NOAA Technical Memorandum NMFS-NE-190

U. S. DEPARTMENT OF COMMERCE

National Oceanic and Atmospheric Administration

National Marine Fisheries Service

Northeast Fisheries Science Center

Woods Hole, Massachusetts

November 2004

Essential Fish Habitat Source Document:

Atlantic Cod, Gadus morhua,

Life History and Habitat Characteristics

Second Edition
167. Assessment and Characterization of Salt Marshes in the Arthur Kill (New York and New Jersey) Replanted after a Severe

Oil Spill. By David B. Packer, ed. December 2001. x + 228 p., 54 figs., 58 tables, 6 app. NTIS Access. No. PB2004-106067.

168. U.S. Atlantic and Gulf of Mexico Marine Mammal Stock Assessments – 2001. By Gordon T. Waring, Janeen M. Quintal, and

Steven L. Swartz, eds., Phillip J. Clapham, Timothy V.N. Cole, Carol P. Fairfield, Aleta Hohn, Debra L. Palka, Marjorie C. Rossman, U.S.

Fish and Wildlife Service, and Cynthia Yeung, contribs. December 2001. vii + 310 p., 43 figs., 54 tables, 2 app. NTIS Access. No. PB2002-

104350.

169. U.S. Atlantic and Gulf of Mexico Marine Mammal Stock Assessments – 2002. By Gordon T. Waring, Janeen M. Quintal, and

Carol P. Fairfield, eds., Phillip J. Clapham, Timothy V.N. Cole, Lance P. Garrison, Georgia Department of Natural Resources, Aleta A. Hohn,

Blair G. Maise, Wayne E. McFee, Debra L. Palka, Patricia E. Rosel, Marjorie C. Rossman, U.S. Fish and Wildlife Service, Frederick W. Wenzel,

and Cynthia Yeung, contribs. September 2002. vii + 318 p., 42 figs., 56 tables, 4 app. NTIS Access. No. PB2003-104167.

170. Interaction of Shelf Water with Warm-Core Rings, Focusing on the Kinematics and Statistics of Shelf Water Entrained

within Streamers. By Ronald J. Schlitz. March 2003. v + 35 p., 26 figs., 3 tables. NTIS Access. No. PB2005-100158.

171. Length-Weight Relationships for 74 Fish Species Collected during NEFSC Research Vessel Bottom Trawl Surveys. By

Susan E. Wigley, Holly M. McBride, and Nancy J. McHugh. March 2003. vi + 26 p., 1 fig., 3 tables. NTIS Access. No. PB2003-106486.

172. Variability of Temperature and Salinity in the Middle Atlantic Bight and Gulf of Maine Based on Data Collected as

Part of the MARMAP Ships of Opportunity Program, 1978-2001. By Jack W. Jossi and Robert L. Benway. March 2003. vi + 92

p., 74 figs., 5 tables. NTIS Access. No. PB2004-100835.

173. Essential Fish Habitat Source Document: Barndoor Skate, Dipturus laevis, Life History and Habitat Characteristics. By

David B. Packer, Christine A. Zetlin, and Joseph J. Vitaliano. March 2003. v + 23 p., 14 figs., 1 table. NTIS Access. No. PB2003-104257.

174. Essential Fish Habitat Source Document: Clearnose Skate, Raja eglanteria, Life History and Habitat Characteristics.

By David B. Packer, Christine A. Zetlin, and Joseph J. Vitaliano. March 2003. v + 50 p., 25 figs., 2 tables. NTIS Access. No. PB2003-

104260.

175. Essential Fish Habitat Source Document: Little Skate, Leucoraja erinacea, Life History and Habitat Characteristics. By

David B. Packer, Christine A. Zetlin, and Joseph J. Vitaliano. March 2003. v + 66 p., 27 figs., 2 tables. NTIS Access. No. PB2003-104259.

176. Essential Fish Habitat Source Document: Rosette Skate, Leucoraja garmani virginica, Life History and Habitat

Characteristics. By David B. Packer, Christine A. Zetlin, and Joseph J. Vitaliano. March 2003. v + 17 p., 11 figs., 1 table. NTIS Access.

No. PB2003-104258.

177. Essential Fish Habitat Source Document: Smooth Skate, Malacoraja senta, Life History and Habitat Characteristics. By

David B. Packer, Christine A. Zetlin, and Joseph J. Vitaliano. March 2003. v + 26 p., 15 figs., 1 table. NTIS Access. No. PB2003-104256.

178. Essential Fish Habitat Source Document: Thorny Skate, Amblyraja radiata, Life History and Habitat Characteristics. By

David B. Packer, Christine A. Zetlin, and Joseph J. Vitaliano. March 2003. v + 39 p., 18 figs., 2 tables. NTIS Access. No. PB2003-104255.

179. Essential Fish Habitat Source Document: Winter Skate, Leucoraja ocellata, Life History and Habitat Characteristics.

By David B. Packer, Christine A. Zetlin, and Joseph J. Vitaliano. March 2003. v + 57 p., 25 figs., 2 tables. NTIS Access. No. PB2003-

104254.

180. Variability in Blood Chemistry of Yellowtail Flounder, Limanda ferruginea, with Regard to Sex, Season, and Geographic

Location. By Renee Mercaldo-Allen, Margaret A. Dawson, Catherine A. Kuropat, and Diane Kapareiko. September 2003. vi + 20 p., 1

fig., 10 tables. NTIS Access. No. PB2004-107074.

181. In press.

182. U.S. Atlantic and Gulf of Mexico Marine Mammal Stock Assessments – 2003. By Gordon T. Waring, Richard M. Pace, Janeen

M. Quintal, Carol P. Fairfield, and Katherine Maze-Foley, eds., Nicole Cabana, Phillip J. Clapham, Timothy V.N. Cole, Gregory L. Fulling,

Lance P. Garrison, Aleta A. Hohn, Blair G. Maise, Wayne E. McFee, Keith D. Mullin, Debra L. Palka, Patricia E. Rosel, Marjorie C. Rossman,

Frederick W. Wenzel, and Amy L. Whitingham, contribs. May 2004. vii + 287 p., 47 figs., 58 tables, 4 app., index. NTIS Access. No.

PB2004-106431.

Recent Issues in This Series:
U. S. DEPARTMENT OF COMMERCE

Donald L. Evans, Secretary

National Oceanic and Atmospheric Administration

Vice Admiral Conrad C. Lautenbacher, Jr., USN (ret.), Administrator

National Marine Fisheries Service

William T. Hogarth, Assistant Administrator for Fisheries

Northeast Fisheries Science Center

Woods Hole, Massachusetts

November 2004

This series represents a secondary level of scientific 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-190

R. Gregory Lough

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

Essential Fish Habitat Source Document:

Atlantic Cod, Gadus morhua,

Life History and Habitat Characteristics

Second Edition
Editorial Notes on "Essential Fish Habitat Source Documents"

Issued in the NOAA Technical Memorandum NMFS-NE Series

Editorial Production

For "Essential Fish Habitat Source Documents" issued in the NOAA Technical Memorandum NMFS-NE series, staff

of the Northeast Fisheries Science Center's (NEFSC's) Ecosystems Processes Division largely assume 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 is performed by,

and all credit for such production rightfully belongs to, the staff of the Ecosystems Processes Division.

Internet Availability and Information Updating

Each original issue of an "Essential Fish Habitat Source Document" is published both as a paper copy and as a Web

posting. The Web posting, which is in "PDF" format, is available at: http://www.nefsc.noaa.gov/nefsc/habitat/efh.

Each issue is updated at least every five years. The updated edition will be published as a Web posting only; the

replaced edition(s) will be maintained in an online archive for reference purposes.

Species Names

The NMFS Northeast Region'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. 1991aa

, bb),

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

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

; McEachran and Dunn 1998g).

a

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

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

Robins, C.R. (chair); Bailey, R.M.; Bond, C.E.; Brooker, J.R.; Lachner, E.A.; Lea, R.N.; Scott, W.B. 1991b. World fishes important to

North Americans. Amer. Fish. Soc. Spec. Publ. 21; 243 p. c

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. d

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.

e

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

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

classification. Fish. Bull. (Washington, DC) 96:686-726. g

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

(Chondrichthyes: Rajidae). Copeia 1998(2):271-290.
Page iii

PREFACE TO SECOND EDITION 

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 NOAA Fisheries to assist the 

regional fishery management councils in the 

implementation of EFH in their respective fishery 

management plans. 

NOAA Fisheries 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 a series of EFH species reports (plus one 

consolidated methods report). The EFH species reports 

are a survey of the important literature as well as 

original analyses of fishery-independent data sets from 

NOAA Fisheries and several coastal states. The species 

reports are also the source for the current EFH 

designations by the New England and Mid-Atlantic 

Fishery Management Councils, and understandably are 

referred to as the “EFH source documents.” 

NOAA Fisheries 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. 

The initial series of EFH species source documents 

were published in 1999 in the NOAA Technical 

Memorandum NMFS-NE series. Updating and review 

of the EFH components of the councils’ Fishery 

Management Plans is required at least every 5 years by 

the NOAA Fisheries Guidelines for meeting the 

Sustainable Fisheries Act/EFH Final Rule. The second 

editions of these species source documents were written 

to provide the updated information needed to meet 

these requirements. The second editions provide new 

information on life history, geographic distribution, and 

habitat requirements via recent literature, research, and 

fishery surveys, and incorporate updated and revised 

maps and graphs. This second edition of the Atlantic 

cod EFH source document is based on the original by 

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

and Wallace W. Morse, with a foreword by Jeffrey N. 

Cross (Fahay et al. 1999). 

Identifying and describing EFH are the first steps 

in the process of protecting, conserving, and enhancing 

essential habitats of the managed species. Ultimately, 

NOAA Fisheries, 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.
Page iv 
Page v

Contents

INTRODUCTION................................................................................................................................................................1

LIFE HISTORY ...................................................................................................................................................................1

GEOGRAPHICAL DISTRIBUTION ..................................................................................................................................4

HABITAT CHARACTERISTICS .......................................................................................................................................6

RESEARCH NEEDS ...........................................................................................................................................................8

REFERENCES CITED ........................................................................................................................................................9

ADDITIONAL REFERENCES .........................................................................................................................................15

Tables

Table 1. Age and length at 50% maturity for two stocks of Atlantic cod, Gadus morhua.............................................20

Table 2. Food habits of Atlantic cod..............................................................................................................................21

Table 3. Minor diet items of Atlantic cod. .....................................................................................................................23

Table 4. Distribution of life history stages of Atlantic cod in representative estuaries between Maine and 

Chesapeake Bay. ..............................................................................................................................................25

Table 5. Summary of life history and habitat parameters for Atlantic cod. ...................................................................26

Figures

Figure 1. The Atlantic cod, Gadus morhua (from Goode 1884). ....................................................................................27

Figure 2. Distribution of Atlantic cod stocks in the North Atlantic showing principle spawning sites...........................28

Figure 3. Percent by weight of the major prey items in the diet of three size categories of Atlantic cod........................29

Figure 4. Overall distribution and abundance of Atlantic cod in the northwest Atlantic Ocean. ....................................30

Figure 5. Distributions and abundances of Atlantic cod eggs collected during NEFSC MARMAP ichthyoplankton 

surveys. ............................................................................................................................................................31

Figure 6. Distributions and abundances of Atlantic cod eggs collected during GLOBEC Georges Bank 

ichthyoplankton surveys. .................................................................................................................................35

Figure 7. Distributions and abundances of Atlantic cod larvae collected during NEFSC MARMAP ichthyoplankton 

surveys. ............................................................................................................................................................39

Figure 8. Distributions and abundances of Atlantic cod larvae collected during GLOBEC Georges Bank 

ichthyoplankton surveys. .................................................................................................................................43

Figure 9. Topographic map of Georges Bank showing gravel distribution, from Valentine and Lough (1991). ...............48

Figure 10. Distribution and abundance of recently-settled juvenile cod on eastern Georges Bank in relation to 

sediments..........................................................................................................................................................49

Figure 11. Seasonal distributions and abundances of juvenile Atlantic cod collected during NEFSC bottom trawl 

surveys. ............................................................................................................................................................52

Figure 12. Distribution and abundance of Atlantic cod along the coasts of Maine and New Hampshire. ........................56

Figure 13. Length frequency plots for Atlantic cod caught along the Maine and New Hampshire coasts, by 

season/year.......................................................................................................................................................57

Figure 14. Regional catch-per-unit-effort of Atlantic cod caught along the Maine and New Hampshire coasts, by 

season/year.......................................................................................................................................................58

Figure 15. Seasonal distributions and abundances of juvenile Atlantic cod in Massachusetts coastal waters. .................59

Figure 16. Seasonal distributions and abundances of adult Atlantic cod collected during NEFSC bottom trawl surveys.61

Figure 17. Seasonal distributions and abundances of adult Atlantic cod in Massachusetts coastal waters. ......................65

Figure 18. Monthly distributions of Atlantic cod eggs collected during NEFSC MARMAP ichthyoplankton surveys 

relative to water column temperature and bottom depth..................................................................................67

Figure 19. Distributions of Atlantic cod eggs collected during GLOBEC ichthyoplankton surveys relative to water 

column temperature..........................................................................................................................................68
Page vi 

Figure 20. Distributions of Atlantic cod eggs collected during GLOBEC ichthyoplankton surveys relative to bottom 

depth.................................................................................................................................................................69

Figure 21. Monthly distributions of Atlantic cod larvae collected during NEFSC MARMAP ichthyoplankton surveys 

relative to water column temperature and bottom depth. .................................................................................70

Figure 22. Distributions of Atlantic cod larvae collected during GLOBEC ichthyoplankton surveys relative to water 

column temperature..........................................................................................................................................71

Figure 23. Distributions of Atlantic cod larvae collected during GLOBEC ichthyoplankton surveys relative to bottom 

depth.................................................................................................................................................................72

Figure 24. Distributions of juvenile Atlantic cod and trawls from NEFSC bottom trawl surveys relative to bottom 

water temperature, depth, and salinity..............................................................................................................73

Figure 25. Distributions of juvenile Atlantic cod and trawls in Massachusetts coastal waters relative to bottom water 

temperature and depth. .....................................................................................................................................75

Figure 26. Distributions of adult Atlantic cod and trawls from NEFSC bottom trawl surveys relative to bottom water 

temperature, depth, and salinity. ......................................................................................................................77

Figure 27. Distributions of adult Atlantic cod and trawls in Massachusetts coastal waters relative to bottom water 

temperature and depth. .....................................................................................................................................79

Appendices

Appendix 1. Table of habitat parameters for Atlantic cod, Gadus morhua. .......................................................................81
Page 1

INTRODUCTION 

The Atlantic cod (Figure 1) is a demersal gadoid 

distributed in the northwest Atlantic Ocean from 

Greenland to Cape Hatteras, North Carolina (Figure 2). 

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. The Georges Bank cod stock is 

the most southerly cod stock in the world (Wise 1958). 

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 areas. Cod 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 10°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. Fahay (NOAA 

Fisheries, NEFSC, James J. Howard Marine Sciences 

Laboratory, Highlands, NJ, pers. comm.) 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. 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 7°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, when 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); see also 

Amendment 13, Vol. II of the Multispecies FMP 

(NEFMC 2003). 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. This document examines dietary 

requirements and expands somewhat on spawning 

patterns, distributions and habitat characteristics of four 

life history stages (eggs, larvae, juveniles, adults). 

This document is mostly concerned with the 

northwest Atlantic stocks. New research applications 

have involved the development of circulation models to 

simulate the potential transport pathways of eggs and 

larvae from spawning sites under realistic conditions, 

and the use of genetic markers to identify stocks and 

potential intermixing. Also, there is a considerable body 

of literature on hypotheses for the collapse of the 

northern Atlantic cod off Newfoundland by the early 

1990’s. While not immediately relevant to the Georges 

Bank/Gulf of Maine stocks, they explore the interplay 

of over-fishing and environmental change, the relative 

contributions of inshore and offshore stocks, and the 

causes and effects of the contraction of spawning stock. 

Since December 1994 there has been a year-round 

closure to commercial fishing of a large part of Georges 

Bank to rebuild the spawning stock. Fortunately, a 

major field program (U.S. GLOBEC) conducted 

monthly (January-July) ichthyoplankton surveys on 

Georges Bank from 1995 to 1999. The resulting cod 

egg and larval data are presented in the same format so 

that a comparison can be made with the prior Northeast 

Fisheries Science Center (NEFSC) Marine Resources 

Monitoring, Assessment and Prediction (MARMAP) 

ichthyoplankton survey data from 1977-1987. 

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 typical spring conditions (Lough et al. 1989). 
Page 2 

Temperature, more than season, also exerts the most 

influence on egg and hatchling sizes (Miller et al.

1995). 

LARVAE 

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 at depths 

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

and Manning 2001). Larvae occur from near-surface to 

depths of 75 m, and larvae move deeper with growth 

(Hardy 1978; Lough and Potter 1993). 

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. 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). By the end of their first year, juvenile cod reach 

a mean length of 26 cm (Penttila and Gifford 1976). 

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 and 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 and 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). As 

of 1994, in U.S. waters, sexual maturity was reached at 

ages between 1.7 and 2.3 years (median) and lengths 

between 32 and 41 cm (average) (O'Brien et al. 1993). 

Presently (2000-2002), age and length at maturity have 

increased slightly for both Georges Bank and Gulf of 

Maine stocks (O’Brien 1999). Age and length at 50% 

maturity for Georges Bank and Gulf of Maine stocks 

are shown in Table 1. Gulf of Maine cod attain sexual 

maturity at a later age than Georges Bank cod which is 

related to differences in growth rates between the two 

stocks. The recently developed maturation reactionnorm analyses (Barot et al. 2004a, b) also indicated a 

shift towards lower ages and sizes of maturation for 

Georges Bank and Gulf of Maine cod stocks. The trend 

for Georges Bank cod to mature earlier than the Gulf of 

Maine cod was thought to be due mostly to 

environmental differences. Georges Bank is a highly 

productive and warmer shallow bank compared to the 

deeper Gulf of Maine. The reaction-norm approach 

supports the hypothesis that the Georges Bank and Gulf 

of Maine cod stocks have changed genetically in 

response to fishing. 

On Georges Bank, an analysis of the MARMAP 

ichthyoplankton data set indicates that 60% of 

spawning occurs between February 23 and April 6, 

based on the abundance of Stage III eggs, backcalculated to spawning date. Ninety percent occurs 

between mid-November and mid-May, with a median 

date of mid-March (Colton et al. 1979; Page et al.

1998). 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. Historically, cod have spawned on both eastern 

and western Georges Bank. During the MARMAP 

period (1978-1987), spawning could either be split 

between eastern and western Georges Bank, or occur 
Page 3

predominantly on one side or the other (Lough et al. 

2002). Composite egg distributions indicate that the 

most intense spawning activity occurs on the Northeast 

Peak of Georges Bank (Page et al. 1998). Data from the 

more recent U.S. GLOBEC Georges Bank surveys 

(1995-1999) also indicated peak spawning occurs 

during the February-March period and mostly on the 

Northeast Peak (Mountain et al. 2003). 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). Within the Gulf of Maine, 

cod generally spawn throughout the winter and early 

spring in most locations, but the period of peak 

spawning varies depending on location (Schroeder 

1930). In general, spawning occurs later in the year in 

the more northerly regions. Within Massachusetts Bay, 

Fish (1928) reported peak spawning activity during 

January and February. Bigelow and Welsh (1924) noted 

that north of Cape Ann, Massachusetts, most spawning 

occurred between February and April and further north, 

between Cape Elizabeth and Mt. Desert Island, Maine, 

the peak spawning period was between March and 

May. It has also been noted that cod spawning occurs 

mostly at night and may be crepuscular (KleinMacPhee 2002). 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 20°C (Elliott et al.

1979). 

Hanke et al. (2000) recently summarized all the 

available ichthyoplankton survey data from the Scotian 

Shelf, eastern Gulf of Maine, and the Bay of Fundy 

region, from 1975-1997, and provided evidence for a 

spring and fall spawning, but with regional differences. 

In March-April spawning was observed off 

southwestern Nova Scotia including Browns Bank, 

Georges Bank, and the Emerald/Western/Sable Island 

Bank area. Spawning occurs again in November and 

December on Georges Bank and the entire Nova Scotia 

coast, west of Grand Manan and on Western/Sable 

Island/ Banquereau Bank. 

Ames (2004) characterized the Gulf of Maine 

historical Atlantic cod fishing and spawning grounds 

during the 1920’s when stocks were high, compared 

with our present day knowledge. Four subpopulations 

were identified: Bay of Fundy, Downeast, Midcoast, 

and Western, each with 3-6 spawning components. 

Inshore cod feeding grounds were generally rocky 

bottoms along the 100 m isobath. Spawning occurred 

in channels and basins bordering the rocky, shallow, 

historic fishing grounds. Compared with recent survey 

data of cod eggs (Berrien and Sibunka 1999), it appears 

that more than half of the historic spawning grounds are 

inactive and show no evidence of spawning. Ames 

cites three factors that contributed to the collapse of the 

spawning components: (1) directed fishing with otter 

trawls and gillnets on coastal spawning aggregations, 

(2) pollution of coastal nursery grounds, and (3) 

destruction of anadromous forage stock by the 

construction of dams. 

FOOD HABITS 

The Atlantic cod has a varied diet. Reported food 

items vary by life history stage and study area (Table 

2). The most frequently observed food items from the 

1973-2001 NEFSC food habits database [see Link and 

Almeida (2000) for details on methodology] for cod 

50 cm were crustaceans; cod  51 cm ate mostly fishes 

(Table 3;Figure 3). A comprehensive analysis and 

summary of cod trophic patterns on the northeastern 

U.S. continental shelf has been made by Link and 

Garrison (2002) based on a 25-year time series from the 

NEFSC food habits database. Early juveniles consumed 

more pelagic than benthic invertebrates, medium cod 

consumed benthic invertebrates and fish, and larger cod 

consumed larger amounts of fish. Cannibalism 

increased with size. Diets shifted significantly over 3 

decades concurrent with shifts in forage species. Cod 

are opportunistic feeders, preferring sand lance, Cancer

crabs, and herring. 

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.

1997). 

PREDATION AND MORTALITY 

Yolk sac larvae are vulnerable to zooplankton 

predators including Aurelia, Thysanoessa, and 

Euchaeta (Bailey 1984). Planktivorous fish can be 

important predators of larval fish, especially Atlantic 

herring and Atlantic mackerel as they migrate 

northward in the spring and overlap with patches of 

larvae on the southern flank of Georges Bank (Garrison 

et al. 2000). Juvenile cod are preyed upon by many 

piscivorous fish, such as dogfish, silver hake, larger 

cod, and sculpin (Edwards and Bowman 1979). 
Page 4 

Because of their large size, adults 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. 

MIGRATION 

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 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 20°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 stock, and the Georges Bank 

and southward stock (Mayo 1995). The inshore Gulf of 

Maine stock appears to be relatively distinct from the 

offshore cod stocks on the banks of the Scotian Shelf 

and Georges Bank based on tagging studies (McKenzie 

1956; Wise 1963; Hunt et al. 1999) and parasitic 

copepods (Sherman and Wise 1961). Although there is 

some mixing of the Gulf of Maine and Georges Bank 

stocks, their life history parameters, growth, and 

maturity, are basically different (Pentilla and Gifford 

1976, Serchuck et al. 1994, O’Brien 1999). Part of the 

difference in growth between stocks may be attributed 

to genetic variations (Imsland and Jónsdóttir 2003). 

General conclusions by Imsland and Jónsdóttir (2003) 

from basin-scale genetic studies suggest that distinct 

subpopulations occur between most inshore and 

offshore areas, and among offshore areas themselves, 

and that the likelihood of inshore spawning stock 

contributing to offshore recovery is low (Beacham et al. 

2002). Recent genetic studies by Lage et al. (2004) 

suggest that Nantucket Shoals cod are distinct from 

Georges Bank cod. Whereas Lage et al. (2004) did not 

find any significant genetic differences between 

Georges Bank and Browns Bank, Ruzzante et al. (1998) 

did. The degree of stock separation may be related to 

the isolation of spawning locations and times, and 

different circulation patterns. On Georges Bank, a 

clockwise gyre circulation pattern tends to retain and 

isolate the eggs and larvae spawned there (Lough and 

Bolz 1989; Werner et al. 1993; Lough and Manning 

2001). Model simulations by Page et al. (1999) suggest 

that cod spawning occurs in areas and times of the year 

that have the longest residence times (> 35 days). 

However, advective losses can occur sporadically off 

the northeast peak and southern flank of Georges Bank 

(Lough et al. 1994). While significant numbers of 

larvae can be advected across the Great South Channel 

to Nantucket shoals, the southwest residual flow in the 

Nantucket Shoals area would tend to keep the early life 

stages from returning to Georges Bank. However, 

based on biophysical modeling of a related species, 

haddock, by Brickman (2003), there is a high 

probability of significant crossover events from Browns 

Bank to Georges Bank by two pathways, directly across 

the Northeast Channel, and from the Gulf of Maine. 

While crossover events are episodic in nature (Smith et 

al. 2003), the study indicates that Browns Bank can be 

a significant source of larvae for Georges Bank cod 

stocks, and similarly, Western Bank can be an upstream 

source for larvae found on Browns Bank. 

GEOGRAPHICAL DISTRIBUTION 

Atlantic cod in the northwest Atlantic are 

distributed from Cape Chidley, Labrador to Cape 

Henry, VA (Figure 4). 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 4. 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 indicators 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, 
Page 5

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 5) 

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 5). Monthly densities peaked 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. 

Model simulations for the MARMAP years (Lough 

et al. 2002) show how variable spawning within a bank 

gyre system can have different consequences for 

transport and survival of eggs and larvae. Particles 

released from the Northeast Peak usually had higher 

retention than releases from western Georges Bank; 

however, the western Georges Bank releases could 

contribute significantly to retention, especially during 

the winter period when there is wind loss of particles 

from the Northeast Peak. 

O’Brien et al. (2003) found a significant 

correlation between egg abundance and spawning stock 

biomass for Georges Bank cod. While there was 

considerable variability in egg survival that was 

unrelated to recruitment, there was a strong positive 

correlation between the abundance of small and large 

larvae and 0-group juveniles and that of recruits at age 

1 (Lough et al. 2002). Variability in egg survival could 

be explained partially by the age diversity of repeat 

spawners, bottom temperature, and the spatial 

distribution of the eggs (O’Brien et al. 2003). The 

proportion of egg mortality that can be attributed to egg 

quality, advective loss, or predation has not been 

quantified. 

During the GLOBEC years, 1995-1999, when 

sampling was only conducted from January through 

July on Georges Bank, the composite egg plots (Figure 

6) show eggs to be broadly distributed across Georges 

Bank with higher concentrations on the eastern part, 

peaking in February and March. However, the station 

abundance estimates were about an order of magnitude 

lower than during the MARMAP period. 

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 7), 

although sampling was light during March in the Gulf 

of Maine. Few larvae were collected between August 

and October. 

During the GLOBEC years, 1995-1999, when 

sampling was only conducted from January through 

July on Georges Bank, the composite larval plots 

(Figure 8) show larvae to be wide spread across the 

Bank from January through May. Highest station 

abundance occurred along the deeper flank waters 

during March and April, but at about an order of 

magnitude lower than observed during the MARMAP 

period. 

Prior to settling to the bottom in early summer, 

pelagic juveniles (20-50 mm) are broadly distributed 

over the entire Georges Bank (Lough et al. 1989). 

JUVENILES 

By July, juvenile pelagic fish on Georges Bank 

have reached a length of 4-6 cm and become more 

associated with the bottom and begin the changeover to 

a demersal feeding life style. Submersible studies on 

eastern Georges Bank (Lough et al. 1989) have 

observed from data collected during five years (1984-

1987, 1989) that the recently-settled juveniles are 

widely dispersed over the Bank and are present on a 

range of sediment types from sand to gravelly sand to 

gravel pavement (Figure 9). However, by late July and 

August, the juveniles are present predominantly on the 

gravel pavement habitat on the northeastern part of the 

Bank and are absent from the sandy bottoms (Figure 

10). The gravel pavement extends along the northern 

edge and Northeast Peak for 150 km and covers an area 

of more than 3000 km2

. The gravel habitat appears to 

favor the survival of recently-settled juveniles through 

predator avoidance and/or increased food availability 

associated with the frontal system. Several studies have 

stressed the importance of cobble substrates over finer 

grained bottoms after settlement (e.g., Bigelow and 

Schroeder 1953; Colton 1978; Klein-MacPhee 2002). 

By day, the young cod remain on the bottom, but at 

night they rise several meters into the water column and 

drift in the tidal current while feeding. During late 

summer, as the juveniles continue to grow, they are 

carried to the east and southeast in the residual bottom 

current, and by fall they are more widely dispersed and 

are no longer confined to the gravel pavement habitat. 

When predators are present, juvenile cod take refuge in 

a wide variety of complex substrates and vegetation and 

their diel activity patterns reported in the literature vary 

considerably (Keats et al. 1987; Keats 1990; Keats and 

Steele 1992; Gotceitas and Brown 1993; Gotceitas et al. 

1994, 1995, 1997; Gregory and Anderson 1997a, b; 

Grant and Brown 1998a, b; Lindholm et al. 1999; 

Laurel et al. 2003, 2004). Nearshore nurseries 

(including grass beds) may be significantly more 

important to survival of juveniles than offshore habitats 
Page 6 

(for examples, see studies cited in Appendix 1: 

Juveniles). 

The distribution of older juveniles (34 cm TL) 

from the NEFSC bottom trawl surveys closely matches 

that of spawning activity, with centers of abundance on 

Georges Bank and the western part of the Gulf of 

Maine [Figure 11; note that winter and summer 

distributions are presented as presence data only, 

precluding a discussion of abundances, for details see 

Reid et al. (1999). Also see the distribution of immature 

Atlantic cod, < 37 cm, resulting from NEFSC bottom 

trawl survey cruises, 1968-1986 in Wigley and Gabriel 

(1991)]. In winter they are concentrated near 

Massachusetts Bay, on the Northeast Peak of Georges 

Bank, and in southern New England near the 50 m 

isobath. During spring trawl surveys, densities are 

highest in the area north and south of Cape Ann, 

Massachusetts. During summer, juveniles are mostly 

found along the western shore of the Gulf of Maine, but 

also occur on the Northeast Peak of Georges Bank, on 

Browns Bank, and along the 50 m isobath south of 

Cape Cod. Large numbers of juveniles are concentrated 

around Cape Ann/Massachusetts Bay and 

south/southeast of Cape Cod in the fall. 

The distributions and abundances of Atlantic cod 

along the coasts of Maine and New Hampshire, based 

on spring and fall 2000-2004 Maine-New Hampshire 

inshore groundfish surveys (Sherman et al. 2005), are 

shown in Figure 12. Cod were patchy in occurrence, 

and the majority were juveniles (Figure 13). Cod 

abundance was low compared to some of the other 

species in the survey, with a slight increase in numbers 

in the spring of 2004 (Figure 14), although Sherman et 

al. (2005) state that no real trends can be seen in overall 

abundance. 

The spring and fall 1978-2003 Massachusetts 

inshore trawl surveys [Figure 15; see Reid et al. (1999) 

for details] show that in the spring, very high numbers 

are found in Massachusetts Bay, with large numbers of 

juveniles also found north of Cape Ann, on the outside 

of Cape Cod, and near Martha’s Vineyard. High 

concentrations are also found in Massachusetts Bay and 

Nantucket Sound. In the fall, large numbers occur 

around Cape Ann and throughout Cape Cod Bay, but 

they are absent in Nantucket Sound. 

Very few juvenile cod were collected during 1990-

1996 trawl surveys of Narragansett Bay undertaken by 

the Rhode Island Division of Fish and Wildlife. See 

below for cod occurrences in Long Island Sound and 

Hudson-Raritan Estuary/Sandy Hook Bay. 

ADULTS 

NEFSC bottom trawl surveys (Figure 16; again, 

winter and summer distributions are presented as 

presence data only, precluding a discussion of 

abundances) show that during winter adults are 

scattered over Georges Bank, southern New England, 

and the central/northern Mid-Atlantic Bight, as well as 

in the western part of the Gulf of Maine. In spring, 

densities are highest in the western part of the Gulf of 

Maine (Massachusetts Bay and Cape Ann), south of 

Cape Cod, and especially on the Northeast Peak of 

Georges Bank, with additional collections made 

throughout southern New England and the 

central/northern part of the nearshore Middle Atlantic 

Bight. During summer, adult cod are concentrated 

along the coastal Gulf of Maine and south/southeast of 

Cape Cod and the Northeast Peak of Georges Bank, as 

well as being scattered throughout the Gulf and on 

Browns Banks; they are mostly absent from southern 

New England and south. In the fall, the highest 

densities are again found in the western part of the Gulf 

of Maine (Massachusetts Bay and Cape Ann), south of 

Cape Cod near the Great South Channel, and on the 

Northeast Peak/northern edge of Georges Bank; adults 

are generally absent south of southern New England. 

The distributions of the adults in both the spring 

and fall 1978-2003 Massachusetts inshore trawl surveys 

are shown in Figure 17. More adults are caught in the 

spring, where they occur abundantly around Cape Ann, 

in Massachusetts Bay, and around the tip and eastern 

side of Cape Cod. Most of the adults caught during the 

fall are restricted to south of Cape Ann and the tip of 

Cape Cod. 

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 

9-10°C. A NEFSC trawl survey of the Hudson-Raritan 

Estuary/Sandy Hook Bay during 1992-1997 collected 

only two cod, both during winter. 

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 some of 

those data are presented in Table 5. These tables 

include data from U.S. (and certain non-U.S.) western 

Atlantic stocks, but exclude 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, distributions of young stages of Atlantic 

cod tend to be restricted to the vicinity of major 
Page 7

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). 

Regime shifts, or rapid, large-scale changes in fish 

populations and other communities in marine 

ecosystems, are driven by both environmental forcing 

and fishing (Rothschild and Shannon 2004). 

Latitudinal shifts for groundfish in the Gulf of Maine 

have been observed in response to temperature changes 

(Mountain and Murawski 1992). Growth of cod 

depends on temperature, and mean bottom temperature 

accounts for most of the observed differences in growth 

rates in Atlantic cod stocks (Brander 1995). 

Physiologically, growth performance of cod is optimal 

near 10°C (Pörtner et al. 2001), so that global warming 

would lead to a northward shift in populations. 

Temperature also affects maturation and spawning 

times (Hutchings and Myers 1994). Changes in 

spawning times and locations have different 

consequences for recruitment. Temperature and salinity 

records for the Gulf of Maine/Scotian Shelf region 

show alternating cold and warm periods which can be 

broadly related to the NAO index (Werner et al. 1999). 

The cooling of the shelf waters in the 1960s was largely 

due to the increased flow of the Labrador Slope water 

penetrating into the shelf. From the 1970s to the mid1990s, there has been a general, but more variable, 

warming on the shelf. Scotian Shelf cold and warm 

anomalies generally precede those in Georges Bank by 

2-3 years. More recently in 1997-1998, cold and fresh 

Labrador Slope water has been observed to again be 

penetrating the Scotian Shelf and Gulf of Maine. All 

cod stocks in this region declined by the late 1960s with 

the intensive fishery effort, and in the 1970s all stocks 

showed some improved recruitment, but declined to 

very low levels in the early 1990s. Failure of these cod 

stocks to recover despite restricted fishing since the 

mid-1990s has been termed “the cod recruitment 

dilemma” and Swain and Sinclair (2000) have 

implicated the increased abundance of herring and 

mackerel in the southern Gulf of St. Lawrence to have 

had a negative effect on cod recruitment by preying on 

and competing with the young stages. Choi et al. 

(2004) continues on the theme of the alternation of the 

pelagic and demersal species but shows how interacting 

factors may have led to the restructuring of the Scotian 

Shelf ecosystem over the past four decades. While 

ground fish have historically dominated the Scotian 

Shelf, their continual removal has allowed the pelagic 

biomass to increase since the mid-1980s at the same 

time that environmental conditions began to favor the 

pelagics (increased water-column stratification) and 

limit the demersals (cold bottom water). The present 

“pelagic regime” appears to have decoupled the 

benthic-pelagic systems where less energy is passing 

from primary production to benthic prey for the 

demersals. 

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; see also 

Figure 18). 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 5). 

Data from the NEFSC MARMAP ichthyoplankton 

surveys and the GLOBEC Georges Bank survey were 

used to determine the relationships between cod egg 

abundances and bottom depth or water column 

temperature. During the MARMAP surveys from 

January to July, eggs were mostly collected at 

temperatures of 4-8°C (Figure 18). From August thru 

November, they were found at higher temperatures of 

approximately 9-14°C, while in December they were 

caught at temperature range of 6-12°C. Most eggs were 

found over a depth range of 30-110 m, occurring in the 

shallower end of the range from October thru January 

(Figure 18). During the GLOBEC Georges Bank survey 

from January to July, the majority of eggs were found 

in a narrow temperature range of about 4-8°C (Figure 

19). Their depth range on Georges Bank during that 

same period was centered around 70-90 m (Figure 20). 

A lab study by Laurence and Rogers (1976) found 

that egg mortality was independent of temperature, but 

that mortality increased at lower salinities within the 

range of 26-36 ppt. 

LARVAE AND PELAGIC JUVENILES 

Several studies have found increased recruitment 

success when dispersion of larvae from spawning areas 

by currents is reduced (Cong et al. 1996). Although 

larvae have been collected from a wide range of 

temperatures, most are found in temperatures < 8°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 -1.8°C but if in 

direct contact with ice they froze at -1.36°C (Valerio et 
Page 8 

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, Lough and 

Potter 1993). 

During the MARMAP surveys (Figure 21), larvae 

were mostly found in a temperature range of about 4-

5°C from February to March, at temperatures of 5-6°C 

in April, 6-8°C in May, and 7-9°C in June, and 8-9°C in 

July. Thereafter they were found in increasingly 

warmer temperatures of about 9-11°C thru November; 

in December they were caught mostly at temperatures 

of 8-11°C and in January they were found in lower 

temperatures of about 4-8°C. The majority of larvae 

were found over a depth range of 30-70 m throughout 

the MARMAP survey period (Figure 21). During the 

GLOBEC Georges Bank survey most larvae were 

caught at temperatures of 4-6°C from February to April 

and 6-7°C from May to June (Figure 22). Most were 

found at depths of 50-70 m in February, 70-90 m in 

March and April, 70 m in May, and 210 m in June 

(Figure 23). 

JUVENILES 

The substrate preferences of juvenile cod have 

already been discussed under Geographic Distribution. 

The spring and fall distributions of juvenile 

Atlantic cod relative to bottom water temperature, 

depth, and salinity based on NEFSC bottom trawl 

surveys from the Gulf of Maine to Cape Hatteras are 

shown in Figure 24. In spring, they were found in 

waters between 2-10oC, with the majority at 4-5oC. 

During that season they were found over a depth range 

of 11-300 m, with most spread between about 21-120 

m. Juveniles were found at salinities between 31-35 

ppt, with almost all of them found between 32-33 ppt. 

During autumn, juveniles were found over a 

temperature range of 3-17°C, with most spread between 

about 8-10°C. During this time, they were found over 

depths ranging from 11-400 m; the majority were 

spread over depths roughly from 31-120 m. They were 

found at salinities ranging from about 31-35 ppt, with 

the majority between 32-33 ppt. 

The spring and autumn distributions of juvenile 

Atlantic cod in Massachusetts coastal waters relative to 

bottom water temperature and depth based on 

Massachusetts inshore trawl surveys are shown in 

Figure 25. During the spring, juveniles were found in 

waters ranging from 2-16°C with the majority spread 

between about 5-12oC. Their depth range was from 6-

85 m, with the majority between about 6-25 m. In the 

autumn they were found in temperatures ranging from 

5-18oC, with most spread between 6-10oC. Juveniles 

were found over a depth range of 6-85 m, with the 

majority found between about 16-65 m. 

ADULTS 

Adult cod are typically found on or near the 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 (Scott 1982b). They 

engage in diel vertical migrations, where they make 

forays off the bottom and into the water column at night 

(several studies; e.g., Beamish 1966). Cod can occur in 

temperatures from near freezing to 20°C, and are 

usually found in temperatures < 10°C, except during 

fall when they can occur in warmer temperatures. 

Larger fish are generally found in colder waters (Cohen 

et al. 1990). 

The spring and fall distributions of adult Atlantic 

cod relative to bottom water temperature, depth, and 

salinity based on NEFSC bottom trawl surveys from the 

Gulf of Maine to Cape Hatteras are shown in Figure 26. 

In spring, they were found in waters between 2-12oC, 

with the majority at 4-6oC. They were found over a 

depth range of 1-300 m. Adults were found at salinities 

between 30-35 ppt, with > 50% at 33 ppt. During 

autumn, adults were found over a temperature range of 

3-17°C, with the majority spread between 6-11°C. 

During this season they were found over depths ranging 

from 11-400 m. They were found at salinities ranging 

from about 31-35 ppt, with the majority between 32-34 

ppt. 

The spring and autumn distributions of adult 

Atlantic cod in Massachusetts coastal waters relative to 

bottom water temperature and depth based on 

Massachusetts inshore trawl surveys are shown in 

Figure 27. During the spring, adults were found in 

waters ranging from 1-14°C, with the majority spread 

between 4-8oC. Their depth range was from 6-85 m, 

with the majority < 56 m. In the autumn they were 

found in temperatures ranging from 4-13oC, with most 

spread between 7-10oC and at 12oC. Adults were found 

over a depth range of 26-85 m, with peaks between 51-

65 m. 

RESEARCH NEEDS 

Essential fish habitat is defined as those waters and 

substrate necessary to fish for spawning, breeding, 

feeding or growth to maturity. 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 
Page 9

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.

1997) 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). However, 

recent studies have documented regime shifts on 

decadal time scales over large areas of the continental 

shelf as a result of complex interaction of 

environmental factors and biological processes. 

Ecosystem based studies such as Choi et al. (2004), 

with continued monitoring of the environment, are 

needed to better understand the long-term changes in 

stocks. 

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Page 18

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Page 19

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Page 20

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

Data for 1994 are from Mayo (1995). Similar results were obtained in a Canadian study for zones near U.S. waters 

(Trippel et al. 1997). Recent data are from L. O'Brien, (NOAA Fisheries, NEFSC, Woods Hole Laboratory, Woods 

Hole, MA, pers.comm.), pooled for the period 2000-2002. 

1994 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 

2000-2002 Georges Bank Georges Bank Gulf of Maine Gulf of Maine 

 Males Females Males Females 

Age at 50% 

Maturity 

2.1 years 2.1years 2.9 years 2.6 years 

Length at 50% 

Maturity 

42.2 cm 43.3cm 44.0 cm 43.3 cm 
Page 21

Table 2. Food habits of Atlantic cod. 

Source Study Area and Food Habits 

Bainbridge and 

McKay (1968) 

LARVAE 

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

Calanus and Temora. Also euphausiids. 

Kane (1984) Georges Bank: Larvae eat nauplii and copepodites of Pseudocalanus mostly; some 

Calanus eggs and nauplii.; some Oithona copepodites. 

Marak (1960) Georges Bank, Gulf of Maine: Larvae eat most abundant prey. 4-18 mm eat mostly 

larval copepods; 18+ mm eat mostly adult copepods. 

McLaren and 

Avendano (1995) 

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

Pseudocalanus. 

McLaren et al. 

(1997) 

Scotian Shelf (Western Bank): Early larvae feed predominantly on nauplii and 

copepodites of Pseudocalanus (mostly P. newmani); fewer Centropages, Oithona, and 

Paracalanus. 

Lough and 

Mountain (1996) 

Georges Bank: Primarily nauplii and copepodites of Pseudocalanus and Oithona; 

some Calanus nauplii. 

Lough et al. (1996) Georges Bank: Early larvae prey on nauplii and copepodites of Pseudocalanus. 

Sherman et al. 

(1981) 

Georges Bank: Larvae eat nauplii and copepodites of Pseudocalanus mostly; some 

Calanus nauplii. 

Bowman (1975) 

JUVENILES AND ADULTS 

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

crabs. 

Bigelow and 

Schroeder (1953); 

Klein-MacPhee 

2002 

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

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 are juvenile redfish (Sebastes sp.). Rate of 

cannibalism very low. 

Hacunda (1981) Central Maine coast: Crustaceans most important, especially amphipods, Unciola, 

Leptocheirus, and decapods Crangon, Cancer. 

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. 

Keats and Steele 

(1992) 

Newfoundland (eastern): Juveniles (Age 0 and 1) feed mostly during daylight and 

most prey was planktonic. 

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. 

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). 

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. 
Page 22

Table 2 Cont’d. 

Source Study Area and Food Habits 

Lilly and Parsons 

(1991) 

JUVENILES AND ADULTS (cont’d.) 

Northeast Newfoundland: Northern shrimp (Pandalus borealis) identified as important 

food item of cod throughout shrimp's range. 

Link and Garrison 

(2002) 

Northeast U.S. Continental Shelf: Summary of 25 year time series of food habits data. 

Cod have omnivorous diet, prefer sand lance, Cancer crabs, and herring. 

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. 

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 

American plaice. 

Perry and Neilson 

(1988) 

Georges Bank: Late pelagic juveniles. Calanoid copepods numerically most abundant, 

mysiid Neomysis americana biomass most important; harpacticoid Tisbe, some 

Pagurus larvae. 

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. 

Sameoto et al. 

(1994) 

Scotian Shelf: Late pelagic juveniles. C. finmarchicus copepodite IV-V, 

Pseudocalanus female, and Temora male preferred prey. (Emerald and Lahave Basin). 

Small euphausiids (Meganytiphanes norvegica) significant part of diet at night, 20 m. 

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

Meganyctiphones, Clupea, Pandalus.

Whitehead et al. 

(1986) 

Northeastern Atlantic: Diet variable: fishes - herring, capelin, haddock, codling; 

invertebrates - euphausiids, hyperiids, amphipods, polychaetes. 

Witman and 

Sebens (1992) 

Gulf of Maine: Cod fed heavily on tethered brittle stars in this experiment. 
Page 23

Table 3. Minor diet items of Atlantic cod. 

Based on the NEFSC Food Habits database from 1973-1990. Listed below are items occurring at 1-5 percent frequency. 

See Figure 3 for items occurring more frequently. Methods for sampling, processing, and analysis of samples differed 

between the time periods [see Reid et al. (1999) for details]. 

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 
Page 24

Table 3 Cont’d. 

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

Percent 

Frequency 

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 25

Table 4. Distribution of life history stages of Atlantic cod 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 

from Jury et al. (1994) and 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 26

Table 5. Summary of life history and habitat parameters for Atlantic cod. 

Based partially on data contained in Appendix 1, Table of Habitat Parameters. This table is the same as that in the first 

Atlantic cod EFH source document (Fahay et al. 1999); more recent studies were reviewed (see Appendix 1), but no new 

information of relevance to this table was found. 

Life 

History 

Stage 

Spatial and 

Temporal 

Distribution 

Temperature Salinity 

Depth/ 

Substrate/ 

Vegetation 

Diel/ Light/ 

Vertical 

Predator/ Prey 

Eggs 1 Pelagic. Bays, 

harbors, offshore 

banks. 

Spawning begins 

in fall, peaks 

winter and 

spring. 

Most 2.0-8.5C 

for incubation. 

12.0C upper 

limit. Mortality 

independent of 

temperature. 

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 4-8C in 

winter-spring, 7-

12C in summerfall. 

Most 32-33 

ppt. 

-- 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, 

during summer. 

Deeper water in 

winter. 

6-20C. More 

tolerant of 

extremes than 

adults. 

Temperature 

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, northeast 

Georges Bank, 

Nantucket 

Shoals. 

Generally < 10C, 

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 27

Figure 1. The Atlantic cod, Gadus morhua (from Goode 1884). 
Page 28

Figure 2. Distribution of Atlantic cod stocks in the North Atlantic showing principle spawning sites. 

Source: Brander (1994). 
Page 29

Diet Composition of Major Prey Items 

<=20 cm

0

10

20

30

40

50

60

Ammodytes

sp.

Amphipods

Annelids

Bivalves

Clupeids

Cottids

Decapods

Euphasiids

Fish Eggs

Flatfishes

Gadids

Gastropods

Isopods

Misc.

Crustaceans

Mysids

Ophiuroids

Other Fish

Polycheates

Rajiformes

Scombrids

Selachimorpha

Squids

Well Digested

Prey

Zoarcids

Percent

21-50 cm

0

5

10

15

20

25

30

Ammodytes

sp.

Amphipods

Annelids

Bivalves

Clupeids

Cottids

Decapods

Euphasiids

Fish Eggs

Flatfishes

Gadids

Gastropods

Isopods

Misc.

Crustaceans

Mysids

Ophiuroids

Other Fish

Polycheates

Rajiformes

Scombrids

Selachimorpha

Squids

Well Digested

Prey

Zoarcids

Percent

51-80 cm

0

5

10

15

20

25

Ammodytes

sp.

Amphipods

Annelids

Bivalves

Clupeids

Cottids

Decapods

Euphasiids

Fish Eggs

Flatfishes

Gadids

Gastropods

Isopods

Misc.

Crustaceans

Mysids

Ophiuroids

Other Fish

Polycheates

Rajiformes

Scombrids

Selachimorpha

Squids

Well Digested

Prey

Zoarcids

Percent

>80 cm

0

5

10

15

20

25

Ammodytes

sp.

Amphipods

Annelids

Bivalves

Clupeids

Cottids

Decapods

Euphasiids

Fish Eggs

Flatfishes

Gadids

Gastropods

Isopods

Misc.

Crustaceans

Mysids

Ophiuroids

Other Fish

Polycheates

Rajiformes

Scombrids

Selachimorpha

Squids

Well Digested

Prey

Zoarcids

Percent

Figure 3. Percent by weight of the major prey items in the diet of three size categories of Atlantic cod. 

From specimens collected during NEFSC bottom trawl surveys from 1973-2001 (all seasons). For details on NEFSC diet 

analysis, see Link and Almeida (2000). 
Page 30

Figure 4. Overall distribution and abundance of Atlantic cod in the northwest Atlantic Ocean. 

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 31

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

Figure 5. Distributions and abundances of Atlantic cod eggs collected during NEFSC MARMAP ichthyoplankton 

surveys. 

For all available months and years from 1978 to 1987 combined. 
Page 32

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

Figure 5. Cont’d. 

From MARMAP ichthyoplankton surveys, January through April, 1978-1987. 
Page 33

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

Figure 5. Cont’d. 

From MARMAP ichthyoplankton surveys, May through August, 1978-1987. 
Page 34

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

Figure 5. Cont’d. 

From MARMAP ichthyoplankton surveys, September through December, 1978-1987 
Page 35

Figure 6. Distributions and abundances of Atlantic cod eggs collected during GLOBEC Georges Bank ichthyoplankton 

surveys. 

For all available years (February-July, 1995; January-June, 1996-1999) combined. 
Page 36

Figure 6. Cont’d. 

From GLOBEC ichthyoplankton surveys, January and February, for all available years combined. 
Page 37

Figure 6. Cont’d. 

From GLOBEC ichthyoplankton surveys, March and April, for all available years combined. 
Page 38

Figure 6. Cont’d. 

From GLOBEC ichthyoplankton surveys, May and June, for all available years combined. 
Page 39

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

Figure 7. Distributions and abundances of Atlantic cod larvae collected during NEFSC MARMAP ichthyoplankton 

surveys. 

For all available months and years from 1977 to 1987 combined. 
Page 40

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

Figure 7. Cont’d. 

From MARMAP ichthyoplankton surveys, January through April, 1977-1987. 
Page 41

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

Figure 7. Cont’d. 

From MARMAP ichthyoplankton surveys, May through August, 1977-1987. 
Page 42

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

Figure 7. Cont’d. 

From MARMAP ichthyoplankton surveys, September through December, 1977-1987. 
Page 43

Figure 8. Distributions and abundances of Atlantic cod larvae collected during GLOBEC Georges Bank 

ichthyoplankton surveys. 

For all available years (February-July, 1995; January-June, 1996-1999) combined. 
Page 44

Figure 8. Cont’d. 

From GLOBEC ichthyoplankton surveys, January and February, for all available years combined. 
Page 45

Figure 8. Cont’d. 

From GLOBEC ichthyoplankton surveys, March and April, for all available years combined. 
Page 46

Figure 8. Cont’d. 

From GLOBEC ichthyoplankton surveys, May and June, for all available years combined. 
Page 47

Figure 8. Cont’d. 

From GLOBEC ichthyoplankton surveys, July 1995. 
Page 48

Figure 9. Topographic map of Georges Bank showing gravel distribution, from Valentine and Lough (1991). 
Page 49

Figure 10. Distribution and abundance of recently-settled juvenile cod on eastern Georges Bank in relation to sediments. 

Source: Valentine and Lough (1991). 
Page 50

Figure 10. Cont’d. 
Page 51

Figure 10. Cont’d. 
Page 52

Figure 11. Seasonal distributions and abundances of juvenile Atlantic cod collected during NEFSC bottom trawl 

surveys. 

From NEFSC winter bottom trawl surveys (1964-2003, all years combined). Distributions are displayed as presence 

only. 
Page 53

Figure 11. Cont’d. 

From NEFSC spring bottom trawl surveys (1968-2003, all years combined). Survey stations where juveniles were not 

found are not shown. 
Page 54

Figure 11. Cont’d. 

From NEFSC summer bottom trawl surveys (1963-1995, all years combined). Distributions are displayed as presence 

only. 
Page 55

Figure 11. Cont’d. 

From NEFSC fall bottom trawl surveys (1963-2003, all years combined). Survey stations where juveniles were not 

found are not shown. 
Page 56

Figure 12. Distribution and abundance of Atlantic cod along the coasts of Maine and New Hampshire. 

From the Maine – New Hampshire spring 2001-2004 and fall 2000-2003 inshore groundfish trawl surveys. 

For details on the survey, see Sherman et al. (2005). 
Page 57

Figure 13. Length frequency plots for Atlantic cod caught along the Maine and New Hampshire coasts, by season/year. 

Based on the Maine – New Hampshire inshore groundfish trawl survey for spring 2001-2004 and fall 2000-2003. 

Source: Sherman et al. (2005). 
Page 58

Figure 14. Regional catch-per-unit-effort of Atlantic cod caught along the Maine and New Hampshire coasts, by 

season/year. 

Based on the Maine – New Hampshire inshore groundfish trawl survey for spring 2001-2004 and fall 2000-2003. 

Region 1 = NH–Southern ME; Region 2 = Casco Bay–Midcoast ME; Region 3 = Penobscot Bay, ME; Region 4 = 

Jerico–Frenchmens Bay, ME; Region 5 = Downeast ME. Source: Sherman et al. (2005). 
Page 59

Figure 15. Seasonal distributions and abundances of juvenile Atlantic cod in Massachusetts coastal waters. 

From spring Massachusetts inshore bottom trawl surveys (1978-2003, all years combined). Survey stations where 

juveniles were not found are not shown. 
Page 60

Figure 15. Cont’d. 

From fall Massachusetts inshore bottom trawl surveys (1978-2003, all years combined). Survey stations where juveniles 

were not found are not shown. 
Page 61

Figure 16. Seasonal distributions and abundances of adult Atlantic cod collected during NEFSC bottom trawl surveys. 

From NEFSC winter bottom trawl surveys (1964-2003, all years combined). Distributions are displayed as presence 

only. 
Page 62

Figure 16. Cont’d. 

From NEFSC spring bottom trawl surveys (1968-2003, all years combined). Survey stations where adults were not found 

are not shown. 
Page 63

Figure 16. Cont’d. 

From NEFSC summer bottom trawl surveys (1963-1995, all years combined). Distributions are displayed as presence 

only. 
Page 64

Figure 16. Cont’d. 

From NEFSC fall bottom trawl surveys (1963-2003, all years combined). Survey stations where adults were not found 

are not shown. 
Page 65

Figure 17. Seasonal distributions and abundances of adult Atlantic cod in Massachusetts coastal waters. 

From spring Massachusetts inshore bottom trawl surveys (1978-2003, all years combined). Survey stations where adults 

were not found are not shown. 
Page 66

Figure 17. Cont’d. 

From fall Massachusetts inshore bottom trawl surveys (1978-2003, all years combined). Survey stations where adults 

were not found are not shown. 
Page 67

Figure 18. Monthly distributions of Atlantic cod eggs collected during NEFSC MARMAP ichthyoplankton surveys 

relative to water column temperature and bottom depth. 

For all available months and years from 1978-1987combined. 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

). Note that 

the bottom depth interval changes with increasing depth. 

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

1030507090

110130150170190

210

230

250270

290

325375

450

750

12501750

>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 68

January

0

20

40

60

80

Percent

Stations

Egg Catch

February

0

20

40

60

80

Percent

March

0

20

40

60

80

Percent

April

0

20

40

60

80

Percent

May

0

20

40

60

80

Percent

June

0

20

40

60

80

Percent

July

0

20

40

60

80

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

Water Column Temperature (0-200m, °C)

Percent

Figure 19. Distributions of Atlantic cod eggs collected during GLOBEC ichthyoplankton surveys relative to water 

column temperature. 

From GLOBEC Georges Bank surveys (February-July, 1995; January-June, 1996-1999) by month for all available years 

combined. Light bars represent the proportion of all stations surveyed, while dark bars represent the proportion of the 

sum of all standardized catches (number/10m2

). 
Page 69

January

0

20

40

60

80

Percent

Stations

Egg Catch

February

0

20

40

60

80

Percent

March

0

20

40

60

80

Percent

April

0

20

40

60

80

Percent

May

0

20

40

60

80

Percent

June

0

20

40

60

80

Percent

July

0

20

40

60

80

1-20

21-4041-6061-80

81-100

101-120121-140141-160161-180181-200201-220221-240241-260261-280281-300301-350351-400401-500

501-1000

1001-15001501-2000

>2001

Bottom Depth (m)

Percent

Figure 20. Distributions of Atlantic cod eggs collected during GLOBEC ichthyoplankton surveys relative to bottom 

depth. 

From GLOBEC Georges Bank surveys (February-July, 1995; January-June, 1996-1999) by month for all available years 

combined. Light bars represent the proportion of all stations surveyed, while dark bars represent the proportion of the 

sum of all standardized catches (number/10m2

). Note that the bottom depth intervals change with depth. 
Page 70

Figure 21. Monthly distributions of Atlantic cod larvae collected during NEFSC MARMAP ichthyoplankton surveys 

relative to water column temperature and bottom depth. 

For all available months and years from 1977-1987combined. 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

). Note that 

the bottom depth interval changes with increasing depth. 

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

1030507090

110130

150170190210230250

270

290

325

375450

750

12501750

>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 71

January

0

20

40

60

80

Percent

Stations

Larvae Catch

February

0

20

40

60

80

Percent

March

0

20

40

60

80

Percent

April

0

20

40

60

80

Percent

May

0

20

40

60

80

Percent

June

0

20

40

60

80

Percent

July

0

20

40

60

80

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

Water Column Temperature (0-200m, °C)

Percent

Figure 22. Distributions of Atlantic cod larvae collected during GLOBEC ichthyoplankton surveys relative to water 

column temperature. 

From GLOBEC Georges Bank surveys (February-July, 1995; January-June, 1996-1999) by month for all available years 

combined. Light bars represent the proportion of all stations surveyed, while dark bars represent the proportion of the 

sum of all standardized catches (number/10m2

). 
Page 72

January

0

20

40

60

80

Percent

Stations

Larvae Catch

February

0

20

40

60

80

Percent

March

0

20

40

60

80

Percent

April

0

20

40

60

80

Percent

May

0

20

40

60

80

Percent

June

0

20

40

60

80

Percent

July

0

20

40

60

80

1-20

21-4041-6061-80

81-100

101-120121-140141-160161-180181-200201-220221-240241-260261-280281-300301-350351-400401-500

501-1000

1001-15001501-2000

>2001

Bottom Depth (m)

Percent

Figure 23. Distributions of Atlantic cod larvae collected during GLOBEC ichthyoplankton surveys relative to bottom 

depth. 

From GLOBEC Georges Bank surveys (February-July, 1995; January-June 1996-1999) by month for all available years 

combined. Light bars represent the proportion of all stations surveyed, while dark bars represent the proportion of the 

sum of all standardized catches (number/10m2

). Note that the bottom depth intervals change with depth. 
Page 73

Atlantic Cod

NEFSC Bottom Trawl Survey

Spring 1968 - 2003

Juveniles (<35 cm)

0

5

10

15

20

1-10

11-2021-3031-4041-5051-6061-7071-8081-90

91-100

101-120121-140141-160161-180181-200201-300301-400401-500

>500

Bottom Depth (m)

Percent

Trawls N=12514

Occurrence N=1400

Catch N=6978

0

10

20

30

40

50

60

24 25 26 27 28 29 30 31 32 33 34 35 36 37 38

Salinity (PPT)

Percent

Trawls N=2270

Occurrence N=189

Catch N=1256

0

10

20

30

40

50

0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30

Bottom Temperature (°C)

Percent

Trawls N=10879

Occurrence N=1210

Catch N=6180

Figure 24. Distributions of juvenile Atlantic cod and trawls from NEFSC bottom trawl surveys relative to bottom water 

temperature, depth, and salinity. 

Based on NEFSC spring bottom trawl surveys (temperature and depth: 1968-2003, all years combined; salinity: 1991-

2003, all years combined). Light bars show the distribution of all the trawls, dark bars show the distribution of all trawls 

in which Atlantic cod occurred and medium bars show, within each interval, the percentage of the total number of 

Atlantic cod caught. Note that the bottom depth interval changes with increasing depth. 
Page 74

Atlantic Cod

NEFSC Bottom Trawl Survey

Fall 1963 - 2003

Juveniles (<35 cm)

0

2

4

6

8

10

12

14

16

1-10

11-2021-3031-4041-5051-6061-7071-8081-90

91-100

101-120121-140141-160161-180181-200201-300301-400401-500

>500

Bottom Depth (m)

Percent

Trawls N=14186

Occurrence N=1226

Catch N=7661

0

10

20

30

40

50

24 25 26 27 28 29 30 31 32 33 34 35 36 37 38

Salinity (PPT)

Percent

Trawls N=2272

Occurrence N=133

Catch N=881

0

5

10

15

20

25

0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30

Bottom Temperature (°C)

Percent

Trawls N=12207

Occurrence N=1047

Catch N=6489

Figure 24. Cont’d. 

Based on NEFSC fall bottom trawl surveys (temperature and depth: 1963-2003, all years combined; salinity: 1991-2003, 

all years combined). Light bars show the distribution of all the trawls, dark bars show the distribution of all trawls in 

which Atlantic cod occurred and medium bars show, within each interval, the percentage of the total number of Atlantic 

cod caught. Note that the bottom depth interval changes with increasing depth. 
Page 75

Atlantic Cod

Massachusetts Inshore Trawl Survey

Spring 1978 - 2003

Juveniles (<35 cm)

0

5

10

15

20

25

30

35

40

1-5

6-10

11-1516-2021-2526-3031-3536-4041-4546-5051-5556-6061-6566-7071-7576-8081-85

Bottom Depth (m)

Percent

Trawls N=2482

Occurrence N=1523

Catch N=102290

0

5

10

15

20

25

30

35

0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30

Bottom Temperature (°C)

Percent

Trawls N=2407

Occurrence N=1480

Catch N=101329

Figure 25. Distributions of juvenile Atlantic cod and trawls in Massachusetts coastal waters relative to bottom water 

temperature and depth. 

Based on spring Massachusetts inshore bottom trawl surveys (1978-2003, all years combined). Light bars show the 

distribution of all the trawls, dark bars show the distribution of all trawls in which Atlantic cod occurred and medium 

bars show, within each interval, the percentage of the total number of Atlantic cod caught. 
Page 76

Atlantic Cod

Massachusetts Inshore Trawl Survey

Fall 1978 - 2003

Juveniles (<35 cm)

0

5

10

15

20

25

30

1-5

6-10

11-1516-2021-2526-3031-3536-4041-4546-5051-5556-6061-6566-7071-7576-8081-85

Bottom Depth (m)

Percent

Trawls N=2338

Occurrence N=602

Catch N=31884

0

5

10

15

20

25

30

0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30

Bottom Temperature (°C)

Percent

Trawls N=2244

Occurrence N=589

Catch N=31851

Figure 25. Cont’d. 

Based on fall Massachusetts inshore bottom trawl surveys (1978-2003, all years combined). Light bars show the 

distribution of all the trawls, dark bars show the distribution of all trawls in which Atlantic cod occurred and medium 

bars show, within each interval, the percentage of the total number of Atlantic cod caught. 
Page 77

Atlantic Cod

NEFSC Bottom Trawl Survey

Spring 1968 - 2003

Adults (>=35 cm)

0

5

10

15

20

25

1-10

11-2021-3031-4041-5051-6061-7071-8081-90

91-100

101-120121-140141-160161-180181-200201-300301-400401-500

>500

Bottom Depth (m)

Percent

Trawls N=12514

Occurrence N=3870

Catch N=26689

0

10

20

30

40

50

60

70

24 25 26 27 28 29 30 31 32 33 34 35 36 37 38

Salinity (PPT)

Percent

Trawls N=2270

Occurrence N=496

Catch N=4058

0

5

10

15

20

25

30

35

0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30

Bottom Temperature (°C)

Percent

Trawls N=10879

Occurrence N=3369

Catch N=23680

Figure 26. Distributions of adult Atlantic cod and trawls from NEFSC bottom trawl surveys relative to bottom water 

temperature, depth, and salinity. 

Based on NEFSC spring bottom trawl surveys (temperature and depth: 1968-2003, all years combined; salinity: 1991-

2003, all years combined). Light bars show the distribution of all the trawls, dark bars show the distribution of all trawls 

in which Atlantic cod occurred and medium bars show, within each interval, the percentage of the total number of 

Atlantic cod caught. Note that the bottom depth interval changes with increasing depth. 
Page 78

Atlantic Cod

NEFSC Bottom Trawl Survey

Fall 1963 - 2003

Adults (>=35 cm)

0

2

4

6

8

10

12

14

1-10

11-2021-3031-4041-5051-6061-7071-8081-90

91-100

101-120121-140141-160161-180181-200201-300301-400401-500

>500

Bottom Depth (m)

Percent

Trawls N=14186

Occurrence N=3209

Catch N=22413

0

10

20

30

40

50

60

70

24 25 26 27 28 29 30 31 32 33 34 35 36 37 38

Salinity (PPT)

Percent

Trawls N=2272

Occurrence N=353

Catch N=2760

0

5

10

15

20

0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30

Bottom Temperature (°C)

Percent

Trawls N=12207

Occurrence N=2807

Catch N=19421

Figure 26. Cont’d. 

Based on NEFSC fall bottom trawl surveys (temperature and depth: 1963-2003, all years combined; salinity: 1991-2003, 

all years combined). Light bars show the distribution of all the trawls, dark bars show the distribution of all trawls in 

which Atlantic cod occurred and medium bars show, within each interval, the percentage of the total number of Atlantic 

cod caught. Note that the bottom depth interval changes with increasing depth. 
Page 79

Atlantic Cod

Massachusetts Inshore Trawl Survey

Spring 1978 - 2003

Adults (>=35 cm)

0

5

10

15

20

25

30

1-5

6-10

11-1516-2021-2526-3031-3536-4041-4546-5051-5556-6061-6566-7071-7576-8081-85

Bottom Depth (m)

Percent

Trawls N=2482

Occurrence N=724

Catch N=9362

0

5

10

15

20

25

30

35

0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30

Bottom Temperature (°C)

Percent

Trawls N=2407

Occurrence N=694

Catch N=8996

Figure 27. Distributions of adult Atlantic cod and trawls in Massachusetts coastal waters relative to bottom water 

temperature and depth. 

Based on spring Massachusetts inshore bottom trawl surveys (1978-2003, all years combined). Light bars show the 

distribution of all the trawls, dark bars show the distribution of all trawls in which Atlantic cod occurred and medium 

bars show, within each interval, the percentage of the total number of Atlantic cod caught. 
Page 80

Atlantic Cod

Massachusetts Inshore Trawl Survey

Fall 1978 - 2003

Adults (>=35 cm)

0

5

10

15

20

25

30

35

40

1-5

6-10

11-1516-2021-2526-3031-3536-4041-4546-5051-5556-6061-6566-7071-7576-8081-85

Bottom Depth (m)

Percent

Trawls N=2338

Occurrence N=80

Catch N=576

0

5

10

15

20

25

30

35

0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30

Bottom Temperature (°C)

Percent

Trawls N=2244

Occurrence N=78

Catch N=573

Figure 27. Cont’d. 

Based on fall Massachusetts inshore bottom trawl surveys (1978-2003, all years combined). Light bars show the 

distribution of all the trawls, dark bars show the distribution of all trawls in which Atlantic cod occurred and medium 

bars show, within each interval, the percentage of the total number of Atlantic cod caught. 
Page 81

Appendix 1. Table of habitat parameters for Atlantic cod, Gadus morhua. 

This table is separated into four parts based on life history stage. Abbreviations: SS = Scotian Shelf; Nfld = Newfoundland; GOSL = 

Gulf of St. Lawrence; PB = Passamaquoddy Bay; GOM = Gulf of Maine; GB = Georges Bank; Mass Bay = Massachusetts Bay; SNE 

= southern New England (Nantucket Shoals to Hudson Canyon); MAB = Mid-Atlantic Bight. 

SPAWNING/EGGS 

Authors Study Area 

and Period

Habitat (Spatial and 

Temporal)

Temperature Salinity Currents/ 

Circulation

Light/Vertical

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. 

Bigelow 

and 

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 River. Always 

< 50 fm. 

Bottom temperatures 

0.6-8.9C for 

spawning (2.2-5.6C 

in Mass Bay). 

5.0-8.3C optimum 

for hatching. High 

mortalities at 0C. 

Sink in spring 

freshets 

Drift southwest 

following 

coastline, 10-

30 days 

Near surface if 

salinities high 

Bonnet 

(1939) 

Lab study Ipswich Bay. Spawns at 

yearly minimum 

temperature (March) 

0.5-3.0C. 

12C upper limit for 

development. 

--- Eggs spawned 

in Ipswich bay 

would drift 120 

miles before 

larvae settled to 

bottom. 

--- 

Brander 

and Hurley 

(1992) 

SS Spring spawning 

proceeds from southwest 

to northeast along shelf. 

--- --- Spawning 

matches 

production of 

copepods. 

--- 

Cohen et 

al. (1990) 

North 

Atlantic 

Most productive area in 

western North Atlantic is 

eastern half of GB and 

Grand Banks, followed 

by southwest GOM. 

0-12C with most 0-

6C. GOM stock 

spawns in colder 

water than others. 

--- --- Spawn near bottom, 

unless temperatures 

unsuitable, then 

migrate into water 

column. 

Colton 

(1978) 

GOM Spawn in Nantucket 

Shoals and Mass Bay, 

Jan.-Apr. (peak Jan.). 

Also Georges and 

Browns Banks, Ipswich 

Bay, southwest GOM. 

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

Fish (1928) Mass Bay, 

southwest 

GOM 

Peak spawning in Mass 

Bay in January 

10.1C (Nov.) to 

0C (Jan.). 

--- Advected out 

of Mass Bay by 

currents. 

--- 

Hanke et 

al. (2000) 

SS, eastern 

GOM, Bay 

of Fundy; 

1975-1997 

Evidence for a spring and 

fall spawning, but with 

regional differences. In 

March-April spawning 

observed off 

southwestern Nova 

Scotia including Browns 

Bank, GB, and the 

Emerald/Western/Sable 

Island Bank area. 

Spawning occurs again in 

November/December on 

GB and entire Nova 

Scotia coast, west of 

Grand Manan and on 

Western/Sable Island/ 

Banquereau Bank. 

--- --- --- --- 
Page 82

Appendix 1. cont’d. 

SPAWNING/EGGS 

Authors Study 

Area and 

Period

Habitat (Spatial and 

Temporal)

Temperature Salinity Currents/ 

Circulation

Light/Vertical

Hardy 

(1978) 

GB, GOM Pelagic. Spawn in inlets, 

bays, harbors, coastal and 

offshore banks. Usually < 

73 m. 

0-6C for spawning. 

2.0-8.5C optimum 

for incubation 

Spawning 

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. 

Lough et 

al. (1994) 

GB, 

JanuaryJune 1982 

vs. 1985 

Particles tracked from 

Northeast Peak spawning 

in monthly mean flow 

fields and the 1982 and 

1985 wind stresses from 

Feb through May. 

--- --- Greater losses 

of particles in 

surface layers < 

25 m along 

southern flank 

and Northeast 

Peak when 

wind stress 

along-shelf to 

the northeast. 

Results 

consistent with 

greater losses 

in 1982 

associated with 

strong 

northeast wind 

in April. 

Particles released in 

six horizontal layers. 

 Lough et 

al. (1996) 

GB, May 

1992 

Vertical distribution of 

eggs at mixed and 

stratified sites on southern 

flank. 

Mixed site: 4-7o

C. 

Stratified site: 4-

10o

C. 

--- Inferred 

southwest 

transport along 

southern flank. 

At shoal site, eggs 

distributed through 

water column. At 

stratified site, eggs 

most abundant in 

surface 20 m with 

maximum density 

just above base of 

thermocline at 20-10 

m. 

Lough et 

al. (2002) 

GB, 

JanuaryMay 1977-

1987 

Modeling specific year, 

weekly transport and 

retention of eggs from 

Northeast Peak and 

Western GB spawning 

areas. 

--- --- Specific year 

flow fields 

estimated from 

January to July. 

Considerable wind 

loss of particles at 

surface; retention 

consistent at depth 

(30 m). High 

recruitment occurred 

during years of high 

retention. 

Miller et 

al. (1995) 

SS, Oct.-

May, 

1991-1993 

Peak spawning during fall. Temperature (more 

than season) exerts 

most influence on 

egg size (and 

hatchling size). 

--- --- --- 

Mountain 

et al. 

(2003) 

GB, 

monthly 

surveys 

JanuaryJuly 1995, 

1996 

Peak egg abundance in 

Februrary-March on 

Northeast Peak of GB 

--- --- Advection of 

egg cohorts 

consistent with 

mean 

climatological 

pattern. 

Seasonal egg 

mortality rates 

12-14% d-1. 

--- 
Page 83

Appendix 1. cont’d. 

SPAWNING/EGGS 

Authors Study 

Area and 

Period

Habitat (Spatial and 

Temporal)

Temperature Salinity Currents/ 

Circulation

Light/Vertical

O’Brien 

et al. 

(2003) 

GB, 1978-

2000 

Egg survivorship was 

significantly related to age 

diversity of repeat 

spawners, spatial 

distribution of eggs, and 

bottom temperature. 

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

Page et 

al. (1999) 

GB, bimonthly Inferred mean spawning 

locations compared with 

patterns in particle 

residence times and 

locations. 

--- --- Spawning 

occurs at times 

and locations 

characterized 

by model 

residence times 

>35 days: 

Northeast Peak 

during MarchApril. 

Particles released at 

1, 10, 20, 30, 40, 50 

m depth in mean 

climatological bimonthly flow fields. 

Rau 

(1974) 

Browns 

Bank, GB, 

Nantucket 

Shoals, 

FebruaryMarch 

1973 

Most eggs found over 

central and northeast GB. 

Most collected at 3-

5C. 

Most collected at 

32-33 ppt. 

--- --- 

Valerio et 

al. (1992) 

Nfld Studied freezing resistance 

of eggs and larvae. No 

antifreeze proteins 

detected. 

If chorion intact, 

capable of 

undercooling to -

4.0C. Froze at -4.1 

to -17.0C. 

--- --- --- 

Werner et 

al. (1993) 

GB, 

MarchApril 

Modeling mean MarchApril transport of eggs 

from Northeast Peak. 

--- --- Eggs in surface 

advected off 

bank, but 

below surface 

transported to 

southwest and 

retained onbank if 

shoalward of 

70-m isobath. 

Vertical position of 

eggs specified in 

simulations based on 

day and night field 

observations. 
Page 84

Appendix 1. cont’d. 

LARVAE 

Authors Study Area 

and Period 

Habitat (Spatial and 

Temporal) 

Temperature Salinity Currents/ 

Circulation 

Light/ 

Vertical 

Predators/ 

Prey (See 

Food Habits 

tables also) 

Garrison et 

al. (2000) 

GB, AprilMay 1990, 

1994, 1995. 

Spatial overlap of cod 

larvae and herring and 

mackerel predators on 

southern flank 

determined. 

Larvae 

occurred 

mostly in wellmixed water 

where mean 

temperature < 

7o

C. 

Mean 

range: 

32.2-32.7 

psu 

Intrusions of 

Scotian Shelf 

water and 

Slope water 

increased 

spatial 

overlap of 

predators. 

--- Atlantic 

herring and 

Atlantic 

mackerel as 

they migrate 

northward in 

the spring and 

overlap with 

patches of 

larvae on the 

southern flank 

of GB. 

Hanke et 

al. (2000) 

SS, 1975-

1982. 

Composite data from 

several programs. Fall 

and spring spawning 

populations observed, 

progressively older 

larvae found on 

western SS. 

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

Laurence 

(1978) 

Laboratory 

study 

Growth rates increase 

with increasing 

temperatures. 

4C: 4.15%/d. 

7C: 6.67%/d. 

10C: 8.75%/d. 

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

Lough and 

Bolz (1989) 

GB, April, 

May 1981, 

May 1983 

Consistent cross-shelf 

age gradient with older 

larvae found nearer the 

shoals. 

--- --- Average 

shoalward age 

gradient 

consistent 

with nearbottom crossisobath 

current of ca. 

1 cm s-1. 

Retention of 

larvae on the 

shoals 

enhanced by 

residing 

nearer to 

bottom in 

waters < 70 

m. 

--- 

Lough and 

Potter 

(1993) 

GB, spring 

and summer 

1981-1986 

Vertical distribution 

patterns of eggs, larvae, 

and juveniles described 

from spawning to 

settlement. 

Range: 4-14o

C. Range: 

32.5-33.2 

ppt 

--- Larvae 

distributed 

throughout 

mixed water 

column, but 

concentrated 

within or 

above 

thermocline 

when 

strongly 

stratified. 

Older larvae 

deeper by 

day and 

shoaler by 

night 

indicating 

diel vertical 

migration. 

--- 
Page 85

Appendix 1. cont’d. 

LARVAE 

Authors Study Area 

and Period 

Habitat (Spatial and 

Temporal) 

Temperature Salinity Currents/ 

Circulation 

Light/ 

Vertical 

Predators/ 

Prey (See 

Food Habits 

tables also) 

Lough and 

Manning 

(2001) 

GB, May 

1997 

Model simulation of 

larvae near the 

developing tidal front 

on southern flank. 

Surface 

signature of 

tidal front 7o

C. 

Sigma-t 

values 

given. 

Complex 

frontal 

circulation of 

converging 

and diverging 

cells. 

Vertical 

positioning 

important. 

Larvae 

caught in 

near surface 

jet 

transported 

southwest 

along flank, 

while larvae 

near bottom 

advected 

shoalward 

across the 

front. 

--- 

Lough and 

Mountain 

(1996) 

GB, AprilMay 1981; 

May 1983. 

Effects of small-scale 

turbulence on larval 

feeding in well-mixed 

and stratified water on 

southern flank. 

Turbulence 

minimal at or 

below 

pycnocline (ca. 

25 m). 

--- Higher 

turbulence 

near surface 

due to wind 

mixing and at 

depth due to 

shear in the 

tidal current 

near bottom. 

Maximum 

feeding 

occurs at 

low to 

intermediate 

turbulence 

levels where 

prey is >10-

20 prey l-1; 

i.e., near 

pycnocline. 

See Food 

Habits table. 

Lough et 

al. (1994) 

GB, JanuaryJune 1982 vs. 

1985 

Particles tracked from 

Northeast Peak 

spawning in monthly 

mean flow fields and 

the 1982 and 1985 

wind stresses from Feb 

through May. 

--- --- Greater losses 

of particles in 

surface layers 

< 25 m along 

southern flank 

and Northeast 

Peak when 

wind stress 

along-shelf to 

the northeast. 

Results 

consistent 

with greater 

losses in 1982 

associated 

with strong 

northeast 

wind in April. 

Particles 

released in 

six 

horizontal 

layers. 

--- 

Lough et 

al. (1996) 

GB, May 

1992 

Vertical distribution of 

larvae at mixed and 

stratified sites on 

southern flank. 

Mixed site: 4-

7o

C. Stratified 

site: 4-10o

C. 

--- Inferred 

southwest 

transport 

along 

southern 

flank. 

At shoal site, 

larvae 

distributed 

through 

water 

column. At 

stratified 

site, larvae 

most 

abundant in 

surface 20 m 

with 

maximum 

density just 

above base 

of 

thermocline 

at 20-10 m. 

--- 
Page 86

Appendix 1. cont’d. 

LARVAE 

Authors Study Area 

and Period 

Habitat (Spatial and 

Temporal) 

Temperature Salinity Currents/ 

Circulation 

Light/ 

Vertical 

Predators/ 

Prey (See 

Food Habits 

tables also) 

Lough et 

al. (2005) 

GB, May 

1993, 1994 

Biophysical 1-D 

growth model used to 

compare field derived 

growth rates (RNADNA based) at 

stratified sites on 

southern flank. Model 

includes effect of light 

on larval feeding 

response. 

Thermocline 

near 20 m. 

Temperatures 

above 20 m, 7-

9o

C; below 20 

m, 6-7o

C. 

--- Higher 

turbulence 

near surface 

due to wind 

mixing and at 

depth due to 

shear in the 

tidal current 

near bottom. 

Vertical 

growth 

profiles 

resulted 

from depthdependent 

food 

limitation 

and prey 

selectivity 

coupled with 

greater 

metabolic 

costs 

induced by 

higher 

temperatures 

in May 

1994. 

Minimum 

light level 

for feeding 

typically 

near 60 m 

depth, so 

that most of 

water 

column had 

non-limiting 

feeding. 

Possible 

feeding 

inhibition in 

surface 10 m 

due to high 

light levels. 

--- 

Mountain 

et al. 

(2003) 

GB, monthly 

surveys 

January-July 

1995, 1996. 

Peak abundance in 

March-April on 

southern flank GB. 

--- --- Movement of 

larval cohorts 

between 

surveys 

consistent 

with middepth 

climatological 

flow fields 

around GB. 

Larvae 

concentrated 

in middle 

and upper 

part of water 

column. 

--- 

Myers and 

Drinkwater 

(1989) 

MAB, 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 87

Appendix 1. cont’d. 

LARVAE 

Authors Study Area 

and Period 

Habitat (Spatial and 

Temporal) 

Temperature Salinity Currents/ 

Circulation 

Light/ 

Vertical 

Predators/ 

Prey (See 

Food Habits 

tables also) 

Perry and 

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. 

--- 

Rau (1974) Browns Bank, 

GB, 

Nantucket 

Shoals, 

FebruaryMarch 1973 

Most larvae (2-7 mm) 

between northeast GB 

and Nantucket Shoals. 

Most collected 

3-5C. 

Most 

collected 

32-33 ppt. 

--- --- --- 

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. 

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 

70 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. 

--- --- 
Page 88

Appendix 1. cont’d. 

JUVENILES 

Authors Study Area and 

Period

Habitat (Spatial 

and Temporal)

Temperature Salinity Substrate/ 

Vegetation

Currents/ 

Circulation 

Light/Diel Predators/ 

Prey (See Food 

Habits tables 

also) 

Clark and 

Green (1990) 

Conception Bay, 

Nfld 

Studied diel, depth, 

seasonal movements 

in Broad Cove. 

Seasonal change in 

diel behavior due to 

disappearance of 

shallow (< 30 m) 

summer 

thermocline. 

Summer: day: 

4.1-4.6C; night: 

10-12C. Fall: 

stayed in warmer 

water. 

--- Summer: wideranging (> 3 km/day), 

between deep, cold 

and 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. 

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 and 

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). 

Gotceitas and 

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. 

Gotceitas et al.

(1994) 

Trinity Bay, Nfld 

and laboratory 

studies, 1993 

Nearshore bay, 

various substrates. 

July-mid-December. 

--- --- Predator absent: 

preferred finer grains 

and avoided 

vegetation. 

Predator present: 

preferred cobble and 

hide in vegetation. 

--- --- See Substrate/ 

Vegetation 

column 

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 and 

without predator 

using SCUBA and 

seines. 

--- --- Eelgrass used as 

nearshore nursery by 

0+ cod. For refuge 

from predation and 

when combined with 

cobble, stem density 

was important. 

--- --- Predator 

absent: 0+ used 

sand and 

gravel. Predator 

present: 0+ hid 

in cobble or 

eelgrass. 

Grant and 

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 

year classes 

do opposite. 

Age 0+ feed 

mostly on 

zooplankton 

during day; 

Age 1+ mostly 

on benthos and 

fish at night. 
Page 89

Appendix 1. cont’d. 

JUVENILES 

Authors Study Area and 

Period

Habitat (Spatial 

and Temporal)

Temperature Salinity Substrate/ 

Vegetation

Currents/ 

Circulation 

Light/Diel Predators/ 

Prey (See Food 

Habits tables 

also) 

Grant and 

Brown 

(1998b) 

Nfld Studied encounters 

between just-settled 

juveniles and older 

cod (predators) in 

eelgrass and noeelgrass habitats in 

Trinity Bay. 

--- --- After settlement, 

juveniles display 

preference for 

eelgrass beds, but 

remain localized over 

grass and no-grass 

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. 

Gregory and 

Anderson 

(1997a) 

Placentia Bay, 

Nfld. April, 

October / 

November 1995 

Submersible and 

QTC View 

acoustical seabed 

classification 

system for habitat 

use by age 1-4 

juveniles. 

Occurred most 

abundantly at 60-

120 m. 

5.5o

C at surface, 

declining to 

minus 1.0o

C at 

75 m. 

--- Substrate selection 

was age specific. Age 

1 cod found primarily 

in areas with gravel 

substrate and low 

relief. Age 2-4 cod 

found mostly 

associated with 

coarse substrate and 

high relief. 

Macroalgae cover 

substrate not selected 

by either group. 

Slight tidal 

current (max 

0.1 to 0.2 m 

s

-1). 

Suggest diel 

movements do 

not occur 

among 

juveniles at 

spring water 

temperatures 

(~-1.0o

C). 

Predator 

avoidance 

behavior 

indicates young 

mottled 

individuals rely 

on crypsis, 

whereas older 

uniformcolored 

individuals 

associated with 

a specific 

physical 

feature. 

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 

8-42 m); 1+ range 

73-274 m. 

Range 6-20C From < 

31.3 to 35.0 

ppt. 

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

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. 

Keats and 

Steele (1992) 

Bonavista Bay, 

Nfld. MayAugust 1986 

Described in Keats 

(1990). 

--- --- --- --- Juveniles 

move into 

shallow water 

at night and 

mostly rest 

near bottom. 

Diet consists 

mostly of 

planktonic prey 

taken during 

daytime. 

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. 
Page 90

Appendix 1. cont’d. 

JUVENILES 

Authors Study Area and 

Period

Habitat (Spatial 

and Temporal)

Temperature Salinity Substrate/ 

Vegetation

Currents/ 

Circulation 

Light/Diel Predators/ 

Prey (See Food 

Habits tables 

also) 

Laurel et al. 

(2003) 

Bonavista Bay, 

Nfld. 

Summer/autumn 

1999 and 2000 

Various sizes of 

artificial eelgrass 

mats deployed with 

tethered age 0-yr 

cod to monitor local 

predation rates. 

--- --- Artificial eelgrass 

mats of 5 sizes. 

--- --- Predation rates 

negatively 

correlated with 

patch size, 

suggesting that 

larger patches 

reduced 

predator 

foraging ability. 

However, high 

predator 

densities in 

largest eelgrass 

mat resulted in 

higher rates of 

predation than 

expected. 

Laural et al. 

(2004) 

Bonavista Bay, 

Nfld 1996, 1998-

2001. 

Shallow coastal 

areas < 6 m depth 

with substrate 

varying from mud 

to bedrock, often 

associated with 

vegetative cover, 

eelgrass being the 

most common. Biweekly seine 

surveys, markrecapture and lab 

experiments 

conducted. 

--- --- Cod initially settle in 

August/September, 

and again in October, 

mostly associated 

with eelgrass but 

periodically over 

sand as density in 

eelgrass increased. 

Cod formed tighter 

aggregations over 

sand than eelgrass. 

Mark-recapture 

experiments indicated 

movement between 

sites. Habitat 

suitability dynamic 

rather than fixed 

variable. 

--- --- Eelgrass 

supports higher 

densities of 

prey such as 

pelagic and 

epiphytic 

zooplankton. 

Lindholm et 

al. (1999) 

Aquarium 

experiments on 

predation of 0-

year juveniles by 

3+ cod over 5 

seafloor habitats. 

Habitats vary in 

complexity to 

mimic the range of 

impacts of mobile 

fishing gear given a 

gradient in fishing 

effort. 

Aquarium 

maintained at 8-

10o

C. 

--- Experimental 

habitats: sand, 

cobble, minimum 

density short sponge, 

maximum density 

short sponge, and tall 

sponge. Significant 

decrease in 0-yr 

mortality with 

epifaunal density 

compared to flat 

sand. Epifaunal 

density found to be 

more significant than 

epifaunal height in 

reducing 0-yr 

mortality. 

--- 12 h light/dark 

regime. 

--- 

Lough et al.

(1989) 

GB Descend to bottom 

at 4-6 cm. 0+ 

(newly settled) fish 

dense on 

northeastern GB, 

70-100 m depth 

during summer. 

--- --- Pebble-gravel 

deposits. 

Fall, 

transported 

southeastward by 

gyre. 

Migrate into 

lower water 

column at 

night to feed 

on invertebrates. 

Coloration 

mimics 

substrate, 

reduces 

vulnerability to 

predation. 
Page 91

Appendix 1. cont’d. 

JUVENILES 

Authors Study Area and 

Period

Habitat (Spatial 

and Temporal)

Temperature Salinity Substrate/ 

Vegetation

Currents/ 

Circulation 

Light/Diel Predators/ 

Prey (See Food 

Habits tables 

also) 

MacDonald et 

al. (1984) 

Bay of Fundy 

and PB 

Juveniles in PB in 

winter, close to 

beach in summer. 

(See "Adults") 

0-6C in winter; 

8-13C in 

summer. 

30-31 ppt 

winter; 31-

32 ppt 

summer. 

Mud, gravel, rock in 

winter; sand, mud, 

rock in summer. 

--- --- --- 

Murawski and 

Finn (1988) 

GB Evaluated species 

co-occurrences 

relative to 

temperature and 

depth preferences 

and spatial 

distribution by 

species and age. 

Overlap with silver 

hake, mostly in fall. 

See also “Adults” 

YOY means: 

winter: 2.9C, 

spring: 5.3C, 

summer: 

9.9C, 

fall: 9.3C. 

--- YOY means: 

winter: 56 m, 

spring: 60 m, 

summer: 71 m, 

fall: 71 m. 

--- --- 

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-

6C. 

Age 1+, fall: 5-

8C. 

Age 2, winter: 2-

7C. 

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

Tupper and 

Boutilier 

(1995) 

St. Margaret's 

Bay, Nova Scotia 

Studied survival and 

0+ densities in four 

different bottom 

habitats (sand, 

seagrass, cobble, 

rock-reef). 

--- --- 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. 
Page 92

Appendix 1. cont’d. 

JUVENILES 

Authors Study Area and 

Period

Habitat (Spatial 

and Temporal)

Temperature Salinity Substrate/ 

Vegetation

Currents/ 

Circulation 

Light/Diel Predators/ 

Prey (See Food 

Habits tables 

also) 

Wigley and 

Serchuk 

(1992) 

GB, SNE. 1982-

1986. 

Commercial 

landings data and 

spring and fall 

research-vessel 

data. 

Ages 1-4 distributed 

at different depths 

in spring (57, 58, 

68, 86 m, 

respectively). 

During autumn age 

3 fish co-occurred 

with age 1-2 fish at 

86 m. 0-group fish 

mean depth at 69 m. 

Seasonal shift in age 

2 fish. Both the 

Nantucket Shoals 

and GB populations 

move to deeper 

water in the 

summer/fall along 

the 100 m contour, 

the western side of 

the Great South 

Channel, and the 

Northern Edge and 

Northeast Peak 

areas. Distribution 

patterns delineated 

more by depth than 

temperature. 0-

group in autumn 

distinct from all 

other age-groups 

with respect to 

temperature and 

depth. 

Mean 

temperatures for 

all age groups 

5.3o

C in spring 

and 9.2o

C in 

autumn. Mean 

temperature for 

0-group 10.0o

C. 

Seasonal shifts 

most likely 

associated with 

temperature. 

--- --- --- --- Fall occurrence 

of some age-3 

fish with ages 

1-2 may be 

related to diet. 
Page 93

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 Food 

Habits tables 

also)

Bigelow and 

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 in 

summer, 3 fm in 

winter. 

0-12.8C. Prefer 

< 10.0 C. 

--- Mostly rocky, 

pebbly, sandy, 

or gravelly 

bottoms. 

--- --- Large sharks and 

spiny dogfish. 

Colvocoresses and 

Musick 

(1984) 

MAB, 

continental 

shelf 

Analyzed faunal 

associations, and 

zones occupied 

seasonally. Occurs 

with Pseudopleuronectes 

americanus and 

Hemitripterus 

americanus. 

Boreal species, 

spring, < 10C. 

"Relatively 

absent" during 

fall. 

--- < 100 m. --- --- --- 

Helser and 

Brodziak 

(1996) 

GOM, GB, 

SNE, MAB 

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 

--- --- --- 

Jean (1965) GOSL; SS GOSL: 35-145 m in 

summer; 130-180 m in 

winter. 

SS: 65-110 m in 

summer; 

90-135 m in winter. 

GOSL: 0-6C in 

summer; 1-3 C 

in winter. 

SS: 1-8C in 

summer; 2-4 C 

in winter. 

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

Link and 

Garrison 

(2002) 

SS, GOM, GB, 

SNE, MAB. 

Spring and fall 

research survey 

cruises 1973-

1998. 25-yr 

time series of 

food habits 

data. 

Omnivorous diet 

shifted significantly 

over 3 decades 

concurrent with forage 

species abundance and 

distribution. 

--- --- --- --- --- Cod are 

opportunistic 

feeders, prefer 

sand lance, 

Cancer spp., 

crabs and 

herring, 

regardless of 

abundance or 

overlap. Early 

juveniles 

consumed more 

pelagic than 

benthic 

invertebrates, 

medium cod 

consumed 

benthic 

invertebrates and 

fish, and larger 

cod consumed 

larger amounts 

of fish. 

Cannibalism 

increased with 

size. 
Page 94

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 Food 

Habits tables 

also)

MacDonald et 

al. (1984) 

Bay of Fundy 

and PB 

Adults in PB summer; 

GOM, SS winter. (See 

"Juveniles"). 

8-13C summer;

4-8C winter. 

31-32 ppt in 

summer; 31-32 

ppt in winter. 

Mud, rock in 

summer. 

--- --- --- 

Mountain and 

Murawski 

(1992) 

SS, GOM, GB, 

SNE, MAB. 

Spring NEFSC 

research survey 

cruises 1963-

1990. 

Significant correlation 

between GB weighted 

mean catch and areal 

average temperature, 

but unable to 

determine if 

distributional change 

either a north-south 

shift or change in 

water depth. 

Significant 

decadal changes 

in spring 

temperatures 

from cold 1960’s 

to warmer 

1970’s and 

intermediate 

1980’s. 

Interannual 

variations of ±2-

4C observed in 

all shelf regions. 

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

Murawski and 

Finn (1988) 

GB Evaluated species cooccurrences relative to 

temperature and depth 

preferences and spatial 

distribution by species 

and age. Overlap with 

silver hake, mostly in 

fall. 

Also see “Juveniles” 

Age 1+ means in 

winter: 4.2C; 

spring: 5.4C; 

summer: 8.0 C; 

fall: 9.3C. 

--- Age 1+ means 

in winter: 88 

m; 

spring: 67 m; 

summer: 72 m; 

fall: 84 m. 

--- --- --- 

Odense et al.

(1966) 

Bay of Chaleur 

(laboratory 

study) 

Studied tolerance to 

low salinity. 

5-6C (not 

manipulated). 

First mortalities 

when salinities 

reached 2.7 

ppt; complete 

mortality at 2.3 

ppt. 

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

Rose and 

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 

8.5C. 

--- --- When 

alongshore 

winds create 

temperature 

changes, cod 

numbers 

decrease. 

--- --- 

Rose and 

Leggett 

(1989) 

GOSL Cod were aggregated 

within narrow 

temperature range, 

unless prey present, 

then found in wider 

range. 

Without prey, 

usually between 

0 and 5C. 

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

present, range -

0.5 to 8.5C. 

Scott (1982a) SS, Bay of 

Fundy 

Determined preferred 

depths, temperatures, 

and salinities for 

several groundfish 

species. Compared to 

other gadoids, cod 

prefers shallower, 

colder, less saline 

waters. 

0-13C (mean 

4.9C). Preferred 

temperature 

showed increase 

northeast to 

southwest, 

means 3.2 to 

7.8C. 

31-34 ppt 

(mean 32.8 

ppt). 

27-366 + m, 

(mean 95 m). 

Preferred range 

37-90 m. 

--- --- --- 

Tyler (1971) PB compared 

to bays south. 

Analyzed 

regular and 

periodic 

components in 

fish 

community. 

 Cod was member of 

'regular' community 

(present throughout 

year), but most 

abundant MarchApril. 

As annual 

temperature 

fluctuations 

increase (in 

southern bays), 

fewer 'regular' 

species. 

29.5-29.6 ppt 

in Mar-Apr.; 

32.3 ppt in 

Sept. 

Sampled brown 

mud bottom, 

sloping from 

38-55 m. 

--- --- --- 
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