NOAA Technical Report NMFS 113 June 1993

Maturation of Nineteen Species of FinfISh

off the Northeast Coast of the

United States, 1985-1990

Loretta O'Brien

Jay Burnett

Ralph K Mayo

U.S. Department of Commerce
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NOAA Technical Report NMFS 113

Maturation of Nineteen Species of FinIlSh

off the Northeast Coast of the

United States, 1985-1990

Loretta O'Brien

Jay Burnett

Ralph K. Mayo

June 1993

U.S. DEPARTMENT OF COMMERCE

Ronald H. Brown, Secretary

National Oceanic and Atmospheric Administration

D.James Baker, Under Secretary for Oceans and Atmosphere

National Marine Fisheries Service
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purchased because of this NMFS publication.

ii
Contents

Abstract

Introduction

Methods

Results

Atlantic Cod: Gadus morhua

Haddock: Melanogrammus aeglefinus

Pollock: Pollachius virens

White Hake: Urophycis tenuis

Red Hake: Urophycis chuss

Silver Hake: Merluccius bilinearis

Redfish: Sebastesfasciatus

Scup: Stenotomus chrysops

Black Sea Bass: Centropristis striata

Ocean Pout: Macrozoarces americanus

Yellowtail Flounder: Pleuronectesferrugineus

Winter Flounder: Pleuronectes americanus

American Plaice: Hippoglossoides platessoides

Witch Flounder: Glyptocephalus cynoglossus

Summer Flounder: Paralichthys dentatus

Windowpane: Scophthalmus aquosus

Atlantic Herring: Clupea harengus

Atlantic Mackerel: Scomber scombrus

Butterfish: Peprilus triacanthus

Discussion

Acknowledgments

Citations

iii

1

1

2

4

10

14

18

20

22

26

30

32

33

34

36

42

48

50

52

54

56

58

60

62

63

63

Maturation of Nineteen Species of FinlIsh off

the Northeast Coast of the United States, 1985 - 1990

LORETTA O'BRIEN,jAYBURNETT, and RALPH K. MAYO

Woods Hole Laboratory

Northeast Fisheries Science Center

Woods Hole, MA 02543

ABSTRACT

Observations on maturation stages of nineteen species of economically important finfish

off the Northeast coast ofthe USA were analyzed to examine relationships between fish size

or age, and maturity. Maturation schedules and median lengths (L50) and ages (A50) at

maturation were derived by fitting the logistic model to the observed proportions. Analyses

were generally restricted to observations from 1985 to 1990 obtained during stratified

random bottom trawl surveys conducted in spring and autumn by the Northeast Fisheries

Science Center and the Commonwealth of Massachusetts Division of Marine Fisheries in

waters of the continental shelf from Nova Scotia to Cape Hatteras, North Carolina. Butterfish, Peprilus triacanthus, attained sexual maturity at the smallest median length (11.4 em,

males) and pollock, Pollachius virens, at the highest (41.8 em, males). Median length at

maturity for gadiforms ranged from 22.2 to 41.8 em. Within the pleuronectiforms, median

length at maturity ranged from 19.1 to 30.4 em. Median lengths for the pelagic and

miscellaneous demersal species were in the same ranges as the pleuronectiforms. Butterfish also attained sexual maturity at the youngest median age (0.9 yr, both sexes) whereas

redfish, Sebastes fasciatus, were the latest to mature (5.5 yr, both sexes). For gadids, the

median age at maturity ranged from 1.3 to 2.3 yr. Within the pleuronectiforms, median age

at maturity ranged from 1.3 to 4.4 yr and, for pelagic species, from 0.9 to 3.0 yr. Median lengths

and ages for many species are lower than those reported in earlier studies of the same general

region of the Northwest Atlantic.

Introduction

Maturation rates, along with rates of growth and mortality, are vital to the characterization ofthe population

dynamics of fish stocks. The age at first reproduction

has a strong influence upon the population growth rate

(Cole 1954); Beverton and Holt (1959) Beverton (1963,

1987) and Garrod and Horwood (1984) have all noted

the interdependence of lifespan, growth, and age at first

maturity implicit in the compensatory response of exploited fish stocks to fishing pressure.

The interactions between growth and maturation are

varied and complex. AIm (1959) and Roff (1981,1982)

identified size and age as codeterminants in the onset

of maturity in fish, but for most species, size was the

more important factor. Several studies (Molander 1925;

AIm 1959; J~gensen 1990; O'Brien 1990) have attributed observed reductions in the age at maturity to

increases in growth rates, particularly during the juvenile stage (Godo and Moksness 1987). However, there

is some evidence that early maturation is associated

with poor growth, i.e. at some point the age effect upon

the maturation process overrides the size effect (Elkin

1955; Schaffer and Elson 1975; Mayo et al. 1990). It is

also possible that observed changes in median age at

maturity values are simply artifacts of changes in growth.

For example, a species f6r which maturation is size-dependent would appear to have lowered its median age at

maturity ifincreased growth caused it to attain the critical

size at a younger age. Interpretations ofmaturity analyses,

therefore, should be made carefully and with some consideration ofpossible changes in growth rates.

Maturity estimates by size or age provide information

about trends in maturation as stock sizes and environmental conditions fluctuate, and may be used directly in the

evaluation offishery management programs. Estimates of
2 NOAA Technical Report NMFS 113

median length at maturity are used to evaluate mean

retention lengths associated with various commercial gear

types. Maturity-at-age data are also employed in the calculation of spawning stock biomass per recruit and maximum spawning potential (Gabriel et al. 1989). Estimates

of spawning stock biomass and recruitment provide the

framework for calculating the biological reference point,

Fre (Sissenwine and Shepherd 1987),for 13 ofthe species

anilyzed in this study which are included in the Northeast

Multispecies Fishery Management Plan (New England Fishery Management Council 1985).

In this report, we provide length- and age-specific

maturation ogives and estimates of median length and

age at maturity for 19 species which have supported

important commercial and recreational fisheries off

the northeast coast of the United States. Exploitation

rates for most of the species analyzed are at historically

high levels and stock sizes are near or at historically low

levels. Since growth and maturation rates are likely to

change as stock sizes decline in abundance (Templeman

and Bishop 1979; Sinclair et al. 1980; Bowering 1989),

it is probable that growth rates for many of the species

included in our study have increased in recent years. In

view of these trends, the primary goal of this study is to

provide a comprehensive summary of recent maturity

information for these species.

Methods _

The data analyzed in this study were collected during

stratified random bottom trawl surveys conducted in

spring and autumn by the Northeast Fisheries Science

Center (NEFSC), National Marine Fisheries Service

(Doubleday 1981; NEFC 1988) and the Massachusetts

Division of Marine Fisheries (MDMF) (Azarovitz et al.

1989). Surveys conducted by the NEFSC cover the inshore and offshore areas of the continental shelf from

Nova Scotia to Cape Hatteras, North Carolina (Fig. 1).

The Massachusetts Division of Marine Fisheries conducts surveys in the inshore waters along the coast of

Massachusetts (Fig. 1). Data from MDMF were used

only for the inshore stocks ofwinter flounder, Pleuronectes

americanus, owing to observed mixing of stocks for this

species in the offshore NEFSC survey.

During each survey, finfish were sampled for determination of length (to nearest cm), sex, and maturity

stage. Fish with forked tails were measured using fork

length (FL); otherwise, all fish were measured using

total length (TL). Atlantic herring, Clupea harengus,

were frozen at sea and measured in the laboratory using

total length. Black sea bass, Centropristis striata, were also

measured using total length, excluding the caudal filament. The criteria for seven stages of maturity classification are presented in Table 1 as similarly described by

Burnett et al. (1989). Fish were also sampled for age

determination by removing either scales or otoliths and

were analyzed in the laboratory by using species-specific

ageing methods as described by Penttilaand Dery (1988).

Nineteen species, comprising twenty-nine stocks, were

analyzed to determine the median length (L50) at maturity; fourteen species, comprising twenty-two stocks,

were analyzed to determine median age (A50) at matuGeorges Bank

Figure 1

Areas of the continental shelf from Nova Scotia to Cape Hatteras, North Carolina surveyed by the Northeast Fisheries Science

Center and the Massachusetts Division of Marine Fisheries spring and autumn bottom trawl surveys.
rity. Maturity classifications were considered as either

immature or mature by combining all stages other than

immature. Length and age based analyses were generally restricted to the period 1985-1989 or 1990 depending upon the availability of data (Table 2). Exceptions

were redfish, Sebastes fasciatus, and red hake, Urophycis

chuss, for which recent age data were not available.

Stock areas (Fig. 1) were delineated by NEFSC bottom

trawl survey strata (Table 2) as defined by current stock

O'Brien et al.: Maturation of Finfish 3

structure (NEFSC 1991). Either spring or autumn data

collected closest to the time of spawning were used in

the analyses for each species (Table 2). This was done

in an attempt to minimize errors in maturity classifications, especially in differentiating between immature

and resting gonads (Halliday 1987).

The observed proportion of fish mature at length

and age was calculated for each species by stock area,

year, season, and sex. Immature fish not identified by

Table I

Current maturity staging criteria used during Northeast Fisheries Science Center bottom trawl surveys.

Stage

Females

Immature

Code Description and criteria

Ovary paired, tube-like, small relative to body cavity; colorless to pink jell-like tissue, no visible eggs; thin, transparent outer membrane.

Butterfish, Peprilus triacanthus: ovary paired and flattened, ovary wall striated or wrinkled.

Ocean pout, Macrozoarces americanus: ovary not paired.

Developing D Ovaries large, occupying up to 2/3 of body cavity; blood vessels prominent when present; ovary appears granular as

yellow to orange yolked eggs develop. A mixture of less than 50% yolked and hydrated eggs denotes D.

Ripe R Ovaries large, may fill entire body cavity; a mixture of 50% or more hydrated eggs denotes R; transparent ovary wall.

Eyed E Redfish Sebastes fasciatus only: ovary large, robust, transparent membrane with dark spotted eggs containing

developing eyed-stage larvae.

Ripe and

Running U Eggs flow from vent with little or no pressure to abdomen.

Spent S Ovaries flaccid, sac-like, similar in size to ripe ovaries; color red to purple; ovary wall thickened, cloudy and

translucent; some hydrated or yolked eggs may adhere to ovary wall.

Resting T Ovaries smaller than ripe ovaries, but larger than immature. Interiorjell-like, no visible eggs.

Haddock, Melanogrammus aeglefinus: ovaries small relative to body cavity, wall thick and tough with purplish

membrane, blood vessels less prominent and purplish.

Pleuronectiformes: ovaries larger relative to the body cavity than in gadids, interior yellow or orange. Ovary wall

cloudy or translucent and thicker and tougher than in ripe ovaries.

Males

Immature

Developing D

Ripe R

Ripe and

Running U

Spent S

Testes small relative to body cavity, colorless to gray and translucent.

Butterfish, Peprilus triacanthus: similar to ovary, but with a smooth wall.

Pleuronectiformes: testis located posterior of body cavity; triangular shape with sharp anterior edge.

Winter flounder, Pleuronectes americanus: posterior portion of testis extends further back similar to ovary but the

shape is different: the endpoint of the testis is rounded, and more flattened as it extends posteriorly.

Gadids: testes narrow, lobed and elongated, resembles crimped ribbon.

Atlantic herring, Clupea harengus, mackerel Scomber scombrus, scup, Stenotomus chrysops: similar shape as ovary, but

there is an edge to the testis vs. being rounded in ovary.

Testes large, grey to off-white, firm consistency with very little or no milt present.

Testes larger than D, chalk white, consistency mostly liquid. Milt flows easily when testis dissected.

Chalk white milt flows easily from the vent with little or no pressure on abdomen. Once dissected, milt flows easily.

Testes flaccid, may contain residual milt, less robust than R. Edges or other parts of the testes starting to turn grey as

milt recedes.

Gadiformes: edges of lobes reddish to brown or grey as milt recedes.

Resting T Testes shrunken in size relative to R. Color is yellow, brown, or grey with little or no milt.
4 NOAA Technical Report NMFS 113

Since exact confidence limits for the statistic yare not

available, approximate 95% confidence limits were calculated (Zar 1984) at increments of 0.05 for proportions mature at length and at whole ages for proportions mature at age. The t-distribution was used at an

alpha level of 0.05 for varying degrees of freedom (df)

with the standard error of y as

sex were assumed to have a 1:1 sex ratio and equal

catchability and were included in the analyses by adding the number of unsexed fish at each length to both

female and male data sets. As a result, the sample size

increased by less than 1% (u. tenuis) to 24% (Stenotomus

chrysaps) in 27 of the 29 stock analyses. No other adjustments were made to the observations.

The proportion of fish mature at length and age was

estimated by fitting the logistic model to the observed

proportions mature at length and age. The form of the

logistic was

y ± to.OS.dj S (y). (4)

P= I 1+e-(a+{Jx) , (1) Results _

Logistic regressions (Dixon 1981) were performed

on each species stock, by sex, to obtain the model

parameters. Median length or age at maturity was calculated from the regression coefficients as [ -alb].

The generally low sample sizes for each sex within a

stock area did not allow for calculation of reliable annual estimates. Thus, years with similar values of L50

and A50 that also had relatively stable stock sizes were

pooled to achieve the objective ofobtaining a representative maturity schedule reflecting current stock conditions. As a result, one or two years of data were excluded for five species and nine analyses. The combined data were then analyzed using the same methods

as described above.

The approximate variance for large samples (Ashton

1972) was calculated for given proportions mature (y)

at length or age as

The computational equation for this formula is

2 I [ 2 a

2

2 2a ] s (Y)=-2 s (a)+-2 s (b)--cov(a,b) . b b b

Butterfish, Peprilus triacanthus, attained sexual maturity

at the smallest median length (11.4 cm, males) and

pollock, Pollachius virens, at the highest (41.8 cm, males)

(Table 3). Median length at maturity for the gadids

ranged from 22.2 cm (red hake, U. chuss, males) to 41.8

cm (pollock, P. virens, males). Within the

pleuronectiforrns, median length at maturity ranged

from 19.1 cm (yellowtail flounder, Pleuronectesferrugineus,

males) to 30.4 cm (witch flounder, Glyptocephalus

cynoglossus, females). Median lengths for the pelagic

and miscellaneous demersal species were in the same

ranges as the pleuronectiforms.

Butterfish, Peprilus triacanthus, also attained sexual

maturity at the youngest median age (0.9 yr, both sexes)

while redfish, Sebastesfasciatus, were the latest to mature

(5.5 yr, both sexes) (Table 4). For gadids, the median

age at maturity ranged from 1.3 yr (haddock,

Melanogrammus aeglefinus, males) to 2.3 yr (cod, Gadus

morhua, and pollock, Pollachius virens, males). Within

the pleuronectiforms, median age at maturity ranged

from 1.3 yr (yellowtail flounder, Pleuronectesferrugineus,

males) to 4.4 yr (witch flounder, G. cynoglossus, females)

and, for pelagic species, from 0.9 yr (butterfish, Peprilus

triacanthus) to 3.0 yr (Atlantic herring, Clupea harengus,

females). Median lengths and ages for many species are

lower than those reported in earlier studies ofthe same

general region of the Northwest Atlantic.

Median lengths vs. median ages at maturation for the

gadiforms and pkuronectiforms are plotted in Figure

2. For gadiforrns, L50 and A50 estimates extend over a

wide range of lengths within a relatively narrow age

span. Pleuronectiforms, however, exhibit an opposite

pattern, with estimates extending over a very wide range

of ages within a narrow length span. This suggests that,

during the study period, the maturation process was

age-dependent for the gadiforms and size-dependent

for the pleuronectiforms.

In each ofthe following species sections, tables ofthe

proportion of fish mature at length are presented in

0.05 increments and tables of proportions of fish mature at age are presented in whole ages.

(2)

estimates of ex and

length or age at maturity for a given proportion

1 I L (nPQ)

probability of a response

1- P

number offish at length or age x

L nPQxl L nPQ

standard error of b.

n =

x

s(b) =

where a, b

y

? (6)

P=

Q=

where P = proportion mature at age or length

x = either length or age, and

a, f3 = model parameters to be estimated.
O'Brien et al.: Maturation of Finfish 5

Table 2

Species by stock area, spawning season (Smith 1985n), survey season, Northeast Fisheries Science Center offshore strata

sets, and years included in each species stock analysis (GB=Georges Bank, NGB= orthern Georges Bank, SGB=Southern

Georges Bank, GM=Gulf of Maine, CC=Cape Cod, SNE=Southern New England, MA=Middle Atlantic, N=North, S=South).

Spawning season Survey

Species Area (peak) Analyzed Strata set Years

Atlantic Cod GB Nov-May (Feb-Mar) Spring 13-25 1985-1990 .

Gadus morhua GM Nov-May (Mar-May) Spring 26-30, 36-40 1985-1990

Haddock GB Jan-May (Mar-Apr) Spring 13-25,29-30 1985-1989

Melanogrammus aeglefinus GM Feb-May (Mar-Apr) Spring 26-28, 36-40 1985-1989

Pollock GB-GM Oct-Mar (Dec-Jan) Autumn 13-34,351, 1986-1988

Pollachius virens 36-40

White hake GB-GM Oct-May Spring 21-30, 33, 34 1987-1989

Urophycis tenuis 351,36-40

Red hake GM-NGB May-Sep Oun-Jul) Spring 20-30, 36-40 1982-1985

Urophycis chuss SGB-MA Mar-Oct (Aug-Sep) Spring 1-19,61-76;

1-46b, 52b, 55b

Silver hake GM-NGB Apr-Oct (May-Aug) Spring 20-30, 36-40 1985-1989

Merluccius bilinearis SGB-MA Apr-Oct (May-Sep) Spring 1-19,61-76;

1-46b, 52b, 55b

Redfish GM Apr-Aug Oun-Jul) Spring' 24, 26-30 1975-1980

Sebastes fasciatus Autumn d 36-40

Scup All May-Aug (May-Jun) Spring 2-3,61-63, 1985

Stenotomus chrysops 65-67,70-71,74-75 1987-1990

Black sea bass All Apr-Oct Oun) Spring 1-12,25,61-76; 1985-1990

Centropristis striata 1-61 b

Ocean pout SNE Sep-Oct (Oct) Spring 1-12,61-76; 1985-1990

Macrozoarces americanus 1-52b

GM Sep-Oct (Sep) Spring 26-40; 57-66b 1985-1990

Yellowtail flounder GB Apr-Aug (May-Jun) Spring 13-21 1985-1990

Pleuronectesferrugineus CC Apr-Aug (May-Jun) Spring 24-26

SNE Apr-Aug (May-Jun) Spring 5,6,9,10

Winter flounder GB Mar-May (Apr) Spring 13-22 1985-1989

Pleuronectes americanus N ofCC Apr-May (Apr) Spring 25-36'

S ofCC Feb-May (Feb-Mar) Spring 11-17'

American plaice GM Feb-Jun (Apr-May) Spring 26-30, 36-40 1986-1990

Hippoglossoides platessoides

Witch flounder GM Apr-Aug (May-Jun) Spring 22-30, 33-34, 1986-1990

Glyptocephalus cynoglossus 351,36-40

Summer tIounder All Aug-Dec (Oct-Nov) Autumn 1-12,45-46, 1985-1989

Paralichthys dentatus 52,55-76; 1-41 b

Windowpane GB Jun-Oct Oul-Aug) Spring 13-21 1985-1990

Scophthalmus aquosus SNE May-Nov (Sep) Spring 5-12

Atlantic herring SNE,GM Aug-Dec (Sep~Oct) Autumn 1-12,24-30, 1987-1989

Clupea harengus 33-34,351,

36-40,61-76

Atlantic mackerel All Apr-Jul (Apr-Jun) Spring 1-34,351, 1987-1989

Scomber scombrus 36-76; 1-81 b

Butterfish All May-Sep Oun-Jul) SpTing 1-25,61-76; 1986-1989

Peprilus triacanthus 1-46b

• W.G. Smith. 1985. Temperal and spatial spawning patterns of the principal species of fish and invertebrates in the Georges Bank

region. NMFSjNEFC, Sandy Hook Laboratory, Lab. Ref. Doc. o. 85-4, 35 p.

b Northeast Fisheries Science Center inshore strata.

, females only.

d males only.

, Massachusetts Division of Marine Fisheries strata.
6 NOAA Technical Report NMFS 113

Table 3

Median length (cm) at maturity (Lso)' parameter values a and b from the logistic regression, standard error (SE) of a and b, and

the number offemales (F) and males (M) of nineteen species offinfish sampled off the northeast coast of the United States.

Species Sex a SE a b SE b L50 n

Atlantic cod, Gadus morhua

1985-1990

Georges Bank F -4.932 0.429 0.127 0.009 38.8 983

M -5.688 0.464 0.139 0.010 41.0 1034

Gulf of Maine F -5.500 0.653 0.171 0.018 32.1 411

M -5.048 0.554 0.140 0.014 36.0 394

Haddock, Melanogrammus aeglefinus

1985-1989

Georges Bank F -6.252 0.765 0.210 0.022 29.7 580

M -5.064 0.738 0.189 0.022 26.8 478

Gulf of Maine F -18.605 11.78 0.539 0.314 34.5 69

M -13.111 5.432 0.374 0.146 35.0 49

Pollock, Pollachius virens

1986-1988 F -6.004 1.120 0.154 0.027 39.1 154

M -6.788 1.158 0.162 0.028 41.8 143

White hake, Uutphycis tenuis

1987-1989 F -4.808 0.538 0.137 0.014 35.1 455

M -7.790 0.894 0.238 0.026 32.7 346

Red hake, Urophycis chuss

1982-1985

Gulf of Maine - Northern F -13.560 1.665 0.504 0.058 26.9 667

Georges Bank M -12.073 1.846 0.543 0.075 22.2 595

Southern Georges

Bank-Middle F -12.767 1.165 0.509 0.043 25.1 1020

Atlantic M -11.614 1.138 0.488 0.043 23.8 753

Silver hake, Merluccius bilinearis

1985-1989

Gulf of Maine - Northern F -11.963 0.687 0.519 0.029 23.1 1410

Georges Bank M -14.369 0.938 0.646 0.041 22.3 1026

Southern Georges

Bank-Middle F -10.753 0.537 0.464 0.021 23.2 2429

Atlantic M -14.263 0.890 0.629 0.037 22.7 1612

Redfish, Sebastes fasciatus

1975-1980 F -13.240 1.017 0.595 0.044 22.3 1457

M -6.929 0.476 0.331 0.020 20.9 1526

Scup, Stenotomus chrysops

1985,1987-1990 F -14.071 1.944 0.907 0.122 15.5 284

M -12.491 1.797 0.801 0.112 15.6 232

Black sea bass, Centropristis striata

1985-1990 F -4.691 0.535 0.245 0.024 19.1 561

M -6.841 0.957 0.360 0.045 19.0 348

Ocean Pout, Macrozoarces americanus

1985-1990

Gulf of Maine F -5.101 2.103 0.195 0.065 26.2 88

M -4.455 2.343 0.147 0.057 30.3 55
O'Brien et al.: Maturation of FiniIsh 7

Table 3 (Continued)

Median length (cm) at maturity (Lso), parameter values a and b from the logistic regression, standard error (SE) of a and b, and

the number offemales (F) and males (M) of nineteen species offinfish sampled off the northeast coast of the United States.

Species Sex a SE a b SE b Lso n

Southern New England F -6.515 1.584 0.208 0.040 31.3 197

M -5.920 1.204 0.186 0.032 31.9 205

Yellowtail flounder, Pleuronectesferrugineus

1985-1990

Georges Bank F -15.136 5.207 0.587 0.181 25.8 167

M -8.145 2.776 0.381 0.098 21.4 271

Cape Cod F -II.738 1.951 0.430 0.071 27.3 140

M -10.103 1.577 0.377 0.058 26.8 165

Southern New England F -11.366 2.833 0.445 0.098 25.5 204

M -7.331 1.734 0.375 0.066 19.6 367

Winter flounder, Pleuronectes americanus

1985-1989

Georges Bank F -10.855 2.245 0.436 0.084 24.9 204

M -7.724 1.551 0.301 0.054 25.6 174

North of Cape Cod F -26.646 3.661 0.896 0.121 29.7 320

M -16.906 2.416 0.613 0.087 27.6 215

South of Cape Cod F -11.895 1.320 0.431 0.046 27.6 398

M -17.099 2.130 0.590 0.074 29.0 301

American plaice, Hippoglossoides platessoides

1986-1990 F -11.255 0.944 0.420 0.034 26.8 714

M -7.414 0.612 0.336 0.026 22.1 633

Witch flounder, Glyptocephalus cynoglossus

1986-1990 F -11.930 2.698 0.392 0.084 30.4 189

M -9.405 2.239 0.371 0.078 25.3 233

Summer flounder, Paralichthys dentatus

1985-1989 F -8.574 1.064 0.306 0.034 28.0 378

M -7.636 0.852 0.307 0.030 24.9 497

Windowpane, Scophthalmus aquosus

1985-1990

Georges Bank F -15.260 3.777 0.678 0.150 22.5 343

M -15.670 3.535 0.704 0.145 22.2 199

Southern New England F -88.592 72.23 4.185 3.441 21.2 143

M -19.595 4.553 0.910 0.201 21.5 133

Atlantic herring, Clupea harengus

1987-1989 F -28.484 3.955 1.123 0.151 25.4 359

M -40.461 6.218 1.597 0.243 25.3 307

Atlantic mackerel, Scomber scombrus

1987-1989 F -16.475 1.601 0.641 0.060 25.7 697

M -17.102 1.516 0.658 0.056 26.0 770

Butterfish, Peprilus triacanthus

1986-1989 F -14.495 1.939 1.213 0.157 12.0 333

M -11.029 1.333 0.968 0.112 11.4 341

O'Brien et al.: Maturation of Finfish 9

Table 4 (Continued)

Median age (yrs) at matUlity (Aso), parameter values a and b from the logistic regression, standard error (SE) of a and b, and the

number of females (F) and males (M) offourteen species offinfish sampled ofT the northeast coast ofthe United States.

Species Sex a SE a b SE b Aso n

American plaice, Hippoglossoides platessoides

1986-1990 F -7.419 0.584 2.089 0.160 3.6 714

M -4.975 0.413 1.659 0.132 3.0 633

Witch flounder, Glyptocephalus cynoglossus

1986-1990 F -6.957 1.562 1.591 0.327 4.4 189

M -8.468 2.284 2.340 0.563 3.6 233

Atlantic herring, Clupea harengus

1987-1989 F -14.503 3.101 4.804 1.018 3.0 359

M -11.480 2.245 3.938 0.726 2.9 307

Atlantic mackerel, gcomber scombrus

1987-1989 F -8.499 1.426 4.511 0.722 1.9 697

M -6.068 0.718 3.199 0.366 1.9 770

Butterfish, Peprilus triacanthus

1986-1989 F -2.608 0.590 3.001 0.521 0.9 333

M -2.553 0.574 2.909 0.521 0.9 341

Median Maturity for Female and Male

Gadiformes and Pleuronectiformes

o [l

4042~

38

36

34

32

E 30

.E 28

.<= 26 0,

c

Q) 24

-' 22

20

18

16

14

12

10 i

0

•

o

•

• •

• 0

•

o

• 0 • • 0

•

0

0

• Gadiformes - females

o Godiformes - Moles

• Pleuronectilormes - temales

o Pleuroneetiformll$ - Moles

i

3

AGE (yearl

Figure 2

Median length (L50 ) and median age (A50 ) at maturity for female

and male Gadiformes and Pleuronectiformes.
10 NOAA Technical Report NMFS 113

Atlantic Cod: Gadus morhua

ill W W W 00 m W 00 00 w 00

Length

Proportion Length 95% Confidence interval

mature (cm) Lower Upper

Females

0.05 15.6 11.2 20.1

0.10 21.5 17.8 25.2

0.15 25.2 21.9 28.4

0.20 27.9 25.0 30.8

0.25 30.2 27.6 32.8

0.30 32.2 29.8 34.6

0.35 34.0 31.7 36.2

0.40 35.6 33.6 37.7

0.45 37.2 35.3 39.2

0.50 38.8 37.0 40.6

0.55 40.4 38.7 42.1

0.60 42.0 40.4 43.7

0.65 43.7 42.1 45.3

0.70 45.5 43.9 47.1

0.75 47.5 45.8 49.1

0.80 49.7 48.0 51.5

0.85 52.5 50.5 54.4

0.90 56.1 53.8 58.4

0.95 62.0 59.1 65.0

0.99 75.0 70.4 79.6

Males

0.05 19.8 15.8 23.7

0.10 25.1 21.9 28.4

0.15 28.5 25.6 31.3

0.20 31.0 28.4 33.5

0.25 33.0 30.7 35.4

0.30 34.9 32.7 37.0

0.35 36.5 34.5 38.5

0.40 38.0 36.2 39.9

0.45 39.5 37.8 41.2

0.50 41.0 39.3 42.6

0.55 42.4 40.8 44.0

0.60 43.9 42.4 45.4

0.65 45.4 43.9 46.9

0.70 47.1 45.6 48.5

0.75 48.9 47.3 50.4

0.80 50.9 49.3 52.6

0.85 53.4 51.7 55.2

0.90 56.8 54.7 58.9

0.95 62.2 59.5 64.8

0.99 74.0 69.9 78.2

a Offshore strata 13-25.

Table 5

Calculated proportion mature at length with approximate 95% confidence intervals based on macroscopic

observations of whole gonads of Georges Bank female

(n=983) and male (n=1034) Atlantic cod, Gadus

morhua, sampled during Northeast Fisheries Science

Center spring bottom trawl surveysa, 1985-1990.

tin 1987 and have recently increased to about 13,000 t

in 1989 (NEFSC 1991).

Median length at maturity for female and male Atlantic cod, sampled from Georges Bank during the

Atlantic cod

Gadus morhua

Georges Bank

females

n = 983

., '. Atlantic cod • • • Gadus morhua

Georges Bank

males

n = 1034

1.0

0.9

0.6

CD

0.7

ro 0.6

c 0.5 0

.;::;

a 0.4 c.

0 0.3 c:: 0.2

0.1

0.0

1.0

0.9

0.8

0.7 Zro 0.6

c 0.5 0

.;::;

a 0.4 c.

2 0.3

"- 0.2

0.1

0.0

Figure 3

Calculated and observed (.) proportion mature at length

based on macroscopic observations of whole gonads of

Georges Bank female (n=983) and male (n=1034) Atlantic

cod, Gadus morhua, sampled during Northeast Fisheries Science Center spring bottom trawl surveys, 1985-1990.

Atlantic cod are distributed in the northwest Atlantic

from Port Burwell, West Greenland to Cape Lookout,

North Carolina (Serchuk and Wood 19791). Within the

New England area, four distinct stocks are recognized

(Wise 1963): Georges Bank, Gulf of Maine, Southern

New England, and the New Jersey coastal cod. The

spawning season is from November to May; peak spawning on Georges Bank occurs during February and March

and in the Gulf of Maine from March to May (Table 2).

Total commercial landings ofAtlantic cod from Georges

Bank declined from a peak of about 64,000 metric tons

(t) in 1982 to a low of about 28,000 t in 1986 and have

increased to about 37,000 t in 1989 (NEFSC 1991).

Landings from the Gulf of Maine region declined from

a peak of about 15,100 tin 1983 to a low of about 8,300

~-,.,....,.-,-,i,-~-'-'-'-TTT'~,..,."rrrr..-.-.,rrr'"-"-'-"""'~""'-'''''

ill W W W 00 m 00 00 00 w

Length

1 F.M. Serchuk and P.W. Wood. 1979. Review and status of lhe

Southern New England - Middle Atlantic Atlantic cod, Gadus

morhua, populations. NEFC, Woods Hole Laboratory, Lab. Ref.

Doc. 79-37, 71 p.
O'Brien et al.: Maturation of Finfish II

spring of 1985-1990, was 38.8 cm and 41.0 cm, respectively (Tables 3 and 5, Fig. 3). From the Gulf of Maine

region, L50 values were 32.1 cm for females and 36.0 cm

for males for Atlantic cod sampled during 1985-1990

(Tables 3 and 7, Fig. 5). Median age at maturity was 1.7

yr and 1.9 yr, respectively, for females and males from

Georges Bank (Table 4, Fig. 4) and 2.1 yr and 2.3 yr for

females and males from the Gulf of Maine (Table 4,

Fig. 6); proportions of mature fish calculated for each

age are presented in Tables 6 and 8.

Median maturity values from the present study are

noticeably lower for both sexes compared with previous studies. Livingstone and Dery (1976) noted that L50

values for Atlantic cod collected from Georges Bank

during the spring of 1972 were 51.5 cm and 44.0 cm for

females and males, respectively. The A50 values were 2.9

yr and 2.6 yr for females and males, respectively. Atlantic cod sampled over the entire region during 1977

(Morse 1979)2 had L50 values of 49.6 cm and 53.7 cm

for females and males, respectively.

Beacham (1983a) reported that slower-growing Atlantic cod of the Scotian Shelf area had L50 values of 52

cm for females and 51 cm for males in 1963 and that by

1978 the L50 values had declined to 35 cm and 38 cm,

respectively. Median age values also declined from 3.7

yr and 4.8 yr for females and males, respectively, for the

years 1959-1964 to 2.9 yr for females and 2.8 yrs for

males during the years 1975-1979.

2 W.W. Morse. 1979. An analysis of maturity observations of 12

groundfish species collected from Cape Hatteras, North Carolina

to Nova Scotia in 1977. NMFS/NEFC Sandy Hook Laboratory

Rep. No. SHL 79-32, 2] p. .

95% Confidence interval

Age Lower Upper

1.0 0.8 1.2

2.0 1.9 2.]

3.0 2.8 3.2

4.0 3.7 4.3

5.0 4.5 5.5

6.0 5.4 6.6

7.0 6.2 7.8

8.0 7.1 8.9

9.0 7.9 10.]

10.0 8.8 11.2

11.0 9.6 12.4

1.0 0.8 1.2

2.0 1.9 2.]

3.0 2.8 3.2

4.0 3.7 4.3

5.0 4.6 5.4

6.0 5.4 6.6

7.0 6.3 7.7

8.0 7.1 8.9

9.0 8.0 10.0

10.0 8.9 ILl

11.0 9.7 ]2.3

12.0 10.6 ]3.4

0.23

0.60

0.88

0.97

0.99

].00'

1.00

1.00

1.00

1.00

1.00

Males

0.]8

0.55

0.87

0.97

1.00

1.00

1.00

1.00

1.00

1.00

1.00

1.00

Females

Proportion

mature

Table 6

Calculated proportion mature at age with approximate 95% confidence intervals based on macroscopic

observations of whole gonads of Georges Bank female

(n=970) and male (n=1021) Atlantic cod, Gadus morhua,

sampled during Northeast Fisheries Science Center

spring bottom trawl surveysa, 1985-1990.

1.0

0.9 Atlantic cod

Gadus morhua 0.8 Geor~es Bank Q) femaes :; 0.7 n = 970 10 0.6

c 0.5 0

'oP

(; 0.4 a.

:f 0.3

0.2

0.1

0.0

6 10 11 12

Age

1.0

0.9 Atlantic cod

Gadus morhua 0.8 Georges Bank

males 0.7 n = 1021 co 0.6

c 0.5 0

'oP

(; 0.4

a.

0 0.3 c: 0.2

0.1

0.0 I

4 6 10 11 12

Age

Figure 4

Calculated and observed (.) proportion mature at age based

on macroscopic observations of whole gonads of Georges

Bank female (n=970) and male (n=1021) Atlantic cod, Gadus

morhua, sampled during Northeast Fisheries Science Center

spring bottom trawl surveys, 1985-1990.

a Offshore strata ]3-25.
12 NOAA Technical Report NMFS 113

Figure 5

Calculated and obsen'ed (.) proportion mature at length

based on macroscopic obsen'ations of whole gonads of Gulf

of Maine female (n=411) and male (n=394) Atlantic cod,

Gadus morhua, sampled during Northeast Fisheries Science

Center spring bottom trawl sUn'eys, 1985-1990.

Table 7

Calculated proportion mature at length with approximate 95% confidence inten'als based on macroscopic

obsen'ations of whole gonads of Gulf.of Maine female

(n=411) and male (n=394) Atlantic cod, Gadus morhua,

sampled during Northeast Fisheries Science Center

spring bottom trawl sUn'eysa, 1985-1990.

Proportion Length 95% Confidence interval

mature (em) Lower Upper

Females

0.05 14.9 10.4 19.5

0.10 19.3 15.6 23.0

0.15 22.0 18.8 25.2

0.20 24.0 21.2 26.9

0.25 25.7 23.1 28.3

0.30 27.2 24.8 29.6

0.35 28.5 26.3 30.8

0.40 29.8 27.7 31.9

0.45 31.0 29.0 33.0

0.50 32.1 30.2 34.1

0.55 33.3 31.4 35.2

0.60 34.5 32.6 36.4

0.65 35.8 33.9 37.7

0.70 37.1 35.1 39.1

0.75 38.6 36.5 40.7

0.80 40.3 38.0 42.5

0.85 42.3 39.7 44.8

0.90 45.0 42.0 48.0

0.95 49.4 45.6 53.1

0.99 59.0 53.4 64.6

Males

0.05 15.0 10.1 19.9

0.10 20.3 16.4 24.2

0.15 23.6 20.2 27.0

0.20 26.1 23.1 29.1

0.25 28.1 25.4 30.8

0.30 29.9 27.5 32.4

0.35 31.6 29.3 33.8

0.40 33.1 30.9 35.2

0.45 34.5 32.5 36.6

0.50 36.0 33.9 38.0

0.55 37.4 35.4 39.4

0.60 38.9 36.8 40.9

0.65 40.4 38.2 42.5

0.70 42.0 39.7 44.3

0.75 43.8 41.3 46.2

0.80 45.8 43.1 48.6

0.85 48.3 45.2 51.4

0.90 51.6 48.0 55.2

0.95 56.9 52.4 61.5

0.99 68.7 61.9 75.5

a Offshore strata 26-30, 36-40.

Atlantic cod

Gadus morhua

Gulf of Maine

males

n = 394

w w m w w ro w W _ M 00

Length

w w m w w ro w W _ M

Length

1.0

·0.9

0.8

Q)

0.7

'" 0.6 ::2:

c 0.5 0.,

(; 0.4 a.

0 0.3 et 0.2

0.1

0.0

to

0.9 Atlantic cod

Gadus morhua

0.8 Gulf of Maine

females

.;l 0.7 n =411

'" 0.8

c 0.5 0.,

(; 0.4 a. 0.3

0.2

0.1

0.0
Figure 6

Calculated and observed (.) proportion mature at age based

on macroscopic observations of whole gonads of Gulf of

Maine female (n=409) and male (n=392) Atlantic cod, Gadus

morhua, sampled during Northeast Fisheries Science Center

spring bottom trawl surveys, 1985-1990.

Atlantic cod

Gadus morhua

Gulf of Maine

females

n = 409

7 W n M

Age

Atlantic cod

Gadus morhua

Gulf of Maine

males

n = 392

7 W " a M

Age

O'Brien et al.: Maturation of Finf"lsh 13

Table 8

Calculated proportion mature at age with approximate 95% confidence intervals based on macroscopic

observations of whole gonads of Gulf of Maine female

(n=409) and male (n=392) Atlantic cod, Gadus morhua,

sampled during Northeast Fisheries Science Center

spring bottom trawl surveysa, 1985-1990.

Proportion 95% Confidence interval

mature Age Lower Upper

Females

0.08 1.0 0.7 1.3

0.44 2.0 1.8 2.2

0.88 3.0 2.8 3.2

0.99 4.0 3.6 4.4

1.00 5.0 4.4 5.6

1.00 6.0 5.2 6.8

1.00 7.0 6.0 8.0

1.00 8.0 6.8 9.2

1.00 9.0 7.6 10.4

1.00 10.0 8.4 11.6

1.00 11.0 9.2 12.8

1.00 12.0 10.0 14.0

1.00 '13.0 10.8 15.2

1.00 14.0 11.6 16.4

Males

0.10 1.0 0.7 1.3

0.37 2.0 1.8 2.2

0.76 3.0 2.8 3.2

0.94 4.0 3.6 4.4

0.99 5.0 4.5 5.5

1.00 6.0 5.3 6.7

1.00 7.0 6.1 7.9

1.00 8.0 6.9 9.1

1.00 9.0 7.6 10.4

a Offshore strata 26-30, 36-40.
14 NOAA Technical Report NMFS 113

Haddock: Melanogrammus aeglefinus

5W~Wmm"~ewew"ro~wem

Length

Figure 7

Calculated and observed (.) proportion mature at length

based on macroscopic observations of whole gonads of

Georges Bank female (n=580) and male (n=478) haddock,

Melanogrammus aeglefinus, sampled during Northeast Fisheries Science Center spring bottom trawl surveys, 1985-1989.

Proportion Length 95% Confidence interval

mature (em) Lower Upper

Females

0.05 15.7 11.7 19.7

0.10 19.3 15.9 22.6

0.15 21.5 18.5 24.4

0.20 23.1 20.5 25.8

0.25 24.5 22.1 26.9

0.30 25.7 23.5 27.9

0.35 26.8 24.7 28.8

0.40 27.8 25.9 29.7

0.45 28.8 27.0 30.6

0.50 29.7 28.0 31.4

0.55 30.7 29.1 32.3

0.60 31.6 30.1 33.2

0.65 32.7 31.2 34.1

0.70 33.7 32.3 35.2

0.75 34.9 33.5 36.4

0.80 36.3 34.8 37.8

0.85 38.0 36.3 39.6

0.90 40.2 38.2 42.1

0.95 43.7 41.2 46.2

0.99 51.6 47.7 55.5

Males

0.05 11.2 6.0 16.4

0.10 15.2 10.9 19.5

0.15 17.6 13.8 21.4

0.20 19.5 16.0 22.9

0.25 21.0 17.9 24.1

0.30 22.3 19.4 25.2

0.35 23.5 20.9 26.2

0.40 24.7 22.2 27.1

0.45 25.8 23.5 28.1

0.50 26.8 24.7 29.0

0.55 27.9 25.9 29.9

0.60 29.0 27.1 30.9

0.65 30.1 28.3 31.9

0.70 31.3 29.5 33.1

0.75 32.6 30.9 34.4

0.80 34.2 32.4 36.0

0.85 36.0 34.0 38.0

0.90 38.5 36.2 40.7

0.95 42.4 39.5 45.4

0.99 51.2 46.4 55.9

a Offshore strata 13-25, 29-30.

Table 9

Calculated proportion mature at length with approximate 95% confidence intervals based on macroscopic

observations of whole gonads of Georges Bank female

(n=580) and male (n=478) haddock, Melanogrammus

aeglefinus, sampled during Northeast Fisheries Science

Center spring bottom trawl surveysa, 1985-1989.

annually; landings have since declined to less than 1,000 t

per year (NEFSC 1991).

Median length at maturity for female and male hadHaddock

Melanogrammus aeglefinus

Georges Bank

males

n = 478

Haddock

Melanogrammus aeglefinus

Georges Bank

females

n = 580

..

""'.,.".,~crrrrcrrrrcrrrrcrrrrcrrrrcrrrrcrrrrcrrrrcrrrr=l~

20 25 30 35 40 45 50 55 60 65 70 75 80 85 90

Length

1.0

0.9

0.8

1" 0.7

0;" 0.6

c 0.5 0..,

0 0.4

Co 0.3 et 0.2

01

0.0

1.0

0.9

0.8

Q)

.3 0.7

co 0.6

c 0.5 0.,

0 0.4 Co 0.3 et 0.2

0.1

0.0

Haddock range from West Greenland to Cape Hatteras

in the northwest Atlantic, but are most common on the

Scotian Shelf and on Georges Bank. Two stocks exist

off New England: the major spawning concentration

occurs on Georges Bank and a second stock with more

dispersed spawning occurs in the Gulf of Maine

(Grosslein 1962). Spawning takes place during late winter and early spring with peak activity occurring in

March and April (Table 2). Commercial landings of

haddock from Georges Bank increased from a longterm annual average of 50,000 metric tons prior to the

1960's to about 150,000 t per year in 1965 and 1966, but

declined precipitously thereafter to about 5,000 t annually during the early-to-mid-1970's; after a temporary

increase to about 25,000 t per year during the late

1970's and early 1980's, total landings from this stock

declined again to less than 10,000 t per year since 1985.

Landings from the Gulf of Maine have generally remained below 5,000 t per year except during the early

1980's when the total ranged between 6,000 and 7,000 t
O'Brien et al.: Maturation of Finfish 15

dock from Georges Bank was 29.7 and 26.8 cm, respectively (Tables 3 and 9, Fig. 7). For haddock from the

Gulf of Maine region, values ot L50 were 34.5 cm for

females and 35.0 cm for males (Tables 3 and 11, Fig. 9).

Median age at maturity was 1.5 yr for females and 1.3 yr

for males from the former region, and 1.8 yr for females and 2.1 yr for males from the latter region (Table

4, Figs. 8 and 10); proportions ofmature fish caltulated

for each age are presented in Tables 10 and 12.

Values of L50 above are considerably lower for both

sexes than those reported by Morse (1979) 2 for the year

1977 over the entire region. Overholtz (1987), however, concluded that L50 values for both sexes on

Georges Bank had increased between 1977 and 1983, a

period dominated by the relatively large 1975 and 1978

year classes. For the overall 1977-1983 period, the median length at maturity on Georges Bank was 40 cm for

females and 37 cm for males. On the southwestern

Scotian Shelf, however, median age at maturity declined substantially between the early 1960's and late

1970's from 4.6 to 3.0 yr for females and from 4.7 to 2.8

yr for males (Beacham 1983b). Templeman eta!. (1978)

and Templeman and Bishop (1979) also noted substantial changes in both L50 and A50 for haddock on the

Grand Bank and St. Pierre Bank, and attributed these

to interactions between growth and exploitation.

Figure 8

Calculated and observed (.) proportibn mature at age based

on macroscopic observations of whole gonads of Georges

Bank female (n=580) and male (n=478) haddock,

Melanogrammus aeglefinus, sampled during Northeast Fisheries Science Center spring bottom trawl surveys, 1985-1989.

Proportion 95% Confidence interval

mature Age Lower Upper

Females

0.26 1.0 0.8 1.2

0.77 2.0 1.9 2.1

0.97 3.0 2.7 3.3

1.00 4.0 3.5 4.5

1.00 5.0 4.3 5.7

1.00 6.0 5.1 6.9

1.00 7.0 5.9 8.1

1.00 8.0 6.6 9.4

1.00 9.0 7.4 10.6

1.00 10.0 8.2 11.8

Males

0.36 1.0 0.8 1.2

0.83 2.0 1.8 2.2

0.98 3.0 2.6 3.4

1.00 4.0 3.4 4.6

1.00 5.0 4.2 5.8

1.00 6.0 4.9 7.1

1.00 7.0 5.7 8.3

1.00 8.0 6.4 9.6

1.00 9.0 7.2 10.8

1.00 10.0 7.9 12.1

a Offshore strata 13-25, 29-30.

Table 10

Calculated proportion mature at age with approximate 95% confidence intervals based on macroscopic

observations of whole gonads of Georges Bank female

(n=580) and male (n=478) haddock, Melanogrammus

aeglefinus, sampled during Northeast Fisheries Science

Center spring bottom trawl surveysa, 1985-1989.

I

10

10

Haddock

Mefanogrammus aeglefinus

Georges Bank

females

n = 580

5

Age

4 5

Age

lOl

0.9

0.8

0.7 2

'" 0.6

c 0.5 0

.",

(; 0.4 C.

0.3

0.2

0.1

0.0

1.0

0.9

0.8 Haddock

Q) Melanogrammus aeglrHinus 0.7 Gllorges Bank

'" males 0.6 n = 478 c 0.5 0

.",

(; 0.4 c.

0 0.3 d:: 0.2

0.1

0.0
16 NOAA Technical Report NMFS 113

Figure 9

Calculated and observed (0) proportion mature at length

based on macroscopic observations of whole gonads of Gulf

of Maine female (n=69) and male (n=49) haddock,

Melanogrammus aeglefinus, sampled during Northeast Fisheries Science Center spring bottom trawl surveys, 1985-1989.

5 ill Th W a m H " 00 " w 00

Length

Table 11

Calculated proportion mature at length with approximate 95% confidence intervals based on macroscopic

observations of whole gonads of Gulf of Maine female

(n=69) and male (n=49) haddock, Melanogrammus

aeglefinus, sampled during Northeast Fisheries Science

Center spring bottom trawl surveys·, 1985-1989.

Proportion Length 95% Confidence interval

mature (em) Lower Upper

Females

0.05 29.0 18.8 39.2

0.10 30.4 21.8 39.1

0.15 31.3 23.5 39.0

0.20 31.9 24.9 39.0

0.25 32.5 25.9 39.0

0.30 32.9 26.9 39.0

0.35 33.3 27.7 39.0

0.40 33.7 28.5 39.0

0.45 34.1 29.2 39.0

0.50 34.5 29.9 39.1

0.55 34.9 30.6 39.1

0.60 35.2 31.3 39.2

0.65 35.6 32.0 39.3

0.70 36.1 32.6 39.5

0.75 36.5 33.3 39.7

0.80 37.1 34.0 40.1

0.85 37.7 34.6 40.8

0.90 38.6 35.2 41.9

0.95 39.9 35.7 44.2

0.99 43.0 35.9 50.2

Males

0.05 27.2 18.8 35.5

0.10 29.2 22.2 36.1

0.15 30.4 24.3 36.5

0.20 31.3 25.9 36.8

0.25 32.1 27.1 37.0

0.30 32.8 28.2 37.3

0.35 33.4 29.2 37.6

0.40 33.9 30.0 37.9

0.45 34.5 30.8 38.1

0.50 35.0 31.6 38.5

0.55 35.6 32.3 38.8

0.60 36.1 33.0 39.2

0.65 36.7 33.6 39.7

0.70 37.3 34.3 40.3

0.75 38.0 34.9 41.0

0.80 38.7 35.5 42.0

0.85 39.7 36.0 43.3

0.90 40.9 36.7 45.1

0.95 42.9 37.5 48.3

0.99 47.3 38.8 55.8

" Offshore strata 26-28, 36-40.

Haddock

Melanogrammus aegletinus

Gulf of Maine

males

n = 49

Haddock

Melanogrammus aegletinus

Gulf of Maine

females

n = 69

i!"lii'-~

5 ill Th W a m H " 00 " w 00

Length

l.°l

0.9

0.8 Q)

0.7

<tl

0.8

c 0.5 0

.~

(; 0.4 C.

0.3

0.2

0.1

0.0

1.0

0.9

0.8

0.7 ;:l

<tl 0.6

c 0.5 0

.~

(; 0.4 C.

e 0.3 c..

0.2

0.1

0.0
O'Brien et al.: Maturation of Finfish 17

Figure 10

Calculated and observed (.) proportion mature at age based

on macroscopic observations of whole gonads of Gulf of

Maine female (n=69) and male n( =49) haddock,

Melanogrammus aeglefinus, sampled during Northeast Fisheries Science Center spring bottom trawl surveys, 1985-1989.

Proportion 95% Confidence interval

mature Age Lower Upper

Females

0.13 1.0 0.0 2.0

0.64 2.0 1.4 2.6

0.96 3.0 2.4 3.6

1.00 4.0 2.9 5.1

1.00 5.0 3.3 6.7

1.00 6.0 3.7 8.3

1.00 7.0 4.0 10.0

1.00 8.0 4.4 11.6

1.00 9.0 4.8 13.2

1.00 10.0 5.2 14.8

Males

0.10 1.0 -0.3 2.3

0.43 2.0 1.3 2.7

0.85 3.0 2.5 3.5

0.97 4.0 2.9 5.1

1.00 5.0 3.3 6.7

1.00 6.0 3.6 8.4

1.00 7.0 3.9 10.1

a Offshore strata 26-28, 36-40.

Table 12

Calculated proportion mature at age with approximate 95% confidence intervals based on macroscopic

observations of whole gonads of Gulf of Maine female

(n=69) and male (n=49) haddock, Melpnogrammus

aeglejinus, sampled during Northeast Fisheries Science

Center spring bottom trawl surveysa, 1985-1989.

10

10

Haddock

Melanogrammus aeglefinus

Gulf of Maine

males

n = 49

5

Age

5

Age

1.0

0.9

0.8

i'! 0.7

'" 0.6 ::E

c 0.5 0

';0

(; OA C.

£ 0.3

0.2

0.1

0.0

10

0.9 Haddock

0.8 Melano~ammusaeglefinus

Q) Gulf of aine

.3 0.7 females

'" 0.6 n = 69

::E

c 0.5 0

'"0 OA C.

£ 0.3

0.2

0.1

00-
Pollock: Pollachius virens

18 NOAA Technical Report NMFS 113

Table 13

Calculated proportion mature at length with approximate 95% confidence intervals based on macroscopic

observations of whole gonads of female (n=154) and

male (n=143) pollock, Pollachius virens, sampled during Northeast Fisheries Science Center autumn bottom trawl surveys·, 1986-1988.

Proportion Length 95% Confidence interval

mature (cm) Lower Upper

Females

0.05 19.9 12.0 27.8

0.10 24.8 18.4 31.2

0.15 27.8 22.2 33.4

0.20 30.1 25.1 35.0

0.25 31.9 27.4 36.4

0.30 33.6 29.4 37.7

0.35 35.1 31.2 38.9

0.40 36.5 32.8 40.1

0.45 37.8 34.3 41.3

0.50 39.1 35.7 42.5

0.55 40.4 37.1 43.7

0.60 41.7 38.4 45.1

0.65 43.1 39.7 46.5

0.70 44.6 41.0 48.2

0.75 46.3 42.4 50.1

0.80 48.1 44.0 52.3

0.85 50.4 45.7 55.1

0.90 53.4 47.9 58.9

0.95 58.3 51.4 65.2

0.99 69.0 58.7 79.3

Males

0.05 23.7 17.1 30.2

0.10 28.3 23.0 33.5

0.15 31.1 26.6 35.6

0.20 33.3 29.2 37.3

0.25 35.0 31.3 38.7

0.30 36.6 33.1 40.0

0.35 38.0 34.7 41.2

0.40 39.3 36.1 42.4

0.45 40.5 37.4 43.7

0.50 41.8 38.7 44.9

0.55 43.0 39.8 46.2

0.60 44.3 41.0 47.6

0.65 45.6 42.1 49.1

0.70 47.0 43.3 50.7

0.75 48.5 44.5 52.6

0.80 50.3 45.9 54.8

0.85 52.5 47.5 57.4

0.90 55.3 49.5 61.1

0.95 59.9 52.8 67.0

0.99 70.1 59.8 80.4

• Offshore strata 13-34, 351, 36-40.

Estimates of Aso reported by Mayo et al. (1989) (3.2 yr

for females and 3.5 yr for males) are at least one full

year higher than those given above. Steele (1963) rePollock

Pollachius virens

males

n = 143

Pollock

Pollachius virens

females

n = 154

..-. -...-~-----

-.. _--",,-,~-----

1.0

0.9

0.8

l'! 0.7 .'l

co 0.6

c 0.5 0.,

0 0.4 c.

0 0.3 a: 0.2

0.1

0.0

to

0.9

0.8

Q)

0.7

co 0.6

c 0.5 0..,

0 0.4 c.

e 0.3 c0.2

0.1

0.0 w m m w W 00 ro 00 00 oc

Length

""T"'""T""'T 1 i "(II .,

10 20 30 40 50 60 70 80 90 100 110

Length

Figure 11

Calculated and observed (.) proportion mature at length

based on macroscopic observations of whole gonads of female (n=154) and male (n=143) pollock, Pollachius virens,

sampled during Northeast Fisheries Science Center autumn

bottom trawl surveys, 1986-1988.

Pollock occur on both sides of the north Atlantic. In

the northwest Atlantic they are most abundant on the

Scotian Shelf and in the Gulf of Maine (Mayo et al.

1989). Spawning takes place during winter with peak

activity occurring in December and January (Table 2).

Total landings of pollock from the Scotian Shelf-Gulf

of Maine region increased sharply from about 38,000

metric tons per year in the mid 1970's to over 68,000 t

in 1986, but have since declined to about 50,000 t in

1989 and 1990 (NEFSC 1991).

Median length at maturity for female and male pollock from the Gulf of Maine was 39.1 and 41.8 cm,

respectively (Tables 3 and 13, Fig. 11). Median age at

maturity was 2.0 yr for females and 2.3 yr for males

(Table 4, Fig. 12); proportions of mature fish calculated for each age are presented in Table 14.

Values of Lso and Aso above are. lower than those of

Mayo et al. (1989) who reported Lso estimates of 47-48

cm for females and 50.5 cm for males, based on USA

and Canadian samples collected between 1977 and 1984.
O'Brien et al.: Maturation of Finfish 19

ported median maturation values of 62.5 em at 5-6 yrs

for females and 58 em at 4-5 yrs for males collected

from the Bay of Fundy in 1960 and 1961. The corresponding median ages are similar to those presented by

Beacham (1983c) for a similar time period from the

southern Scotian Shelf. Beacham further noted substantial declines in pollock Lso and Aso values of 5-6 em

and 1-2 yr between the early 1960's and late 1970's in

the same region.

Table 14

Calculated proportion mature at age with approximate 95% confidence intervals based on macroscopic

observations of whole gonads of female (n=154) and

male (n=143) pollock, Pollachius virens, sampled during Northeast Fisheries Science Center autumn bottom trawl surveysa, 1986-1988.

Proportion 95% Confidence interval

mature Age Lower Upper

Females

0.24 1.0 0.4 1.6

0.50 2.0 1.6 2.4

0.76 3.0 2.5 3.5

0.91 4.0 3.3 4.7

0.97 5.0 3.9 6.1

0.99 6.0 4.6 7.4

1.00 7.0 5.2 8.8

1.00 8.0 5.8 10.2

1.00 9.0 6.5 11.5

1.00 10.0 7.1 12.9

1.00 11.0 7.7 14.3

1.00 12.0 8.4 15.6

1.00 13.0 9.0 17.0

1.00 14.0 9.6 18.4

1.00 15.0 10.2 19.8

Males

0.07 1.0 0.5 1.5

0.35 2.0 1.7 2.3

0.78 3.0 2.6 3.4

0.96 4.0 3.3 4.7

0.99 5.0 4.0 6.0

1.00 6.0 4.6 7.4

1.00 7.0 5.3 8.7

1.00 8.0 5.9 10.1

1.00 9.0 6.5 11.5

1.00 10.0 7.2 12.8

1.00 11.0 7.8 14.2

1.00 12.0 8.5 15.5

1.00 13.0 9.1 16.9

1.00 14.0 9.7 18.3

1.00 15.0 10.4 19.6

1.00 16.0 11.0 21.0

1.00 17.0 11.7 22.3

1.00 18.0 12.3 23.7

a Offshore strata 13-34, 351, 36-40.

1.0

0.9 Pollock

0.8 Pollachius virens ., females 0.7 n = 154

'" 0.6

c 0.5 0.,

0 0.4 0.

e 0.3 c..

0.2

0.1

0.0-

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 16

Age

1.0

0.9 Pollock

0.8 Pollachius virens ., males

:; 0.7 n = 143

«l 0.6

c 0.5 0.,

0 0.4 0.

0 0.3 a:: 0.2

0.1

0.0 I I I I I

1 2 3 4 5 6 7 6 9 10 11 12 13 14 15 16 17 18

Age

Figure 12

Calculated and observed (.) proportion mature at age based

on macroscopic observations of whole gonads of female

(n=154) and male (n=143) pollock, Pollachius virens, sampled

during Northeast Fisheries Science Center autumn bottom

trawl surveys, 1986-1988.
20 NOAA Technical Report NMFS 113

White Hake: Urophycis tenuis

m w m w W 00 ro 00 M 00 w Length

Table 15

Calculated proportion mature at length with approximate 95% confidence intervals based on macroscopic

observations of whole gonads of female (n=455) and

male (n=346) white hake, Urophycis tenuis, sampled

during Northeast Fisheries Science Center spring bottom trawl surveysa, 1987-1989.

Proportion Length 95% Confidence interval

mature (em) Lower Upper

Females

0.05 13.6 8.4 18.8

0.10 19.1 14.9 23.3

0.15 22.5 18.8 26.1

0.20 25.0 21.8 28.3

0.25 27.1 24.2 30.0

0.30 29.0 26.3 31.6

0.35 30.6 28.2 33.1

0.40 32.2 29.9 34.5

0.45 33.7 31.6 35.8

0.50 35.1 33.1 37.2

0.55 36.6 34.7 38.6

0.60 38.1 36.2 40.0

0.65 39.7 37.7 41.6

0.70 41.3 39.3 43.4

0.75 43.2 41.0 45.3

0.80 45.3 42.9 47.7

0.85 47.8 45.1 50.5

0.90 51.2 48.0 54.4

0.95 56.7 52.6 60.8

0.99 68.7 62.5 75.0

Males

0.05 20.3 17.1 23.6

0.10 23.5 20.9 26.1

0.15 25.4 23.2 27.7

0.20 26.9 24.9 28.9

0.25 28.1 26.3 29.9

0.30 29.2 27.5. 30.8

'0.35 30.1 28.6 31.6

0.40 31.0. 29.6 32.4

0.45 31.9 30.5 33.2

0.50 32,7 31.4 34.0

0.55 33.6 32.3 34.8

0.60 34.4 33.2 35.6

0.65 35.3 34.1 36.5

0.70 36.3 35.0 37.5

0.75 37.3 36.0 38.7

0.80 38.5 37.0 40.0

0.85 40.0 38.3 41.7

0.90 41.9 39.9 44.0

0.95 45.1 42.5 47.7

0.99 52.0 48.1 55.9

a Offshore strata 21-30, 33-34, 351, 36-40.

3 J. Burnett, S.H. Clark, and L. O'Brien. 1984. A preliminary assessment of white hake in the Gulf of Maine-Georges Bank area.

NMFS/NEFC, Woods Hole Lab. Ref, Doc. No. 84-31,33 p.

White hake

Urophycis tenuis

males

n = 346

to

0.9

0.8

0.7 ;:l

'" 0.6

c 0.5 0

.;::;

(; 0.4 c.

0 0.3 et 0.2

0.1

0.0

to .._- ...

0.9 White hake

0.8 Urophycis tenuis

females

:> 0.7 n = 455

ro 0.6

c 0.5 0

.;::;

0 0.4 c.

e 0.3 n. 0.2

0.1

0.0

Figure 13

Calculated and observed (.) proportion mature at length

based on macroscopic observations of whole gonads of female (n=455) and male (n=346) white hake, Urophycis tenuis,

sampled during Northeast Fisheries Science Center spring

bottom trawl surveys, 1987-1989.

liii!I-r-r;-~

m w m w W 00 ro 00 M 00 w Length

White hake are widely distributed from Labrador to

Georges Bank, and in deeper slope waters southward to

Florida. In U.S. waters, white hake ofthe Gulf ofMaineGeorges Bank region are considered to be a unit stock.

Information relative to white hake spawning in this

region is both limited and conflicting, although ripe

fish have been observed from October to May (Table

2). Commercial landings of white hake averaged 4,700

metric tons per year during 1975-1980, increased to an

average of 6,700 t from 1981 to 1988, and subsequently

declined to 5,600 tin 1989 (NEFSC 1991).

Median length at maturity for female and male white

hake was 35.1 and 32.7 em, respectively (Tables 3 and

15, Fig. 13). Median age at maturity was 1.4 yr for both

sexes (Table 4, Fig. 14); proportions of mature fish

calculated for each age are presented in Table 16.

Values ofL50 above are considerably lower than those

obtained by Morse (1979)2 from 1977 data (47.6 and

43.0 em for females and males, respectively) and by

Burnett et al. (1984)3 from data collected during 1977-
O'Brien et at.: Maturation of Finfish 21

82 (42 cm for both sexes) for the GulfofMaine-Georges

Bank region. Musick (1969) noted that females matured at 48 to 64 cm and males at 40 to 52 cm, but his

data included fish from both U.S. and Canadian waters.

Maturation of white hake in the Gulf of MaineGeorges Bank region occurs at a smaller size and

younger age than for slower-growing white hake in

Canadian waters. Battle (1951) observed no spawning

females below 57 cm in size and 4 yr in age within the

Bay of Fundy, and Beacham and Nepszy (1980) and

Beacham (1983c) reported values of L50 ranging from

40.1 to 53.9 cm for females and from 36.6 to 44.1 cm for

males in the Gulf of St. Lawrence and Scotian Shelf regions during 1971-78, corresponding to ages of 3 to 5 yr.

However, maturation of white hake in the Gulf of

Maine-Georges Bank region may be a moot point in

view of evidence that the species does not successfully

spawn in that region. Musick (1969) observed that

spawning was weak and aperiodic, and hypothesized

that recruits from the Scotian Shelfsustained the population. More recently, Fahay and Able (1989) reported

the absence ofwhite hake eggs and larvae in the Gulf of

Maine, and presented evidence which suggested that

the local population was sustained primarily by recruits

from a spring-spawning continental slope population

and secondarily by recruits from the summer-spawning

and fall-spawning Scotian Shelf and southern Gulf of

St. Lawrence populations.

Proportion 95% Confidence interval

mature Age Lower Upper

Females

0.33 1.0 0.8 1.2

0.74 2.0 1.8 2.2

0.94 3.0 2.7 3.3

0.99 4.0 3.5 4.5

1.00 5.0 4.3 5.7

1.00 6.0 5.1 6.9

1.00 7.0 5.9 8.1

1.00 8.0 6.7 9.3

1.00 9.0 7.5 10.5

1.00 10.0 8.3 11.7

1.00 11.0 9.1 12.9

1.00 12.0 9.9 14.1

1.00 13.0 10.7 15.3

1.00 14.0 U.S 16.5

1.00 15.0 12.3 17.7

1.00 16.0 13.1 18.9

1.00 17.0 13.9 20.1

1.00 18.0 14.7 21.3

Males

0.29 1.0 0.8 1.2

0.82 2.0 1.8 2.2

0.98 3.0 2.7 3.3

1.00 4.0 3.4 4.6

1.00 5.0 4.2 5.8

1.00 6.0 5.0 7.0

1.00 7.0 5.8 8.2

Table 16

Calculated proportion mature at age with approximate 95% confidence intervals based on macroscopic

observations of whole gonads of female (n=455) and

male (n=346) white hake, Urophycis tenuis, sampled

during Northeast Fisheries Science Center spring bottom trawl surveys", 1987-1989.

1.0

0.9 White hake

Urophycis tenuis 0.8 females Q) n = 455 :; 0.7

ro 0.6

c 0.5 0.,

a 0.4 a.

e 0.3

"- 0.2

0.'

0.0 i i i i i i i

I 2 3 4 5 6 7 8 9 10 '1 12 13 14 15 16 17 16

Age

1.0

0.9 White hake

Urophycis tenuis 0.8 males

n = 346 0.7

<tl 0.6

c 0.5 0.,

a 0.4 a.

:f. 0.3

0.2

0.'

0.0 i i i i i i i i i i i

I 2 3 4 5 8 9 10 11 12 13 14 15 16 17 18

Age

Figure 14

Calculated and observed (.) proportion mature at age based

on macroscopic observations of whole gonads of female

(n=455) and male (n=346) white hake, Urophycis tenuis,

sampled during Northeast Fisheries Science Center spring

bottom trawl surveys, 1987-1989.

a Offshore strata 21-30, 33-34, 351, 36-40.
22 NOAA Technical Report NMFS 113

Red Hake: Urophycis chuss

Table 17

Calculated proportion mature at length with approximate 95% confidence intervals based on macroscopic

observations of whole gonads of female (n=667) and

male (n=595) red hake, Urophycis chuss, from the Gulf

of Maine-northern Georges Bank region sampled during Northeast Fisheries Science Center spring bottom

trawl surveys", 1982-1985.

Proportion Length 95% Confidence interval

mature (cm) Lower Upper

Females

0.05 21.0 19.2 22.9

0.10 22.5 21.0 24.1

0.15 23.4 22.1 24.8

0.20 24.1 22.9 25.4

0.25 24.7 23.5 25.9

0.30 25.2 24.1 26.3

0.35 25.7 24.6 26.7

0.40 26.1 25.1 27.0

0.45 26.5 25.6 27.4

0.50 26.9 26.0 27.7

0.55 27.3 26.5 28.1

0.60 27.7 26.9 28.5

0.65 28.1 27.3 28.9

0.70 28.6 27.8 29.3

0.75 29.1 28.3 29.8

0.80 29.6 28.8 30.4

0.85 30.3 29.5 31.2

0.90 31.2 30.3 32.2

0.95 32.7 31.5 33.9

0.99 36.0 34.2 37.8

Males

0.05 16.8 14.5 19.1

0.10 18.2 16.2 20.1

0.15 19.0 17.3 20.8

0.20 19.7 18.1 21.3

0.25 20.2 18.7 21.7

0.30 20.7 19.3 22.1

0.35 21.1 19.8 22.4

0.40 21.5 20.2 22.7

0.45 21.9 20.7 23.0

0.50 22.2 21.1 23.3

0.55 22.6 21.5 23.7

0.60 23.0 22.0 24.0

0.65 23.4 22.4 24.3

0.70 23.8 22.8 24.7

0.75 24.2 23.3 25.2

0.80 24.8 23.8 25.7

0.85 25.4 24.5 26.4

0.90 26.3 25.2 27.3

0.95 27.6 26.4 28.9

0.99 30.7 28.8 32.6

a Offshore strata 20-30, 36-40.

ern Georges Bank region, values of L50 were 25.1 cm

for females and 23.8 cm for males (Tables 3 and 19, Fig.

Red hake

UrOPhrCiS chuss

Gulf a MaineNorthern Georges Bank

females

n = 667

Red hake

UroPhrcis chuss

Gulf 0 MaineNorthern Georges Bank

males

n = 595

1.0

0.9

0.8

OJ

0.7

m 0.6 ::?'

c 0.5 0.,

0 0.4 0-

0 0.3 n:: 0.2

0.1

0.0

Figure 15

Calculated and observed (.) proportion mature at length

based on macroscopic observations of whole gonads of female (n=667) and male (n=595) red hake, Urophycis chuss,

from the Gulf of Maine-northern Georges Bank region

sampled during Northeast Fisheries Science Center spring

bottom trawl surveys, 1982-1985.

Red hake are distributed from the Gulf of St. Lawrence

to Cape Hatteras, North Carolina. It is assumed that

two stocks exist in U.S. waters, one occupying the Gulf

of Maine and the northern portion of Georges Bank,

and the other situated on southern Georges Bank and

throughout the Southern New England-Middle Atlantic region. Spawning occurs from May to September for

the northern stock, with peak activity during June and

July, while the southern stock spawns over a protracted

period from March to October (Table 2). Commercial

landings for this under-exploited species have averaged

1,000 metric tons per year since 1980 for the northern

stock, whereas landings from the southern stock have

decreased from over 4,000 t in 1980 to 800 t in 1989

(NEFSC 1991).

Median length at maturity for female and male red

hake from the Gulf of Maine-northern Georges Bank

region was 26.9 and 22.2 cm, respectively (Tables 3and

17, Fig. 15). For red hake from the Mid-Atlantic-south-

+-............,..-.~~·, ....·-rT i I "I! 10'1'1 IIi i I r i

W m w W H Q W 00 m Length
O'Brien et al.: Maturation of Finfish 23

17). Median age at maturity was 1.8 yr for females and

1.4 yr for males in the former region and 1.7 yr for

females and 1.8 yr for males in the latter region (Table

4, Figs. 16 and 18); proportions of mature fish calculated for each age are presented in Tables 18 and 20.

Morse (1979)2 reported an Lso of 27.8 and 24.8 cm,

respectively, for female and male red hake in the same

general region during 1977 but did not distinguish

between stock areas. Musick (1969) observed that red

hake matured at 2 yr of age, with females maturing at

27 to 33 cm and males at 24 to 30 cm. Markle et al.

(1982) also reported that maturation occurred essentially at age 2, with most fish mature by 30 cm.

Figure 16

Calculated and observed (.) proportion mature at age based

on macroscopic observations of whole gonads of female

(n=667) and male (n=595) red hake, Urophycis chuss, from

the Gulf of Maine-northern Georges Bank region sampled

during Northeast Fisheries Science Centerspring bottom trawl

surveys, 1982-1985.

Proportion 95% Confidence interval

mature Age Lower Upper

Females

0.04 1.0 0.7 1.3

0.73 2.0 1.9 2.1

0.99 3.0 2.7 3.3

1.00 4.0 3.4 4.6

1.00 5.0 4.2 5.8

1.00 6.0 4.9 7.1

1.00 7.0 5.6 8.4

1.00 8.0 6.3 9.7

1.00 9.0 7.1 10.9

1.00 10.0 7.8 12.2

1.00 11.0 8.5 13.5

1.00 12.0 9.2 14.8

Males

0.15 1.0 0.8 1.2

0.91 2.0 1.9 2.1

1.00 3.0 2.7 3.3

1.00 4.0 3.5 4.5

1.00 5.0 4.2 5.8

1.00 6.0 5.0 7.0

1.00 7.0 5.8 8.2

1.00 8.0 6.5 9.5

1.00 9.0 7.3 10.7

1.00 10.0 8.1 11.9

1.00 11.0 8.8 13.2

1.00 12.0 9.6 14.4

a Offshore strata 20-30, 36-40.

Table 18

Calculated proportion mature at age with approximate 95% confidence intervals based on macroscopic

observations of whole gonads of female (n=667) and

male (n=595) red hake Urophycis chuss from the Gulf of

Maine-northern Georges Bank region sampled during

Northeast Fisheries Science Center spring bottom trawl

surveys", 1982-1985.

10 11 12

10 11 12

Red hake

Urophrcis chuss

Gulf 0 MaineNorthern Georges Bank

males

n = 595

6

Age

6

Age

4

to

0.9 Red hake

UrofhrciS chuss 0.6 Gul ° Maine- Q) Northern Georges Bank 0.7 females

'" 0.6 n = 667

c 0.5 0

.;::;

0 0.4 n 0.3

0.2

0.1

0.0

1.0

0.9

0.6

0.7 2

'" 0.6

c 0.5 0

.;::;

0 0.4 n 0.3

0.2

0.1

0.0
24 NOAA Technical Report NMFS 113

Figure 17

Calculated and observed (.) proportion mature at length

based on macroscopic observations of whole gonads of female (n=1020) and male (n=753) red hake, Urophycis chuss,

from southern Georges Bank - Middle Atlantic sampled during Northeast Fisheries Science Center spring bottom trawl

surveys, 1982-1985.

I' I 'I i r i 1-"T""'T"l

m ffi w a m Q W E W

Length

Table 19

Calculated proportion mature at length with approximate 95% confidence intervals based on macroscopic

observations of whole gonads of female (n=1020) and

male (n=753) red hake, Urophycis chuss, from southern

Georges Bank - Middle Atlantic sampled during Northeast Fisheries Science Center spring bottom trawl

surveysa, 1982-1985.

Proportion Length 95% Confidence interval

mature (em) Lower Upper

Females

0.05 19.3 17.9 20.7

0.10 20.8 19.6 22.0

0.15 21.7 20.6 22.7

0.20 22.4 21.4 23.3

0.25 22.9 22.1 23.8

0.30 23.4 22.6 24.3

0.35 23.9 23.1 24.7

0.40 24.3 23.6 25.0

0.45 24.7 24.0 25.4

0.50 25.1 24.4 25.8

0.55 25.5 24.8 26.2

0.60 25.9 25.3 26.5

0.65 26.3 25.7 26.9

0.70 26.8 26.2 27.4

0.75 27.3 26.6 27.9

0.80 27.8 27.2 28.5

0.85 28.5 27.8 29.2

0.90 29.4 28.7 30.2

0.95 30.9 30.0 31.8

0.99 34.1 32.8 35.5

Males

0.05 17.8 16.2 19.3

0.10 19.3 18.0 20.6

0.15 20.2 19.1 21.4

0.20 21.0 19.9 22.0

0.25 21.5 20.6 22.5

0.30 22.1 21.2 23.0

0.35 22.5 21.7 23.4

0.40 23.0 22.2 23.7

0.45 23.4 22.6 24.1

0.50 23.8 23.1 24.5

0.55 24.2 23.5 24.9

0.60 24.6 24.0 25.3

0.65 25.1 24.5 25.7

0.70 25.5 24.9 26.1

0.75 26.0 25.5 26.6

0.80 26.6 26.0 27.2

0.85 27.3 26.7 28.0

0.90 28.3 27.6 29.0

0.95 29.8 28.9 30.7

0.99 33.2 31.8 34.6

a Inshore strata 1-46, 52, 55, offshore strata 1-19, 61-76.

...

Red hake . Urophycis chuss

Southern Georges Bank -

Middle Atlantic

males

n = 753

Red hake

Urophycis chuss

Southern Georges Bank - Middle Atlantic

females

n = 1020

..

·"'-'-~~""-'-~rrr-'''''-'-~·1....-rT"'''-1 I I

25 30 35 40 45 50 55 60

Length

..

10

to ...~-~-----

0.9

0.6

0.7 i3

'" 0.6

c 0.5 0.,

(; 0.4

C.

0 0.3 0: 0.2

0.1

0.0

to

0.9

0.6

0.7 i3

co 0.6

c 0.5 0.,

(; 0.4 c.

0 0.3 0: 0.2

0.1

0.0
O'Brien et al.: Maturation of Finfish 25

Red hake

Urophycis chuss

Southern Georges Bank -

Middle Atlantic

females

n = 1020

Table 20

Calculated proportion mature at age with approximate 95% confidence intervals based on macroscopic

observations of whole gonads of female (n=1020) and

male (n=753) red hake, Urophycis chuss, from southern

Georges Bank - Middle Atlantic sampled during Northeast Fisheries Science Center spring bottom trawl

surveys", 1982-1985.

10

0.9

0.8 Q)

:; 0.7

10 0.8

C 0.5 0

.'"{) 0.4 C.

0 0.3 a: 0.2

0.1

0.0 8

Age

10 11 12

Proportion

mature

Females

Age

95% Confidence interval

Lower Upper

Figure 18

Calculated and observed (.) proportion mature at age based

on macroscopic observations of whole gonads of female

(n=1020) and male (n=753) red hake, Urophycis chuss, from

southern Georges Bank - Middle Atlantic sampled during

Northeast Fisheries Science Center spring bottom trawl surveys,1982-1985.

Red hake

Urophycis chuss

Southern Georges Bank -

Middle Atlantic

males

n = 753

10

0.9

0.8

Q)

3 0.7

'" 0.6

c 0.5 0

.'"{) 0.4

C.

£ 0.3

0.2

0.1

0.0 4 6

Age

10 11 12

0.09

0.70

0.98

1.00

1.00

1.00

1.00

1.00

1.00

1.00

Males

0.10

0.66

0.97

1.00

1.00

1.00

1.00

1.00

1.00

1.00

1.00

1.00

1.0 0.8 1.2

2.0 1.9 2.1

3.0 2.8 3.2

4.0 3.7 4.3

5.0 4.5 5.5

6.0 5.4 6.6

7.0 6.2 7.8

8.0 7.1 8.9

9.0 7.9 10.1

10.0 8.8 11.2

1.0 0.8 1.2

2.0 1.9 2.1

3.0 2.8 3.2

4.0 3.6 4.4

5.0 4.5 5.5

6.0 5.3 6.7

7.0 6.1 7.9

8.0 7.0 9.0

9.0 7.8 10.2

10.0 8.7 11.3

11.0 9.5 12.5

12.0 10.3 13.7

a Inshore strata 1-46, 52, 55, offshore strata 1-19, 61-76.
26 NOAA Technical Report NMFS 113

Silver Hake: Merluccius bilinearis

W lli W m e % W M 00

Length

W lli W m e % W M 00

Length

Figure 19

Calculated and observed (.) proporti<>n mature at length

based on macroscopic observations of whole gonads of Gulf

of Maine-northern Georges Bank female (n=141O) and male

(n=1026) silver hake, Merluccius bilinearis, sampled during

Northeast Fisheries Science Center spring bottom trawl surveys, 1985-1989.

Proportion Length 95% Confidence interval

mature (cm) Lower Upper

Females

0.05 17.4 16.6 18.2

0.10 18.8 18.2 19.5

0.15 19.7 19.2 20.3

0.20 20.4 19.9 20.9

0.25 20.9 20.5 21.4

0.30 21.4 21.0 21.9

0.35 21.9 21.5 22.3

0.40 22.3 21.9 22.7

0.45 22.7 22.3 23.1

0.50 23.1 22.7 23.5

0.55 23.5 23.1 23.8

0.60 23.8 23.5 24.2

0.65 24.3 23.9 24.7

0.70 24.7 24.3 25.1

0.75 25.2 24.8 25.6

0.80 25.7 25.3 26.2

0.85 26.4 25.9 26.9

0.90 27.3 26.7 27.9

0.95 28.7 28.0 29.4

0.99 31.9 30.9 32.9

Males

0.05 17.7 17.0 18.4

0.10 18.9 18.3 19.4

0.15 19.6 19.0 20.1

0.20 20.1 19.6 20.6

0.25 20.6 20.1 21.0

0.30 20.9 20.5 21.4

0.35 21.3 20.9 21.7

0.40 21.6 21.2 22.0

0.45 21.9 21.6 22.3

0.50 22.3 21.9 22.6

0.55 22.6 22.2 22.9

0.60 22.9 22.5 23.3

0.65 23.2 22.8 23.6

0.70 23.6 23.2 24.0

0.75 24.0 23.5 24.4

0.80 24.4 23.9 24.9

0.85 24.9 24.4 25.4

0.90 25.7 25.1 26.2

0.95 26.8 26.1 27.5

0.99 29.4 28.4 30.3

a Offshore strata 20-30, 36-40.

Table 21

Calculated proportion mature at length with approximate 95% confidence intervals based on macroscopic

observations of whole gonads of Gulf of Maine-northern Georges Bank female (n=1410) and male (n=1026)

silver hake, Merluccius bilinearis, sampled during Northeast Fisheries Science Center spring bottom trawl surveysa,1985-1989.

4, Figs. 20 and 22); proportions of mature fish calculated for each age are presented in Tables 22 and 24.

Silver hake

Merluccius bilinearis

Gulf of Maine - Northern Georges Bank

males

n = 1026

1.0

0.9

0.8

0.7 2

<0 0.6

c 0.5 0.,

a 0.4 Q.

0 0.3 ti: 0.2

0.1

0.0

1.0

0.9 Silver hake

Merluccius bilinearis

0.8 Gulf of Maine -

0.7 Northern Georges Bank

2 females <0 0.6 n = 1410

c 0.5 0

.,

a 0.4 Q.

0.3

0.2

0.1

0.0

Silver hake are widely distributed in the northwest Atlantic from Newfoundland to South Carolina, but are

most abundant in coastal waters from Maine to New

Jersey; two stocks inhabit this region, with Georges

Bank as the boundary (Almeida 1987). Spawning of

both stocks takes place from spring through early autumn with most activity occurring between May and

September (Table 2). Total landings from both stocks

combined declined from over 100,000 metric tons annually during the early 1970's, when distant water fleets were

dominant, to less than 20,000 t since 1986 (NEFSC 1991).

Median length at maturity for female and male silver

hake from the Gulf of Maine-northern Georges Bank

stock was 23.1 and 22.3 em, respectively (Tables 3 and

21, Fig. 19). For silver hake from the southern Georges

Bank stock, values of Lso were 23.2 em for females and

22.7 em for males (Tables 3 and 23, Fig. 21). Median

age at maturity for both sexes was 1.7 yr from the

former region, and 1.6 yr from the latter region (Table
O'Brien et al.: Maturation of Finfish 27

Values of Lso above are 2-4 em lower for both sexes

than those reported by Morse (1979) 2 for the year 1977

over the entire region. Doubleday and Halliday (1975)

observed that the median length at maturity for silver hake

from the Scotian Shelf occurred at 26-27 em in females

and at 23-24 em in males, with "0 values lying between

ages 1 and 2 for both sexes. Beacham (1983e) further

noted a decline in Lso for females from 31 em during the

1960's to 26 em during the late 1970's in the same area.

A similar decline from 27 em to 24 em was found for

males during the same period, although "0values generally remained between 1 and 2 yr for both sexes.

4 5

Age

Table 22

Calculated proportion mature at age with approximate 95% confidence intervals based on macroscopic

observations of whole gonads of Gulf of Maine-northern Georges Bank female (n=141O) and male (n=1026)

silver hake Merluccius bilinearis sampled during Northeast Fisheries Science Center spring bottom trawl

surveysa, 1985-1989.

to

0.9

0.8

0.7 Eco 0.6

c 0.5 0

.;:

0 0.4 C.

0 0.3 a: 0.2

0.1

0.0

Silver hake

Merluccius bifinearis

Gulf of Maine -

Northern Georges Bank

females

n = 1410

Proportion

mature

Females

Age

95% Confidence interval

Lower Upper

4 5

Age

Figure 20

Calculated and observed (.) proportion mature at age based

on macroscopic observations of whole gonads of Gulf of

Maine-northern Georges Bank female (n=141O) and male

(n=1026) silver hake, Merluccius bilinearis, sampled during

Northeast Fisheries Science Center spring bottom trawl surveys, 1985-1989.

a Offshore strata 20-30, 36-40.

1.0 0.9 1.1

2.0 1.9 2.1

3.0 2.9 3.1

4.0 3.8 4.2

5.0 4.7 5.3

6.0 5.6 6.4

7.0 6.5 7.5

8.0 7.4 8.6

9.0 8.3 9.7

1.0 0.9 1.1

2.0 1.9 2.1

3.0 2.8 3.2

4.0 3.7 4.3

5.0 4.6 5.4

6.0 5.5 6.5

7.0 6.4 7.6

8.0 7.3 8.7

0.08

0.70

0.99

1.00

1.00

1.00

1.00

1.00

1.00

Males

0.07

0.74

0.99

1.00

1.00

1.00

1.00

1.00

Silver hake

Merluccius bifinearis

Gulf of Maine -

Northern Georges Bank

males

n = 1026

1.0

0.9

0.8

OJ

0.7

co 0.8

c 0.5 0

.;:

0 0.4

C.

e 0.3 0-

0.2

0.1

0.0
28 NOAA Technical Report NMFS 113

Figure 21

Calculated and observed (.) proportion mature at length

based on macroscopic observations ofwhole gonads ofsouthern Georges Bank - Middle Atlantic female (n=2429) and

male (n=1612) silver hake, Merluccius bilinearis, sampled during Northeast Fisheries Science Center spring bottom trawl

surveys, 1985-1989.

+...........~+1"""--~~-.-I.-.-p-r,.,,-~'T'""~~..,,-~,,-r-rr-r~.,

m lli w m W H W W w Length

+,...,.....,.~..,+.~.h,."....,-

m lli w m W H W W w Length

Table 23

Calculated proportion mature at length with approximate 95% confidence intervals based on macroscopic

observations ofwhole gonads ofsouthern Georges Bank

- Middle Atlantic female (n=2429) and male (n=1612)

silver hake, Merluccius bilinearis, sampled during Northeast Fisheries Science Center spring bottom trawl

surveysa, 1985-1989.

Proportion Length 95% Confidence interval

mature (em) Lower Upper

Females

0.05 16.8 16.0 17.6

0.10 18.4 17.7 19.1

0.15 19.4 18.8 20.1

0.20 20.2 19.6 20.8

0.25 20.8 20.3 21.3

0.30 21.4 20.9 21.8

0.35 21.8 21.4 22.3

0.40 22.3 21.9 22.8

0.45 22.7 22.3 23.2

0.50 23.2 22.8 23.6

0.55 23.6 23.2 24.0

0.60 24.1 23.7 24.4

0.65 24.5 24.1 24.9

0.70 25.0 24.6 25.4

0.75 25.5 25.2 25.9

0.80 26.2 25.8 26.6

0.85 26.9 26.5 27.3

0.90 27.9 27.4 28.4

0.95 29.5 29.0 30.1

0.99 33.1 32.2 33.9

Males

0.05 18.0 17.2 18.8

0.10 19.2 18.5 19.9

0.15 19.9 19.3 20.5

0.20 20.5 19.9 21.0

0.25 20.9 20.4 21.4

0.30 21.3 20.9 21.8

0.35 21.7 21.3 22.1

0.40 22.0 21.6 22.5

0.45 22.4 22.0 22.8

0.50 22.7 22.3 23.1

0.55 23.0 22.6 23.4

0.60 23.3 23.0 23.7

0.65 23.7 23.3 24.0

0.70 24.0 23.7 24.4

0.75 24.4 24.1 24.8

0.80 24.9 24.5 25.2

0.85 25.4 25.1 25.8

0.90 26.2 25.8 26.6

0.95 27.4 26.9 27.9

0.99 30.0 29.2 30.7

a Inshore strata 1-46, 52, 55, offshore strata 1-19, 61-76.

Silver Hake

Merluccius bilinearis

Southern Georges Bank -

Middle Atlantic

males

n = 1612

Silver Hake

Merluccius bilinearis

Southern Georges Bank -

Middle Atlantic

females

n = 2429

1.0

0.9

0.8

::J 0.7

OJ

::i: 0.8

c 0.5 0

'';::;

(; 0.4 a.

0 0.3 c:: 0.2

0.1

0.0

1.0

0.9

0.8

0.7 <l

OJ 0.6 ::i:

c 0.5 0

'';::;

(; 0.4 a.

0 0.3 c:: 0.2

0.1

0.0
Figure 22

Calculated and observed (.) proportion mature at age based

on macroscopic observations of whole gonads of southern

Georges Bank - Middle Atlantic female (~2429) and male

(~1612) silver hake, Merluccius bilinellris, sampled during

Northeast Fisheries Science Center spring bottom trawl surveys, 1985-1989.

O'Brien et al.: Maturation of Finfish 29

Table 24

Calculated proportion mature at age with approximate 95% confidence intervals based on macroscopic

observations ofwhole gonads ofsouthern Georges Bank

- Middle Atlantic female (~2429) and male (n=1612)

silver hake, Merluccius bilinearis, sampled during Northeast Fisheries Science Center spring bottom trawl

surveysa, 1985-1989.

Proportion 95% Confidence interval

mature Age Lower Upper

Females

0.10 1.0 0.9 1.1

0.81 2.0 2.0 2.0

0.99 3.0 2.9 3.1

1.00 4.0 3.8 4.2

1.00 5.0 4.7 5.3

1.00 6.0 5.6 6.4

1.00 7.0 6.6 7.4

Males

0.08 1.0 0.9 1.1

0.79 2.0 1.9 2.1

0.99 3.0 2.9 3.1

1.00 4.0 3.8 4.2

1.00 5.0 4.7 5.3

1.00 6.0 5.6 6.4

1.00 7.0 6.5 7.5

1.00 8.0 7.4 8.6

1.00 9.0 8.3 9.7

a Inshore strata 1-46, 52, 55, offshore strata 1-19, 61-76.
30 NOAA Technical Report NMFS 113

Redfish: Sebastesfasciatus

Proportion Length 95% Confidence interval

mature (cm) Lower Upper

Females

0.05 17.3 16.4 18.2

0.10 18.6 17.8 19.3

0.15 19.3 18.7 20.0

0.20 19.9 19.3 20.5

0.25 20.4 19.9 20.9

0.. 30 20.8 20.3 21.3

0.35 21.2 20.8 21.7

0.40 21.6 21.1 22.0

0.45 21.9 21.5 22.3

0.50 22.3 21.9 22.7

0.55 22.6 22.2 23.0

0.60 22.9 22.5 23.3

0.65 23.3 22.9 23.7

0.70 23.7 23.3 24.1

0.75 24.1 23.7 24.5

0.80 24.6 24.1 25.0

0.85 25.2 24.6 25.7

0.90 25.9 25.3 26.5

0.95 27.2 26.5 27.9

0.99 30.0 28.9 31.1

Males

0.05 12.0 10.6 13.5

0.10 14.3 13.1 15.5

0.15 15.7 14.6 16.7

0.20 16.7 15.8 17.7

0.25 17.6 16.8 18.5

0.30 18.4 17.6 19.2

0.35 19.1 18.3 19.8

0.40 19.7 19.1 20.4

0.45 20.3 19.7 20.9

0.50 20.9 20.4 21.5

0.55 21.5 21.0 22.1

0.60 22.2 21.7 22.7

0.65 22.8 22.3 23.3

0.70 23.5 23.0 24.0

0.75 24.3 23.8 24.7

0.80 25.1 24.6 25.6

0.85 26.2 25.6 26.7

0.90 27.6 26.9 28.2

0.95 29.8 29.0 30.7

0.99 34.8 33.4 36.2

a Offshore strata 24, 26--30, 36--40.

Table 25

Calculated proportion mature at length with approximate 95% confidence intervals based on macroscopic

observations of whole gonads of female (n=1457) and

male (n=1526) redfish, Sebastesfasciatus, from the Gulf

of Maine sampled, respectively, during Northeast Fisheries Science Center spring and autumn bottom trawl

surveysa, 1975-1980.

1980, the most recent period for which a consistent

series of maturation data are available from the Northeast Fisheries Science Center survey. Because of the

Redfish

Sebasres fasciarus

males

n = 1526

Redfish

Sebastes fasciatus

females

n = 1457

"j 0.9

0.8

0.7 ;e

<1l

::i: 06~

c 0.5 0

.'"(; 0.4

a.

0 0.3 a: 0.2

0.1

0.0

1.0 1 09

0)

0.8'

0.71 <1l 0.6 ::i:

c 0.5 0

.'"(; 0.4 a.

0 0.3 a: 0.2

0.1

0.0

Figure 23

Calculated and observed (.) proportion mature at length

based on macroscopic observations of whole gonads of female (n=1457) and male (n=1526) redfish, Sebastesfasciatus,

from the Gulf of Maine sampled, respectively, during Northeast Fisheries Science Center spring and autumn bottom

trawl surveys, 1975-1980.

-,-"rh--..,..-~,...,-.,...,,~",~~~

m m w m w e %

Length

Redfish occur throughout the north Atlantic from Norway to Georges Bank; off New England, S. fasciatus are

most abundant in deeper waters of the Gulf of Maine

where a single stock is thought to exist (Mayo 1980).

Reproduction is viviparous and mating takes place in

autumn when most males are mature; larval extrusion

occurs during the following spring and summer (Table

2). Total commercial landings of this species have declined from a peak of 60,000 metric tons per year in the

early 1940's to about 15,000 t in the late 1970's; total

landings have declined further to less than 2,000 t per

year since 1987 (NEFSC 1991).

Median length at maturity for female and male redfish from the Gulf of Maine was 22.3 and 20.9 cm,

respectively (Tables 3 and 25, Fig. 23). Median age at

maturity was 5.5 yr for both sexes (Table 4, Fig. 24);

proportions of mature fish calculated for each age are

presented in Table 26. These results, extracted from

Mayo et al. (1990), are representative ofthe years 1975-

~._~_-,,"~,--:;:c,-~,...t -.-FT-,,--,--~"--'--'---'-'-I'I I t

5 m m w m w e %

Length
1 23'56789m"U~MmfflDrn.W~nUM~

Age

Figure 24

Calculated and observed (.) proportion mature at age based

on macroscopic observations of whole gonads of female

(n=1457) and male (n=1526) redfish, Sebastesfasciatus, from

the Gulf of Maine sampled during Northeast Fisheries Science Center spring and autumn bottom trawl surveys, 1975-

1980.

O'Brien et al.: Maturation of Finfish 31

Table 26

Calculated proportion mature at age with approximate 95% confidence intervals based on macroscopic

observations of whole gonads of female (n=1457) and

male (n=1526) redfish, Sebastesfasciatus, from the Gulf

of Maine sampled during Northeast Fisheries Science

Center spring and autumn bottom trawl surveysa,

1975-1980.

Proportion 95% Confidence interval

mature Age Lower Upper

Females

Spring

om 1.0 0.2 1.8

0.02 2.0 1.4 2.6

0.05 3.0 2.5 3.5

0.15 4.0 3.7 4.3

0.36 5.0 4.8 5.2

0.64 6.0 5.8 6.2

0.85 7.0 6.7 7.3

0.95 8.0 7.6 8.4

0.98 9.0 8.5 9.5

0.99 10.0 9.3 10.7

1.00 11.0 10.1 11.9

1.00 12.0 11.0 13.0

1.00 13.0 11.8 14.2

1.00 14.0 12.7 15.3

1.00 15.0 13.5 16.5

1.00 16.0 14.4 17.6

1.00 17.0 15.2 18.8

1.00 18.0 16.0 20.0

1.00 19.0 16.9 21.1

1.00 20.0 b 17.7 22.3

Males

Autumn

0.06 1.0 0.1 1.9

0.11 2.0 1.3 2.7

0.18 3.0 2.4 3.6

0.28 4.0 3.6 4.4

0.42 5.0 4.7 5.3

0.57 6.0 5.7 6.3

0.71 7.0 6.7 7.3

0.81 8.0 7.6 8.4

0.89 9.0 8.5 9.5

0.94 10.0 9.3 10.7

0.96 11.0 10.2 11.8

0.98 12.0 11.0 13.0

0.99 13.0 11.9 14.1

0.99 14.0 12.7 15.3

1.00 15.0 13.6 16.4

1.00 16.0 14.4 17.6

1.00 17.0 15.2 18.8

1.00 18.0 16.1 19.9

1.00 19.0 16.9 21.1

1.00 20.0 b 17.7 22.3

a Offshore strata 24, 26-30, 36-40.

b Older ages (21-53) are 100% mature.

Redfish

Seba$/es fascialUs

males

n = 1526

.. .......

• 5 6 7 8 9 10 11 12 13 I' 15 16 17 18 19 20 21 22 23 2. 25

Age

1.0

0.9 Redfish

0.8 Sebas/es fascia/us

Q) females 0.7 n = 1457

'" 0.6

c: 0.5 0

...

0 0.' c. 0.3

0.2

0.1

0.0

1.0

0.9

0.8 Q)

:; 0.7

10 0.6

c: 0.5 0

...

0 a.' a.

0 0.3 et 0.2

0.1

0.0

disparity in seasonal maturation between sexes related

to redfish's viviparous reproduction, analyses were performed on spring data for females and autumn data for

males.

Values ofL5o above are comparable to those for both

sexes reported by Morse (1979) 2 for the year 1977.

However considerable variability in size and age at maturation in relation to early growth and environmental

conditions was noted by Mayo et aI. (1990). Substantial

differences between sexes were observed on the southern Scotian Shelf where Ni and Sandeman (1984) reported L50 values of 25.9 and 15.9 cm for S. fasciatus

females and males, respectively. Information of growth

ofimmature redfish presented by Perlmutter and Clarke

(1949) suggested that the median age at maturation in

the 1940's was likely to have been in the range of8-9 yr,

in contrast to the more recent value of 5.5 yr noted

above.
32 NOAA Technical Report NMFS 113

Scup: Stenotomus chrysops

Figure 25

Calculated and observed (.) proportion mature at length

based on macroscopic observations of whole gonads of female (n=284) and male (n=232) scup, Stenotomus chrysops,

sampled during Northeast Fisheries Science Center spring

bottom trawl surveys, 1985, 1987-1990.

Table 27

Calculated proportion mature at length with approximate 95% confidence intervals based on macroscopic

observations ofwhole gonads offemale (n=284) and male

(n=232) scup, Stenotomus chrysryps, sampled during Northeast Fisheries Science Centerspring bottom trawl surveysa,

1985,1987-1990.

Proportion Length 95% Confidence interval

mature (cm) Lower Upper

Females

0.05 12.3 I\.2 13.4

0.10 13.1 12.2 14.0

0.15 13.6 12.8 14.4

0.20 14.0 13.2 14.7

0.25 14.3 13.6 15.0

0.30 14.6 13.9 15.2

0.35 14.8 14.2 15.5

0.40 15.1 14.5 15.7

0.45 15.3 14.7 15.9

0.50 15.5 14.9 16.1

0.55 15.7 15.2 16.3

0.60 16.0 15.4 16.5

0.65 16.2 15.6 16.8

0.70 16.4 15.8 17.0

0.75 16.7 16.1 17.4

0.80 17.0 16.4 17.7

0.85 17.4 16.7 18.1

0.90 17.9 17.1 18.7

0.95 18.8 17.8 19.7

0.99 20.6 19.2 22.0

Males

0.05 11.9 10.6 13.2

0.10 12.9 I \.8 13.9

0.15 13.4 ]2.5 14.4

0.20 13.9 13.0 14.8

0.25 14.2 ]3.4 15.]

0.30 14.5 13.8 15.3

0.35 14.8 ]4.1 15.6

0.40 15.1 14.4 15.8

0.45 15.4 ]4.6 16.1

0.50 15.6 ]4.9 ]6.3

0.55 15.9 ]5.1 16.6

0.60 16.] 15.4 16.8

0.(i5 16.4 ]5.7 ] 7.]

0.70 16.7 ]5.9 ] 7.4

0.75 17.0 ]6.2 ] 7.8

0.80 ] 7.3 16.5 ]8.2

0.85 ]7.8 ]6.9 ]8.7

0.90 ]8.3 ] 7.4 19.3

0.Y5 19.3 18.1 20.5

0.99 2\.3 19.7 23.0

a Offshore strata 2, 3, 61-63, 65-67, 70-71, 74-75.

40

40

35

35

30

30

Scup

Stenotomus chrysops

males

n = 232

15 20 25

Length

15 20 25

Length

'0

,0

10

09

0.6

1!

::l 0.7

10 0.6

c: 0.5 0

.'"

0 04

a.

0 0.3 et 0.2

0.1

00

to

09 Scup

0.6 Stenotomus chrysops

Q) females

5 0.7 n = 284

10 0.6

c: 0.5 0

.'"0 04

a.

0 0.3 et 0.2

0.'

0.0

Scup range from the Gulf of Maine to Cape Hatteras,

North Carolina (Bigelow and Schroeder 1953). Spawning occurs in coastal waters from May to August with

peak spawning during May and June (Table 2). Commerciallandings ofscup were between 4,000 and 5,000

metric tons in the early 1970's and by 1980 had increased to about 12,000 t, subsequently declining to

about 7,000 t in 1989 (NEFSC 1991).

Median length at maturity was 15.5 cm and 15.6 cm

for females and males, respectively, collected during the

spring of 1985, and 1987-1990 (Tables 3 and 27, Fig. 25).

Similar values were calculated for scup in the Peconic

Bays of eastern Long Island during 1964-1966. Both

female and male scup were determined to be sexually

mature at age two (Finkelstein 1969b), which corresponded to a length of about 16 cm for both sexes

(Finkelstein 1969a).
O'Brien et al.: Maturation of Finfish 33

Black Sea Bass: Centropristis striata

Table 28

Calculated proportion mature at length with approximate 95% confidence intervals based on macroscopic

observations ofwhole gonads offemale (n=561) and male

(n=348) black sea bass, Centropristis striata, sampled during Northeast Fisheries Science Center spring bottom

trawl surveysa, 1985-1990.

Proportion Length 95% Confidence interval

mature (em) Lower Upper

Females

0.05 7.1 4.2 10.1

0.10 10.2 7.8 12.6

0.15 12.1 10.0 14.2

0.20 13.5 11.6 15.3

0.25 14.7 13.0 16.3

0.30 15.7 14.2 17.2

0.35 16.6 15.3 18.0

0.40 17.5 16.3 18.7

0.45 18.3 17.2 19.5

0.50 19.1 18.1 20.2

0.55 20.0 19.0 20.9

0.60 20.8 19.9 21.7

0.65 21.7 20.8 22.6

0.70 22.6 21.7 23.5

0.75 23.6 22.7 24.6

0.80 24.8 23:7 25.9

0.85 26.2 25.0 27.5

0.90 28.1 26.6 29.6

0.95 31.2 29.2 33.2

0.99 37.9 34.7 41.1

Males

0.05 10.8 8.2 13.5

0.10 12.9 10.7 15.1

0.15 14.2 12.3 16.1

0.20 15.1 13.4 16.8

0.25 15.9 14.4 17.5

0.30 16.6 15.2 18.1

0.35 17.3 16.0 18.6

0.40 17.9 16.6 19.1

0.45 18.4 17.3 19.6

0.50 19.0 17.9 20.1

0.55 19.5 18.5 20.6

0.60 20.1 19.1 21.1

0.65 20.7 19.7 21.7

0.70 21.3 20.4 22.3

0.75 22.0 21.0 23.1

0.80 22.8 21.7 23.9

0.85 23.8 22.6 25.0

0.90 25.1 23.7 26.5

0.95 27.2 25.3 29.0

0.99 31.7 28.9 34.6

a Inshore strata 1-61, offshore strata 1-12, 25, 61-76.

the fact that black sea bass are protogynous hermaphrodites (Lavenda 1949), and that the proportion of

mature males obtained through sex succession of females is still uncertain (Mercer 1978; Wenner et al. 1986).

4 D.M. Cupka, R.K. Dias and J. Tucker. 1973. Biology of the black

sea bass, eentropristis striata, from South Carolina waters. Unpub!. manuser. South Carolina Wildlife and Marine Resources Department, P.O. Box 12559, Charleston, SC 29412, 93 p.

Black sea bass

Centropristis striata

females

n = 561

Black sea bass

Centropristis striata

males

n = 348

.'

to

0.9

0.8 Q)

0.7

'" 0.6

c 0.5 0...,

0 0.4 C.

0.3

0.2

0.1

0.0

to

0.9

0.8

[1' 0.7 .::!

'" 0.6

c 0.5 0...,

0 0.4

C.

E' 0.3

"- 0.2

0.1

0.0

Black sea bass range from Cape Cod, Massachusetts, to

northern Florida, but are most abundant in the MidAtlantic region. Meristic and morphometric studies indicate that only one stock exists north ofCape Hatteras,

North Carolina (Shepherd 1991). Spawning ofthis stock

progresses northward from March off North Carolina

to October in Cape Cod waters (NEFSC 1991). Commercial landings of black sea bass have averaged 1,500

metric tons per year during 1980-1989 while annual

recreational landings have fluctuated between 500 t

and 8,100 t over the same period (NEFSC 1991).

Median length at maturity for female and male black

sea bass was 19.1 and 19.0 cm (TL), respectively (Tables

3 and 28, Fig. 26). These sizes occur between ages 2 and

3 according to growth functions developed by Mercer

(1978) for black sea bass north and south of Cape

Hatteras and by Wenner et al. (1986) for black sea bass

in the South Atlantic. Cupka et al. (1973)4 reported

that both sexes matured between 14 and 18 cm (standard length) in the South Carolina region. Wenner et

al. (1986) reported that most females mature at age 2;

Mercer (1978) observed mature males in all age groups,

including age 1. Maturity analyses are complicated by

+;;'ff.t~~~rrr'+ro~-rrrTTT~..,-r"-rrr~.,..".-~rrr'-rr'~·'I

W lli m m H g w u w Length

.....,-.....-..... ii'Iii i

W lli m m H g W U w Length

Figure 26

Calculated and observed (.) proportion mature at length

based on macroscopic observations of whole gonads of female (n=561) and male (n=348) black sea bass, Centropristis

striata, sampled during Northeast Fisheries Science Center

spring bottom trawl surveys, 1985-1990.
34 NOAA Technical Report NMFS 113

Ocean Pout: Macrozoarces americanus

5 m m w m m H % W H 00 w 00

Length

5 m m w m m H % W H W W 00

Length

Figure 27

Calculated and observed (.) proportion mature at length

based on macroscopic observations of whole gonads of female (n=88) and male (n=55) ocean pout, Macrozoarces

americanus, from the Gulf of Maine sampled during Northeast Fisheries Science Center spring bottom trawl surveys,

1985-1990.

a Inshore strati! 57-66, offshore strata 26-40.

Proportion Length 95% Confidence interval

mature (cm) Lower Upper

Females

0.05 ILl -3.3 25.5

0.10 14.9 2.9 26.9

0.15 17.3 6.8 27.8

0.20 19.1 9.6 28.5

0.25 20.6 12.0 29.2

0.30 21.8 14.0 29.7

0.35 23.0 15.8 30.3

0.40 24.1 17.4 30.8

0.45 25.2 19.0 31.3

0.50 26.2 20.5 31.9

0.55 27.2 22.0 32.5

0.60 28.3 23.4 33.2

0.65 29.4 24.8 34.0

0.70 30.5 26.2 34.9

0.75 31.8 27.5 36.1

0.80 33.3 28.9 37.7

0.85 35.1 30.3 39.9

0.90 37.5 31.8 43.2

0.95 41.3 33.7 48.9

0.99 49.8 37.1 62.5

Males

0.05 10.3 -13.8 34.4

0.10 15.4 -4.9 35.7

0.15 18.5 0.5 36.5

0.20 20.9 4.6 37.1

0.25 22.8 8.0 37.7

0.30 24.6 10.9 38.2

0.35 26.1 13.5 38.7

0.40 27.6 16.0 39.2

0.45 29.0 18.3 39.7

0.50 30.3 20.5 40.2

0.55 31.7 22.6 40.8

0.60 33.1 24.8 41.4

0.65 34.5 26.9 42.2

0.70 36.1 29.1 43.1

0.75 37.8 31.3 44.4

0.80 39.8 33.4 46.1

0.85 42.1 35.6 48.7

0.90 45.3 37.7 52.9

0.95 50.4 40.1 60.7

0.99 61.6 43.5 79.7

Table 29

Calculated proportion mature at length with approximate 95% confidence intervals based on macroscopic

observations of whole gonads of female (n=88) and

male (n=55) ocean pout, Macrozoarces americanus, from

the Gulf of Maine sampled during Northeast Fisheries

Science Center spring bottom trawl surveys·,

1985-1990.

corresponded to an age of either 6 or 7 yr. All male

ocean pout below 25 em were immature and nearly all

Ocean pout . Macrozoarces amencanus

Gulf of Maine

males

n = 55

Ocean pout

Macrozoarces americanus

Gulf of Maine

females

n = 88

............,~.--""~~~~-

................------

''''1' i I' i'iii "I ii". i 'I i i

1.0

0.9

0.8

0.7 3

CD

0.6

c 0.5 0

.'"0 0.4

a.

0 0.3 d: 0.2

0.1

0.0

1.0

0.9

0.8

Q)

Z 0.7

CD

0.6

c 0.5 0

.'"0 0.4 a.

:f. 0.3

0.2

0.1

0.0

Ocean pout are distributed from the Gulf of St.

Lawrence to Delaware (Olsen and Merriman 1946); off

the coast ofNew England they are abundant in the Gulf

of Maine and Southern New England area. Spawning

occurs in rocky areas from September to October (Table

2). Landings of ocean pout fluctuated about an average

of 600 metric tons during 1975-1983, then increased to a

peak of about 2,200 tin 1987 and have recently declined

to about 1,300 t (NEFSC 1991).

Median length at maturity for female and male ocean

pout from the Gulf of Maine area was 26.2 cm and 30.3

cm, respectively (Tables 3 and 29, Fig. 27). Ocean pout

from the Southern New England area had L50 values of

31.3 cm and 31.9 cm for females and males, respectively (Tables 3 and 30, Fig. 28).

Larger L50 values were calculated by Olsen and

Merriman (1946) for ocean pout taken in the Southern

New England area in May of 1944. Females were found

to be mature at an average length of 55 cm which
O'Brien et a1.: Maturation of Finfish 35

5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85

Length

5 m m w m m H Q W e w m w Length

Figure 28

Calculated and observed (.) proportion mature at length

based on macroscopic observations of whole gonads of female (n=197) and male (n=205) ocean pout, Macrozoarces

americanus, from Southern New England sampled during

Northeast Fisheries Science Center spring bottom trawl surveys, 1985-1990.

Table 30

Calculated proportion mature at length with approximate 95% confidence intervals based on macroscopic

observations of whole gonads of female (n=197) and

male (n=205) ocean pout, Macrozoarces americanus, from

Southern New Englano sampled during Northeast

Fisheries Science Center spring bottom trawl surveysa,

1985-1990.

Proportion Length 95% Confidence interval

mature (em) Lower Upper

Females

0.05 17.1 8.4 25.8

0.10 20.7 13.3 28.2

0.15 22.9 16.3 29.6

0.20 24.6 18.5 30.7

0.25 26.0 20.3 31.7

0.30 27.2 21.9 32.5

0.35 28.3 23.3 33.3

0.40 29.3 24.6 34.0

0.45 30.3 25.9 34.7

0.50 31.3 27.1 35.5

0.55 32.2 28.2 36.2

0.60 33.2 29.4 37.0

0.65 34.2 30.6 37.8

0.70 35.3 31.9 38.8

0.75 36.5 33.2 39.9

0.80 37.9 34.6 41.2

0.85 39.6 36.3 42.9

0.90 41.8 38.3 45.3

0.95 45.4 41.1 49.7

0.99 53.3 46.7 60.0

Males

0.05 16.0 8.4 23.7

0.10 20.0 13.6 26.5

0.15 22.5 16.8 28.3

0.20 24.4 19.2 29.6

0.25 26.0 21.2 30.7

0.30 27.3 22.9 31.8

0.35 28.5 24.4 32.7

0.40 29.7 25.8 33.6

0.45 30.8 27.1 34.5

0.50 31.9 28.4 35.4

0.55 32.9 29.6 36.3

0.60 34.1 30.9 37.2

0.65 35.2 32.1 38.3

0.70 36.4 33.4 39.5

0.75 37.8 34.8 40.8

0.80 39.3 36.2 42.4

0.85 41.2 37.9 44.5

0.90 43.7 40.0 47.4

0.95 47.7 43.1 52.4

0.99 56.6 49.4 63.8

a Inshore strata 1-52, offshore strata 1-12, 61-76.

year for three years, spawning in the third year. This

maturation process would lead to misclassification of

immature fish as developing for two years, therefore

artificially lowering the LSD value.

Ocean pout

Macrozoarces americanus

Southern New England

males .

n = 205

Ocean pout

Macrozoarces americanus

Southern New England

females

n = 197

I f I I I Iii I

.............,~...,.....----~

1.0

0.9

0.6 Ql

0.7

<tl 0.6

c 0.5 0

...

a 0.4 a.

£ 0.3

0.2

0.1

0.0

1.0

0.9

0.6

0.7 ."

<tl 0.6

c 0.5 0

...

a 0.4 a.

e 0.3 0-

0.2

0.1

0.0

males greater than 39 cm were mature at an age of 3 or

4 yr. A study conducted by Keats et al. (1985) in Newfoundland waters during July and August, 1983-1984,

reported that the mean lengths of nesting pairs of

ocean pout were 70.5 cm and 81.1 cm for females and

males, respectively.

The difference in LSD values offemales in the present

study compared to that of Olsen and Merriman (1946)

may be partly due to difficulty in identifying a mature

female. Larger females appear to have three different

sizes of eggs present while developing; however, Keats

et al. (1985) reported that egg masses guarded by females were uniform and appeared to be from one

spawning, and concluded that multiple spawning was

unlikely. Possibly, immature females develop eggs each
36 NOAA Technical Report NMFS 113

Yellowtail Flounder: Pleuronectesfenugineus

m ffi W a % % W

Length

Table 31

Calculated proportion mature at length with approximate 95% confidence intervals based on macroscopic

observations of whole gonads of Georges Bank female

(n=167) and male ( n=27l) yellowtail flounder,

Pleuronectes jerrugineus, sampled during Northeast

Fisheries Science Center spring bottom trawl surveysa,

1985-1990.

Proportion Length 95% Confidence interval

mature (cm) Lower Upper

Females

0.05 20.8 15.7 25.9

0.10 22.1 17.7 26.4

0.15 22.8 18.9 26.8

0.20 23.4 19.9 27.0

0.25 23.9 20.6 27.3

0.30 24.4 21.3 27.5

0.35 24.8 21.9 27.6

0.40 25.1 22.4 27.8

0.45 25.5 22.9 28.0

0.50 25.8 23.4 28.2

0.55 26.1 23.9 28.4

0.60 26.5 24.4 28.6

0.65 26.9 24.9 28.8

0.70 27.3 25.4 29.1

0.75 27.7 26.0 29.4

0.80 28.2 26.5 29.8

0.85 28.8 27.2 30.4

0.90 29.6 27.9 31.2

0.95 30.8 28.8 32.9

0.99 33.6 30.2 37.0

Males

0.05 13.7 6.1 21.2

0.10 15.6 9.0 22.2

0.15 16.8 10.8 22.9

0.20 17.7 12.1 23.3

0.25 18.5 13.3 23.7

0.30 19.2 14.2 24.1

0.35 19.8 15.1 24.4

0.40 20.3 15.9 24.7

0.45 20.9 16.7 25.0

0.50 21.4 17.5 25.3

0.55 21.9 18.2 25.6

0.60 22.4 19.0 25.9

0.65 23.0 19.8 26.2

0.70 23.6 20.6 26.6

0.75 24.3 21.5 27.0

0.80 25.0 22.5 27.5

0.85 25.9 23.7 28.2

0.90 27.1 25.1 29.2

0.95 29.1 27.1 31.1

0.99 33.4 30.1 36.8

a Offshore strata 13-21.

about 900 t in 1988. Landings increased in 1989 to 2,500 t

owing to the recruiting 1987 year class (NEFSC 1991).

Yellowtail flounder

Pleuronectes ferrugineus

Georges Bank

females

n = 167

1.0

0.9

o.a Q)

0.7

<tJ

o.a

c 0.5 0..,

(; 0.4 Co 0.3 It 0.2

0.1

0.0

1.0

0.9

O.a Yellowtail flounder

Pleuronectes ferrugineus 0.7 Georges Bank

<tJ males 0.6 n = 271 c 0.5 0

.;:;

(; 0.4 Co 0.3 It 0.2

0.1

0.0

Figure 29

Calculated and observed (.) proportion mature at length

based on macroscopic observations of whole gonads of

Georges Bank female (n:=167) and male (n=271) yel10wtail

flounder, Pleuronectes jerrugineus, sampled during Northeast

Fisheries Science Center spring bottom trawl surveys, 1985-

1990.

-r,..,...,.....,...,.....,-+'f"'........."T"""'".-;;.~-.,~~rr-r-.-rr~..,.-~,.,...,.-,.,,~.-,

m ffi W a % % W

Length

Yellowtail flounder range from Labrador to Virginia

with three major stocks occurring off the coast of New

England: Georges Bank, Cape Cod, and Southern New

England (Royce et al. 1959; Lux 1963). The spawning

season is from April to August with peak spawning

occurring in May and June' (Table 2). Commercial

landings for the Georges Bank stock declined from

about 15,000 metric tons in the early 1970's to about

4,500 t by 1978, increased to over 11,000 tin 1983, then

subsequently declined to a record low of 1,100 tin 1989

(NEFSC 1991). Landings in 1990 were about 12,000 t,

attributable to a strong 1987 year class. Landings of the

Cape Cod stock increased from about 1,500 t in the

early 1970's to a peak of about 5,000 t by 1980, then

subsequently declined to about 900 t by 1989 (NEFSC

1991). Commercial landings of the Southern New England stock declined from a high of about 32,000 t in

1969 to a low of1,700 in 1976, increased to a peak ofabout

18,000 tin 1983 and subsequently declined to a low of
Median length at maturity for female and male yellowtail flounder sampled during spring 1985-1990 was,

respectively, 25.8 cm and 21.4 cm for the Georges Bank

stock (Tables 3 and 31, Fig. 29), 27.3 cm and 26.8 cm

for the Cape Cod stock (Tables 3 and 33, Fig. 31), and

25.5 cm and 19.6 cm for the Southern New England

stock (Tables 3 and 35, Fig. 33). Median age at maturity

for female and male Georges Bank yellowtail flounder

was 1.8 yr and 1.3 yr, respectively (Table 4, Fig. 30). For

the Cape Cod stock, A50 values were 2.6 yr for both

sexes (Table 4, Fig. 32). The Southern New England

stock had A50 values of 1.6 yr for females and 1.8 yr for

males (Table 4, Fig. 34). Proportions of mature fish at

age are presented in Tables 32, 34, and 36.

Morse and Morris (1981)5 calculated similar L50 values of27.3 cm and 24.2 cm for female and male yellowtail flounder collected east of 72° long. during 1975-

1980. Yellowtail flounder collected over the entire re5 W.W. Morse and A. Morris. 1981. An analysis of yellowtail flounder, Limanda ferruginea, length at maturity east and west of 72"

long. for 1975-1980. NMFS/NEFC, Sandy Hook Lab. Rep. No.

81-16,4 p.

1.0

0.9 Yellowtail flounder

0.8 Pleuronectes ferrugineus OJ Geor~es Bank .3 0.7 fema es co 0.6 n = 167

c 0.5 0...,

a d.•

c.

0 0.3 ) c: 0.2

0.1

0.0

Age

1.0

0.9 Yellowtail flounder

0.8 Pleuronectes ferrugineus

l" 0.7 Georges Bank

a males co 0.6 n = 271

c 0.5 0...,

a d.•

c.

0 0.3 c: 0.2

0.1

0.0

Age

Figure 30

Calculated and observed (.) proportion mature at age based

on macroscopic observations of whole gonads of Georges

Bank female (n=167) and male (n=271) yellowtail flounder,

Pleuronectes ferrngineus, sampled during Northeast Fisheries

Science Center spring bottom trawl surveys, 1985-1990.

O'Brien et al.: Maturation of Finf'Ish 37

gion during 1977 had L50 values of27.5 cm and 24.3 cm

for females and males, respectively (Morse 1979) 2. Scott

(1954) examined yellowtail flounder collected during

July-September 1946 between Nantucket Shoals and

Montauk Point, and determined that there were no

immature females over 32 cm, and that 100% maturation was reached by age 3. Royce et al. (1959) determined from Southern New England samples collected

in May 1943 that L50 for females was 32 cm and that

males became sexually mature before recruitment to

the commercial catch, at about 26 cm. Female yellowtail had A50 values of about 2 yr and males probably

matured at about age 1.

Median length at maturity of yellowtail flounder collected during July in the Scotian Shelf area was 24 cm

during 1970-1974 for females and increased to 29 cm

during 1975-1979; for males, L50 remained at about

19-20 cm during the same time periods (Beacham

1983d). Values of A50 declined for females and males

from 3.1 yr and 3.2 yr, respectively, during 1970-1974

to 2.9 yr and 2.0 yr, respectively, during 1975-1979

(Beacham 1983d).

Table 32

Calculated proportion mature at age with approximate 95 % confidence intervals based on macroscopic

observations of whole gonads of Georges Bank female

(n=167) and male (n=271) yellowtail flounder,

Pleuronectes ferrugineus, sampled during Northeast

Fisheries Science Center spring bottom trawl surveysa,

1985-1990.

Proportion 95% Confidence interval

mature Age Lower Upper

Females

0.00 1.0 -2.1 4.1

0.88 2.0 1.9 2.1

1.00 3.0 -0.1 6.1

1.00 4.0 -2.1 10.1

1.00 5.0 -4.2 14.2

1.00 6.0 -6.3 18.3

1.00 7.0 -8.3 22.3

Males

0.22 1.0 0.4 1.6

0.93 2.0 1.8 2.2

1.00 3.0 2.4 3.6

1.00 4.0 2.8 5.2

1.00 5.0 3.2 6.8

1.00 6.0 3.7 8.3

1.00 7.0 4.1 9.9

a Offshore strata 13-21.
38 NOAA Technical Report NMFS 113

Figure 31

Calculated and observed (.) proportion mature at length

based on macroscopic observations ofwhole gonads of Cape

Cod female (n=140) and male (n=165) yellowtail flounder,

Pleuronecles Jerrugineus, sampled during Northeast Fisheries

Science Center spring bottom trawl surveys, 1985-1990.

~.........,,...,......,....~~..-.c-r---.--.,'''+',,,,,,,,~,,,,,,,,,,~,,,,,,,,-...-rr~,...,,.-,-,-,-,

ill ffi m H w e 0

Length

Table 33

Calculated proportion mature at length with approximate 95% confidence intervals based on macroscopic

observations of whole gonads of Cape Cod female

(n=140) and male (n=165) yellowtail flounder,

Pleuronecles Jerrugineus, sampled during Northeast

Fisheries Science Center spring bottom trawl surveysa,

1985-1990.

Proportion Length 95% Confidence interval

mature (em) Lower Upper

Female

0.05 20.5 17.8 23.1

0.10 22.2 20.0 24.4

0.15 23.3 21.3 25.2

0.20 24.1 22.3 25.9

0.25 24.7 23.1 26.4

0.30 25.3 23.8 26.9

0.35 25,9 24.3 27.4

0.40 26.4 24.9 27.8

0.45 26.8 25.4 28.3

0.50 27.3 25.9 28.7

0,55 27.8 26,3 29.2

0.60 28.2 26,8 29.7

0.65 28.7 27.2 30.3

0.70 29.3 27.7 30.9

0.75 29.9 28.2 31.5

0,80 30,5 28.7 32.3

0,85 31.3 29,4 33.3

0.90 32.4 30.2 34.6

0.95 34.1 31.5 36,8

0.99 38.0 34.2 41.8

Males

0.05 19.0 16.2 21.7

0.10 21.0 18.7 23.2

0.15 22.2 20.3 24.1

0.20 23.1 21.4 24.8

0.25 23.9 22.3 25.4

0.30 24.5 23.1 26.0

0.35 25.1 23.8 26.5

0.40 25.7 24.4 27.0

0.45 26.3 25.0 27.5

0.50 26.8 25.5 28.0

0.55 27,3 26,1 28.6

0.60 27.9 26.6 29.1

0.65 28.4 27.1 29.8

0.70 29.0 27.6 30.4

0.75 29.7 28.2 31.2

0,80 30.5 28.8 32.1

0.85 31.4 29,6 33.2

0.90 32.6 30.5 34.7

0,95 34.6 32.0 37,2

0.99 39.0 35.1 42.8

a Offshore strata 24-26,

Yellowtail flounder

Pleuronectes ferrugineus

Cape Cod

males

n = 165

Yellowtail flounder

Pleuronectes ferrugineus

Cape Cod

females

n = 140

+~""""""""""""""""'O'F.-..~.,.......,..."-\...,.-,,,,.-,..,.,~'T"'~T""""""'~-'

ill ffi m H W e 0

Length

10

0.9

0.8

!"

:J 0.7

<i 0.6

c 0.5 0

.'"a 0.4 Q.

0 0.3' rt 0.2

0.1

0.0

10

0.9

0.8

!" 0.7 i:l

co 0.6

c 0.5 0

.'"a 0.4 Q.

0 0.3 rt 0.2

0.1

0.0
O'Brien et at.: Maturation of Finfish 39

Figure 32

Calculated and observed (.) proportion mature at age based

on macroscopic observations of whole gonads of Cape Cod

female (n=140) and male (n=165) yellowtail flounder,

Pleuronectes ferrugineus, sampled during Northeast Fisheries

Science Center spring bottom trawl surveys, 1985-1990.

Proportion 95% Confidence interval

mature Age Lower Upper

Females

0.00 1.0 0.5 1.5

0.08 2.0 1.8 2.2

0.81 3.0 2.8 3.2

1.00 4.0 3.6 4.4

1.00 5.0 4.3 5.7

1.00 6.0 5.0 7.0

1.00 7.0 5.7 8.3

1.00 8.0 6.4 9.6

Males

0,0} 1.0 0.5 1.5

0.16 2.0 1.8 2.2

0.77 3.0 2.8 3.2

0.98 4.0 3.6 4.4

1.00 5.0 4.3 5.7

1.00 6.0 5.0 7.0

1.00 7.0 5.7 8.3

1.00 8.0 6.4 9.6

1.00 9.0 7.1 10.9

1.00 10.0 7.8 12.2

1.00 11.0 8.5 13.5

a Offshore strata 24-26.

Table 34

Calculated proportion mature at age with approximate 95% confidence intervals based on macroscopic

observations of whole gonads of Cape Cod female

(n=140) and male (n=165) yellowtaii flounder,

Pleuronectes ferrugineus, sampled during Northeast

Fisheries Science Center spring bottom trawl surveys·,

1985-1990.

10 11

10 11

Yellowtail flounder

Pleuronectes ferrugineus

Cape Cod

males

n = 165

5 6

Age

5 6

Age

4

1.0

0.9 Yellowtail flounder

0.8 Pleuronectes ferrugineus

Q) Cape Cod 0.7 females co 0.6 n = 140

c 0.5 0

'';::;

0 0.4 a.

0 0.3 Q: 0.2

0.1

0.0

1.0

0.9

0.8

::> 0.7

10 0.6

c 0.5 .g

0 0.4 a.

£. 0.3

0.2

0.1

0.0
Figure 33

Calculated and observed (.) proportion mature at length

based on macroscopic observations ofwhole gonads of Southern New England female (n=204) and male (n=367) yellowtail flounder, Pleuronectes ferrugineus, sampled during Northeast Fisheries Science Center spring bottom trawl surveys,

1985-1990.

Table 35

Calculated proportion mature at length with approximate 95% confidence intervals based on macroscopic

observations of whole gonads of Southern New England female (n=204) and male (n=367) yellowtail

flounder, Pleuronectesferrugineus, sampled during Northeast Fisheries Science Center spring bottom trawl

surveysa, 1985-1990.

Proportion Length 95% Confidence interval

mature (em) Lower Upper

Females

0.05 18.9 14.5 23.3

0.10 20.6 16.9 24.3

0.15 21.6 18.4 24.9

0.20 22.4 19.5 25.4

0.25 23.1 20.4 25.7

0.30 23.6 21.2 26.1

0.35 24.1 21.9 26.4

0.40 24.6 22.5 26.7

0.45 25.1 23.2 27.0

0.50 25.5 23.8 27.3

0.55 26.0 24.4 27.6

0.60 26.4 25.0 27.9

0.65 26.9 25.6 28.3

0.70 27.4 26.2 28.7

0.75 28.0 26.9 29.1

0.80 28.6 27.5 29.7

0.85 29.4 28.3 30.6

0.90 30.5 29.1 31.8

0.95 32.1 30.3 34.0

0.99 35.8 32.6 39.1

Males

0.05 11.7 6.5 16.9

0.10 13.7 9.2 18.2

0.15 14.9 10.8 19.1

0.20 15.9 12.0 19.7

0.25 16.6 13.0 20.2

0.30 17.3 13.9 20.7

0.35 17.9 14.7 21.1

0.40 18.5 15.5 21.5

0.45 19.0 16.2 21.9

0.50 19.6 16.9 22.3

0.55 20.1 17.5 22.7

0.60 20.6 18.2 23.0

0.65 21.2 19.0 23.5

0.70 21.8 19.7 23.9

0.75 22.5 20.5 24.4

.0.80 23.3 21.5 25.1

0.85 24.2 22.6 25.8

0.90 25.4 23.9 26.9

0.95 27.4 25.9 29.0

0.99 31.8 29.3 34.3

a Offshore strata 5-6, 9-10.
O'Brien et at.: Maturation of Finfish 41

Proportion 95% Confidence interval

mature Age Lower Upper

Females

0.13 1.0 0.6 1.4

0.74 2.0 1.9 2.1

0.98 3.0 2.6 3.4

1.00 4.0 3.3 4.7

1.00 5.0 3.9 6.1

1.00 6.0 4.6 7.4

Males

0.00 1.0 -1.3 3.3

0.92 2.0 1.9 2.1

1.00 3.0 0.7 5.3

1.00 4.0 -0.7 8.7

1.00 5.0 -2.0 12.0

1.00 6.0 -3.4 15.4

Table 36

Calculated proportion mature at age with approximate 95% confidence intervals based on macroscopic

observations of whole gonads of Southern New England female (n=204) and male (n=367) yellowtail

flounder, Pleuronectesfenugineus, sampled during Northeast Fisheries Science Center spring bottom trawl

surveysa,1985-1990.

to·

0.9

0.8 ., 0.7 Yellowtail flounder

'" 0.6 Pleuronectes ferru~ineus

Southern New Eng and c:

0 0.5 males .'" n = 367 (; 0.4 co 0.3 c:: 0.2

0.1

0.0

10

0.9

0.8 .,

:; 0.7 Yellowtail flounder ro 0.6 Pleuronectes ferrutneus

Southern New Eng and c:

0 0.5 females .'" n = 204 (; 0.4 co 03 c:: 0.2·

0.1

0.0

3 4

Age

3

Age

a Offshore strata 5-6, 9-10.

Figure 34

Calculated and observed (.) proportion mature at age based

on macroscopic observations of whole gonads of Southern

New England female (n=204) and male (n=367) yellowtail

flounder, Pleuronectesfenugineus, sampled during Northeast Fisheries Science Center spring bottom trawl surveys, 1985-1990.
42 NOAA Technical Report NMFS 113

Winter Flounder: Pleuronectes americanus

W lli W m m u % W W "

Length

Table 37

Calculated proportion mature at length with approximate 95% confidence intervals based on macroscopic

observations of whole gonads of Georges Bank female

(n=204) and male (1'1'=174) winter flounder, Pleuronectes

americanus, sampled during Northeast Fisheries Science Center spring bottom trawl surveys·, 1985-1989.

Proportion Length 95% Confidence interval

mature (em) Lower Upper

Female

0.05 18.2 14.8 21.6

0.10 19.9 17.1 22.7

0.15 20.9 18.5 23.4

0.20 21.7 19.5 23.9

0.25 22.4 20.4 24.4

0.30 23.0 21.2 24.8

0.35 23.5 21.8 25.2

0.40 24.0 22.4 25.6

0.45 24.5 23.0 25.9

0.50 24.9 23.5 26.3

0.55 25.4 24.1 26.7

0.60 25.9 24.6 27.1

0.65 26.3 25.1 27.6

0.70 26.9 25.6 28.1

0.75 27.4 26.1 28.8

0.80 28.1 26.7 29.5

0.85 28.9 27.3 30.5

0.90 30.0 28.1 31.8

0.95 31.7 29.3 34.0

0.99 35.5 31.8 39.1

Males

0.05 15.9 11.1 20.6

0.10 18.3 14.4 22.2

0.15 19.9 16.4 23.3

0.20 21.0 17.9 24.1

0.25 22.0 19.2 24.8

0.30 22.8 20.2 25.4

0.35 23.6 21.2 25.9

0.40 24.3 22.1 26.5

0.45 25.0 22.9 27.0

0.50 25.6 23.7 27.5

0.55 26.3 24.5 28.1

0.60 27.0 25.2 28.7

0.65 27.7 26.0 29.4

0.70 28.4 26.8 30.1

0.75 29.3 27.6 31.0

0.80 30.2 28.4 32.0

0.85 31.4 29.4 33.4

0.90 32.9 30.6 35.2

0.95 35.4 32.4 38.4

0.99 40.9 36.1 45.6

a Offshore strata 13-22.

Median length at maturity for female and male winter flounder from Georges Bank was 24.9 and 25.6 em,

respectively (Tables 3 and 37, Fig. 35). For inshore

Winter flounder

Pleuronectes americanus

Georges Bank

females

n = 204

1.0

0.9

0.8 Winter flounder

0.7 Pleuronectes americanus :J

:0 Georges Bank

::2: 0.6 males

c 0.5 n = 174 0

.'"a 0.4 c. 0.3

0.2

0.1

0.0

1.0

0.9

0.8

0.7 ;l

'" 0.6

c 0.5 0

.'"a 0.4 c. 0.3

0.2

0.1

0.0 iiiiii "I

W lli W a m u % W W ft

Length

Figure 35

Calculated and observed (.) proportion mature at length

based on macroscopic observations of whole gonads of

Georges Bank female (1'1'=204) and male (1'1'=174) winter flounder, Pleuronectes americanus, sampled during Northeast Fisheries Science Center spring bottom trawl surveys, 1985-1989.

Winter flounder are widely distributed in the northwest

Atlantic from Labrador to Georgia, but abundance is

highest from the Gulf of St. Lawrence to Chesapeake

Bay. Tagging and meristic studies indicate three stocks

of winter flounder in U.S. waters: two inshore stocks

north and south of Cape Cod (Lux et al. 1970; Howe

and Coates 1975; Pierce and Howe 1977) and an offshore stock occupying Georges Bank (Lux 1973). Spawning occurs from February to May, with peak activity

during February and March in southern areas and April

farther north (Table 2). Commercial landings ofwinter

flounder from Georges Bank averaged 3,800 metric

tons per year during 1980-1984 but have subsequently

declined to about 2,300 t annually since then (NEFSC

1991). Combined commercial and recreational catch

for inshore s~ocks has similarly declined in recent years,

from about 6,400 t per year during 1980-1982 to 2,700 t

annually since 1983 for the northern stock, and from an

average of 14,000 t per year during 1980-1985 to 7,800 t

from 1986-1989 for the southern stock (NEFSC 1991) ..
stocks, values of L50 were 29.7 cm for females and 27.6

cm for males north of Cape Cod, and 27.6 cm for

females and 29.0 cm for males south of Cape Cod

(Tables 3,39, and 41, Figs. 37 and 39). Median age at

maturity was 1.9 yr for both sexes on Georges Bank

(Table 4, Fig. 36); proportions of mature fish calculated for each age are presented in Table 38. For inshore stocks, values of A50 were 3.5 yr for females and

3.3 yr for females north of Cape Cod, and 3.0 yr for

females and 3.3 yr for males south of Cape Cod (Table

4, Figs. 38 and 40); proportions mature calculated for

each age are presented in Tables 40 and 42.

Morse (1979)2 reported values for L50 derived from

1977 data of 26.3 cm for females and 24.8 cm for males,

but did not distinguish between inshore stocks and the

faster-growing (Lux 1973) Georges Bank winter floun~

der. Comparisons of maturity analyses from other studFigure 36

Calculated and observed (.) proportion mature at age based

on macroscopic observations of whole gonads of Georges

Bank female (n=204) and male (n=174) winter flounder,

Pleuronectes americanus, sampled during Northeast Fisheries

Science Center spring bottom trawl surveys, 1985-1989.

O'Brien et al.: Maturation of Finfish 43

ies are complicated by the complex stock structure for

the species. Perlmutter (1947) observed that winter

flounder in the Long Island Sound region mature at

20-25 cm and 2-3 yr of age, while Kennedy and Steele

(1971) reported values for L50 of 25 cm for females and

21 cm for males in Newfoundland waters, with ages at

full maturity of 7 yr for females and 6 yr for males,

leaving these authors to conclude that maturation was

related to size and not age. However, Beacham (1982)

presented evidence that maturation of winter flounder

in the Scotian Shelf and southern Gulf of S1. Lawrence

region was highly variable from year to year, and Burton and Idler (1984) found large numbers of

nonreproductive individuals in a given year, suggesting

that interpretations of maturity data for winter flounder must be conducted with caution.

Table 38

Calculated proportion mature at age with approximate 95% confidence intervals based on macroscopic

observations of whole gonads of Georges Bank female

(n=204) and male (n=174) winter flounder, Pleuronectes

americanus, sampled during Northeast Fisheries Science Center spring bottom trawl surveysa, 1985-1989.

Proportion 95% Confidence interval

mature Age Lower Upper

Females

0.03 1.0 0.4 1.6

0.62 2.0 1.9 2.1

0.99 3.0 2.5 3.5

1.00 4.0 3.0 5.0

1.00 5.0 3.5 6.5

1.00 6.0 3.9 8.1

1.00 7.0 4.4 9.6

1.00 8.0 4.9 11.1

1.00 9.0 5.4 12.6

1.00 10.0 5.8 14.2

Males

0.10 1.0 0.5 1.5

0.56 2.0 1.8 2.2

0.94 3.0 2.6 3.4

0.99 4.0 3.2 4.8

1.00 5.0 3.8 6.2

1.00 6.0 4.4 7.6

1.00 7.0 5.0 9.0

1.00 8.0 ~.6 10.4

1.00 9.0 6.2 11.8

a Offshore strata 13-22.
44 NOAA Technical Report NMFS 113

1.0

m lli W e m H w Length

Table 39

Calculated proportion mature at length with approximate 95% confidence intervals based on macroscopic

observations of whole gonads of female (n=320) and

male (n=215) winter flounder, Pleuronectes americanus,

sampled north ofCape Cod during Massachusetts Division of Marine Fisheries spring bottom trawl surveysa,

1985-1989.

Proportion Length 95% Confidence interval

mature (em) Lower Upper

Females

0.05 26.5 25.3 27.6

0.10 27.3 26.4 28.2

0.15 27.8 27.0 28.6

0.20 28.2 27.5 28.9

0.25 28.5 27.8 29.2

0.30 28.8 28.2 29.4

0.35 29.0 28.5 29.6

0.40 29.3 28.7 29.8

0.45 29.5 29.0 30.1

0.50 29.7 29.2 30.3

0.55 30.0 29.5 30.5

0.60 30.2 29.7 30.7

0.65 30.4 29.9 30.9

0.70 30.7 30.2 31.2

0.75 31.0 30.4 31.5

0.80 31.3 30.7 31.9

0.85 31.7 31.0 32.3

0.90 32.2 31.5 32.9

0.95 33.0 32.1 33.9

0.99 34.9 33.5 36.2

Males

0.05 22.8 21.2 24.3

0.10 24.0 22.8 25.2

0.15 24.8 23.7 25.8

0.20 25.3 24.4 26.3

0.25 25.8 24.9 26.7

0.30 26.2 25.4 27.0

0.35 26.6 25.8 27.3

0.40 26.9 26.2 27.6

0.45 27.3 26.6 28.0

0.50 27.6 26.9 28.3

0.55 27.9 27.2 28.6

0.60 28.2 27.5 29.0

0.65 28.6 27.9 29.3

0.70 29.0 28.2 29.7

0.75 29.4 28.5 30.2

0.80 29.8 28.9 30.8

0.85 30.4 29.4 31.4

0.90 31.2 30.0 32.4

0.95 32.4 30.9 33.9

0.99 35.1 32.9 37.3

a Strata 25-36.

Winter Flounder

Pleuronectes americanus

North of Cape Cod

males

n = 215

0.6

0.9

0.2

m lli W e m H w Length

0.1

1.0

0.9 Winter Flounder

Pleuronectes americanus O.B North of Cape Cod

females 0.7 n = 320

'" 0.6

c: 0.5 0.,

(; 0.4 C.

e 0.3 0..

0.2

0.1

0.0

0.7

'" 0.6

6 05+-----------{

..,

(; 0.4 c.

o 0.3 0:

Figure 37

Calculated and observed (.) proportion mature at length

based on macroscopic observations of whole gonads of female (n=320) and male (n=215) winter flounder, Pleuronectes

americanus, sampled north of Cape Cod during Massachusetts Division of Marine Fisheries spring bottom trawl surveys, 1985-1989.
O'Brien et at.: Maturation of FinfISh 45

Figure 38

Calculated and observed (.) proportion mature at age based

on macroscopic observations of whole gonads of female

(n=320) and male (n=215) winter flounder, Pleuronectes

americanus, sampled north of Cape Cod during Massachusetts Division of Marine Fisheries spring bottom trawl surveys, 1985-1989.

PropOrtion 95% Confidence interval

Mature Age Lower Upper

Females

0.00 1.0 0.5 1.5

0.01 2.0 1.7 2.3

0.16 3.0 2.9 3.1

0.86 4.0 3.9 4.1

0.99 5.0 4.7 5.3

1.00 6.0 5.5 6.5

1.00 7.0 6.3 7.7

1.00 8.0 7.1 8.9

1.00 9.0 7.9 10.1

1.00 10.0 8.7 11.3

1.00 11.0 9.5 12.5

1.00 12.0 10.3 13.7

1.00 13.0 ILl 14.9

Males

0.00 1.0 0.4 1.6

0.04 2.0 1.6 2.4

0.34 3.0 2.9 3.1

0.87 4.0 3.7 4.3

0.99 5.0 4.4 5.6

1.00 6.0 5.2 6.8

1.00 7.0 5.9 8.1

1.00 8.0 6.6 9.4

1.00 9.0 7.3 10.7

a Strata 25-36.

Table 40

Calculated proportion mature at age with approximate 95% confidence intervals based on macroscopic

observations of whole gonads of female (n=320) and

male (n=215) winter flounder, Pleuronectes americanus,

sampled north ofCape Cod during Massachusetts Division of Marine Fisheries spring bottom trawl surveys",

1985-1989.

10 11 12 13

10 11 12 13

Winter flounder

Pleuronectes americanus

North of Cape Cod

males

n = 215

8 7

Age

8 7

Age

4

1.0

0.9

0.8

:J 0.7

10 0.6

c 0.5 0.,

0 0.4 c. 0.3

0.2

0.1

0.0

1.0

0.9 Winter flounder

0.8 Pleuronectes americanus Q) North of Cape Cod

:; 0.7 females

10 n = 320 0.8

c 0.5 0.,

0 0.4 C.

0 0.3 a: 0.2

0.1

0.0
46 NOAA Tec~nical Report NMFS 113

Figure 39

Calculated and observed (.) proportion mature at length

based on macroscopic observations of whole gonads of female (n=398) and male (n=301) winter flounder, Pleuronectes

americanus, sampled south of Cape Cod during Massachusetts Division of Marine Fisheries spring bottom trawl surveys, 1985-1989.

'.

Table 41

Calculated proportion mature at length with approximate 95% confidence intervals based on macroscopic

observations of whole gonads of female (n=398) and

male (n=301) winter flounder, Pleuronectes americanus,

sampled south ofCape Cod during Massachusetts Division of Marine Fisheries spring bottom trawl surveysa,

1985-1989.

Proportion Length 95% Confidence interval

mature (cm) Lower Upper

Females

0.05 20.8 19.0 22.5

0.10 22.5 21.0 23.9

0.15 23.6 22.3 24.8

0.20 24.4 23.2 25.5

0.25 25.0 24.0 26.1

0.30 25.6 24.7 26.6

0.35 26.1 25.3 27.0

0.40 26.6 25.8 27.5

0.45 27.1 26.3 27.9

0.50 27.6 26.8 28.3

0.55 28.1 27.3 28.8

0.60 28.5 27.8 29.3

0.65 29.0 28.3 29.8

0.70 29.6 28.8 30.3

0.75 30.1 29.3 30.9

0.80 30.8 29.9 31.7

0.85 31.6 30.6 32.6

0.90 32.7 31.5 33.8

0.95 34.4 33.0 35.9

0.99 38.2 36.1 40.4

Males

0.05 24.0 22.6 25.3

0.10 25.2 24.1 26.3

0.15 26.0 25.1 27.0

0.20 26.6 25.8 27.5

0.25 27.1 26.3 27.9

0.30 27.5 26.8 28.3

0.35 27.9 27.2 28.6

0.40 28.3 27.6 29.0

0.45 28.6 28.0 29.3

0.50 29.0 28.3 29.6

0.55 29.3 28.6 30.0

0.60 29.7 29.0 30.4

0.65 30.0 29.3 30.7

0.70 30.4 29.6 31.2

0.75' 30.8 30.0 31.7

0.80 31.3 30.4 32.2

0.85 31.9 30.9 32.9

0.90 32.7 31.5 33.8

0.95 34.0 32.5 35.4

0.99 36.8 34.7 38.8

a Strata 11-17.

I.' iii I

Winter flounder

Pleuronectes americanus

South of Cape Cod

males

n = 301

+,..,~,..............,. ..........,..,..~;:r-r~,,--,..l,...,-T""'""""~""~TT'~'--'-'

m ffi w e m H • w Length

m ffi W e m H • w Length

Winter flounder

Pleuronectes americanus

South of Cape Cod

females

n = 398

1.0

0.9

0.8

'":; 0.7

10 0.6

c 0.5 0.,

(; 0.4

a.

0 0.3 a:: 0.2

0.1

0.0

1.0

0.9

0.8

'":; 0.7

iii 0.8

c 0.5 0.,

(; 0.4 a.

0 0.3 a:: 0.2

0.1

0.0
Figure 40

Calculated and observed (.) proportion mature at age based

on macroscopic observations of whole gonads of female

(n=398) and male (n=301) winter flounder, Pleuronecles

americanus, sampled south of Cape Cod during Massachusetts Division of Marine Fisheries spring bottom trawl surveys, 1985-1989.

"1

0.9

0.8

0.7 .;!

'" 0.6

c: 0.5 0.,

0 0.4 a.

e 0.3

"- 0.2

0.1

0.0

1.0

0.9

0.8

Q)

B 0.7

'" 0.6

c: 0.5 0.,

0 0.4 a.

e 0.3

"- 0.2

0.1

0.0

5

Age

5

Age

Winter flounder

Pleuronectes americanus

South of Cape Cod

females

n = 398

Winter flounder

Pleuronectes americanus

South of Cape Cod

males

n = 301

10

10

O'Brien et al.: Maturation of Finfish 47

Table 42

Calculated proportion mature at age with approximate 95% confidence intervals based on macroscopic

observations of whole gonads of female (n=398) and

male (n=301) winter flounder, Pleuronecles americanus,

sampled south ofCape Cod during Massachusetts Division of Marine Fisheries spring bottom trawl surveys",

1985-1989.

Proportion 95% Confidence interval

mature Age Lower Upper

Females

0.00 1.0 0.5 1.5

0.06 2.0 1.7 2.3

0.53 3.0 2.9 3.1

0.95 4.0 3.8 4.2

1.00 5.0 4.5 5.5

1.00 6.0 5.3 6.7

1.00 7.0 6.1 7.9

1.00 8.0 6.8 9.2

1.00 9.0 7.6 10.4

1.00 10.0 8.4 11.6

Males

0.00 1.0 0.4 1.6

0.04 2.0 1.7 2.3

0.32 3.0 2.9 3.1

0.83 4.0 3.8 4.2

0.98 5.0 4.5 5.5

1.00 6.0 5.3 6.7

1.00 7.0 6.1 7.9

1.00 8.0 6.8 9.2

1.00 9.0 7.6 10.4

a Strata 11-17.
48 NOAA Technical Report NMFS 113

American Plaice: Hippoglossoides platessoides

ill lli W H m H %

Length

Table 43

Calculated proportion mature at length with approximate 95% confidence intervals based on macroscopic

observations of whole gonads of female (n=714) and

male (n=633) American plaice, Hippoglossoides

platessoides, sampled during Northeast Fisheries Science Center spring bottom trawl surveysa, 1986--1990.

Proportion Length 95% Confidence interval

mature (cm) Lower Upper

Females

0.05 19.8 18.4 21.2

0.10 21.6 20.4 22.7

0.15 22.7 21.7 23.7

0.20 23.5 22.6 24.4

0.25 24.2 23.3 25.0

0.30 24.8 24.0 25.5

0.35 25.3 24.6 26.0

0.40 25.8 25.1 26.5

0.45 26.3 25.6 27.0

0.50 26.8 26.1 27.4

0.55 27.3 26.6 27.9

0.60 27.7 27.1 28.4

0.65 28.3 27.6 28.9

0.70 28.8 28.1 29.5

0.75 29.4 28.7 30.1

0.80 30.1 29.3 30.9

0.85 30.9 30.0 31.8

0.90 32.0 31.0 33.0

0.95 33.8 32.6 35.0

0.99 37.7 35.9 39.5

Males

0.05 13.3 11.7 14.9

0.10 15.5 14.2 16.8

0.15 16.9 15.8 18.0

0.20 18.0 17.0 18.9

0.25 18.8 17.9 19.7

0.30 19.6 18.7 20.4

0.35 20.2 19.5 21.0

0.40 20.9 20.2 21.6

0.45 21.5 20.8 22.2

0.50 22.1 21.4 22.7

0.55 22.7 22.0 23.3

0,60 23.3 22.6 24.0

0.65 23.9 23.3 24.6

0.70 24.6 23.9 25.3

0.75 25.4 24.6 26.1

0.80 26.2 25.4 27.1

0.85 27.3 26.3 28.2

0.90 28.6 27.5 29.7

0.95 30.9 29.5 32.3

0.99 35.8 33.7 37.9

a Offshore strata 26--30, 36--40.

These valu~s are similar to those reported by Sullivan

(1981) for females but not for males. Samples taken in

the Gulf of Maine in spring 1980 had L50 and A50 values

+---------JAmerican 'plaice Hippoglossoides platessoides

females

n = 714

1.0

0.9

0.6 Q)

:; 0.7

iii 0.6

c 0.5 0

.;:;

0 0.4 0-

:f- 0.3

0.2

0.1

0.0

1.0

0.9

0.6

0.7 ;:l

co 0.6

c 0.5 American plaice 0

.;:; Hippoglossoides platessoides

0 0.4 males 0- n = 633 0 0.3 a: 0.2

0.1

0.0

American plaice, or dab, occurs on both sides of the

north Atlantic. In the northwest Atlantic, American

plaice are distributed along the continental shelf from

southern Labrador to Rhode Island with large commercial concentrations existing off the coast of New England in the Gulf of Maine - Georges Bank region

(Sullivan 1981). Spawning takes place from February

through June with peak spawning occurring in April

and May (Table 2). Total commercial landings ofAmerican plaice increased from a low of about 3,000 metric

tons in the mid-1970's to a peak of more than 15,000 t

in 1982; landings subsequently declined to levels similar to the mid-1970's (NEFSC 1991).

Median length at maturity ofAmerican plaice sampled

from the Gulf of Maine region during spring 1986-

1990 was 26.8 cm for females and 22.1 for males (Tables

3 and 43, Fig. 41). Median age at maturity for females

and males was 3.6 yr and 3.0 yr, respectively (Table 4,

Fig. 42); proportions of mature fish calculated for each

age are presented in Table 44.

Figure 41

Calculated and observed (.) proportion mature at length

based on macroscopic observations of whole gonads of female (n=714) and male (n=633) American plaice,

Hippoglossoides platessoides, sampled during Northeast Fisheries Science Center spring bottom trawl surveys, 1986--1990.

+-~""""''''''''''''''''''''''::;:'''---'-r-rJ,..,...,.TrY-rry~,.,..~~

ill lli W H m H %

Length
O'Brien et al.: Maturation of Finfish 49

for females of 27.4 em and 3.4 yr, and 26.5 em and 3.4

yr for males, respectively. Morse (1979)2 calculated a

larger L50 value of 33.6 em for females and a similar

value of27.2 em for males for American plaice sampled

from Cape Hatteras, N.C. to Nova Scotia during 1977.

Median length and age at maturity offemale American

plaice in the Scotian Shelf area declined from 31.0 em

and 6 yr during 1970-1974 to 30.8 em and 4.7 yr during

1975-1979. Median values for males similarly declined

from 24.8 em and 4.5 yr, respectively, to 21.9 em and

3.5 yr, respectively, during the same time periods

(Beacham 1983d).

Figure 42

Calculated and observed (.) proportion mature at age based

on macroscopic observations of whole gonads of female

(n=714) and male (n=633) American plaice, Hippoglossoides

platessoides, sampled during Northeast Fisheries Science Center spring bottom trawl surveys, 1986-1990.

Proportion 95% Confidence interval

mature Age Lower Upper

Females

0.00 1.0 0.6 1.4

0.04 2.0 1.7 2.3

0.24 3.0 2.9 3.1

0.72 4.0 3.9 4.1

0.95 5.0 4.8 5.2

0.99 6.0 5.6 6.4

1.00 7.0 6.5 7.5

1.00 8.0 7.3 8.7

1.00 9.0 8.2 9.8

1.00 10.0 9.0 11.0

1.00 11.0 9.9 12.1

1.00 12.0 10.7 13.3

Males

0.04 1.0 0.7 1.3

0.16 2.0 1.8 2.2

0.50 3.0 2.9 3.1

0.84 4.0 3.8 4.2

0.97 5.0 4.7 5.3

0.99 6.0 5.5 6.5

1.00 7.0 6.4 7.6

1.00 8.0 7.2 8.8

1.00 9.0 8.1 9.9

a Offshore strata 26-30, 36-40.

Table 44

Calculated proportion mature at age with approximate 95% confidence intervals based on macroscopic

observations of whole gonads of female (n=714) and

male (n=633) American plaice, Hippoglossoides

platessoides, sampled during Northeast Fisheries Science Center spring bottom trawl surveysa, 1986-1990.

10 11 12

6 10 11 12

Age

8

Age

4

1.0

0.9

0.8 Q)

:; 0.7

1;; 0.6

c: 0.5 American plaice 0.., Hippoglossoides platessoides

a 0.4 males a. n = 633 0 0.3 Ii: 0.2

0.1

0.0

10

09

0.8

0.7 .3

'" 0.6

c: 0.5 American plaice ..,

0 Hippoglossoides platessoides

a 0.4 females a. n = 714 2 0.3 c..

0.2

0.1

0.0
50 NOAA Technical Report NMFS 113

Witch Flounder: Glyptocephalus cynoglossus

Proportion Length 95% Confidence interval

mature (cm) Lower Upper

Females

0.05 22.9 18.8 27.0

0.10 24.8 21.5 28.2

0.15 26.0 23.1 28.9

0.20 26.9 24.3 29.5

0.25 27.6 25.2 30.0

0.30 28.3 26.1 30.5

0.35 28.8 26.8 30.9

0.40 29.4 27.5 31.3

0.45 29.9 28.1 31.7

0.50 30.4 28.7 32.2

0.55 30.9 29.3 32.6

0.60 31.5 29.8 33.1

0.65 32.0 30.4 33.7

0.70 32.6 30.9 34.3

0.75 33.2 31.5 35.0

0.80 34.0 32.1 35.9

0.85 34.9 32.7 37.0

0.90 36.0 33.6 38.5

0.95 37.9 34.8 41.1

0.99 42.1 37.4 46.9

Males

0.05 17.4 12.6 22.2

0.10 19.4 15.4 23.5

0.15 20.7 17.1 24.2

0.20 21.6 18.4 24.8

0.25 22.4 19.4 25.3

0.30 23.0 20.3 25.8

0.35 23.7 21.1 26.2

0.40 24.2 21.9 26.6

0.45 24.8 22.6 26.9

0.50 25.3 23.3 27.3

0.55 25.9 24.0 27.7

0.60 26.4 24.7 28.2

0.65 27.0 25.3 28.7

0.70 27.6 26.0 29.2

0.75 28.3 26.7 29.8

0.80 29.1 27.5 30.6

0.85 30.0 28.3 31.7

0.90 31.2 29.3 33.2

0.95 33.3 30.7 35.8

0.99 37.7 33.6 41.8

a Offshore strata 22-30, 33-34, 351, 36-40.

Table 45

Calculated proportion mature at length with approximate 95% confidence intervals based on macroscopic

observations of whole gonads of female (=189) and

male (=233) witch flounder, Glyptocephalus cynoglossus,

sampled during Northeast Fisheries Science Center

spring bottom trawl surveysa, 1986-1990.

females and 33.0 cm for males) and by Burnett et al.

(1992) for the period 1977-84 (33.5 and 27.6 cm for

females and males, respectively). Additionally, Aso for

Witch flounder

Glyptocephalus cynoglossus

males

n = 233

Witch flounder

Gfyptocephalus cynoglossus

females

n = 189

1.0

0.9

0.8

OJ

0.7

co 0.6

c 0.5 a

.'"0 0.4 n

e 0.3 0-

0.2

0.1

0.0

to

0.9

0.8

OJ

0.7

co 0.6

c

a 0.5 .'"0 0.4 n

a 0.3 0: 0.2

0.1

0.0 f,.,....,........,.,-..,..-~~·rrfrrrrrCTTTl~TT'TTTTTTTT"rrrrCTTTl~-rrrn'

5 ill lli W H m H e W M U m M

Length

-I~"""""""~"""····f""+-+-rrrr~~TT'TTTTTTTT"rrrr~~TT'T"'TTT""'" 5 ill lli W H m H e W M U ro M

Length

Figure 43

Calculated and observed (.) proportion mature at length

based on macroscopic observations of whole gonads of female (=189) and male (=233) witch flounder, Glyptocephalus

cynoglossus, sampled during Northeast Fisheries Science Center spring bottom trawl surveys, 1986-1990.

Witch flounder range from Labrador to Cape Hatteras,

North Carolina, but are not commercially abundant

south of Cape Cod, Massachusetts. The population inhabiting the Gulf of Maine-Georges Bank region is

considered to be a unit stock. Spawning in this region is

protracted, encompassing a period from early spring to

late summer, but peak activity appears to occur during

May andJune (Table 2). Commercial landings of witch

flounder averaged 2,800 metric tons from 1960 to 1981,

rose sharply to an average of 5,500 t during 1982-86,

and have subsequently declined to 2,100 t in 1989

(NEFSC 1991).

Median length at maturity for female and male witch

flounder was 30.4 and 25.3 cm, respectively (Tables 3

and 45, Fig. 43). Median age at maturity was 4.4 yr for

females and 3.6 yr for males (Table 4, Fig. 44); proportions of mature fish calculated for each age are presented in Table 46.

Values ofLso above are lower than those obtained for

witch flounder in the Gulf of Maine-Georges Bank region by Morse (1979)2 from 1977 data (34.9 cm for
O'Brien et al.: Maturation of Finfish 51

Table 46

Calculated proportion mature at age with approximate 95% confidence intervals based on macroscopic

observations of whole gonads of female (n=189) and

male (n=233) witch flounder, Glyptocephalus cynoglossus,

sampled during Northeast Fisheries Science Center

spring bottom trawl surveysa, 1986-1990.

Proportion 95% Confidence interval

mature Age Lower Upper

Females

0.00 1.0 -0.5 2.5

0.02 2.0 0.8 3.2

0.10 3.0 2.2 3.8

0.36 4.0 3.5 4.5

0.73 5.0 4.6 5.4

0.93 6.0 5.4 6.6

0.98 7.0 6.0 8.0

1.00 8.0 6.6 9.4

1.00 9.0 7.2 10.8

1.00 10.0 7.8 12.2

1.00 11.0 8.4 13.6

1.00 12.0 9.0 15.0

1.00 13.0 9.6 16.4

1.00 14.0 10.2 17.8

1.00 15.0 10.8 19.2

1.00 16.0 11.4 20.6

1.00 17.0 12.0 22.0

1.00 18.0 12.6 23.4

1.00 19.0 13.2 24.8

1.00 20.0 13.8 26.2

1.00 21.0 14.4 27.6

1.00 22.0 15.0 29.0

1.00 23.0 15.6 30.4

1.00 24.0 16.2 31.8

Males

0.00 1.0 -0.5 2.5

0.02 2.0 1.0 3.0

0.19 3.0 2.5 3.5

0.71 4.0 3.8 4.2

0.96 5.0 4.5 5.5

1.00 6.0 5.0 7.0

1.00 7.0 5.6 8.4

1.00 8.0 6.1 9.9

1.00 9.0 6.6 11.4

1.00 10.0 7.2 12.8

1.00 11.0 7.7 14.3

1.00 12.0 8.2 15.8

1.00 13.0 8.7 17.3

1.00 14.0 9.3 18.7

1.00 15.0 9.8 20.2

1.00 16.0 10.3 21.7

1.00 17.0 10.9 23.1

1.00 18.0 11.4 24.6

1.00 19.0 11.9 26.1

1.00 20.0 12.4 27.6

1.00 21.0 13.0 29.0

a Offshore strata 22-30,33-34,351,36-40.

to

0.9 Witch flounder

0.8 Glyptocepha/us cynoglossus

females 0.7 n = 189

'" 0.6

c: 0.5 0

.'"15 0.4 c.

:f. 0.3

0.2

0.1

0.0

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24

Age

to

0.9 Witch flounder

0.8 GIYFetocePhalus cynoglossus Q) maes :; 0.7 n = 233

10 0.6

c: 0.5 0

.'"15 0.4 c.

e 0.3 a. 0.2

0.1

0.0 I I I I I I I I I I I I

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24

Age

both sexes has been reduced by about a year from

1977-84 values (Burnett et al. 1992).

In general, maturation of witch flounder in the Gulf

of Maine-Georges Bank region occurs at a similar size

but at an earlier age than slower-growing fish in colder

Canadian waters. Beacham (1983e) reported ranges

for L50 of 33.0 to 34.3 cm for females and 29.2 to 33.0

cm for males offNova Scotia, with corresponding ranges

for A50 of 7.2 to 8.8 yr and 5.1 to 9.2 yr. Bowering

(1976) and Bowering and Brodie (1984) observed that

maturation of female witch flounder in Newfoundland

waters and the Gulf of St. Lawrence occurred at a

greater size and age than in any other region (values of

L50 ranged from 40.0 to 50.0 cm off Newfoundland and

39.8 to 45.0 cm in the Gulf of St. Lawrence; associated

values ofA50 ranged from 8.4 to 10.2 yr and 9.8 to 14.5

yr), but that maturation of males was comparable to

that noted by Beacham (1983e). Recently, Bowering

(1987, 1989) has related changes in biological parameters, including maturation rates, for witch flounder in

the Labrador and Newfoundland regions to commercial exploitation patterns.

Figure 44

Calculated and observed (.) proportion mature at age based

on macroscopic observations of whole gonads of female

(n=189) and male (n=233) witch flounder, Glyptocephalus

cynoglossus, sampled during Northeast Fisheries Science Center spring bottom trawl surveys, 1986-1990.
52 NOAA Technical Report NMFS 113

Swnmer Flounder: Paralichthys dentatus

Table 47

Calculated proportion mature at length with approximate 95% confidence intervals based on macroscopic

observations of whole gonads of female (n=378) and

male (n=497) summer flounder, Paralichthys dentatus,

sampled during Northeast Fisheries Science Center

autumn bottom trawl surveysa, 1985-1989.

Proportion Length 95% Confidence interval

mature (em) Lower Upper

Females

0.05 18.4 15.4 21.3

0.10 20.8 18.4 23.3

0.15 22.3 20.2 24.5

0.20 23.5 21.5 25.4

0.25 24.4 22.6 26.2

0.30 25.2 23.5 26.9

0.35 26.0 24.4 27.5

0.40 26.7 25.2 28.1

0.45 27.3 25.9 28.7

0.50 28.0 26.6 29.3

0.55 28.6 27.4 29.9

0.60 29.3 28.1 30.6

0.65 30.0 28.8 31.2

0.70 30.8 29.5 32.0

0.75 31.6 30.3 32.8

0.80 32.5 31.2 33.8

0.85 33.6 32.2 35.1

0.90 35.2 33.6 36.8

0.95 37.6 35.6 39.6

0.99 43.0 40.0 46.0

Males

0.05 15.3 12.7 17.9

0.10 17.7 15.5 19.9

0.15 19.2 17.3 21.2

0.20 20.4 18.6 22.1

0.25 21.3 19.7 22;9

0.30 22.1 20.6 23.6

0.35 22.9 21.5 24.2

0.40 23.6 22.3 24.8

0.45 24.2 23.0 25.4

0.50 24.9 23.8 26.0

0.55 25.5 24.5 26.6

0.60 26.2 25.2 27.2

0.65 26.9 25.9 27.9

0.70 27.6 26.7 28.6

0.75 28.5 27.5 29.4

0.80 29.4 28.4 30.4

0.85 30.5 29.5 31.6

0.90 32.0 30.8 33.2

0.95 34.5 33.0 36.0

0.99 39.9 37.4 42.3

a Inshore strata 1-41, offshore strata 1-12, 45-46, 52, 55-76.

Gillikin and Holland (1983), however, suggested that

female summer flounder collected offthe coast ofNorth

Carolina in late 1975 and early 1976 first matured at

Summer flounder

Parafichthys dentatus

males

n = 497

Summer flounder

Parafichthys dentatus

females

n = 378

'.

1.0

0.9

0.8

0.7

ro 0.8

c: 0.5 0.,

(; 0.4

a. 0.3

0.2

0.1

0.0

~:1 0.8

0.7

0.8

§ 0.5+---------/

.~ 0.4

a. £. 0.3

0.2

0.1

00 1

5 ill ffi W H m n a w w u m Length

+.......,....~~~...,..,.,...r\-rro"'T""fT"'1 iii i I I i

5 ill ffi W H m n a w w u m Length

Figure 45

Calculated and observed (.) proportion mature at length

based on macroscopic observations of whole gonads of female (n=378) and male (n=497) summer flounder, Paralichthys

dentatus, sampled during Northeast Fisheries Science Center

autumn bottom trawl surveys, 1985-1989.

Summer flounder occur from the southern Gulf of

Maine to South Carolina but are most common between Cape Cod and Cape Hatteras, where a single

stock is thought to exist (Fogarty et al. 1983). Spawning

takes place during an autumn migration from coastal

embayments to the outer continental shelf with most

activity occurring in October and November (Table 2).

Commercial landings of summer flounder increased

sharply from less than 6,000 metric tons annually prior

to 1974 to about 12,000 t per year during the 1980's. An

equivalent amount of recreational landings was also

taken during the same period (NEFSC 1991).

Median length at maturity for female and male summer flounder was 28.0 and 24.9 em, respectively (Tables

3 and 47, Fig. 45). These sizes occur at about age 2.5 for

females and age 2 for males according to the growth

functions presented by Penttila et al. (1989) for the entire

northwest Atlantic.

Values of L50 above are comparable to those for both

sexes reported by Morse (1979)2 for the year 1977.
age 3 with full maturation occurring after age 4. Their

study also indicated that some males matured at age 2,

but the majority deferred spawning until age 3 at a

median length of 33.1 cm. In a more comprehensive

study, Morse (1981) reported an increase in L50 for

males from 25.0 to 27.3 cm between 1974-75 and 1978-

79. However, there appeared to be no trend in female

O'Brien et al.: Maturation of Finfish 53

L50 estimates which fluctuated between 30.2 and 33.3

cm during the same period.

However, a revision to ageing convention (Smith et aI.

1981; Almeida et al. 1992) has resulted in median lengths

being attained a year earlier than reported above. This

interpretation has been supported by recent growth studies by Able et al. (1990) and Szedlmayer et al. (1992).
54 NOAA Technical Report NMFS 113

Windowpane: Scophthalmus aquosus

Proportion Length 95% Confidence interval

mature (cm) Lower Upper

Females

0.05 18.2 14.9 21.4

0.10 19.3 16.4 22.1

0.15 19.9 17.4 22.5

0.20 20.5 18.1 22.8

0.25 20.9 18.7 23.1

0.30 21.2 19.2 23.3

0.35 21.6 19.6 23.5

0.40 21.9 20.0 23.8

0.45 22.2 20.4 24.0

0.50 22.5 20.8 24.2

0.55 22.8 21.2 24.4

0.60 23.1 21.6 24.6

0.65 23.4 22.0 24.9

0.70 23.7 22.4 25.1

0.75 24.1 22.8 25.4

0.80 24.5 23.3 25.8

0.85 25.1 23.8 26.3

0.90 25.7 24.4 27.0

0.95 26.8 25.4 28.3

0.99 29.3 27.0 31.5

Males

0.05 18.1 15.4 20.7

0.10 19.1 16.8 21.4

0.15 19.8 17.7 21.8

0.20 20.3 18.4 22.1

0.25 20.7 19.0 22.4

0.30 21.0 19.4 22.6

0.35 21.4 19.9 22.9

0.40 21.7 20.3 23.1

0.45 22.0 20.6 23.3

0.50 22.2 21.0 23.5

0.55 22.5 21.4 23.7

0.60 22.8 21.7 23.9

0.65 23.1 22.1 24.2

0.70 23.4 22.5 24.4

0.75 23.8 22.9 24.7

0.80 24.2 23.3 25.1

0.85 24.7 23.8 25.6

0.90 25.4 24.3 26.4

0.95 26.4 25.2 27.7

0.99 28.8 26.7 30.8

a Offshore strata 13-21.

Table 48

Calculated proportion mature at length with approximate 95% confidence intervals based on macroscopic

observations of whole gonads of female (n=343) and

male (n= 199) windowpane, Scophthalmus aquosus,

from Georges Bank sampled during Northeast Fisheries Science Center spring bottom trawl surveys a,

1985-1990.

age 3; this is consistent with the observation by Moore

(1947) that windowpane attain maturity during the

third or fourth year.

Windowpane

Scophthalmus aquosus

Georges Bank

males

n = 199

Windowpane

Scophthalmus aquosus

Georges Bank

females

n = 343

1.0

09

0.8

0.7 ;:!

'" 0.6

c: 0.5 0

',-=

0 O.a

a.

0 0.3 c: 0.2

0.1

0.0

1.0

09

0.8 (l)

:; 0.7

10 0.6

c: 0.5 0

',-=

0 04 a.

2 0.3 [L

02

0.1'

0.0

Figure 46

Calculated and observed (.) proportion mature at length

based on macroscopic observations of whole gonads of female (n=343) and male (n=199) windowpane, Scophthalmus

aquosus, from Georges Bank sampled during Northeast Fisheries Science Center spring bottom trawl surveys, 1985-1990.

+~~,......,......................"..-;-,.,......,...,., ,'11111' I' I

m ffi w m m _ e w

Length

Windowpane are distributed from the Gulf of St.

Lawrence to South Carolina, but are commercially abundant only in the Georges Bank-Southern New England

region. No information relative to stock structure exists, but differences in growth rates suggest that fish

from Georges Bank and Southern New England comprise separate stocks (Thorpe 1991). Spawning occurs

from June to October on Georges Bank, with peak

activity during July and August; in Southern New England, spawning takes place from May to November

with a peak in September (Table 2). Commercial landings of windowpane have averaged 1,100 metric tons

from Georges Bank and 600 t from Southern New

England during 1976-1989 (Thorpe 1991).

Median length at maturity for female and male windowpane from Georges Bank was 22.5 and 22.2 em,

respectively, and 21.2 em for females and 21.5 cm for

males from the Southern New England region (Tables

3, 48 and 49; Figs. 46 and 47). Applying the growth

function of Moore (1947) to these values ofLso results

in estimates of median age at maturity slightly above

-ror-i-,....,,~'T"~.,...~,-.-,~r-.-.-.-,

m ffi w m m _ e w

Length

-u.S. GOVERNMENT PRINTING OFFICE 1993-0-790·258/80002
1.0 r 0.9

0.8 Q) Windowpane Z 0.7 Scophthalmus aqubsus

'" 0.8 Southern New England

c females 0 0.5 n = 143 .;:;

(; 0.4 n

e 0.3 0-

0.2

0.1

0.0 / I I li'l

5 10 15 20 25 30 35 40

Length

1.0

0.9

0.8

0.7 Windowl1ane ::> Scophthalmus aquosus 10 0.6 Southern New Englimd

c males 0 0.5 n = 133 .;:;

(; 0.4

) n

0 0.3 et 0.2

0.1

0.0

5 10 15 20 25 30 35 40

Length

Figure 47

Calculated and observed (.) proportion mature at length

based on macroscopic observations of whole gonads of female (n=143) and male (n=133) windowpane, Scophthalmus

aquosus, from Southern New England grounds sampled during Northeast Fisheries Science Center spring bottom trawl

surveys, 1985-1990.

O'Brien et al.: Maturation of Finfish ,55

Table 49

Calculated proportion mature at length with approximate 95% confidence intervals based on macroscopic

observations of whole gonads of female (n=143) and

male (n=133) windowpane, Scophthalmus aquosus, from

Southern New England grounds sampled during Northeast Fisheries Science Center spring bottom trawl

surveysa, 1985-1990.

Proportion Length 95% Confidence interval

mature (em) Lower Upper

Females

0.05 20.5 19.5 21.4

0.10 20.6 19.9 21.3

0.15 20.8 20.2 21.3

0.20 20.8 20.4 21.3

0.25 20.9 20.5 21.3

0.30 21.0 20.6 21.4

0.35 21.0 20.6 21.4

0.40 21.1 20.7 21.5

0.45 21.1 20.7 21.6

0.50 21.2 20.7 21.7

0.55 21.2 20.7 21.8

0.60 21.3 20.7 21.9

0.65 21.3 20.7 22.0

0.70 21.4 20.6 22.1

0.75 21.4 20.6 22.2

0.80 21.5 20.6 22.4

0.85 21.6 20.5 22.6

0.90 21.7 20.5 22.9

0.95 21.9 20.4 23.4

0.99 22.3 20.2 24.4

Males

0.05 18.3 16.3 20.4

0.10 19.1 17.4 20.9

0.15 19.6 18.1 21.2

0.20 20.0 18.6 21.4

0.25 20.3 19.0 21.6

0.30 20.6 19.4 21.8

0.35 20.9 19.7 22.0

0.40 21.1 20.0 22.2

0.45 21.3 20.3 22.3

0.50 21.5 20.6 22.5

0.55 21.8 20.8 22.7

0.60 22.0 21.1 22.9

0.65 22.2 21.3 23.1

0.70 22.5 21.6 23.3

0.75 22.7 21.9 23.6

0.80 23.1 22.2 24.0

0.85 23.4 22.5 24.4

0.90 24.0 22.9 25.0

0.95 24.8 23.5 26.1

0.99 26.6 24.6 28.6

a Offshore strata 5-12
56 NOAA Technical Report NMFS 113

Atlantic Herring: aupea harengus

Figure 48

Calculated and observed (.) proportion mature at length

based on macroscopic observations of whole gonads of female (n=359) and male (n=307) Atlantic herring, ClupPa

harengus, sampled during Northeast Fisheries Science Center autumn bottom trawl surveys, 1987-1989.

Atlantic herring are widely distributed in the northwest

Atlantic from Labrador to Cape Hatteras, North Carolina. Spawning in the Gulf of Maine occurs from late

August to December, with peak activity during September and October (Table 2). Historically, important commercial fisheries in U.S. waters have occurred in the

coastal areas of the Gulf of Maine and on Georges

Bank. In the former region, the fishery targetsjuvenile

herring; in the latter region, no fishery has been prosecuted since the total collapse of the stock in the mid

1970's. Commercial landings ofherring averaged 57,000

metric tons per year during 1942-1963, declined to

31,000 t annually from 1964-1975, increased to 60,000 t

per year during the period 1976-1981, and have fluctuated around an average of about 33,000 t per year since

then (NEFC 1990).6

Median length at maturity for female and male Atlantic herring was 25.4 and 25.3 cm (TL), respectively

(Tables 3 and 50, Fig. 48). Median age at maturity was

3.0 yr for females and 2.9 yr for males (Table 4, Fig. 49);

) 10 15 20 25 30 35 "40

Length

Table 50

Calculated proportion mature at length with approximate 95% confidence intervals based on macroscopic

observations of whole gonads of female (n=359) and

male (n=307) Atlan tic herring, Clupea harengus, sampled

during Northeast Fisheries Science Center autumn

bottom trawl surveys·, 1987-1989.

Proportion Length 95% Confidence interval

mature (cm) Lower Upper

Females

0.05 22.8 21.8 23.7

0.10 23.4 22.6 24.2

0.15 23.8 23.1 24.5

0.20 24.1 23.5 24.8

0.25 24.4 23.8 25.0

0.30 24.6 24.1 25.1

0.35 24.8 24.3 25.3

0.40 25.0 24.6 25.5

0.45 25.2 24.8 25.6

0.50 25.4 25.0 25.8

0.55 25.6 25.2 25.9

0.60 25.7 25.4 26.1

0.65 25.9 25.6 26.3

0.70 26.1 25.8 26.5

0.75 26.4 26.0 26.7

0.80 26.6 26.2 27.0

0.85 26.9 26.5 27.3

0.90 27.3 26.9 27.8

0.95 28.0 27.4 28.6

0.99 29.5 28.5 30.4

Males

0.05 23.5 22.8 24.2

0.10 24.0 23.4 24.5

0.15 24.2 23.7 24.8

0.20 24.5 24.0 24.9

0.25 24.6 24.2 25.1

0.30 24.8 24.4 25.2

0.35 24.9 24.6 25.3

0.40 25.1 24.7 25.4

0.45 25.2 24.9 25.5

0.50 25.3 25.0 25.6

0.55 25.5 25.2 25.8

0.60 25.6 25.3 25.9

0.65 25.7 25.4 26.0

0.70 25.9 25.6 26.2

0.75 26.0 25.7 26.3

0.80 26.2 25.9 26.5

0.85 26.4 26.0 26.8

0.90 26.7 26.3 27.1

0.95 27.2 26.6 27.7

0.99 28.2 27.4 29.0

a Offshore strata 1-12,24-30,33-34,351,36-40,61-76.

proportions of mature fish calculated for each age are

presented in Table 51.

I

40 I

30 35

Atlantic herring

Clupea harengus

males

n = 307

Atlantic herring

Clupea harengus

females

n = 359

15 20 25

Length

10

10l

0.9

0.8

:0 0.7

10 0.6

c 0.5 0.,

0 0.4

a.

0 0.3 c: 0.2

01

0.0

10

0.9

0.8

0.7 i:J

<1l 0.6

c 0.5 0.,

0 0.4 a.

0 0.3 c: 0.2

0.1

0.0
Values of L50 and Aso above are comparable to those

reported for Nova Scotia herring for the period 1966-

75, during which Lso for both sexes combined varied

from 25.3 to 27.4 cm (Sinclair et al. 198~), and Aso

varied between 2.9 and 3.6 yr for females and 2.8 and

3.6 yr for males (Sinclair et al. 1979). Maturity at age

(Table 51) is similar to that obtained for Gulf of Maine

herring from monthly commercial sampling during

1985-89 (0.39 of age 3 fish, 0.98 of age 4 fish, 1.00 age

5+; NEFC 1990)6. However, Sinclair et al. (1982) noted

Figure 49

Calculated and observed (.) proportion mature at age based

on macroscopic observations of whole gonads of female

(n=359) and male (n=307) Atlantic herring, Clupea harengus,

sampled during Northeast Fisheries Science Center autumn

bottom trawl surveys, 1987-1989.

O'Brien et al.: Maturation of Finfish 57

a positive relationship between juvenile growth rates

and Lso' and Winters (1976) reported decreases in Aso

with decreasing adult biomass for herring in the Gulf of

St. Lawrence, suggesting that density-dependent processes may influence maturation rates of Atlan tic

herring.

6 NEFC. 1990. Report of the eleventh NEFC Stock Assessment

Workshop Fall 1990. NEFC Ref. Doc., 90-09: 58-65.

Table 51

Calculated proportion mature at age with approximate 95% confidence intervals based on macroscopic

observations of whole gonads of female (n=359) and

male (n=307) Atlantic herring, Clupea harengus, sampled

during Northeast Fisheries Science Center autumn

bottom trawl surveysa, 1987-1989.

Proportion 95% Confidence interval

mature Age Lower Upper

Females

0.00 1.0 0.1 1.9

0.01 2.0 1.6 2.4

0.48 3.0 2.9 3.1

0.99 4.0 3.6 4.4

1.00 5.0 4.2 5.8

1.00 6.0 4.8 7.2

1.00 7.0 5.3 8.7

1.00 8.0 5.9 10.1

1.00 9.0 6.5 11.5

1.00 10.0 7.1 12.9

1.00 11.0 7.7 14.3

Males

0.00 1.0 0.2 1.8

0.03 2.0 1.6 2.4

0.58 3.0 2.9 3.1

0.99 4.0 3.6 4.4

1.00 5.0 4.3 5.7

1.00 6.0 4.9 7.1

1.00 7.0 5.6 8.4

1.00 8.0 6.2 9.8

1.00 9.0 6.8 11.2

a Offshore strata 1--'12, 24-30, 33-34, 351, 36-40, 61-76.
58 NOAA Technical Report NMFS 113

Atlantic Mackerel: Scomber scombrus

The range of the migratoryAtlantic mackerel extends

from North Carolina to Newfoundland (Sette 1950).

Although considered to be a single stock there are two

spawning groups: the southern contingent spawns in

the Mid-Atlantic Bight from April to July (Table 2) and

the northern contingent spawns in the Gulf of St.

Lawrence during June and July (NEFSC 1991). Total

landings of Atlantic mackerel peaked at about 400,000

metric tons in 1973, then declined to about 30,000 t in

the late 1970's, and have recently increased to about

74,000 tin 1989 (NEFSC 1991).

Median length at maturity offemale and male Atlantic mackerel was 25.7 cm and 26.0 cm, respectively

(Tables 3 and 52, Fig. 50) for samples collected during

spring 1987-1989. Median age at maturity was 1.9 yr for

both females and males (Table 4, Fig. 51); proportions

of mature fish calculated for each age are presented in

Table 53.

Mackerel sampled in the Newfoundland area from

June-September during 1970-1973 had higher values

Figure 50

Calculated and observed (.) proportion mature at length

based on macroscopic observations of whole gonads of female (n=697) and male (n=770) mackerel, Scomber scombrus,

sampled during Northeast Fisheries Science Center spring

bottom trawl surveys, 1987-1989.

for L50 of 34 cm and 35 cm for females 'and males,

respectively (Moores et al. 1975). MacKay (1967) reported that first spawning for mackerel occurred at age

2 and at lengths greater than 30 cm for Atlantic mackTable 52

Calculated proportion mature at length with approximate 95% confidence intervals based on macroscopic

observations of whole gonaqs of female (n=697) and

male (=-770) mackerel, Scomber scombrus, sampled during Northeast Fisheries Science Center spring bottom

trawl surveysa, 1987-1989.

Proportion Length 95% Confidence interval

mature (em) Lower Upper

Females

0.05 21.1 20.0 22.2

0.10 22.3 21.3 23.2

0.15 23.0 22.2 23.8

0.20 23.5 22.8 24.3

0.25 24.0 23.3 24.7

0.30 24.4 23.7 25.0

0.35 24.7 24.1 25.4

0.40 25.1 24.5 25.7

0.45 25.4 24.8 26.0

0.50 25.7 25.1 26.3

0.55 26.0 25.5 26.6

0.60 26.3 25.8 26.9

0.65 26.7 26.1 27.2

0.70 27.0 26.5 27.6

0.75 27.4 26.8 28.0

0.80 27.9 27.3 28.5

0.85 28.4 27.8 29.1

0.90 29.1 28.4 29.9

0.95 30.3 29.4 31.2

0.99 32.9 31.6 34.2

Males

0.05 21.5 20.5 22.5

0.10 22.6 21.8 23.5

0.15 23.3 22.6 24.1

0.20 23.9 23.2 24.5

0.25 24.3 23.7 24.9

0.30 24.7 24.1 25.3

0.35 25,0 24.5 25.6

0.40 25.4 24.8 25.9

0.45 25.7 25.2 26.2

0.50 26.0 25.5 26.4

0.55 26.3 25.8 26.7

0.60 26.6 26.1 27.0

0.65 26.9 26.5 27.4

0.70 27.3 26.8 27.7

0.75 27.6 27.2 28.1

0.80 28.1 27.6 28.6

0.85 28.6 28.1 29.2

0.90 29.3 28.7 29.9

0.95 30.4 29.7 31.2

0.99 33.0 31.8 34.1

a Inshor~ strata 1-81, offshore strata 1-34, 351, 36--76.
O'Brien et al.: Maturation of Finfish 59

erel sampled during May-July 1965-1966, from locations in the Gulf of St. Lawrence and along the coast of

Nova Scotia and Massachusetts. The differences in median maturity between these studies and that reported

above may be due to the slower growth rate of large

year classes that may delay spawning from one to three

years (Mackay 1973; Overholtz 1989).

Table 53

Calculated proportion mature at age with approximate 95% confidence intervals based on macroscopic

observations of whole gonads of female (n=697) and

male (n=770) Atlantic mackerel, Scomber scomlrrus,

sampled during Northeast Fisheries Science Center

spring bottom trawl surveysa, 1987-1989.

Proportion

mature Age

95% Confidence interval

Lower Upper

10

1 234 5 6 7 89m " g M m w Age

Figure 51

Calculated and observed (.) proportion mature at age based

on macroscopic observations of whole gonads of female

(n=697) and male (n=770) Atlantic mackerel, Scomberscomlrrus,

sampled during Northeast Fisheries Science Center spring

bottom trawl surveys, 1987-1989.

1.3

2.1

3.3

4.6

6.0

7.3

8.6

9.9

11.2

12.5

13.8

15.2

16.5

17.8

19.1

20.4

1.2

2.1

3.3

4.5

5.7

6.9

8.1

9.4

10.6

1l.8

13.0

14.3

15.5

16.7

17.9

19.2

0.7

1.9

2.7

3.4

4.0

4.7

5.4

6.1

6.8

7.5

8.2

8.8

9.5

10.2

10.9

11.6

0.8

1.9

2.7

3.5

4.3

5.1

5.9

6.6

7.4

8.2

9.0

9.7

10.5

11.3

12.1

12.8

1.0

2.0

3.0

4.0

5.0

6.0

7.0

8.0

9.0

10.0

11.0

12.0

13.0

14.0

15.0

16.0

1.0

2.0

3.0

4.0

5.0

6.0

7.0

8.0

9.0

10.0

11.0

12.0

13.0

14.0

15.0

16.0

a Inshore strata 1-81, offshore strata 1-34, 351, 36-76.

Females

0.02

0.63

0.99

1.00

1.00

1.00

1.00

1.00

1.00

1.00

1.00

1.00

1.00

1.00

1.00

1.00

Males

0.05

0.58

0.97

1.00

1.00

1.00

1.00

1.00

1.00

1.00

1.00

1.00

1.00

1.00

1.00

1.00

Atlantic mackerel

Scomber scombrus

males

n = 770

Atlantic mackerel

Scomber scombrus

females

n = 697

2 3 4 5 6 7 8 9 10 " 12 13 14 15 16

Age

0.9

0.8

10

0.1

0.9

0.8

:::J 0.7

10::2 0.6

5 05 .,

o 04 0. £ 0.3

0.2

2 0.7

::2'" 06

5 0.5 .,

o 0.4 0.

03

0.2

0.1

0.0 +--4---+---,-,-.,--,----,----,--,-,-,--,----,---,-,--
60 NOAA Technical Report NMFS 113

Butterf'Ish: Peprilus triacanthus

Figure 52

Calculated and observed (.) proportion mature at length

based on macroscopic observations of whole gonads of female (n=333) and male (n=341) butterfish, Peprilus triacanthus,

sampled during Northeast Fisheries Science Center spring

bottom trawl surveys, 1986-1989.

Butterfish are distributed along the Atlantic coast of

North America from Newfoundland to Florida, but are

most common between Southern New England and

Cape Hatteras where a single stock is thought to exist

(Murawski and Waring 1979). Spawning takes place in

late spring and summer with most activity occurring in

June and July (Table 2). Total commercial landings

fluctuated between 4,000 and 20,000 metric tons during the 1960's and 1970's, but remained relatively stable

at about 5,000 t between 1977 and 1981; landings have

since declined to about 2,000 tin 1988 (NEFSC 1991).

Median length at maturity for female and male butterfish was 12.0 and 11.4 cm, respectively (Tables 3 and

54, Fig. 52). Median age at maturity was 0.9 yr for both

sexes (Table 4, Fig. 53); proportions of mature fish

calculated for each age are presented in Table 55.

Values of Lso above are comparable to those for both

sexes reported by Morse (1979)2 for the year 1977.

DuPaul and McEachran (1973) also noted that maturation of butterfish collected from Chesapeake Bay commenced at about age 1 and that almost all two-year-old

Proportion Length 95% Confidence interval

mature (cm) Lower Upper

Female

0.05 9.5 8.7 10.3

0.10 10.1 9.5 10.8

0.15 10.5 9.9 ILl

0.20 10.8 10.3 11.3

0.25 11.0 10.6 11.5

0.30 11.3 10.8 11.7

0.35 11.4 11.0 11.9

0.40 11.6 11.2 12.0

0.45 11.8 11.4 12.2

0.50 12.0 11.6 12.3

0.55 12.1 11.8 12.5

0.60 12.3 11.9 12.6

0.65 12.5 12.1 12.8

0.70 12.7 12.3 13.0

0.75 12.9 12.5 13.2

0.80 13.1 12.7 13.5

0.85 13.4 12.9 13.8

0.90 13.8 13.2 14.3

0.95 14.4 13.7 15.0

0.99 15.7 14.8 16.7

Males

0.05 8.4 7.5 9.2

0.10 9.1 8.4 9.8

0.15 9.6 9.0 10.2

0.20 10.0 9.4 10.5

0.25 10.3 9.8 10.8

0.30 10.5 10.1 11.0

0.35 10.8 10.3 11.2

0.40 11.0 10.6 11.4

0.4-5 11.2 10.8 11.6

0.50 11.4 11.0 11.8

0.55 11.6 11.3 12.0

0.60 11.8 11.5 12.2

0.65 12.0 11.7 12.4

0.70 12.3 11.9 12.6

0.75 12.5 12.1 12.9

0.80 12.8 12.4 13.2

0.85 13.2 12.7 13.7

0.90 13.7 13.1 14.2

0.95 14.4 13.8 15.1

0.99 16.1 15.1 17.2

a Inshore strata 1-46, offshore strata 1-25,61-76.

Table 54

Calculated proportion mature at length with approximate 95% confidence intervals based on macroscopic

observations of whole gonads of female (n=333) and

male (7'!'=34l) butterfish, Peprilus triacanthus, sampled

during Northeast Fisheries Science Center spring bottom trawl surveys·, 1986-1989.

fish were sexually mature. In an earlier work, however,

Horn (1970) suggested that maturation may have occurred in fish as small as 12 cm but was not common

until about 14 cm.

20 25

Butterfish

Peprilus triacanthus

males

n = 341

15

Length

Length

10

1.0

0.9

0.6

:0 0.7

1;; 0.6

c 0.5 0

.'"0 0.4

c.

0 0.3 0: 0.2

0.1

0.0

1.0

0.9

0.8 Butterfish

Pepri/us triacanthus

0.7 females

n = 333 '" 0.6

c 0.5 0

.'"0 0.4

C.

0.3

0.2

0.1

0.0
O'Brien et al.: Maturation of Finfish 61

a Inshore strata 1-46, offshore strata 1-25, 61-76.

Proportion 95% Confidence interval

mature Age Lower Upper

Females

0.60 1.0 0.9 1.1

0.97 2.0 1.7 2.3

1.00 3.0 2.3 3.7

1.00 4.0 3.0 5.0

Males

0.59 1.0 0.9 1.1

0.96 2,0 1.7 2.3

1.00 3.0 2.3 3.7

1.00 4.0 3.0 5.0

Table 55

Calculated proportion mature at age with approximate 95% confidence intervals based on macroscopic

observations of whole gonads of female (n=333) and

male (n=341) butterfish, Peprilus triacanthus, sampled

during Northeast Fisheries Science Center spring bottom trawl surveys a, 1986-1989.

1.0

0.9

0.8 Butterfish

Q) Peprilus triacanthus

Z 0.7 females

'" n = 333 0.8

c 0.5 0.,

a 0.4 a.

0

et 0.2

0.1

0.0

3 4

Age

1.0

0.9

0.8 Butterfish

t" Pepri/us triacanthus

;l 0.7 males

'" n = 341 0.8

c 0.5 0.,

a 0.4 a.

e 0.3 a. 0.2

0.1

0.0

3 4

Age

Figure 53

Calculated and observed (.) proportion mature at age based

on macroscopic observations of whole gonads of female

(n=333) and male (n=341) butterfish, Peprilus triacanthus,

sampled during Northeast Fisheries Science Center spring

bottom trawl surveys, 1986-1989. '
62 NOAA Technical Report NMFS 113

Discussion _

The results presented in this report are intended to

describe current maturation patterns for the nineteen

included species. However, it is evident from even a

cursory comparison of our results with those from earlier periods that, for most species, A50 and, in many

cases, L50 values have declined substantially in recent

years. While it is often difficult to draw conclusions

about changes in maturation from diverse studies which

may have employed different model fitting techniques,

staging criteria, and seasonal sampling schemes, a comparison between our length-based results and those

presented by Morse (1979)2 is warranted since both

studies have drawn on the same Northeast Fisheries

Science Center trawl survey data base. Our study expands on the initial work of Morse (1979) 2 to include

finer spatial and seasonal resolution, and we have fitted

logistic curves rather than employing probit analysis.

Given the same set of data, however, both fitting techniques will estimate the inflection point (A50, L50) with

the same degree of accuracy (Ashton 1972). In addition, we have analyzed maturation data collected on

cruises conducted only since 1985, with the exception

of red hake and redfish, whereas Morse (1979)2 restricted analyses only to 1977 cruises.

The changes in median size at maturity between

1977 and the mid-to-Iate 1980's are substantial enough

to suggest a real decline rather than a bias resulting

from different sampling techniques. Criteria for maturation stages presently in use on NEFSC and MDMF

cruises have not changed appreciably since the 1970's

and criteria for discriminating between immature and

all other mature stages are identical (Burnett et al.

1989). Our initial analyses of the data on an annual

basis indicated a gradual decline from the late 1970's

through the present. In addition, studies which were

conducted in the same general region of the coast

prior to the mid-1970's indicate that maturation for

most species occurred at older median ages and larger

median sizes than those reported by Morse (1979)2.

Given these changes, it is clear that current estimates

should not be used to represent historical maturation

patterns as in the estimation of spawning stock over

time in sequential population analyses such as VPA or

cohort analysis. Our results are appropriate for use in

short-term projections ofspawning stock and in spawning stock biomass per recruit analyses (Gabriel et al.

1989) in which the current maturation pattern is expected to represent the short-term equilibrium condition of the stock.

A more comprehensive analysis ofthe entire data set,

with a longer time series, will be required before any

definitive conclusions can be drawn about compensatory changes in maturation over time. One such study

(O'Brien 1990) found significant declines in median

size and age at maturation in year classes of Georges

Bank and Gulf of Maine Atlantic cod, Gadus morhua,

between 1970 and 1987. Similar results were noted by

Bowering (1987) for witch flounder, Glyptocephalus

cynoglossus, and several reports by Beacham (1983 a, b,

and d) indicated long-term changes in maturation for

several species on the Scotian Shelf.

To ensure the broadest possible synoptic coverage of

the maturity data included in our study, we included

observations only from standard bottom trawl survey

cruises conducted during spring and autumn. We recognize, however, that such multi-purpose sampling programs often impose some limitations on the utility of

certain data. In our case, the spring and autumn coverage of the surveys closely coincided with peak spawning

periods for most of the species offlounders, but spring

coverage for the winter spawning gadids often occurred

1-2 months after peak spawning. As a result, observations for cod, haddock, pollock, and white hake often

contained a large proportion of resting fish whose gonads are most similar superficially to immature specimens. Given this greater potential for misclassification

of immature and mature fish, the results obtained for

some of the gadiforms may be less reliable than those

for pleuronectiforms and otherspring or autumn spawners. In particular, we note that median sizes and ages at

maturity for cod, haddock, pollock, and white hake

obtained from our analyses are considerably lower than

previously reported.

Determination of maturation stages based on macroscopic examination of gonads generally involves a degree ofsubjectivejudgment on the part ofthe observer.

This difficulty, combined with a high turnover of seagoing personnel from year to year may impart a high

degree of variability to the observations unless training

is continually monitored as noted by Halliday (1987).

Since 1986, the NEFSC Woods Hole Laboratory has

conducted a series of workshops during each survey

season to monitor and calibrate maturity criteria employed by each scientific party involved in data collection. By examining fresh specimens collectively, members of the various teams are able to coordinate their

observations through comparison and discussion ofstaging criteria. Despite these efforts, however, the inherent subjectivity of the approach remains problematic.

To rectify this potential problem in the future, at-sea

maturation observations should be coupled with more

objective techniques in order to ascertain the degree of

precision and bias of the macroscopic method. Other

methods which have demonstrated some success include histological identification of reproductive tissue

(Morrison 1990), analysis of plasma parameters

Qohnson and Casillas 1991), and comparisons with

gonadosomatic indices (O'Brien 1990).
Despite these caveats, our results may be viewed as

baseline maturation patterns in relation to current stock

conditions (abundance, age structure, sex ratio, etc.).

In the future, further monitoring of maturation will be

required on a routine basis coincident with proposed

management actions designed to increase spawning

stock biomass. Any compensatory mechanisms which

result in declines in median size and age at maturation

accompanying declining spawning stock will likely act

in reverse if substantial increases in stock biomass occur over the long-term.

Acknowledgments _

We would like to thank W. Morse, M. Fogarty, and R.

Halliday for their critical review of this manuscript. We

also appreciate the efforts of all the diligent sea-going

personnel whose observations contributed to this analysis.

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