NOAA Technical Memorandum NMFS-NE-135

Essential Fish Habitat Source Document:

Silver Hake, Merluccius bilinearis,

Life History and Habitat Characteristics

U. S. DEPARTMENT OF COMMERCE

National Oceanic and Atmospheric Administration

National Marine Fisheries Service

Northeast Region

Northeast Fisheries Science Center

Woods Hole, Massachusetts

September 1999
Recent Issues

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

Access. No. PB98-119159.

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

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

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

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

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

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

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

Access. No. PB98-112345.

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

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

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

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

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

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

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

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

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

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

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

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

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

William Daley, Secretary

National Oceanic and Atmospheric Administration

D. James Baker, Administrator

National Marine Fisheries Service

Penelope D. Dalton, Assistant Administrator for Fisheries

Northeast Region

Northeast Fisheries Science Center

Woods Hole, Massachusetts

September 1999

Essential Fish Habitat Source Document:

Silver Hake, Merluccius bilinearis,

Life History and Habitat Characteristics

 Wallace W. Morse, Donna L. Johnson, Peter L. Berrien,

and Stuart J. Wilk

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

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

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

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

All issues may be cited in formal scientific communications.

NOAA Technical Memorandum NMFS-NE-135
Editorial Notes on Issues 122-152

in the

NOAA Technical Memorandum NMFS-NE Series

Editorial Production

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

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

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

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

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

Special Acknowledgments

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

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

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

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

152.

Internet Availability

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

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

Information Updating

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

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

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

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

Species Names

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

the American Fisheries Societys lists of scientific and common names for fishes (i.e., Robins et al. 1991a), mollusks (i.e.,

Turgeon et al. 1998b

), and decapod crustaceans (i.e., Williams et al. 1989c), and to follow the Society for Marine

Mammalogy's guidance on scientific and common names for marine mammals (i.e., Rice 1998d). Exceptions to this policy

occur when there are subsequent compelling revisions in the classifications of species, resulting in changes in the names

of species (e.g., Cooper and Chapleau 1998e

).

a

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

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

b

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

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

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

c

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

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

d

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

e

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

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

FOREWORD

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

commercial and recreational fisheries is the continuing

loss of marine, estuarine, and other aquatic habitats.

Magnuson-Stevens Fishery Conservation and

Management Act (October 11, 1996)

The long-term viability of living marine resources

depends on protection of their habitat.

NMFS Strategic Plan for Fisheries

Research (February 1998)

The Magnuson-Stevens Fishery Conservation and

Management Act (MSFCMA), which was reauthorized

and amended by the Sustainable Fisheries Act (1996),

requires the eight regional fishery management councils to

describe and identify essential fish habitat (EFH) in their

respective regions, to specify actions to conserve and

enhance that EFH, and to minimize the adverse effects of

fishing on EFH. Congress defined EFH as “those waters

and substrate necessary to fish for spawning, breeding,

feeding or growth to maturity.” The MSFCMA requires

NMFS to assist the regional fishery management councils

in the implementation of EFH in their respective fishery

management plans.

NMFS has taken a broad view of habitat as the area

used by fish throughout their life cycle. Fish use habitat

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

most habitats provide only a subset of these functions.

Fish may change habitats with changes in life history

stage, seasonal and geographic distributions, abundance,

and interactions with other species. The type of habitat,

as well as its attributes and functions, are important for

sustaining the production of managed species.

The Northeast Fisheries Science Center compiled the

available information on the distribution, abundance, and

habitat requirements for each of the species managed by

the New England and Mid-Atlantic Fishery Management

Councils. That information is presented in this series of

30 EFH species reports (plus one consolidated methods

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

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

HIGHLANDS, NEW JERSEY

SEPTEMBER 1999

independent data sets from NMFS and several coastal

states. The species reports are also the source for the

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

understandably begun to be referred to as the “EFH source

documents.”

NMFS provided guidance to the regional fishery

management councils for identifying and describing EFH

of their managed species. Consistent with this guidance,

the species reports present information on current and

historic stock sizes, geographic range, and the period and

location of major life history stages. The habitats of

managed species are described by the physical, chemical,

and biological components of the ecosystem where the

species occur. Information on the habitat requirements is

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

available, habitat and environmental variables that control

or limit distribution, abundance, growth, reproduction,

mortality, and productivity.

Identifying and describing EFH are the first steps in

the process of protecting, conserving, and enhancing

essential habitats of the managed species. Ultimately,

NMFS, the regional fishery management councils, fishing

participants, Federal and state agencies, and other

organizations will have to cooperate to achieve the habitat

goals established by the MSFCMA.

A historical note: the EFH species reports effectively

recommence a series of reports published by the NMFS

Sandy Hook (New Jersey) Laboratory (now formally

known as the James J. Howard Marine Sciences

Laboratory) from 1977 to 1982. These reports, which

were formally labeled as Sandy Hook Laboratory

Technical Series Reports, but informally known as “Sandy

Hook Bluebooks,” summarized biological and fisheries

data for 18 economically important species. The fact that

the bluebooks continue to be used two decades after their

publication persuaded us to make their successors – the 30

EFH source documents – available to the public through

publication in the NOAA Technical Memorandum NMFSNE series.

JEFFREY N. CROSS, CHIEF

ECOSYSTEMS PROCESSES DIVISION

NORTHEAST FISHERIES SCIENCE CENTER
Page v

Contents

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

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

Habitat Characteristics ..............................................................................................................................................................................2

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

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

Research Needs .........................................................................................................................................................................................6

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

Tables

Table 1. Mean length at age in silver hake, Merluccius bilinearis ..........................................................................................................9

Table 2. Observations of silver hake, Merluccius bilinearis, age and length at maturity ......................................................................10

Table 3. Published observations about silver hake: bottom water temperature, depth distributions, and preferences. .........................11

Table 4. Summary of habitat parameters for silver hake, Merluccius bilinearis ...................................................................................12

Table 5. Published reports of nearshore and estuarine occurrences of silver hake eggs and larvae from south of Cape Cod ...............13

Table 6. Average number of silver hake, Merluccius bilinearis, in Narragansett Bay, per tow by season. ...........................................14

Table 7. Distribution and abundance of silver hake, Merluccius bilinearis, in North Atlantic and Mid-Atlantic estuaries ..................15

Figures

Figure 1. The silver hake, Merluccius bilinearis (Mitchell) (from Goode 1884)..................................................................................16

Figure 2. Abundance of silver hake eggs relative to bottom temperature and depth from NEFSC MARMAP surveys .......................17

Figure 3. Abundance of silver hake larvae relative to bottom temperature and depth from NEFSC MARMAP surveys.....................18

Figure 4. Abundance of juvenile and adult silver hake relative to bottom temperature and depth based on NEFSC trawl surveys.....19

Figure 5. Abundance of juvenile and adults relative to bottom temperature and depth based on Massachusetts inshore surveys .......20

Figure 6. Abundance of juveniles relative to bottom temperature, DO, depth, and salinity from Hudson-Raritan trawl surveys ........21

Figure 7. Seasonal abundance of silver hake juveniles relative to bottom temperature and depth from Narragansett Bay surveys......22

Figure 8. Seasonal abundance of silver hake adults relative to bottom temperature and depth from Narragansett Bay surveys ..........23

Figure 9. Overall distribution of silver hake in the northwest Atlantic Ocean during 1975-1994 ........................................................24

Figure 10. Distribution and abundance of silver hake eggs collected during NEFSC MARMAP surveys.............................................25

Figure 11. Distribution and abundance of silver hake larvae collected during NEFSC MARMAP surveys ..........................................29

Figure 12. Distribution of juvenile and adult silver hake collected during NEFSC trawl surveys..........................................................33

Figure 13. Distribution and abundance of juvenile and adult silver hake collected during Massachusetts inshore surveys...................35

Figure 14. Distribution and abundance of juvenile silver hake collected in the Hudson-Raritan estuary...............................................36

Figure 15. Distribution, abundance and length frequencies of juvenile and adults collected during Narragansett Bay surveys ............37

Figure 16. Distribution, abundance, and length frequencies of juvenile and adults collected in Long Island Sound.............................40

Figure 17. Commercial landings and abundance indices for silver hake stocks .....................................................................................41

Figure 18. Distribution and abundance of juveniles and adults during low and high abundance periods from NEFSC trawl surveys ..42
Page 1

INTRODUCTION

Silver hake, Merluccius bilinearis (Figure 1), are

distributed on the continental shelf of the northwest

Atlantic Ocean from Cape Fear, North Carolina (Karnella

1973) to the Gulf of St. Lawrence and the southern edge

of the Grand Banks, Newfoundland, Canada (Leim and

Scott 1966). An early report of their southern range as

being deep waters off the Bahamas (Norman 1939) was

probably a misidentification of Merluccius albidus, the

offshore hake. Silver hake are most abundant from Nova

Scotia to New Jersey.

Silver hake are slender, fast swimming gadids that are

often found in dense schools associated with specific

hydrographic conditions, prey concentrations, and

spawning requirements. Analyses of bottom trawl catches

in U.S waters show that adult silver hake are found

throughout the survey area (Cape Hatteras, North Carolina

to Cape Sable, Nova Scotia) in winter and spring, but are

concentrated in deep basins in the Gulf of Maine and

along the continental slope from Nova Scotia to Cape

Hatteras (Almeida 1987; Helser et al. 1995; Helser 1996).

In U.S. waters, two stocks of silver hake have been

identified based on morphometric differences. One stock

occurs in the Gulf of Maine to northern Georges Bank

while the other stock ranges from southern Georges Bank

to Cape Hatteras. Juveniles and adults migrate to deeper

waters of the continental shelf as water temperatures

decline in the autumn and return to shallow waters in

spring and summer to spawn. Major spawning areas are

coastal Gulf of Maine, southern Georges Bank, and waters

south of Rhode Island. Silver hake are relatively fast

growing, reach sexual maturity at 2-3 years of age (20-30

cm), and live a maximum of 15 years, although in recent

years few fish older than 6 years are caught.

LIFE HISTORY

EGGS

The eggs are pelagic, 0.88-0.95 mm in diameter, drift

with the prevailing currents, and hatch in about two days

at 20o

C.

LARVAE

Newly hatch larvae are pelagic and are about 2.6-3.5

mm long. Pelagic life lasts about 2 months and at about

17-20 mm long the larvae descend to the bottom as

juveniles.

JUVENILES AND ADULTS

Studies of age and growth of silver hake in U.S.

waters began with Schaefer (1960). Nichy (1969) aged

juvenile fish and conducted an age validation study. In an

investigation of the effect of stock size on growth of

various age classes in the northern Georges Bank-Gulf of

Maine stock, Ross and Almeida (1986) found that mean

weight-at-age (2-5 years) was significantly inversely

correlated with three measures of stock density during

1962-1979. Almeida (1978) and Penntila et al. (1989)

used von Bertalanffy growth functions to describe growth

of the northern and southern stocks. Almeida (1978)

found faster growth and greater size in the northern stock

compared to the southern stock.

Helser (1996) made a detailed analysis of the growth

of silver hake in four areas of the U.S. continental shelf

during 1975-1980, 1982-1987, 1988-1992. He found

significant differences in growth between the Middle

Atlantic and southern Georges Bank in all three periods,

between northern Georges Bank and the Gulf of Maine

during 1975-1980 and 1982-1987, and between northern

and southern Georges Bank during 1982-1987. Growth in

the Gulf of Maine, on average, was slow, but the fish

attained the large asymptotic length (k = 0.33, L∞ = 47

cm) compared to the Middle Atlantic Bight (k = 0.51, L∞

= 43 cm); growth on Georges Bank was intermediate.

Females grow faster and live longer than males.

Reported maximum lengths and ages are 34 cm and 6

years for males and 60-64 cm and 12 years for females

(Bigelow and Schroeder 1953; Nichy 1969). Interestingly,

maximum lengths of silver hake collected during the

NMFS Northeast Fisheries Science Center (NEFSC)

bottom trawl survey are 78 cm in spring and 76 cm in

autumn. Table 1 lists mean lengths at age to indicate

relative size-at-age for Gulf of Maine, Middle Atlantic,

northern Georges Bank, and southern Georges Bank for

1988-1992.

Helser and Almeida (1997) performed a detailed

analysis of the possible effects of stock abundance,

growth, spring water temperatures, and depths on the

proportion of silver hake that are mature at age 2 and 3.

Population abundance accounted for most of the variation

in sexual maturity and growth in the southern stock

accounted for some additional variation. Both catchweighted water temperature and catch-weighted bottom

depth had no statistically significant effect on the

proportion mature at age 2 or 3 for the northern stock, or

at age 2 for the southern stock. A slight effect was found

for the proportion mature at age 3 for the southern stock.

REPRODUCTION

Female silver hake are asynchronous spawners that

produce and release several batches of eggs during the
Page 2

spawning season (Sauskan and Serebryakov 1968).

Silver hake eggs and larvae have been collected in all

months on the continental shelf in U.S. waters, although

the onset of spawning varies regionally (Bigelow and

Schroeder 1953; Marak and Colton 1961; Sauskan and

Serebryakov 1968; Fahay 1974; Morse et al. 1987;

Waldron 1988; Berrien and Sibunka 1999). Silver hake

spawn over a wide range of temperatures and depths. In

the Middle Atlantic Bight, newly spawned eggs were

collected at surface water temperatures between 13o

C and

22o

C (Fahay 1974). In the Gulf of Maine, Bigelow and

Schroeder (1953) reported that spawning temperatures

ranged from 5o

C to 13oC.

Spawning begins in January along the shelf and slope

in the Middle Atlantic Bight and proceeds north and east

to Georges Bank into May. By June spawning has spread

into the Gulf of Maine and continues to be centered on

Georges Bank through summer. In October, spawning is

centered in southern New England and by December

spawning is observed again along the shelf and slope in

the Middle Atlantic Bight. Over the U.S. continental shelf,

significant numbers of eggs are produced beginning in

May, numbers increase through August, and then decline

rapidly during September and October (Berrien and

Sibunka 1999).

The primary spawning grounds probably coincide

with concentrations of ripe adults and newly spawned

eggs. These grounds occur between Cape Cod,

Massachusetts, and Montauk Point, New York (Fahay

1974), on the southern and southeastern slope of Georges

Bank (Sauskan 1964) and the area north of Cape Cod to

Cape Ann, Massachusetts (Bigelow and Schroeder 1953).

Silver hake median length at maturity (i.e., 50%

mature) has declined in recent years. Table 2 lists

observations of silver hake age and length at maturity.

FOOD HABITS

The diet of silver hake consists primarily of fish,

crustaceans, and squids, depending on the size, age, and

sex of the silver hake (Schaefer 1960; Domanevsky and

Nozdrin 1963; Dexter 1969; Edwards and Bowman 1979;

Bowman 1984; Waldron 1993; Helser et al. 1995).

Young fish (< 20 cm) eat mainly crustaceans, such as

euphausiids and shrimps. As silver hake grow they

consume a larger proportion of fish and individuals > 35

cm feed almost exclusively on fish (Bowman 1984).

MIGRATION

During spring and summer, silver hake move into

nearshore waters in the Gulf of Maine, to the northern

edge of Georges Bank, and northward in the Middle

Atlantic Bight. By autumn, they return again to the

deeper basins in the Gulf and along the continental slope.

The pattern for juveniles is similar to adults in general

distribution and movements, except that the centers of

juvenile abundance occur in shallower waters. Juveniles

are abundant inshore along the Middle Atlantic and on the

shoals of Georges Bank.

STOCK STRUCTURE

Silver hake occurring on the U.S. continental shelf

have been divided into at least two stocks. Numerous

studies using a variety of methods, including

morphometrics (Conover et. al. 1961; Almeida 1987),

growth patterns on otoliths (Nichy 1969), serological

analyses (Konstantinov and Noskov 1969; Schenk 1981),

seasonal distribution patterns (Anderson 1974; Almeida

1987), and growth (Helser 1996), indicate that fish in the

Middle Atlantic Bight are distinct from fish in the Gulf of

Maine. The line dividing these two stocks occurs

somewhere between Nantucket Shoals and the northern

edge of Georges Bank. However, the results of these

studies are inconclusive and additional work is needed to

confirm the existence of biologically separate stocks (e.g.,

Helser 1996).

HABITAT CHARACTERISTICS

EGGS

Data from the NEFSC Marine Resources Monitoring,

Assessment and Prediction (MARMAP) ichthyoplankton

survey was used to determine the relationships between

bottom depth and water temperature in the upper 15 m

and silver hake egg abundances (Figure 2). Eggs occurred

in relatively deeper waters than the stations sampled. The

bottom depths where eggs were captured ranged from 10-

1250 m, but most eggs were collected between 50-150 m.

A shift to shallower shelf waters during late spring is

evident (Figure 2); the average depth of egg occurrences

declined from about 100 m in spring to about 60 m in

summer.

The percent frequencies of stations sampled show the

expected annual cycle in water temperatures (Figure 2)

and the occurrences of eggs show a similar cycle. During

the months of coldest temperatures (March and April)

silver hake eggs occurred in the coldest temperatures of

the year (5-12o

C). As the water warmed in the spring, the

occurrences of eggs shifted to warmer waters until

summer, when eggs were found mostly between 13 and

20o

C. During autumn the waters began to cool and egg

occurrences shifted to cooler waters (10-15o

C). Peak

abundance of eggs occurred from June to September and

during these months most eggs were found in

temperatures 11-17o

C. The large bar in June at 21oC
Page 3

reflects an unusually large catch of eggs (18,908 eggs/10

m2

).

The results presented for the NEFSC MARMAP

survey agree with published observations of depth and

temperature occurrences of silver hake eggs (Bigelow and

Schroeder 1953; Fahay 1974; Waldron 1988).

LARVAE

The relationships of bottom depth and water

temperature in the upper 15 m of water to the abundance

of silver hake larvae from the NEFSC MARMAP survey

are shown in Figure 3. Larvae occurred in relatively

deeper water than the overall depths of stations sampled

although generally shallower than eggs. The bottom

depths where larvae were captured ranged from 10 to

1250 m, but most occurred between 50-130 m. The

depths of larvae occurrence remained stable throughout

most of the year but a shift to slightly deeper waters

occurred during May and June.

The occurrences of larvae in relation to water

temperature in the top 15 m showed a shift in preferred

temperatures that followed the annual warming and

cooling cycle (Figure 3). During the months of coldest

temperatures (February and March) silver hake larvae

were found in the coldest water of the year (5-12o

C). As

the water warmed in the spring, the occurrences of larvae

shifted to warmer waters until summer when they were

found mostly between 10 and 16o

C. During autumn, the

waters began to cool, but larvae remained in warmer

waters (10-16o

C). Peak abundance of larvae occurred

from July to October and during these months most were

found in temperatures 11-16o

C.

JUVENILES

Based on the NEFSC bottom trawl survey, the

relationships of bottom temperature and depth to catches

of juvenile silver hake in spring and autumn are shown in

Figure 4. In spring, silver hake were captured at

temperatures of 3-17o

C and bottom depths of 5-350 m.

Their preferred temperatures and depths were 6-9o

C and

150-275 m. In autumn, they occurred in temperatures and

depths of 5-22o

C and 5-350 m and their preferred ranges

were 10-17o

C and 25-75 m.

The relationships of bottom temperature and depth to

catches of juvenile silver hake in spring and autumn from

the Massachusetts trawl survey are shown in Figure 5.

Juveniles were caught at all depths and temperatures

during both seasons. No clear temperature preference was

detected in spring, but in autumn, 7-11o

C was preferred.

During both seasons, the shallowest depths (< 20 m) had

the smallest catches of juveniles.

Analyses of the Hudson-Raritan estuary trawl study

data on the relationships of bottom temperature, dissolved

oxygen, salinity, and depth to catches of juvenile silver

hake in spring and autumn are shown in Figure 6. Silver

hake occurred at temperatures from 1-17o

C and preferred

temperatures from 9-14o

C. The preferred levels of

dissolved oxygen were 7-9 mg/l. They occurred at all

depths sampled except 10 m and showed preference for

depths of 10-20 m. Juveniles avoided salinities less than

20 ppt and showed preferences for salinities above 28 ppt.

In the Rhode Island trawl surveys, juvenile hakes

were relatively abundant in Narragansett Bay at depths

near 30 m during winter, spring and summer and at 10 m

in autumn (Figure 7). They occurred at most bottom

temperatures but preferred 9o

C temperatures in summer.

ADULTS

Silver hake adults and juveniles are found over wide

temperature and depth ranges in U.S. continental shelf

waters (Table 3). The relationships of bottom temperature

and depth to catches of adult silver hake in spring and

autumn from the NEFSC bottom trawl survey are shown

in Figure 4. In spring, adult silver hake were captured at

temperatures of 3-19o

C and bottom depths of 5–400 m.

Their preferred temperature and depths in spring were 7-

13o

C and 125–325 m. In autumn, they occurred in

temperatures and depths of 4-22o

C and 5–500 m and their

preferred ranges were 7-11o

C and 150–225 m.

Based on the Massachusetts trawl survey, the

relationships of bottom temperature and depth to catches

of adult silver hake in spring and autumn are shown in

Figure 5. They occurred at all temperatures in spring and

no clear temperature preference could be detected. In

autumn, they occurred in temperatures from 5-17o

C but

preferred temperature from 7-11o

C. They were caught at

depths > 5 m in spring and > 15 m in autumn. During

both seasons, the lowest numbers of adults were caught in

the shallower depths (< 20 m).

The Hudson-Raritan estuary trawl surveys caught a

total of just one adult silver hake in January 1995. In

Narragansett Bay, adult hakes were relatively abundant at

depths > 20 m in all seasons (Figure 8) and showed a

preference for bottom temperatures between 7 and 16o

C.

In Long Island Sound, silver hake were found at all

temperatures sampled, except at 23o

C in autumn, and they

showed no particular preference for temperature in either

spring or autumn. Hakes were captured at most depths

sampled and showed no preference for particular depths in

spring or autumn. Silver hake were captured throughout

the range of salinities observed in the sound. No clear

salinity preference was evident in spring, but in autumn,

hakes were captured at higher than average salinities.

Scott (1982) reports that silver hake on the Scotian

Shelf prefer salinities between 33 and 34 ppt, but were

captured in waters with salinity from 31 to 34 ppt. In a
Page 4

large-scale analysis of research bottom trawl surveys on

the Scotian Shelf, Scott (1982) found silver hake occurred

on all bottom types from gravel to fine silt and clay, but

were mainly associated with silts and clays. The areal

trends in bottom type on the Scotian Shelf shows that

coarse sand and gravel are associated with shallow water

and finer grain deposits with deeper water and that the

proportion of gravel increases from east to west. Thus,

the areal trends in grain size and bottom water

temperatures, as well as prey distributions, confound our

ability to determine which factors contribute to

distribution patterns of silver hake on the Scotian Shelf.

On the extremely fine-scale, Auster et al. (1997)

found that silver hake (1.5-5 cm) were more abundant on

silt-sand bottoms containing amphipod tubes at 55 m deep

in the Middle Atlantic Bight. Silver hake (12.6-27.6 cm)

were found on flat sand, sand-wave crests, shell and

biogenic depressions, but were most often found on flat

sand at one site in the Middle Atlantic Bight (Auster et al.

1991).

A summary of the ranges and preferences of various

environmental parameters of the life stages of silver hake

are presented in Table 4.

GEOGRAPHICAL DISTRIBUTION

The overall distribution of silver hake is from the

Gulf of St. Lawrence to Cape Hatteras (Figure 9). The

areas of highest abundance are the southern edge of the

Grand Bank, the Scotian Shelf, the Gulf of Maine,

Georges Bank, and the Middle Atlantic Bight off Long

Island.

EGGS

Silver hake eggs were found throughout the area

surveyed during NEFSC MARMAP ichthyoplankton

surveys (Figure 10). They were most abundant in the

deeper parts of Georges Bank (> 60 m) and the shelf off

southern New England. Eggs were captured in all months

of the year. From January to March, eggs occurred in

small numbers in the deep waters of the Middle Atlantic

Bight. By April, the occurrence of eggs extended

eastward along the southern edge of Georges Bank and

the total number of eggs increased slightly. During May

and June the catches of eggs extended onto the shelf and

into nearshore waters in the Middle Atlantic Bight and

southern New England areas. Some eggs were captured in

the western part of the Gulf of Maine. By July and

August the center of abundance had shifted east onto

Georges Bank with southern New England and the Gulf of

Maine continuing to show some catches of eggs. In

September and October the occurrences of eggs began to

decline with centers of abundance still on Georges Bank

and into southern New England. Few eggs were captured

in November or December but most occurred again in

deeper waters of the Middle Atlantic Bight.

LARVAE

The individual survey distributions of silver hake

larvae from Cape Hatteras, North Carolina to Nova

Scotia, based on 50 ichthyoplankton surveys in the

NEFSC MARMAP series (1977-1984), reveal

considerable year-to-year differences in the temporal and

spatial patterns of abundance. Centers of abundance in

July - September occurred on Georges Bank and in

southern New England in 1977, 1978, 1982, and 1983. In

1981 few larvae were found anywhere in the survey area.

Only in 1979 and 1980 were significant numbers of larvae

encountered in the Gulf of Maine (Morse et al. 1987).

The cumulative distribution and abundance of silver

hake larvae from all NEFSC MARMAP surveys is shown

in Figure 11. The overall pattern of distribution is similar

to the distribution of eggs, wherein the center of

abundance is on Georges Bank and a secondary center is

in the southern New England area. Few larvae were

captured from January through March, none in April, and

most occurred in the Middle Atlantic Bight (Figure 11).

The low catches reflect the relatively low egg production

of silver hake during the early months of the year. During

May and June larvae were abundant from off Virginia to

the southwestern part of Georges Bank in depths from 60-

130 m. The peak months of larval abundance were JulySeptember and the centers of abundance were now in

southern New England and on Georges Bank.

Distribution of larvae during October to December had

shifted to the west from Georges Bank to southern New

England and the Middle Atlantic Bight and abundance

had dropped following the decrease in egg production

during the late autumn and early winter. Table 5 lists the

published reports of the nearshore and estuarine

occurrences of silver hake eggs and larvae south of Cape

Cod.

JUVENILES

Based on the NEFSC bottom trawl survey, juvenile

silver hake occurred across the shelf in the Middle

Atlantic Bight and southern New England areas, along the

southern and northern edges of Georges Bank, and

scattered throughout the Gulf of Maine in the winter

(Figure 12). In the spring, they occurred throughout the

survey area but tended to avoid the shallowest part of

Georges Bank. Concentrations occurred in relatively

shallow waters in southern New England and in most of

the southern and western parts of the Gulf of Maine.

Positive catches during summer surveys show a
Page 5

distribution similar to that in the spring. By autumn, the

distribution of juveniles again covered the shelf with small

catches in the southern part of the Middle Atlantic Bight

and in the center of the Gulf of Maine. Centers of

abundance occurred in nearshore waters off New Jersey

and Long Island, south of Rhode Island, on Georges

Bank, and along the coast of Massachusetts and Maine.

Silver hake juveniles were caught throughout the

Massachusetts trawl survey area in spring and autumn and

were concentrated off Cape Ann, in Cape Cod Bay and

south of Martha’s Vineyard. Light catches were made in

Vineyard Sound and Buzzards Bay (Figure 13).

Juvenile silver hake were collected throughout most

of the Hudson-Raritan estuary survey area but were

concentrated in areas near the ocean (Figure 14). The

highest catches occurred in autumn (Oct.-Dec.) and no

juveniles were captured in summer (July-Aug.).

Juvenile silver hake were captured throughout

Narragansett Bay in all seasons with the highest average

catches of juveniles (~3 hake/tow) occurring in summer

(Table 6; Figure 15). In general, low numbers of hake

occurred throughout the Bay and the highest average

catches were at the ocean station 1. Seasonal length

frequencies indicate that juveniles and adults occurred in

similar proportions during all seasons except summer

when juveniles dominated the catches.

The catches of silver hake in Long Island Sound were

dominated by fish < 23 cm long in both seasons and

occurred throughout the bay (Figure 16).

ADULTS

Based on the NEFSC bottom trawl survey, silver hake

were distributed across the shelf in the northern Middle

Atlantic Bight and southern New England areas, along the

southern and northern edges of Georges Bank, and

scattered throughout the Gulf of Maine in the winter

(Figure 12). In the spring, they occurred throughout the

survey area but tended to avoid the shallowest parts of the

Middle Atlantic Bight and Georges Bank. Concentrations

occurred in relatively deep waters of the Middle Atlantic,

southern New England, along the southern and northern

edges of Georges Bank, and in the western part of the

Gulf of Maine. Positive catches during summer surveys

showed a distribution similar to that in the spring. By

autumn, the distribution of adults again covered the shelf

except for the southwestern part of the Middle Atlantic

Bight and in the center of Georges Bank. Centers of

abundance occurred in south of Rhode Island, on the

northern edge of Georges Bank, and most of the Gulf of

Maine.

Based on the Massachusetts trawl survey, silver hake

adults were caught throughout the survey area in spring

and north of Cape Cod in autumn. They were

concentrated south of Martha’s Vineyard and Nantucket

in spring and off Cape Ann and in Cape Cod Bay in

autumn. Small catches were made in Vineyard Sound and

Buzzards Bay in both seasons (Figure 13).

The Hudson-Raritan estuary trawl survey caught a

total of just one adult silver hake in January 1995. Results

of the Rhode Island trawl survey showed that, in general,

low numbers of hake occurred throughout Narragansett

Bay and the highest average catches were at the ocean

station 1. Adult hakes occurred throughout the bay in

small numbers in all seasons (Figure 15). Seasonal length

frequencies indicate that juveniles and adults occurred in

similar proportions during all seasons except summer

when juveniles dominated the catches (Figure 15).

The catches of silver hake in Long Island Sound

showed a high incidence of adults (> 22 cm) in spring.

Based on the wide distribution of silver hake adults, it

appears that they occur in all areas of the sound (Figure

16).

Jury et al. (1994) compiled summaries of the

occurrence and relative abundance of eggs, larvae,

juveniles, and adults in estuaries north of Cape Cod and

Stone et al. (1994) compiled similar data for Cape Cod to

Cape Hatteras (Table 7).

STATUS OF THE STOCKS

According to the Report to Congress on the Status of

Fisheries of the United States (National Marine Fisheries

Service 1997), the Gulf of Maine/northern Georges Bank

stock (GBGM) of silver hake is not overfished while the

southern Georges Bank/Middle Atlantic stock (SGBMA)

is overfished. The GBGM silver hake stock biomass

accounts for, on average, about 80% of the NEFSC

autumn survey stratified mean catch-per-tow (in

kilograms). The NEFSC autumn survey mean catch-pertow for the two stocks is used herein to indicate interannual changes in stock size (Figure 17).

GULF OF MAINE/NORTHERN GEORGES

BANK STOCK

The autumn research bottom trawl catches declined in

the mid- to late 1960s to the lowest catches on record

when there was a period of heavy exploitation by distant

water fleets. Strong year classes in 1973 and 1974 helped

to increase stock biomass during the mid-1970s, but stock

size again declined until the early 1980s. Since that time

biomass indices have increased significantly but with wide

annual fluctuations. From the low biomass estimates in

the 1960s when catch-per-tows were 2-3 kg, the stock size

has increased to about 10 kg/tow during the last 10 years.

Contrary to the bottom trawl catches, results from virtual

population analysis showed a significant decline through

1986 in stock biomass from the pre-1975 period (Helser
Page 6

1995).

SOUTHERN GEORGES BANK/MIDDLE

ATLANTIC STOCK

Similar to the GBGM stock, the SGBMA stock

apparently declined during the 1960s and early 1970s

based on a significant decline in the autumn stratified

mean catch-per-tow. Stock size increased somewhat until

about 1985, but has declined to historically low levels in

recent years. Research bottom trawl catches have ranged

from about 3-4 kg/tow in the 1960s to about 0.5-0.8

kg/tow in the mid-1990s.

Periods of high (1989-1993) and low abundance

(1967-1971) (see Figure 17) were analyzed for the

distribution and relative abundance of juveniles and adults

in autumn (Figure 18). The overall distribution of

juveniles and adults appears about the same regardless of

stock size. The relative abundance is quite different

between the two time periods. Much higher catches of

juveniles and adults occurred on Georges Bank and

particularly in the Gulf of Maine during the period of high

abundance.

RESEARCH NEEDS

• Questions remain about the definition of silver hake

stocks. Research is needed to define the biological

basis of the two (or more) stocks. Seasonal

distributions indicate considerable movement of fish

across the current stock boundary line on Georges

Bank, which raises the question of the degree of

intermixing between the stocks.

• The habitat parameters used in this report are

location, depth, temperature, and, for Long Island

Sound, salinity. A critical parameter is bottom type,

which needs to be included in future habitat

considerations.

• Little is known about the effects of the prey field on

the distribution in space and time of silver hake.

Additional food habits analysis is needed to

determine the possible relationships of predator-prey

and distribution and abundance.

• There are indications that fine scale (less than shelf

wide) habitat characteristics may be important at

various times in the life of silver hake. Examples are

food and predator abundance during the larval stage,

fine-scale bottom structure for small juveniles, and

the contribution of estuaries to the success of year

classes.

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Page 9

Table 1. Mean length (cm) at age (years) in silver hake, Merluccius bilinearis, for Gulf of Maine (GM), Middle Atlantic

(MA), northern Georges Bank (NGB), and southern Georges Bank (SGB) from samples collected during 1988-1992;

based on Helser (1996).

Area

Age GM MA NGB SGB

1 12.3 9.1 12.1 11.7

2 22.0 21.2 22.1 21.4

3 28.8 28.7 28.8 27.8

4 33.6 33.5 33.3 31.9

5 37.0 36.4 36.3 34.6

6 39.3 38.2 38.3 36.4

7 41.0 39.4 39.7 37.5

8 42.1 40.1 40.6 38.3

9 43.0 40.5 41.2 38.8

10 43.5 40.8 41.6 39.1

11 43.9 41.0 41.9 39.3

12 44.2 41.1 42.1 39.4
Page 10

Table 2. Observations of silver hake, Merluccius bilinearis, age and length at maturity.

Author Years Area Age (years) Length (cm)

Bigelow and Schroeder

1953

1950s Gulf of

Maine

~ 2

Sauskan 1964 1962-

1964

Georges

Bank

2-3 29-33

Morse 1979 1977 US Shelf 24-26

Beacham 1983 1960s1970sScotian Shelf 1-2 31 females

1960s;

26 females 1970s

O’Brien et al. 1993 1985-

1989

US Shelf 1.6-1.7 22.3-22.7 males

23.1-23.2 females

Helser and Almeida

1997

1973-

1990

US Shelf 2 - 20% mature in 1973

2 - 80% mature in 1990
Page 11

Table 3. Published observations about silver hake, Merluccius bilinearis: bottom water temperature, depth distributions,

and preferences.

Author Area Temperature (°C) Depth (m)

Range Preference Range Preference

Bigelow and

Schroeder

1953

Gulf of

Maine

4-18 > 6 tide line -

> 700

Domanevsky

and Nozdrin

1963

Southeast

Georges

Bank

9-11 90-110

Sauskan 1964 Georges

Bank;

1962-1963

6-12 10-12: ripe

adults, 6-10:

post spawn

85-200 spring

40-110 summer

Fritz 1965 Continental

Shelf, NJ to

Nova Scotia;

Autumn,

1955-1961

3.9-19.4 6-12 30-410 70-210

Sarnits and

Sauskan 1967

Georges

Bank 1964

7-8 140-230

Edwards

1965

Southern

New England

> 9

Scott 1982 Eastern Gulf

of Maine

1-13 7-10 15 - > 200

fathoms

80-89 fathoms

Almeida

1987

U.S

Continental

Shelf

Adults:

inshore - 400

Murawski

and Finn

1988

Georges

Bank

Winter: 5.97

Spring: 8.45

Summer: 8.95

Autumn: 8.42

Winter: 208

Spring: 186

Summer: 97

Autumn: 163

Murawski

1993

U.S

Continental

Shelf

Spring: 6.76

Summer: 8.03

Autumn: 10.00

Spring: 186

Summer: 97

Autumn: 163

Helser and

Almeida

1997

U.S

Continental

Shelf

5.5-10.5 most > 8.0 southern

Stock

50-150 most > 80 southern

Stock
Page 12

Table 4. Summary of habitat parameters for silver hake, Merluccius bilinearis.

Life

Stage

Temperature

Range (o

C)

Temperature

Preference (oC)

Depth

Range

(m)

Depth

Preference

(m)

Salinity

Preference

(ppt)

Dissolved

Oxygen

(mg/l)

Bottom

Type

Eggs 5-20 11-17 10-1250 50-150

Larvae 7-20 10-16 10-1250 50-130

Juveniles 3-17 Spring,

5-22 Autumn

6-9 Spring,

10-17 Autumn

5-350

Spring,

5-350

Autumn

150-270

Spring,

25-75

Autumn

HudsonRaritan: >

18, Long

Island

Sound: 28-

30

HudsonRaritan: 5-7Silt-sand in

Mid-Atlantic

Bight. All

types on

Scotian Shelf

Adults 3-9 Spring,

4-22 Autumn

7-13 Spring,

7-11 Autumn

5-400

Spring,

5-500

Autumn

125-325

Spring,

150-225

Autumn

All types on

Scotian Shelf
Page 13

Table 5. Published reports of the nearshore and estuarine occurrences of silver hake, Merluccius bilinearis, eggs and

larvae from the area south of Cape Cod.

Study Area and Dates Eggs Larvae

Herman 1963 Narragansett Bay

March 1957 - March

1958, weekly sampling

6 eggs July - October.

Temperatures 14.8 -

21.4o

C

33 larvae July - October

Temperatures 12.0 - 22.4o

C

Bourne and

Govoni 1988

Narragansett Bay, RI

June 1972 - August

1973

Listed as present in low

numbers

Listed as present in low

numbers

Perlmutter 1939 Salt waters of Long

Island, NY 1938

Small numbers off

Montauk Point in June

& July

37 Larvae (2.6-6.0 mm)

from June to September,

most in June in Block

Island Sound

Merriman and

Sclar 1952

Block Island Sound, RI

1943 - 1946

None 16 larvae (4.0 - 9.0mm)

July and November

Wheatland 1956 Long Island Sound

March 1952 - March

1954

None None

Richards 1959 Long Island Sound

1954 - 1955

None None

Monteleone

1992

Great South Bay, NY

April 1985 - December

1986

None None

Dovel 1981 Hudson River March -

December 1972

None None

Virginia Institute

of Marine

Science

Fisheries

Laboratory 1961

Lower Chesapeake Bay

and nearshore ocean

December 1959 -

December 1960

None 31 larvae (4-21mm) caught

only in the ocean.

December - April, June
Page 14

Table 6. Average number of silver hake, Merluccius bilinearis, in Narragansett Bay, per tow by season. From the Rhode

Island Division of Fish and Wildlife bottom trawl surveys of Narragansett Bay, 1990 - 1996.

Species Juveniles Adults

Winter Spring Summer Autumn Winter Spring Summer Autumn

Silver Hake 2.353 0.286 3.031 1.425 1.495 0.449 0.179 0.187
Page 15

Table 7. Summary of the distribution and abundance of silver hake, Merluccius bilinearis, in North Atlantic and MidAtlantic estuaries based on Jury et al. (1994) and Stone et al. (1994).

Adults Sp Adults Juveniles Larvae Eggs

Estuary T M S T M S T M S T M S T M S

 Passamaquoddy Bay c a r c a * * r * * r

 Englishman/Machias Bays c a r c a * * r * * r

 Narragaugus Bay c a r c a * * r * * r

 Blue Hill Bay c a r c a * * r * * r

 Penobscot Bay c a r c a * * r * * r

 Muscongus Bay c c r c c * * r * * r

 Damariscotta Bay c c r c c * * r * * r

 Sheepscot Bay c a r c c * * r * * r

 Kennebec/Androscoggin Rivers c c n c c * * n * * n

 Casco Bay c c r c c * r c r c

 Saco Bay c c r c c r r r r

 Wells Harbor nz r nz * nz r nz r nz r

 Great Bay r r r r

 Merrimack River r nz nz r nz r nz r nz

 Massachusetts Bay nz nz c nz nz c nz nz c nz nz c nz nz c

 Boston Harbor nz c c nz nz c c nz r c nz r c

 Cape Cod Bay nz c c nz c nz c c nz r c nz r c

 Waquoit Bay n n n n n n n n n n n n n n n

 Buzzards Bay n n n n n n n n n n n n n n n

 Narragansett Bay n n n n n n n n n n n n n n n

 Connecticut River n n n n n n n n n n n n n n n

 Gardiners Bay n n n n n n n n n n n n n n n

 Long Island Sound n n n n n n n n n n n n n n n

 Great South Bay n n n n n n n n n n n n n n n

 Hudson River/Raritan Bay n n n n n n n n n n n n n n n

 Barnegat Bay n n n n n n n n n n n n n n n

 New Jersey Inland Bays n n n n n n n n n n n n n n n

 Delaware Bay n n n n n n n n n n n n n n n

 Delaware Inland Bays n n n n n n n n n n n n n n n

 Chincoteague Bay n n n n n n n n n n n n n n n

 Chesapeake Bay mainstream n n n n n n n n n n n n n n n

 Chester River n n n n n n n n n n n n n n n

 Choptank River n n n n n n n n n n n n n n n

 Patuxent River n n n n n n n n n n n n n n n

 Potomac River n n n n n n n n n n n n n n n

 Tangier/Pocomoke Sounds n n n n n n n n n n n n n n n

 Rappahannock River n n n n n n n n n n n n n n n

 York River n n n n n n n n n n n n n n n

 James River n n n n n n n n n n n n n n n

Relative Abundance

h = Highly abundant, a = abundant,

c = common, r = rare, blank = not present,

n = no data presented, * = no data available,

nz = particular zone not present

Data Reliability for Life Stages

Highly Certain = Bold and Underlined Text

Moderately Certain = Bold Text

Reasonable Inference = Normal Text

Tidal Zones

T = Tidal Fresh 0.0-0.5 ppt

M= Mixing Zone 0.5-25 ppt

S = Seawater Zone > 25 ppt
Page 16

Figure 1. The silver hake, Merluccius bilinearis (Mitchell) (from Goode 1884).
Page 17

Figure 2. Abundance of silver hake eggs relative to water column temperature and bottom depth from NEFSC

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

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

).

January

0

10

20

30

40

Stations

Egg Catch

April

0

10

20

30

May

0

10

20

30

June

Percent

0

10

20

30

July

0

10

20

August

0

10

20

October

0

10

20

30

Silver Hake Eggs

September

0

10

20

February

0

10

20

60

80

March

0

10

20

30

November

0

10

20

30

December

Water Temperature (0 to 15m, C)

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

0

10

20

30

January

0

10

20

30

40

Stations

Egg Catch

April

0

10

20

30

40

October

0

10

20

30

Silver Hake Eggs

September

0

10

20

30

May

0

10

20

30

June

Percent

0

10

20

30

40

July

0

10

20

30

40

August

0

20

40

60

December

Bottom Depth (m), Interval Midpoint

10

30

50

70

90

110

130

150

170

190

210

230

250

270

290

325

375

450

750

1250

1750

>2000

0

10

20

30

November

0

10

20

30

March

0

10

20

30

February

0

10

20

60

70
Page 18

Figure 3. Abundance of silver hake larvae relative to water column temperature and bottom depth from NEFSC

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

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

).

January

0

10

20

30

60

70

Stations

Larva Catch

December

Bottom Depth (m), Interval Midpoint

10

30

50

70

90

110

130

150

170

190

210

230

250

270

290

325

375

450

750

1250

1750

>2000

0

10

20

30

40

Silver Hake Larvae (<20mm length)

September

0

10

20

30

40

June

Percent

0

10

20

30

40

July

0

10

20

30

40

50

August

0

10

20

30

40

October

0

10

20

30

40

March

0

10

20

30

90

100

February

0

10

20

40

50

November

0

10

20

40

60

May

0

10

20

30

January

0

10

20

30

Stations

Larva Catch

May

0

10

20

30

June

Percent

0

10

20

30

40

July

0

10

20

30

40

August

0

10

20

30

November

0

10

20

30

Silver Hake Larvae (<20mm length)

September

0

10

20

30

March

0

10

20

90

100

October

0

10

20

30

February

0

10

20

30

40

December

Water-Column Temperature (C)

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

0

10

20

30

40
Page 19

Figure 4. Abundance of juvenile and adult silver hake relative to bottom water temperature and depth based on NEFSC

bottom trawl surveys for spring (1968-1997) and autumn (1963-1996), all years combined. Open bars represent the

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

(number/10 m2

).

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

10

20

30

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

4

8

12

16

0

4

8

12

16

0

10

20

30

40

0

4

8

12

16

20

0

4

8

12

16

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

4

8

12

16

20

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

5

10

15

20

Juveniles 25 Adults

Stations

Catches

Spring Spring

Spring Spring

Autumn Autumn

Autumn Autumn

Bottom Depth (m) Bottom Depth (m)

Bottom Depth (m) Bottom Depth (m)

Bottom Temperature (C) Bottom Temperature (C)

Bottom Temperature (C) Bottom Temperature (C)

NMFS Bottom Trawl Surveys

Silver Hake
Page 20

Figure 5. Abundance of juvenile and adult silver hake relative to bottom water temperature and depth based on

Massachusetts inshore bottom trawl surveys (spring and autumn 1978-1996) for all years combined. Open bars represent

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

(number/10 m2

).

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

4

8

12

16

20

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

5

10

15

20

25

0

5

10

15

20

25

0

5

10

15

20

25

0

5

10

15

20

25

0

10

20

30

40

50

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

10

20

30

40

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

5

10

15

20

25

Juveniles Adults

Stations

Catches

Spring Spring

Spring Spring

Autumn Autumn

Autumn Autumn

Bottom Depth (m) Bottom Depth (m)

Bottom Depth (m) Bottom Depth (m)

Bottom Temperature (C) Bottom Temperature (C)

Bottom Temperature (C) Bottom Temperature (C)

Mass. Inshore Trawl Surveys

Silver Hake
Page 21

Figure 6. Abundance of juvenile silver hake (< 23 cm) relative to bottom water temperature, dissolved oxygen, depth,

and salinity from Hudson-Raritan estuary trawl surveys (January 1992 - June 1997, all years combined).

Temperature (C)

Depth (ft)

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

0

2

4

6

8

10

12

14

Stations

Catches

10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85

0

5

10

15

20

25

30

35

Dissolved Oxygen (mg/l)

Salinity (ppt)

0 1 2 3 4 5 6 7 8 9 10 11 12 13

0

5

10

15

20

25

30

35

15 17 19 21 23 25 27 29 31 33 35

0

5

10

15

20

25

30
Page 22

Figure 7. Seasonal abundance of silver hake juveniles (< 23 cm) relative to mean bottom water temperature and bottom

depth from Rhode Island Narragansett Bay trawl surveys, 1990-1996. Open bars represent the proportion of all stations

surveyed, while solid bars represent the proportion of the sum of all catches.

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

0

10

20

30

40

50

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

0

20

40

60

80

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

0

4

8

12

16

20

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

0

20

40

60

80

Bottom Temperature (C)

Winter

Spring

Summer

Autumn

Stations

Catches

10 20 30 40 50 60 70 80 90 100 110 120

0

10

20

30

40

50

10 20 30 40 50 60 70 80 90 100 110 120

0

10

20

30

40

10 20 30 40 50 60 70 80 90 100 110 120

0

20

40

60

10 20 30 40 50 60 70 80 90 100 110 120

0

20

40

60

80

Winter

Autumn

Summer

Spring

Stations

Catches

Bottom Depth (ft)
Page 23

Figure 8. Seasonal abundance silver hake adults (≥ 23 cm) relative to mean bottom water temperature and bottom depth

from Rhode Island Narragansett Bay trawl surveys, 1990-1996. Open bars represent the proportion of all stations

surveyed, while solid bars represent the proportion of the sum of all catches.

10 20 30 40 50 60 70 80 90 100 110 120

0

10

20

30

40

50

10 20 30 40 50 60 70 80 90 100 110 120

0

10

20

30

40

50

10 20 30 40 50 60 70 80 90 100 110 120

0

20

40

60

80

10 20 30 40 50 60 70 80 90 100 110 120

0

20

40

60

Autumn

Summer

Spring

Stations

Catches

Bottom Depth (ft)

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

0

10

20

30

40

50

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

0

20

40

60

80

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

0

20

40

60

80

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

0

20

40

60

80

Bottom Temperature (C)

Winter

Spring

Summer

Autumn

Stations

Catches

Winter
Page 24

Figure 9. Overall distribution of silver hake in the northwest Atlantic Ocean during 1975-1994. Data are from the U.S.

NOAA/Canada DFO East Coast of North America Strategic Assessment Project (http://www-orca.nos.noaa.gov/projects/

ecnasap/ecnasap_table1.html).
Page 25

Figure 10. Distribution and abundance of silver hake eggs collected during NEFSC MARMAP ichthyoplankton surveys,

January to December, 1978-1987 [see Reid et al. (1999) for details].

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

35

36

37

38

39

40

41

42

43

44

45

Eggs

MARMAP Ichthyoplankton Surveys

61-cm Bongo Net; 0.505-mm mesh

January to December; 1978 to 1987

Number of tows = 9478, with eggs = 1897

Silver Hake

Eggs / 10m2

1 to <10

10 to <100

100 to <1000

1000 to <10000

10000 to 24264

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

35

36

37

38

39

40

41

42

43

44

45

January, 1978 to 1987

Number of tows = 433, with eggs = 19

None

1 to < 10

10 to < 100

100 to 132

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

February, 1978 to 1987

Number of tows = 459, with eggs = 6

None

1 to < 10

10 to < 100

100 to 111

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

March, 1978 to 1987

Number of tows = 853, with eggs = 29

None

1 to < 10

10 to < 100

100 to 133

Eggs / 10m2
Page 26

Figure 10. cont’d.

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

35

36

37

38

39

40

41

42

43

44

45

April, 1978 to 1987

Number of tows = 1020, with eggs = 63

None

1 to < 10

10 to < 100

100 to 835

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

May, 1978 to 1987

Number of tows = 1085, with eggs = 276

None

1 to < 10

10 to < 100

100 to < 1000

1000 to 7073

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

June, 1978 to 1987

Number of tows = 709, with eggs = 216

None

1 to < 10

10 to < 100

100 to < 1000

1000 to < 10000

Eggs / 10m2

10000 to 18908

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

35

36

37

38

39

40

41

42

43

44

45

July, 1978 to 1987

Number of tows = 781, with eggs = 294

None

1 to < 10

10 to < 100

100 to < 1000

1000 to < 10000

Eggs / 10m2

10000 to 10168
Page 27

Figure 10. cont’d.

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

35

36

37

38

39

40

41

42

43

44

45

August, 1978 to 1987

Number of tows = 863, with eggs = 329

None

1 to < 10

10 to < 100

100 to < 1000

1000 to < 10000

Eggs / 10m2

10000 to 24264

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

35

36

37

38

39

40

41

42

43

44

45

September, 1978 to 1987

Number of tows = 747, with eggs = 212

None

1 to < 10

10 to < 100

100 to < 1000

1000 to 6416

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

October, 1978 to 1987

Number of tows = 1044, with eggs = 320

None

1 to < 10

10 to < 100

100 to < 1000

1000 to 2735

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

November, 1978 to 1987

Number of tows = 915, with eggs = 117

None

1 to < 10

10 to < 100

100 to 303

Eggs / 10m2
Page 28

Figure 10. cont’d.

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

35

36

37

38

39

40

41

42

43

44

45

December, 1978 to 1987

Number of tows = 569, with eggs = 16

None

1 to < 10

10 to 37

Eggs / 10m2
Page 29

Figure 11. Distribution and abundance of silver hake larvae collected during NEFSC MARMAP ichthyoplankton

surveys, 1977-1987 [see Reid et al. (1999) for details].

MARMAP Ichthyoplankton Surveys

61-cm Bongo Net; 0.505-mm mesh

Jan. to March / May to Dec.; 1977 to 1987

Silver Hake

Number of Tows = 10157, with larvae = 1544

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

35

36

37

38

39

40

41

42

43

44

45

1 to < 10

10 to < 100

100 to < 1000

1000 to 9396

Number of Larvae / 10m2

January, 1977 to 1987

Number of Tows = 434, 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 34

February, 1977 to 1987

Number of Tows = 686, with larvae = 6

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

March, 1977 to 1987

Number of Tows = 1031, with larvae = 1

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
Page 30

Figure 11. cont’d.

May, 1977 to 1987

Number of Tows = 1472, with larvae = 58

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 403

June, 1977 to 1987

Number of Tows = 893, with larvae = 87

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 < 50

50 to < 250

250 to < 1000

1000 to 2388

Number of Larvae / 10m2

July, 1977 to 1987

Number of Tows = 938, with larvae = 269

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 < 50

50 to < 250

250 to < 1000

1000 to 2853

Number of Larvae / 10m2

April, 1977 to 1987

Number of Tows = 1281, 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 4
Page 31

Figure 11. cont’d.

September, 1977 to 1987

Number of Tows = 774, with larvae = 168

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 < 50

50 to < 300

300 to < 1000

1000 to 3807

Number of Larvae / 10m2

August, 1977 to 1987

Number of Tows =1148, with larvae = 377

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 < 50

50 to < 250

250 to < 5000

5000 to 9396

Number of Larvae / 10m2

October, 1977 to 1987

Number of Tows = 1147, with larvae = 340

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 < 50

50 to < 300

300 to 689

November, 1977 to 1987

Number of Tows = 1031, with larvae = 196

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 < 50

50 to < 250

250 to 487
Page 32

Figure 11. cont’d.

December, 1977 to 1987

Number of Tows = 603, with larvae = 63

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 < 50

50 to < 100

100 to 148
Page 33

Figure 12. Distribution of juvenile and adult silver hake collected during NEFSC bottom trawl surveys during winter

(1964-1997), spring (1968-1997), summer (1963-1995), and autumn (1963-1996). Densities are represented by dot size

in spring and fall plots, while only presence and absence are represented in winter and summer plots [see Reid et al.

(1999) for details].

NMFS Trawl Surveys

Winter 1964 - 97

Juveniles (<23cm)

 = Absent

 = Present

Silver Hake

Number/Tow

 0 to 25

 25 to 100

 100 to 500

 500 to 1000

 1000 to 3867

NMFS Trawl Surveys

Spring 1968 - 97

Juveniles (<23cm)

Silver Hake

NMFS Trawl Surveys

Summer 1963 - 95

Juveniles (<23cm)

= Absent

 = Present

Silver Hake

Number/Tow

 1 to 100

 100 to 250

 250 to 1000

 1000 to 2000

 2000 to 3993

NMFS Trawl Surveys

Autumn 1963 - 96

Juveniles (<23cm)

Silver Hake
Page 34

Figure 12. cont’d.

NMFS Trawl Surveys

Winter 1964 - 97

Adults (>=23cm)

 = Absent

 = Present

Silver Hake

Number/Tow

 1 to 50

 50 to 100

 100 to 500

 500 to 1000

 1000 to 11690

NMFS Trawl Surveys

Spring 1968 - 97

Adults (>=23cm)

Silver Hake

NMFS Trawl Surveys

Summer 1963 - 95

Adults (>=23cm)

= Absent

 = Present

Silver Hake

Number/Tow

 1 to 50

 50 to 100

 100 to 500

 500 to 1000

 1000 to 2551

NMFS Trawl Surveys

Autumn 1963 - 96

Adults (>=23cm)

Silver Hake
Page 35

Figure 13. Distribution and abundance of juvenile and adult silver hake in Massachusetts coastal waters collected during

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

where no fish were taken are denoted by ‘+’.

Silver Hake

Mass. Inshore Trawl Survey

 Spring 1978 - 1996

 Juveniles (<23cm)

Number/Tow

 1 to <25

 25 to <50

 50 to <100

 100 to <500

 500 to <928

Silver Hake

Mass. Inshore Trawl Survey

 Autumn 1978 - 1996

 Juveniles (<23cm)

Number/Tow

 1 to <50

 50 to <100

 100 to <500

 500 to <1000

 1000 to <2399

Silver Hake

Mass. Inshore Trawl Survey

 Spring 1978 - 1996

 Adults (>=23cm)

Number/Tow

 1 to <50

 50 to <100

 100 to <200

 200 to <500

 500 to <1665

Silver Hake

Mass. Inshore Trawl Survey

 Autumn 1978 - 1996

 Adults (>=23cm)

Number/Tow

 1 to <50

 50 to <100

 100 to <200

 200 to <500

 500 to <807
Page 36

Figure 14. Distribution and abundance of juvenile silver hake collected in the Hudson-Raritan estuary from January

1992 - June 1997, based on Hudson-Raritan trawl surveys [see Reid et al. (1999) for details].

Staten

Island

NEW

YORK

NEW

JERSEY

No/Tow

 1 - 4

5 - 9

10 - 19

20 - 39

40 - 60

Silver Hake

Hudson-Raritan Estuary

January 1992 - June 1997

All Juveniles (<23 cm)

Staten

Island

NEW

YORK

NEW

JERSEY

No/Tow

 1 - 4

5 - 9

10 - 19

20 - 39

40 - 60

Silver Hake

Hudson-Raritan Estuary

Winter 1992 - 1997

Juveniles (<23 cm)

Staten

Island

NEW

YORK

NEW

JERSEY

No/Tow

 1 - 4

5 - 9

10 - 19

20 - 39

40 - 60

Hudson-Raritan Estuary

Spring 1992 - 1997

Juveniles (<23 cm)

Silver Hake

Staten

Island

NEW

YORK

NEW

JERSEY

No/Tow

 1 - 4

5 - 9

10 - 19

20 - 39

40 - 60

Silver Hake

Hudson-Raritan Estuary

Fall 1992 - 1996

Juveniles (<23 cm)
Page 37

Figure 15. Distribution, abundance and length frequencies of juvenile and adult silver hake collected during each season

in Narragansett Bay during 1990-1996 Rhode Island bottom trawl surveys. The numbers shown at each station are the

average catch per tow rounded to one decimal place [see Reid et al. (1999) for details].

4.9

0.2

0.1

0.0

0.1

0.0

0.0

0.0

0.0

0.1

2.6

0.6 0.1

1.1

0.1

0.1

0.0

0.2

0.0

0.0

0.1

0.1

0.4

0.5

0.4 0.0

12.6

0.0

0.0

0.0

0.2

0.1

0.0

0.2

0.0

0.5

1.8

0.0 0.0

3.2

0.3

0.1

0.0

1.4

0.1

0.3

0.5

0.3

1.3

2.9

0.4 0.5

Spring

Summer Autumn

Winter

Silver Hake Juveniles (<23cm)
Page 38

Figure 15. cont’d.

3.2

0.0

0.0

0.0

0.1

0.0

0.0

0.0

0.0

0.0

5.3

0.3 0.0

0.5

0.0

0.0

0.0

0.4

0.0

0.0

0.0

0.2

1.1

1.1

0.7 0.0

0.8

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

0.0

1.2

0.0 0.0

1.6

0.0

0.0

0.0

0.1

0.0

0.0

0.0

0.0

0.0

0.6

0.0 0.1

Spring

Summer Autumn

Winter

Silver Hake Adults (>=23cm)
Page 39

Figure 15. cont’d.

5 7 9 11 13 15 17 19 21 23 25 27 29 31 33 35 37

0

20

40

60

80

100

5 7 9 11 13 15 17 19 21 23 25 27 29 31 33 35 37

0

3

6

9

12

5 7 9 11 13 15 17 19 21 23 25 27 29 31 33 35 37

0

50

100

150

200

250

5 7 9 11 13 15 17 19 21 23 25 27 29 31 33 35 37

0

20

40

60

80

100

Total Length (cm)

Winter

Spring

Summer

Autumn
Page 40

Figure 16. Distribution, abundance, and length frequencies of juvenile and adult silver hake collected during spring and

autumn in Long Island Sound, from the Connecticut bottom trawl surveys, 1992-1997 [see Reid et al. (1999) for details].

Number/Tow

 1 to <10

 10 to <25

 25 to <50

 50 to <100

 100 to <135

Number/Tow

 1 to <10

 10 to <25

 25 to <50

 50 to <100

 100 to <118

State of Connecticut DEP

Fisheries Division

Long Island Sound Trawl Survey

SPRING 1992 - 1997

State of Connecticut DEP

Fisheries Division

Long Island Sound Trawl Survey

AUTUMN 1992 - 1997

Silver Hake

Silver Hake
Page 41

Figure 17. Commercial landings and abundance indices (from the NEFSC bottom trawl surveys) for the Gulf of MaineGeorges Bank and southern Georges Bank-Middle Atlantic stocks of silver hake.

Gulf of Maine - Northern Georges Bank

Year

1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000

Landings (mt x 1000)

0

20

40

60

80

100

Stratified mean catch/tow (kg)

0

5

10

15

20

25

30

Commercial landings (mt)

Autumn survey index (kg)

Smoothed survey index (kg)

Southern Georges Bank - Middle Atlantic

Year

1950 1955 1960 1965 1970 1975 1980 1985 1990 1995 2000

Landings (mt x 1000)

0

50

100

150

200

250

300

350

Stratified mean catch/tow (kg)

0

1

2

3

4

5

Commercial + recreational landings (mt)

Autumn survey index (kg)

Smoothed survey index (kg)
Page 42

Figure 18. Distribution and abundance of juvenile and adult silver hake from NEFSC autumn bottom trawl surveys

during a period of relatively low abundance (autumn 1967-1971) and a period of relatively high abundance (autumn

1989-1993).

Number/Tow

 1 to < 50

 50 to < 100

 100 to < 500

 500 to < 1000

 1000 to < 3611

NMFS Trawl Surveys

Autumn 1967 - 71

Juveniles (<23cm)

Low Abundance

Silver Hake

Number/Tow

 1 to < 50

 50 to < 100

 100 to < 500

 500 to < 1000

 1000 to < 3611

NMFS Trawl Surveys

Autumn 1967 - 71

Adults (>=23cm)

Low Abundance

Silver Hake

Number/Tow

 1 to < 50

 50 to < 100

 100 to < 500

 500 to < 1000

 1000 to < 3611

NMFS Trawl Surveys

Autumn 1989 - 93

Adults (>=23cm)

High Abundance

Silver Hake

Number/Tow

 1 to < 50

 50 to < 100

 100 to < 500

 500 to < 1000

 1000 to < 3611

NMFS Trawl Surveys

Autumn 1989 - 93

Juveniles (<23cm)

High Abundance

Silver Hake
NORTHEAST FISHERIES SCIENCE CENTER

Dr. Michael P. Sissenwine, Science & Research Director

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

Teri L. Frady, Research Communications Unit Chief

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

Publishing in NOAA Technical Memorandum NMFS-NE

Manuscript Qualification

This series represents a secondary level of scientific publishing in the National Marine Fisheries Service (NMFS). For

all issues, the series employs thorough internal scientific review,

but not necessarily external scientific review. For most issues,

the series employs rigorous technical and copy editing. Manuscripts that may warrant a primary level of scientific publishing

should be initially submitted to one of NMFSs primary series

(i.e., Fishery Bulletin, NOAA Technical Report NMFS, or Marine Fisheries Review).

Identical, or fundamentally identical, manuscripts should

not be concurrently submitted to this and any other publication

series. Manuscripts which have been rejected by any primary

series strictly because of geographic or temporal limitations may

be submitted to this series.

Manuscripts by Northeast Fisheries Science Center

(NEFSC) authors will be published in this series upon approval

by the NEFSC's Deputy Science & Research Director. Manuscripts by non-NEFSC authors may be published in this series if:

1) the manuscript serves the NEFSCs mission; 2) the manuscript meets the Deputy Science & Research Directors approval; and 3) the author arranges for the printing and binding

funds to be transferred to the NEFSCs Research Communications Unit account from another federal account. For all manuscripts submitted by non-NEFSC authors and published in this

series, the NEFSC will disavow all responsibility for the manuscripts contents; authors must accept such responsibility.

The ethics of scientific research and scientific publishing

are a serious matter. All manuscripts submitted to this series are

expected to adhere -- at a minimum -- to the ethical guidelines

contained in Chapter 1 (Ethical Conduct in Authorship and

Publication) of the CBE Style Manual, fifth edition (Chicago,

IL: Council of Biology Editors). Copies of the manual are

available at virtually all scientific libraries.

Manuscript Preparation

Organization: Manuscripts must have an abstract, table of

contents, and -- if applicable -- lists of tables, figures, and

acronyms. As much as possible, use traditional scientific manuscript organization for sections: Introduction, Study Area,

Methods & Materials, Results, Discussion and/or Conclusions, Acknowledgments, and References Cited.

Style: All NEFSC publication and report series are obligated to conform to the style contained in the most recent edition

of the United States Government Printing Office Style Manual.

That style manual is silent on many aspects of scientific manuscripts. NEFSC publication and report series rely more on the

CBE Style Manual, fifth edition.

For in-text citations, use the name-date system. A special

effort should be made to ensure that the list of cited works

contains all necessary bibliographic information. For abbreviating serial titles in such lists, use the most recent edition of the

Serial Sources for the BIOSIS Previews Database (Philadelphia,

PA: Biosciences Information Service). Personal communications must include date of contact and full name and mailing

address of source.

For spelling of scientific and common names of fishes,

mollusks, and decapod crustaceans from the United States and

Canada, use Special Publications No. 20 (fishes), 26 (mollusks),

and 17 (decapod crustaceans) of the American Fisheries Society

(Bethesda, MD). For spelling of scientific and common names

of marine mammals, use Special Publication No. 4 of the

Society for Marine Mammalogy (Lawrence, KS). For spelling in

general, use the most recent edition of Websters Third New

International Dictionary of the English Language Unabridged

(Springfield, MA: G.&C. Merriam).

Typing text, tables, and figure captions: Text, including

tables and figure captions, must be converted to, or able to be

coverted to, WordPerfect. In general, keep text simple (e.g.,

dont switch fonts, dont use hard returns within paragraphs,

dont indent except to begin paragraphs). Especially, dont use

WordPerfect graphics for embedding tables and figures in text.

If the automatic footnoting function is used, also save a list of

footnotes as a separate WordPerfect file. When the final draft is

ready for review, save the text, tables, figure captions, footnotes,

and front matter as separate document files.

Tables should be prepared using all tabs or all spaces

between columnar data, but not a combination of the two.

Figures must be original (even if oversized) and on paper; they

cannot be photocopies (e.g., Xerox) unless that is all that is

available, nor be on disk. Except under extraordinary circumstances, color will not be used in illustrations.

Manuscript Submission

Authors must submit one paper copy of the double-spaced

manuscript, one magnetic copy on a disk, and original figures (if

applicable). NEFSC authors must include a completely signedoff NEFSC Manuscript/Abstract/Webpage Review Form.

Non-NEFSC authors who are not federal employees will be

required to sign a Release of Copyright form.

Send all materials and address all correspondence to:

Jon A. Gibson, Biological Sciences Editor

Northeast Fisheries Science Center

National Marine Fisheries Service

166 Water Street

Woods Hole, MA 02543-1026 USA
Research Communications Unit

Northeast Fisheries Science Center

National Marine Fisheries Service, NOAA

166 Water St.

Woods Hole, MA 02543-1026

NOAA Technical Memorandum NMFS-NE -- This series is issued irregularly. The series includes: data reports of longterm or large area studies; synthesis reports for major resources or habitats; annual reports of assessment or monitoring programs;

documentary reports of oceanographic conditions or phenomena; manuals describing field and lab techniques; literature surveys of major

resource or habitat topics; findings of task forces or working groups; summary reports of scientific or technical workshops; and indexed

and/or annotated bibliographies. All issues receive internal scientific review and most issues receive technical and copy editing. Limited

free copies are available from authors or the NEFSC. Issues are also available from the National Technical Information Service, 5285

Port Royal Rd., Springfield, VA 22161.

Fishermen's Report and The Shark Tagger -- The Fishermen's Report (FR) is a quick-turnaround report on the

distribution and relative abundance of commercial fisheries resources as derived from each of the NEFSC's periodic research vessel

surveys of the Northeast's continental shelf. There is no scientific review, nor any technical or copy editing, of the FR; copies are available

through free subscription. The Shark Tagger (TST) is an annual summary of tagging and recapture data on large pelagic sharks as derived

from the NMFS's Cooperative Shark Tagging Program; it also presents information on the biology (movement, growth, reproduction, etc.)

of these sharks as subsequently derived from the tagging and recapture data. There is internal scientific review, but no technical or copy

editing, of the TST; copies are available only to participants in the tagging program.

Northeast Fisheries Science Center Reference Document -- This series is issued irregularly. The series

includes: data reports on field and lab observations or experiments; progress reports on continuing experiments, monitoring, and

assessments; background papers for scientific or technical workshops; and simple bibliographies. Issues receive internal scientific review

but no technical or copy editing. No subscriptions. Free distribution of single copies.

The mission of NOAA's National Marine Fisheries Service (NMFS) is "stewardship of living marine resources for the

benefit of the nation through their science-based conservation and management and promotion of the health of their

environment." As the research arm of the NMFS's Northeast Region, the Northeast Fisheries Science Center (NEFSC)

supports the NMFS mission by "planning, developing, and managing multidisciplinary programs of basic and applied

research to: 1) better understand the living marine resources (including marine mammals) of the Northwest Atlantic, and

the environmental quality essential for their existence and continued productivity; and 2) describe and provide to

management, industry, and the public, options for the utilization and conservation of living marine resources and

maintenance of environmental quality which are consistent with national and regional goals and needs, and with

international commitments." Results of NEFSC research are largely reported in primary scientific media (e.g.,

anonymously-peer-reviewed scientific journals). However, to assist itself in providing data, information, and advice to

its constituents, the NEFSC occasionally releases its results in its own media. Those media are in three categories:

Publications and Reports

of the

Northeast Fisheries Science Center

To obtain a copy of a technical memorandum or a reference document, or to subscribe to the fishermen's report,

write: Research Communications Unit, Northeast Fisheries Science Center, 166 Water St., Woods Hole, MA

02543-1026. An annual list of NEFSC publications and reports is available upon request at the above address.

Any use of trade names in any NEFSC publication or report does not imply endorsement.

STANDARD

 MAIL A