most important. Also other invertebrates.

Langton and Bowman

1980

Gulf of Maine: Diet by weight (%): Pisces 69.5; Clupeidae 23.3; Crustacea 26.1; other decapods 14.1;

Mollusca 0.7; Echinodermata 0.4.

Tyler 1972 Passamaquoddy Bay: Winter - Meganyctiphones, Mysis, Pandalus; summer - Meganyctiphones, Clupea,

Pandalus.

Keats et al. 1987 Conception Bay, Newfoundland: < 12.5 cm ate mostly small zooplankton; > 12.5 cm ate mostly benthic

organisms, in areas with thick macroalgal cover. Latter not used as food source, however.

Whitehead et al. 1986 Northeastern Atlantic: Diet variable: (fishes) herring, capelin, haddock, codling; (invertebrates)

euphausiids, hyperiids, amphipods, polychaetes.

Kohler and Fitzgerald

1969

Gulf of St. Lawrence, offshore Nova Scotian Banks: Small cod ate mostly crustaceans, switch to fish diet as

they grow. Species taken depends on relative abundance of prey. Herring most important in GOSL, sand

lance on Nova Scotian Banks. Some seasonal variation within areas and by depth.

Casas and Paz 1994 Flemish Cap: Invertebrates (crustaceans and polychaetes) dominant in juvenile diets; adults consume

mostly fish, mainly redfish (Sebastes sp.).

Casas et al 1991 Flemish Cap: Hyperiid amphipods main item in juvenile cod; as size increases, shift to fish as food item.

Most important fish prey juvenile redfish (Sebastes sp.). Rate of cannibalism very low.

Keats and Steele 1992 Newfoundland (eastern): Juveniles (Age 0 and 1) feed mostly during daylight and most prey was

planktonic.

Witman and Sebens

1992

Gulf of Maine: Cod fed heavily on tethered brittle stars in this experiment.

Robichaud et al. 1991 Cape Breton I., Nova Scotia: Cod fed on snow crabs (Chionecetes sp.) and toad crabs (Hyas spp.), with the

latter selected somewhat more often.

Methven and Piatt 1989 Newfoundland: Capelin very important diet item. When abundance is high, occurrences in cod stomachs

high; when abundance low, occurrences in cod stomachs low.

Lilly and Parsons 1991 Northeast Newfoundland: Northern shrimp (Pandalus borealis) identified as important food item of cod

throughout shrimp’s range.

Minet and Perodou

1978

SW Newfoundland and NE Gulf of St. Lawrence: Capelin and crustaceans most important components. In

some areas, larger cod ate more herring, redfish and plaice.
Page 12

Table 3. Minor diet items of Atlantic cod (Gadus morhua) based on NEFSC Food Habits Study during bottom trawl

surveys. Listed below are items occurring at 1-5 percent frequency. See Figure 1 for items occurring more frequently.

1973-1980: Diet Item Percent Frequency 1981-1990: Diet Item Percent Frequency

Polychaeta 4.70 Euphausiidae 4.68

Unciola irrorata 4.70 Decapoda (shrimp) 3.92

Eualus pusiolus 4.50 Paguridae 3.77

Trematoda 4.35 Ophiuroidea 3.64

Pagurus acadianus 3.49 Cancer sp. 3.24

Gastropoda 3.24 Bivalvia 2.81

Decapoda (crab) 3.03 Cancer irroratus 2.54

Ophiopholis aculeata 2.98 Gastropoda 2.26

Pandalidae 2.88 Merluccius bilinearis 2.26

Pandalus montagui 2.53 Gammaridea 2.11

Ammodytes sp. 2.53 Crustacea 1.63

Caprellidae 2.43 Mollusca 1.63

Cancridae 2.43 Cancer borealis 1.61

Decapoda 2.38 Isopoda 1.61

Paguridae 2.33 Crangon septemspinosa 1.56

Cephalapoda 2.22 Rock 1.45

Lysianassidae 2.18 Aphroditidae 1.44

Cancer borealis 2.18 Pectinidae 1.15

Ophiuroidea 2.12

Aphroditidae 2.07

Pagurus sp. 2.07

Sand 2.07

Aeginna longicornis 1.97

Holothuroidea 1.87

Pontogeneia inermis 1.82

Cirolanidae 1.82

Hyas sp. 1.72

Axius serratus 1.52

Bivalvia 1.52

Politolana polita 1.47

Pectinidae 1.47

Pandalus borealis 1.32

Neomysis americana 1.32

Calanoida 1.32

Gastropoda operculum 1.32

Copepoda 1.26

Anonyx sarsi 1.16

Crangonidae 1.11

Mollusca 1.11

Clupeidae 1.11

Syrrhoe crenulata 1.01

Euphausiidae 1.01
Page 13

Table 4. Summary of life history and habitat parameters for Atlantic cod, Gadus morhua. Based on data contained in

Appendix 1, Table of Habitat Parameters.

Life

History

Stage

Spatial and

Temporal

Distribution

Temperature Salinity

Depth/

Substrate/

Vegetation

Diel/ Light/

Vertical

Predator/ Prey

Eggs 1 Pelagic. Bays,

harbors, offshore

banks.

Begins fall, peaks

winter and

spring.

Most 2.0-8.5°C

for incubation.

12.0°C upper

limit. Mortality

independent of

temp.

Most 32-33

ppt. Eggs sink

in spring

freshets.

Inverse

relationship

with mortality,

26-36 ppt.

Usually < 70 m Near surface

unless salinities

low. Eggs in poor

condition may

sink.

--

Larvae 2 Pelagic. Most

over Georges

Bank, perimeter

of Gulf of Maine,

southern New

England,

continental shelf.

Densest in

spring.

Most 4-8°C

(winter-spring), 7-

12°C (summerfall).

Most 32-33

ppt.

NA Youngest from

surface to 75 m.

Move deeper with

age. Migrate

vertically in

reaction to light.

Growth

strongly

correlated with

zooplankton

volume. Yolk

sac larvae

vulnerable to

zooplankton

predators.

Juveniles 3 Mostly in shoal

waters, coastal or

offshore banks,

summer. Deeper

water winter.

6-20°C. More

tolerant of

extremes than

adults. Temp.

preferences differ

winter-summer.

30-35 ppt. ‘Cobble’ preferred

over finer grains.

Uses vegetation

for predator

avoidance.

Survival may be

enhanced in

structurally

complex habitats.

Some changes in

vertical

distribution,

day/night (see

Appendix 1).

Avoid

predation by

seeking refuge

in structured

habitats.

Adults 4 Seasonal

migrations except

in Gulf of Maine.

Most dense

Massachusetts

Bay, NE Georges

Bank, Nantucket

Shoals.

Generally < 10°C.

Varies seasonally.

Wide range of

oceanic

salinities.

Mortality < 2.3

ppt.

Rocky, pebbly,

gravelly. Avoid

finer sediments.

Usually on bottom

during day, may

move up into

water column at

night.

Varied diet.

Predation by

large sharks,

spiny dogfish,

and, as

juveniles, older

cod.

1

 Bonnet 1939, Bigelow and Schroeder 1953, Laurence and Rogers 1976, Hardy 1978

2

 Rau 1974, Hardy 1978, Bailey 1984, Suthers et al. 1989 3

 Bigelow and Schroeder 1953, Hardy 1978, MacDonald et al. 1984, Clark and Green 1990, Gotceitas and Brown 1993 4

 Bigelow and Schroeder 1953, Beamish 1966, Odense et al. 1966, Hardy 1978, Scott 1982b, Cohen et al. 1990
Page 14

Table 5. Distribution of life history stages of Atlantic cod (Gadus morhua) in representative estuaries between Maine

and Chesapeake Bay. Occurrences are not quantitative and may be based on a single, or very few, specimens. Estimates

of relative abundance after Jury et al. (1994), Stone et al. (1994).

Estuary Eggs Larvae Juveniles Adults

Passamaquoddy Bay None Common Common Common

Englishman, Machias Bays Common Common Abundant Common

Narraguagus Bay Common Common Abundant Common

Blue Hill Bay Common Common Abundant Common

Penobscot Bay None Common Common Common

Muscongus Bay Rare Rare Common Common

Damariscotta Bay Rare Rare Common Common

Sheepscot River Abundant Abundant Common Abundant

Kennebec/Androscoggin

Rivers

None None Common Common

Casco Bay Common Common Common Common

Saco Bay Common Common Common Common

Wells Harbor Rare Rare Rare None

Great Bay Common Common Rare Rare

Merrimack River Rare Rare Rare Rare

Massachusetts Bay Common Common Common Common

Boston Harbor Common Common Common Common

Cape Cod Bay Common Common Common Common

Waquoit Bay Rare Rare Rare None

Buzzards Bay Common Common Common Common

Narragansett Bay Rare Rare Rare Rare

Long Island Sound Rare Rare Rare Rare

Connecticut River None None None None

Gardiners Bay Rare Rare Rare Rare

Great South Bay None None None None

Hudson River/Raritan Bay None Rare None None

Barnegat Bay to Chesapeake

Bay

None None None None
Page 15

Figure 1. The Atlantic cod, Gadus morhua (from Goode 1884).
Page 16

Figure 2. Abundance of the major prey items in the diet of Atlantic cod, based on NEFSC bottom trawl survey data on

food habits collected during 1973-1980 and 1981-1990. Methods for sampling, processing, and analysis of samples

differed between the time periods [see Reid et al. (1999) for details]. All other diet items less than 5 percent frequency

are listed in Table 3. The category “animal remains” refers to unidentifiable animal matter.

Unid. Animal Remains

Crustacea

Unid. Fish

Dichelopandalus leptocerus

Crangon septemspinosa

Empty

Decapoda (shrimp)

Gammaridea

Nematoda Cancer irroratus

Rocks

Hyas coarctatus

Meganyctiphanes norvegica

Terebellida

Leptocheirus pinguis

Atlantic Cod

Trawl Survey 1981-1990

Empty

Unid. Fish

Crustacea

Decapoda

Unid. Animal Remains

Amphipoda

Polychaeta

Pandalidae

Ammodytes sp.

Trawl Survey 1973-1980
Page 17

Figure 3. Distribution and abundance of Atlantic cod from Newfoundland to Cape Hatteras based on research trawl

surveys conducted by Canada (DFO) and the United States (NMFS) from 1975-1994 (http://www-orca.nos.noaa.

gov/projects/ecnasap/ecnasap_table1.html).
Page 18

Figure 4. Distribution and abundance of Atlantic cod eggs collected during NEFSC MARMAP ichthyoplankton surveys,

January to December, 1978-1987 [see Reid et al. (1999) for details]. Abundance is represented by dot size, and

sampling effort is indicated by small x.

76 75 74 73 72 71 70 69 68 67 66 65

35

36

37

38

39

40

41

42

43

44

45

Atlantic Cod

Eggs

MARMAP Ichthyoplankton Surveys

61-cm Bongo Net; 0.505-mm mesh

January to December; 1978 to 1987

Number of tows = 9478, with eggs = 1354

Eggs / 10m2

1 to <10

10 to <100

100 to <1000

1000 to <10000

10000 to <100000

100000 to 150040
Page 19

Figure 4. cont’d.

76 75 74 73 72 71 70 69 68 67 66 65

35

36

37

38

39

40

41

42

43

44

45

Atlantic Cod

Eggs

MARMAP Ichthyoplankton Surveys

61-cm Bongo Net; 0.505-mm mesh

January; 1978 to 1987

Number of tows = 433, with eggs = 112

None

1 to <10

10 to <100

100 to 474

Eggs / 10m2

76 75 74 73 72 71 70 69 68 67 66 65

35

36

37

38

39

40

41

42

43

44

45

Atlantic Cod

Eggs

MARMAP Ichthyoplankton Surveys

61-cm Bongo Net; 0.505-mm mesh

February; 1978 to 1987

Number of tows = 459, with eggs = 106

None

1 to <10

10 to <100

100 to <1000

Eggs / 10m2

1000 to 8540

76 75 74 73 72 71 70 69 68 67 66 65

35

36

37

38

39

40

41

42

43

44

45

Atlantic Cod

Eggs

MARMAP Ichthyoplankton Surveys

61-cm Bongo Net; 0.505-mm mesh

March; 1978 to 1987

Number of tows = 853, with eggs = 235

None

1 to <10

10 to <100

100 to <1000

Eggs / 10m2

1000 to <10000

10000 to <100000

100000 to 150039

76 75 74 73 72 71 70 69 68 67 66 65

35

36

37

38

39

40

41

42

43

44

45

Atlantic Cod

Eggs

MARMAP Ichthyoplankton Surveys

61-cm Bongo Net; 0.505-mm mesh

April; 1978 to 1987

Number of tows = 1020, with eggs = 329

None

1 to <10

10 to <100

100 to <1000

Eggs / 10m2

1000 to 3196
Page 20

Figure 4. cont’d.

76 75 74 73 72 71 70 69 68 67 66 65

35

36

37

38

39

40

41

42

43

44

45

Atlantic Cod

Eggs

MARMAP Ichthyoplankton Surveys

61-cm Bongo Net; 0.505-mm mesh

May; 1978 to 1987

Number of tows = 1085, with eggs = 127

None

1 to <10

10 to <100

100 to 751

Eggs / 10m2

76 75 74 73 72 71 70 69 68 67 66 65

35

36

37

38

39

40

41

42

43

44

45

Atlantic Cod

Eggs

MARMAP Ichthyoplankton Surveys

61-cm Bongo Net; 0.505-mm mesh

June; 1978 to 1987

Number of tows = 709, with eggs = 56

None

1 to <10

10 to <100

100 to 583

Eggs / 10m2

76 75 74 73 72 71 70 69 68 67 66 65

35

36

37

38

39

40

41

42

43

44

45

Atlantic Cod

Eggs

MARMAP Ichthyoplankton Surveys

61-cm Bongo Net; 0.505-mm mesh

July; 1978 to 1987

Number of tows = 781, with eggs = 16

None

1 to <10

10 to <100

100 to 173

Eggs / 10m2

76 75 74 73 72 71 70 69 68 67 66 65

35

36

37

38

39

40

41

42

43

44

45

Atlantic Cod

Eggs

MARMAP Ichthyoplankton Surveys

61-cm Bongo Net; 0.505-mm mesh

August; 1978 to 1987

Number of tows = 863, with eggs = 4

None

1 to <10

10 to 56

Eggs / 10m2
Page 21

Figure 4. cont’d.

76 75 74 73 72 71 70 69 68 67 66 65

35

36

37

38

39

40

41

42

43

44

45

Atlantic Cod

Eggs

MARMAP Ichthyoplankton Surveys

61-cm Bongo Net; 0.505-mm mesh

September; 1978 to 1987

Number of tows = 747, with eggs = 3

None

1 to <10

10 to 13

Eggs / 10m2

76 75 74 73 72 71 70 69 68 67 66 65

35

36

37

38

39

40

41

42

43

44

45

Atlantic Cod

Eggs

MARMAP Ichthyoplankton Surveys

61-cm Bongo Net; 0.505-mm mesh

October; 1978 to 1987

Number of tows = 1044, with eggs = 48

None

1 to <10

10 to <100

100 to 154

Eggs / 10m2

76 75 74 73 72 71 70 69 68 67 66 65

35

36

37

38

39

40

41

42

43

44

45

Atlantic Cod

Eggs

MARMAP Ichthyoplankton Surveys

61-cm Bongo Net; 0.505-mm mesh

November; 1978 to 1987

Number of tows = 915, with eggs = 153

None

1 to <10

10 to <100

100 to 696

Eggs / 10m2

76 75 74 73 72 71 70 69 68 67 66 65

35

36

37

38

39

40

41

42

43

44

45

Atlantic Cod

Eggs

MARMAP Ichthyoplankton Surveys

61-cm Bongo Net; 0.505-mm mesh

December; 1978 to 1987

Number of tows = 569, with eggs = 165

None

1 to <10

10 to <100

100 to <1000

Eggs / 10m2

1000 to 1328
Page 22

Figure 5. Mean water column temperature and bottom depth associated with collections of Atlantic cod eggs during

NEFSC MARMAP ichthyoplankton surveys (1978-1987) by month for all years combined. Open bars represent the

proportion of all stations which were surveyed, while solid bars represent the proportion of the sum of all standardized

catches (number/10 m2

).

January

0

10

20

30

Stations

Egg Catch

April

0

10

20

30

60

70

May

0

10

20

30

June

Percent

0

10

20

40

50

July

0

10

20

30

40

August

0

10

20

60

October

0

10

20

30

Atlantic Cod Eggs

September

0

10

20

70

80

February

0

10

20

30

40

March

0

10

20

80

90

November

0

10

20

30

40

December

Water-Column Temperature (0-200m, C)

0 2 4 6 8 10 12 14 16 18 20 22 24 26 28

0

10

20

30

January

0

10

20

30

Stations

Egg Catch

April

0

10

20

30

October

0

10

20

30

40

Atlantic Cod Eggs

September

0

10

20

30

60

80

May

0

10

20

30

June

Percent

0

10

20

50

July

0

10

20

30

40

50

August

0

10

20

30

40

December

Bottom Depth (m), Interval Midpoint

10

30

50

70

90

110

130

150

170

190

210

230

250

270

290

325

375

450

750

1250

1750

>2000

0

10

20

40

50

November

0

10

20

50

60

March

0

10

20

30

80

90

February

0

10

20

30

40

50
Page 23

Figure 6. Distribution and abundance of Atlantic cod larvae collected during NEFSC MARMAP ichthyoplankton

surveys, January to December, 1977-1987 [see Reid et al. (1999) for details]. Abundance is represented by dot size, and

sampling effort is indicated by small x.

MARMAP Ichthyoplankton Surveys

61-cm Bongo Net; 0.505-mm mesh

All Seasons, All Years (1977 to 1987)

Atlantic Cod

Number of Tows = 11438, with larvae = 897

76 75 74 73 72 71 70 69 68 67 66 65

35

36

37

38

39

40

41

42

43

44

45

Larvae < 21.0 mm

1 to < 10

10 to < 100

100 to < 1000

1000 to 1394

Number of Larvae / 10m2
Page 24

Figure 6. cont’d.

76 75 74 73 72 71 70 69 68 67 66 65

35

36

37

38

39

40

41

42

43

44

45

January, 1977 to 1987

Number of Tows = 434, with larvae = 63

Number of Larvae / 10m2

None

1 to < 10

10 to < 100

100 to 275

February, 1977 to 1987

Number of Tows = 686, with larvae = 75

76 75 74 73 72 71 70 69 68 67 66 65

35

36

37

38

39

40

41

42

43

44

45

Number of Larvae / 10m2

None

1 to < 10

10 to < 100

100 to 195

March, 1977 to 1987

Number of Tows = 1031, with larvae = 136

76 75 74 73 72 71 70 69 68 67 66 65

35

36

37

38

39

40

41

42

43

44

45

None

1 to < 10

10 to < 100

100 to < 1000

1000 to 1394

Number of Larvae / 10m2

April, 1977 to 1987

Number of Tows = 1281, with larvae = 242

76 75 74 73 72 71 70 69 68 67 66 65

35

36

37

38

39

40

41

42

43

44

45

None

1 to < 10

10 to < 100

100 to < 1000

1000 to 1229

Number of Larvae / 10m2
Page 25

Figure 6. cont’d.

May, 1977 to 1987

Number of Tows = 1472, with larvae = 216

76 75 74 73 72 71 70 69 68 67 66 65

35

36

37

38

39

40

41

42

43

44

45

Number of Larvae / 10m2

None

1 to < 10

10 to < 100

100 to 363

June, 1977 to 1987

Number of Tows = 893, with larvae = 56

76 75 74 73 72 71 70 69 68 67 66 65

35

36

37

38

39

40

41

42

43

44

45

Number of Larvae / 10m2

None

1 to < 10

10 to 89

July, 1977 to 1987

Number of Tows = 938, with larvae = 12

76 75 74 73 72 71 70 69 68 67 66 65

35

36

37

38

39

40

41

42

43

44

45

Number of Larvae / 10m2

None

1 to < 10

10 to < 100

100 to 143

August, 1977 to 1987

Number of Tows = 1148, with larvae = 5

76 75 74 73 72 71 70 69 68 67 66 65

35

36

37

38

39

40

41

42

43

44

45

Number of Larvae / 10m2

None

1 to < 10

10 to 14
Page 26

Figure 6. cont’d.

September, 1977 to 1987

Number of Tows = 774, with larvae = 2

76 75 74 73 72 71 70 69 68 67 66 65

35

36

37

38

39

40

41

42

43

44

45

Number of Larvae / 10m2

None

1 to 6

October, 1977 to 1987

Number of Tows = 1147, with larvae = 3

76 75 74 73 72 71 70 69 68 67 66 65

35

36

37

38

39

40

41

42

43

44

45

Number of Larvae / 10m2

None

1 to 7

November, 1977 to 1987

Number of Tows = 1031, with larvae = 25

76 75 74 73 72 71 70 69 68 67 66 65

35

36

37

38

39

40

41

42

43

44

45

Number of Larvae / 10m2

None

1 to < 10

10 to 37

December, 1977 to 1987

Number of Tows = 603, with larvae = 62

76 75 74 73 72 71 70 69 68 67 66 65

35

36

37

38

39

40

41

42

43

44

45

Number of Larvae / 10m2

None

1 to < 10

10 to 78
Page 27

Figure 7. Mean water column temperature and bottom depth associated with collections of Atlantic cod larvae during

NEFSC MARMAP ichthyoplankton surveys (1977-1987) by month for all years combined. Open bars represent the

proportion of all stations which were surveyed, while solid bars represent the proportion of the sum of all standardized

catches (number/10 m2

).

January

0

10

20

30

Stations

Larva Catch

April

0

10

20

30

60

70

May

0

10

20

30

June

Percent

0

10

20

30

July

0

10

50

60

August

0

10

20

50

60

November

0

10

20

30

40

Atlantic Cod Larvae (<=20.0mm Length)

September

0

10

90

100

March

0

10

20

30

40

October

0

10

20

30

40

February

0

10

20

30

40

December

Water-Column Temperature (0-200m, C)

0 2 4 6 8 10 12 14 16 18 20 22 24 26 28

0

10

20

30

January

0

10

20

30

40

50

Stations

Larva Catch

April

0

10

20

50

60

December

Bottom Depth (m), Interval Midpoint

10

30

50

70

90

110

130

150

170

190

210

230

250

270

290

325

375

450

750

1250

1750

>2000

0

10

20

30

Atlantic Cod Larvae (<=20.0mm Length)

September

0

10

20

80

100

May

0

10

20

30

40

June

Percent

0

10

20

40

50

July

0

10

20

60

70

August

0

10

20

30

40

50

October

0

10

20

30

40

March

0

10

20

50

60

February

0

10

20

30

40

November

0

10

20

30
Page 28

Figure 8. Distribution and abundance of juvenile (< 35 cm) and adult (≥ 35 cm) Atlantic cod from spring (1968-1997),

summer (1963-1995), autumn (1963-1996), and winter (1964-1997) NEFSC bottom trawl surveys. Densities are

represented by dot size in spring and fall plots, while only presence and absence are represented in winter and summer

plots [see Reid et al. (1999) for details].

Number/Tow

 1 to 10

 10 to 50

 50 to 100

 100 to 500

 500 to 1162

NMFS Trawl Surveys

Spring 1968 - 97

Juveniles (<35cm)

Atlantic Cod

NMFS Trawl Surveys

Summer 1963 - 95

Juveniles (<35cm)

 = Total Tows

 = Positive Tow

Atlantic Cod

Number/Tow

 1 to 10

 10 to 25

 25 to 100

 100 to 200

 200 to 393

NMFS Trawl Surveys

Autumn 1963 - 96

Juveniles (<35cm)

Atlantic Cod

NMFS Trawl Surveys

Winter 1964 - 97

Juveniles (<35cm)

 = Total Tows

 = Positive Tow

Atlantic Cod
Page 29

Figure 8. cont’d.

Number/Tow

 1 to 10

 10 to 50

 50 to 100

 100 to 500

 500 to 2930

NMFS Trawl Surveys

Spring 1968 - 97

Adults (>=35cm)

Atlantic Cod

NMFS Trawl Surveys

Summer 1963 - 95

Adults (>=35cm)

 = Total Tows

 = Positive Tow

Atlantic Cod

Number/Tow

 1 to 10

 10 to 50

 50 to 100

 100 to 200

 200 to 467

NMFS Trawl Surveys

Autumn 1963 - 96

Adults (>=35cm)

Atlantic Cod

NMFS Trawl Surveys

Winter 1964 - 97

Adults (>=35cm)

 = Total Tows

 = Positive Tow

Atlantic Cod
Page 30

Figure 9. Distribution of juvenile and adult Atlantic cod in relation to bottom temperature and depth based on spring

(1968-1997) and autumn (1963-1996) NEFSC bottom trawl surveys. Open bars represent the proportion of all stations

which were surveyed, while solid bars represent the proportion of the sum of all standardized catches (number/10 m2

).

1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 0

10

20

30

40

1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 0

4

8

12

16

20

0

10

20

30

40

0

10

20

30

40

0

5

10

15

20

25

0

10

20

30

40

1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 0

4

8

12

16

1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 0

10

20

30

Juveniles 40 Adults

Stations

Catches

Spring Spring

Spring Spring

Autumn Autumn

Autumn Autumn

Bottom Depth (m) Bottom Depth (m)

Bottom Depth (m) Bottom Depth (m)

Bottom Temperature (C) Bottom Temperature (C)

Bottom Temperature (C) Bottom Temperature (C)

NMFS Bottom Trawl Surveys

Atlantic Cod
Page 31

Figure 10. Distribution and abundance of juvenile (< 35 cm) and adult (≥ 35 cm) Atlantic cod collected during spring

and autumn Massachusetts inshore bottom trawl surveys, 1978-1996 [see Reid et al. (1999) for details].

Atlantic Cod

Mass. Inshore Trawl Survey

 Spring 1978 - 1996

 Juveniles (<35cm)

Number/Tow

 1 to 25

 25 to 100

 100 to 200

 200 to 500

 500 to 1765

Atlantic Cod

Mass. Inshore Trawl Survey

 Autumn 1978 - 1996

 Juveniles (<35cm)

Number/Tow

 1 to 25

 25 to 50

 50 to 100

 100 to 500

 500 to 2925

Atlantic Cod

Mass. Inshore Trawl Survey

 Spring 1978 - 1996

 Adults (>=35cm)

Number/Tow

 1 to 10

 10 to 20

 25 to 50

 50 to 100

 100 to 373

Atlantic Cod

Mass. Inshore Trawl Survey

 Autumn 1978 - 1996

 Adults (>=35cm)

Number/Tow

 1 to 5

 5 to 10

 10 to 50

 50 to 100

 100 to 121
Page 32

Figure 11. Distribution of juvenile and adult Atlantic cod in relation to bottom temperature and depth based on spring

and autumn Massachusetts inshore bottom trawl surveys, 1978-1996. Open bars represent the proportion of all stations

which were surveyed, while solid bars represent the proportion of the sum of all standardized catches (number/10 m2

).

1 3 5 7 9 11 13 15 17 19 21 23 0

5

10

15

20

25

1 3 5 7 9 11 13 15 17 19 21 23 0

5

10

15

20

25

0

5

10

15

20

25

0

5

10

15

20

25

0

20

40

60

0

5

10

15

20

25

1 3 5 7 9 11 13 15 17 19 21 23 0

10

20

30

40

1 3 5 7 9 11 13 15 17 19 21 23 0

5

10

15

20

25

Juveniles Adults

Stations

Catches

Spring Spring

Spring Spring

Autumn Autumn

Autumn Autumn

Bottom Depth (m) Bottom Depth (m)

Bottom Depth (m) Bottom Depth (m)

Bottom Temperature (C) Bottom Temperature (C)

Bottom Temperature (C) Bottom Temperature (C)

Mass. Inshore Trawl Surveys

Atlantic Cod
Page 33

Figure 12. Annual commercial landings (including recreational catches) and estimates of spawning stock biomass (from

the NEFSC bottom trawl surveys) for the Gulf of Maine and Georges Bank and south stocks of Atlantic cod.

Gulf of Maine

Year

1960 1965 1970 1975 1980 1985 1990 1995 2000

Metric tons (x1000)

0

10

20

30

Commercial landings

Spawning stock biomass

Georges Bank and South

Year

1960 1965 1970 1975 1980 1985 1990 1995 2000

Metric tons (x1000)

0

20

40

60

80

100

Commercial landings

Spawning stock biomass
Page 34

Figure 13. Distribution and abundance of juvenile (< 35 cm) and adult (≥ 35 cm) Atlantic cod during a period of

relatively high abundance (1979-1982) and a period of relatively low abundance (1993-1996), from spring NEFSC

bottom trawl surveys.

Number/Tow

 1 to 10

 10 to 25

 25 to 50

 50 to 100

 100 to 212

NMFS Trawl Surveys

Spring 1979 - 82

Juveniles (<35cm)

High Abundance

Atlantic Cod

Number/Tow

 1 to 10

 10 to 25

 25 to 50

 50 to 100

 100 to 212

NMFS Trawl Surveys

Spring 1993 - 96

Juveniles (<35cm)

Low Abundance

Atlantic Cod

Number/Tow

 1 to 10

 10 to 50

 50 to 100

 100 to 500

 500 to 1621

NMFS Trawl Surveys

Spring 1979 - 82

Adults (>=35cm)

High Abundance

Atlantic Cod

Number/Tow

 1 to 10

 10 to 50

 50 to 100

 100 to 500

 500 to 1621

NMFS Trawl Surveys

Spring 1993 - 96

Adults (>=35cm)

Low Abundance

Atlantic Cod
Page 35

Appendix 1. Table of Habitat Parameters for Atlantic cod, Gadus morhua. This table is separated into four parts based on life history

stage. "Present Study" refers to data presented herein. Abbreviations: GB = Georges Bank; GOM = Gulf of Maine; GOSL = Gulf of

St. Lawrence; Mass Bay = Massachusetts Bay; Nfld. = Newfoundland; SNE = southern New England (Nantucket Shoals to Hudson

Canyon); SS = Scotian Shelf.

SPAWNING/EGGS

Authors Study Area

and Period

Habitat (Spatial and

Temporal)

Temperature Salinity Currents/

Circulation

Light/Vertical

Bigelow &

Schroeder

1953

GOM Pelagic. Spawn Mass Bay 3-10

miles from shore Nov-Apr.;

Ipswich Bay Feb-May; West

coast Maine Mar-May (into

mid-summer). Also Isles of

Shoals, Casco Bay, Sheepscot

R. Always < 50 fm.

Bottom temps 0.6-8.9°C

for spawning (2.2-5.6°C

in Mass Bay). 

5.0-8.3°C optimum for

hatching. High

mortalities at 0°C.

Sink in spring

freshets

Drift southwest

following

coastline, 10-30

days

Near surface if salinities

high

Hardy

1978

GB, GOM Pelagic. Spawn in inlets, bays,

harbors, coastal & offshore

banks. Usually < 73 m.

0-6°C for spawning.

2.0-8.5°C optimum for

incubation

Spawn salinity thru

range: 10.0-35.5

ppt.

Eggs sink in spring

freshets. High

mortality at low

salinites (9.9-12.5

ppt)

--- Upper 10 m. Sink with

age

Fish 1928 Mass Bay,

SW GOM

Peak spawning, Mass Bay,

January

10.1°C (Nov) to 0°C

(January)

--- Advected out of

Mass Bay by

currents.

---

Bonnet

1939

Lab study Ipswich Bay. Spawns at yearly

minimum temp. (March)

0.5-3.0°C.

12°C upper limit for

development

--- Eggs spawned in

Ipswich bay

would drift 120

miles before

larvae settled to

bottom

---

Colton

1978

GOM Spawn Nantucket Shoals and

Mass Bay, January-April (peak

January). Also Georges and

Browns banks, Ipswich Bay,

SW GOM.

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

Cohen et

al. 1990

North

Atlantic

Most productive area in

western North Atlantic is

eastern half GB & Grand

Banks, followed by SW GOM.

0-12°C with most 0-

6°C. GOM stock

spawns in colder water

than others.

--- --- Spawn near bottom,

unless temperatures

unsuitable, then migrate

into water column.

Rau 1974 Browns

Bank, GB,

Nantucket

Shoals, FebMar 1973

Most eggs found over central

and northeast GB.

Most collected at 3-5°C Most collected at

32-33 ppt

--- ---

Anderson

and de

Young

1995

Northeastern

Nfld. shelf

Studied vertical distribution

and relative condition of eggs.

Temperature has effect

on vertical distribution

Salinity (water

density) has effect

on vertical

distribution

--- Eggs in poor condition

found deeper in water

column.

Miller et

al. 1995

SS, OctoberMay, 1991-

1993

Peak spawn during fall. Temperature (more than

season) exerts most

influence on egg size

(and hatchling size).

--- --- ---

Valerio et

al. 1992

Nfld. Studied freeze resistance of

eggs & larvae. No antifreeze

proteins detected.

If chorion intact,

capable of undercooling

to -4.0°C. Froze at -4.1

to -17.0°C.

--- --- ---

Brander &

Hurley

1992

SS Spring spawning proceeds from

SW to NE along shelf.

--- --- Spawning

matches

production of

copepods.

---
Page 36

Appendix 1. cont’d.

LARVAE

Authors Study Area

and Period

Habitat (Spatial and

Temporal)

Temperature Salinity Currents/

Circulation

Light/

Vertical

Predators/ Prey

(See Tables)

Rau 1974 Browns Bank,

GB, 

Nantucket

Shoals, FebMar 1973

Most larvae (2-7 mm)

between northeast GB

and Nantucket Shoals.

Most collected

3-5°C

Most

collected

32-33 ppt

--- --- ---

Laurence

1978

Laboratory

study

Growth rates increase

with increasing

temperatures.

4°C: 4.15%/d

7°C: 6.67%/d

10°C: 8.75%/d

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

Werner et

al. 1993.

GB Examined tidal

currents, wind stress,

Scotian Shelf inflow,

advection and vertical

distribution of larvae

on Northeast Peak. 

Spawning shoalward

of 50-m isobath

enhances eventual

retention of larvae on

Georges Bank.

--- --- Larvae in

surface layers

subject to offshelf

advection via

Ekman

transport. 

Downwelling

near shelf

break allows

larvae to

avoid

advection.

--- ---

Suthers et

al. 1989

SS Recent growth in

presumed inshore

nursery area was less

than in offshore

waters, based on

examination of

birthdate distributions.

Temperature

only rarely

correlated with

growth.

--- --- --- Growth rate

strongly

correlated with

zooplankton

biomass.

Perry &

Neilson

1988

GB Studied diel vertical

distributions of cod

and haddock late

larvae in isothermal

and stratified sites.

Thermocline

may limit

nightly upward

migration.

--- --- Near

bottom

during day,

in midwater

at night.

Migrations

in reaction

to light

levels.

Late larval

haddock did not

change depth as

much as cod

larvae.

Myers &

Drinkwater

1989

Middle

Atlantic

Bight, GB,

Grand Banks

Examined effect of

warm core ring

activity on recruitment

success in 17

groundfish stocks,

1973-1986.

--- --- Increased ring

activity

reduced

recruitment in

all stocks

except GB

cod.

Rings

presumably

entrained

larvae of

most stocks

offshore.

---
Page 37

Appendix 1. cont’d.

JUVENILES

Authors Study Area

and Period

Habitat (Spatial

and Temporal)

Temperature Salinity Substrate/

Vegetation

Currents/

Circulation

Light/

Diel

Predators/

Prey

Gotceitas

et al. 1994

Trinity Bay,

Nfld. and

laboratory

studies, 1993

Nearshore bay,

various

substrates. Julymid-December.

--- --- Predator

absent:

preferred finer

grains &

avoided

vegetation.

Predator

present:

preferred

cobble & hid 

in vegetation.

--- --- See

Substrate/

Vegetation

column

Gotceitas

& Brown

1993

Laboratory

Study

Studied substrate

preference with

and without a

predator (e.g. a

larger cod)

present.

--- --- Cobble

preferred over

finer grained

substrates

when predator

present. After

predator leaves,

larger juveniles

return to fine

grains, smaller

remain in

cobble.

--- --- Fewer

juveniles

succumb to

predation in

cobble than

in finer

grained

substrates.

Hardy

1978

Northwest

Atlantic

Coastal waters,

rock pools,

shallow inlets,

river mouths,

harbors. Leave

coastal areas by

mid-June

(Massachusetts).

0+ average 35 m

(range 8-42m);

1+ range 73-274

m.

Range 6-20°C From <

31.3 to

35.0 ppt

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

Lough et

al. 1989

GB Descend to

bottom @ 4-6

cm. 0+ (newly

settled) fish

dense on

northeastern GB,

70-100 m depth,

during summer.

--- --- Pebble-gravel

deposit

Fall,

transported

southeastward by

gyre

Migrate

into

lower

water

column

at night

to feed

on

invertebrates

Coloration

mimics

substrate,

reduces

vulnerability

to predation.

Tatyankin

1972

Barents Sea,

1967-1969

(laboratory

study)

Determined

preferred

temperatures in

gradient tank. In

general, lower

temperatures

selected in

winter, higher in

summer. Older

age classes

preferred colder

temperatures

than younger.

Age 0+,

summer: 7-11

°C.

Age 1, winter: 3-

6°C.

Age 1+, fall: 5-

8°C.

Age 2, winter: 2-

7°C

--- --- --- --- ---
Page 38

Appendix 1. cont’d.

JUVENILES

Authors Study Area and

Period

Habitat (Spatial

and Temporal)

Temperature Salinity Substrate/

Vegetation

Currents/

Circulation

Light/

Diel

Predators/

Prey

MacDonald

et al. 1984

Bay of Fundy

and

Passamaquoddy

Bay

Juveniles in

Passamaquoddy

Bay in winter,

close to beach in

summer. (See

"Adults")

0-6°C

(winter);

8-13°C

(summer)

30-31

ppt

winter;

31-32

ppt

summer

Mud, gravel,

rock (winter);

sand, mud,

rock (summer)

--- --- ---

Clark &

Green 1990

Conception Bay,

Nfld.

Studied diel,

depth, seasonal

movements in

Broad Cove.

Seasonal change

in diel behavior

due to

disappearance of

shallow (< 30m),

summer

thermocline.

Summer: day:

4.1-4.6°C;

night: 10-

12°C. Fall:

stayed in

warmer water.

--- Summer: wideranging (>

3km/day),

between deep,

cold & shallow,

warmer water;

Fall: small

home ranges

over sand in

shallows;

resting areas

over rocks in

shallows.

--- Summer:

day,

inactive;

night,

active.

Fall: day,

active;

night,

inactive.

Active

periods

coincide

with

feeding.

Keats et al.

1987

Conception Bay,

Eastern Nfld.

Observations of

juveniles in

macroalgal

habitat and

adjacent seaurchin

dominated

’barrens’.

--- --- More abundant

in macroalgal

areas, used as

cover, than in

’barrens’.

--- Diel not

tested

Epiphytic

food source

not

utilized.

Gotceitas et

al. 1995

Nfld. Studied

reactions of 0+

cod to predator

in combinations

of substrates and

artificial ’kelp’.

--- --- With no

predator, 0+

prefer fine

grain

substrates,

avoid ’kelp’.

When predator

present, ’kelp’

provides

protection from

predation.

--- --- Juveniles

select

refuge type

(cobble or

’kelp’)

when

predator

present.

Gotceitas et

al. 1997 Nfld. Studied

vegetated and

non-vegetated

habitats, plus

several bottom

substrates with

& without

predator using 

SCUBA and

seines.

--- --- Eelgrass used

as nearshore

nursery by 0+

cod. For refuge

from predation

& when

combined with

cobble, stem

density was

important.

--- --- Predator

absent: 0+

used sand

& gravel.

Predator

present: 0+

hid in

cobble or

eelgrass.
Page 39

Appendix 1. cont’d.

JUVENILES

Authors Study Area and

Period

Habitat (Spatial and

Temporal)

Temperature Salinity Substrate/

Vegetation

Currents/

Circulation

Light/ Diel Predators/

Prey

Fraser et

al. 1996

Laboratory Study Studied interactions of

0+, 1+ and 3+ (predator)

cod and their reactions

to two different

substrate types,

sand/cobble &

sand/gravel.

--- --- Some habitat

segregation

between Age 0+

and Age 1+,

except when

Age 3+ present,

then both hid in

cobble.

--- --- When

predator

present, 0+

and 1+ cod

used same

refuge

(cobble).

Tupper &

Boutilier

1995

St. Margaret’s

Bay, Nova Scotia

Studied survival and 0+

densities in 4 different

bottom habitats (sand,

seagrass, cobble, rockreef).

--- --- Settlement equal

among habitats,

but subsequent

densities highest

in structurally

complex habitat

types.

--- --- Higher

survival and

densities

appear to be

related to

shelter

opportunities

and reduced

predation.

Keats 1990 Bonavista Bay,

Nfld.

Examined diel depth

distributions of 

juveniles.

--- --- --- --- Arrive in

shallow

water at

dusk,

remain until

pre-dawn,

then

migrate

into deeper

water.

Murawski

& Finn

1988

GB Evaluated species cooccurrences relative to

temperature & depth

preferences, spatial

distribution by species

& age. Overlap with

silver hake, mostly in

fall.

See also “Adults”

YOY Means:

winter: 2.9°C

spring: 5.3°C

summer:

9.9°C

fall: 9.3°C

--- YOY Means:

winter: 56 m

spring: 60 m

summer: 71 m

fall: 71 m

--- ---

Grant &

Brown

1998a

Nfld. Studied diel distribution

in eelgrass habitat and

diet differences between

0+ and 1+ cod.

--- --- After settlement

in grass beds,

Age 0+ change

habits on diel

basis.

--- Age 0+ in

water

column

during day,

disperse to

bottom at

night.

Older yr.

classes do

opposite.

Age 0+ feed

mostly on

zooplankton

during day;

Age 1+

mostly on

benthos and

fish at night.

Grant &

Brown

1998b

Nfld. Studied encounters

between just-settled

juveniles and older cod

(predators) in eelgrass

and no-eelgrass habitats

in Trinity Bay.

--- --- After settlement,

juveniles display

preference for

eelgrass beds,

but remain

localized over

grass and nograss habitats

for several

weeks, perhaps

through first

winter.

--- Juveniles

aggregate

in grass

beds during

day,

disperse at

night.

Different

pattern by

older cod

results in

reduced

encounters.

Risk of

cannibalism

high in

coastal

habitats. 

Localized

movements

and

preference

for grass

beds are

mechanisms

to avoid

predation.
Page 40

Appendix 1. cont’d.

ADULTS

Authors Study Area and

Period

Habitat (Spatial

and Temporal)

Temperature Salinity Depth/

Substrate/

Vegetation

Currents/

Circulation

Light/

Diel/

Vertical

Predator/

Prey (See

Tables)

Bigelow &

Schroeder

1953

GOM Non-migratory in

GOM.

Surface to 250 fm,

but few > 100 fm.

Most 5-75 fm. 

Usually within 1

fm of bottom. As

shallow as 7 fm

(summer), 3 fm

(winter).

0-12.8°C. Prefer

< 10.0 °C

--- Mostly rocky,

pebbly, sandy

or gravelly

bottoms.

--- --- Large

sharks and

spiny

dogfish.

Jean 1965 GOSL; SS GOSL: 35-145 m

(summer); 130-

180 m (winter).

SS: 65-110 m

(summer);

90-135 m (winter).

GOSL: 0-6°C

(summer); 1-3 °C

(winter).

SS: 1-8°C

(summer); 2-4 °C

(winter).

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

Odense et

al. 1966

Bay of Chaleur

(laboratory study)

Studied tolerance

to low salinity

5-6°C (not

manipulated)

First

mortalities

when

reached

2.7 ppt;

complete

mortality

at 2.3 ppt

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

MacDonald

et al. 1984

Bay of Fundy and

Passamaquoddy

Bay

Adults in

Passamaquoddy

Bay summer,

GOM, SS winter.

(See "Juveniles")

8-13°C (summer);

4-8°C (winter)

31-32 ppt

(summer);

31-32 ppt

(winter)

Mud, rock

(summer)

--- --- ---

Scott 1982a SS, Bay of Fundy Determined

preferred depths,

temperatures &

salinities for

several groundfish

species. Compared

to other gadoids,

cod prefers

shallower, colder

and less saline.

0-13°C (mean

4.9°C). Preferred

temperature

showed increase

NE to SW, means

3.2 to 7.8°C.

31-34 ppt

(mean

32.8 ppt)

27-366 + m,

(mean 95 m).

Preferred

range 37-90

m.

--- --- ---

Colvocoresses

and Musick

1984

Middle Atlantic

Bight, continental

shelf

Analyzed faunal

associations, and

zones occupied

seasonally. Occurs

with Pseudopleuronectes

americanus and

Hemitripterus

americanus.

Boreal species,

spring, < 10°C.

"Relatively

absent" during

fall

--- < 100 m --- --- ---
Page 41

Appendix 1. cont’d.

ADULTS

Authors Study Area and

Period

Habitat

(Spatial and

Temporal)

Temperature Salinity Depth/

Substrate/

Vegetation

Currents/

Circulation

Light/

Diel/

Vertical

Predators/

Prey (See

Tables)

Tyler

1971

Passamaquoddy

Bay, compared

to bays south.

Analyzed

regular and

periodic

components in

fish community.

 Cod was

member of

’regular’

community

(present

throughout

year), but most

abundant

March-April. 

As annual

temperature

fluctuations

increase (in

southern bays),

fewer ’regular’

species.

29.5-29.6

ppt in

Mar-Apr.;

32.3 ppt

in

September

.

Sampled

brown mud

bottom,

sloping from

38-55m.

--- --- ---

Rose &

Leggett

1988

GOSL Onshore

movements and

inshore

abundance of

cod were

affected by

winds,

upwellings, and

downwellings.

Cod usually

located where

temps -0.5 to

8.5°C.

--- --- When

alongshore

winds

create

temperature

changes,

cod

numbers

decrease.

--- ---

Rose &

Leggett

1989

GOSL Cod were

aggregated

within narrow

temperature

range, unless

prey present,

then found in

wider range.

Without prey,

usually between

0 & 5°C

--- --- --- --- When capelin

present,

range -0.5 to

8.5°C

Helser &

Brodziak

1996

GOM, GB,

SNE, Middle

Atlantic Bight

Demonstrated

seasonal

differences in

depth and

bottom

temperature

preferences.

Spring: < 4.9 °C

Fall: weaker

association with

temperatures

--- Spring: < 72 m

Fall: weaker

association

with depth

--- --- ---

Murawski

& Finn

1988

GB Evaluated

species cooccurrences

relative to

temperature &

depth

preferences,

spatial

distribution by

species & age. 

Overlap with

silver hake,

mostly in fall.

Also see

“Juveniles”

Age 1+ Means:

winter: 4.2°C

spring: 5.4°C

summer:

8.0 °C

fall: 9.3°C

--- Age 1+

Means:

winter: 88 m

spring: 67 m

summer: 72 m

fall: 84 m

--- --- ---
NORTHEAST FISHERIES SCIENCE CENTER

Dr. Michael P. Sissenwine, Science & Research Director

CAPT John T. Moakley, Operations, Management & Information Services Staff Chief

Teri L. Frady, Research Communications Unit Chief

Jon A. Gibson, Biological Sciences Editor & Laura S. Garner, Editorial Assistant

Publishing in NOAA Technical Memorandum NMFS-NE

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National Marine Fisheries Service

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Northeast Fisheries Science Center

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166 Water St.

Woods Hole, MA 02543-1026

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STANDARD

 MAIL A