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Report of the 2005 GARM

Fishes of the Gulf of Maine 

by Bigelow & Schroeder, 

1953

Essential Fish Habitat 

Source Document

Age Determination Methods

SARC 36 Assessment 

Report 

SARC 36 Advisory 

Report

SARC 34 Assessment 

Report

SARC 34 Summary 

Report

Framework 42

Historical Perspective on 

the Abundance and 

Biomass of NE Demersal 

Complex Stocks from NMFS 

and MA Inshore Bottom 

Trawl Surveys, 1963-2002

 

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Status of Fishery Resources off the Northeastern US 

NEFSC - Resource Evaluation and Assessment Division 

 

Revised 

December 2006 

Winter flounder (Pseudopleuronectes americanus) 

by Lisa Hendrickson, Paul Nitschke, and Mark Terceiro 

PDF Version 

Archives 

Stocks 

Gulf of Maine 

Georges Bank 

So. New England/ 

Mid-Atlantic Bight

 

Figure 11.1 Statistical Areas Used

Distribution, Biology and Management

The winter flounder, blackback, or lemon sole, Psuedopleuronectes americanus, is a 

demersal flatfish distributed in the Northwest Atlantic from Labrador to Georgia. Important 

U.S. commercial and recreational fisheries exist from the Gulf of Maine to the the MidAtlantic Bight. In USA waters, the resource is assessed and managed as three stocks: 

Gulf of Maine, Southern New England/Mid-Atlantic Bight (SNE/MAB), and Georges Bank 

(Figure 11.1 ). Winter flounder generally occur in inshore bays and estuaries during the 

winter, and move to deeper water in the summer. Spawning occurs during the winter and 

spring months (Pereira et al. 1999). Growth and maturity vary by stock; Georges Bank 

fish have the fastest growth and reach the largest size, and reach maturity at the earliest 

age and smallest size. Gulf of Maine fish grow the slowest and reach the smallest size, 

and reach maturity at the oldest age and largest size (O’Brien et al. 1993). Winter 

flounder may grow up to 58 cm in total length and attain 15-20 years of age (Pentilla et al. 

1989, Pereira et al. 1999). 

U.S. commercial and recreational fisheries for winter flounder are managed in federal waters under the New England Fishery 

Management Council’s Northeast Multispecies Fishery Management Plan (FMP), and in state waters under Atlantic States 

Marine Fisheries Commission’s Fishery Management Plan for Inshore Stocks of Winter Flounder. FMP provisions include 

restrictions on commercial permits, limits on commercial fishery days-at-sea, commercial and recreational fishery time-area 

closures, commercial fishery mesh sizes, commercial and recreational fishery fish size limits, and commercial and recreational 

fishery possession limits. The information provided herein reflects the results of the most recent peer-reviewed assessments for 

the Gulf of Maine, Georges Bank, and Southern New England winter flounder stocks (Mayo and Terceiro 2005). 

GULF OF MAINE WINTER FLOUNDER

The Fishery 

Commercial landings from the Gulf of Maine (GOM) winter flounder stock increased 

from an annual average of about 1,000 mt during 1964 to 1975 to nearly 3,000 mt in 

1982 (Figure 11.2 [Fig 11.2 Data]). Commercial landings have since declined to 300 

mt in 2005. Otter trawls accounted for about 95% of the GOM commercial winter 

flounder landings during 1964-1985, but their percentage declined to 75% between 

1986 and 2001 because of increased landings from gillnets (average of 20% from 

1986-2001). Since 2001, gillnets have accounted for 15% of the landings. The 

recreational rod-and-reel fishery historically harvested a significant proportion of the 

total landings, but recreational catches have sharply declined over the last decade 

from over 2,500 mt in the early 1980s to less than 100 mt during 1997-2005 ( Table 

11.1 ). 

GOM winter flounder landings in numbers have generally been dominated by age 3-5 

fish (Figure 11.3 [Fig 11.3 Data]). The proportion of ages 2 and 3 winter flounder in 

the commercial and recreational landings has been greatly reduced by the effects of 

increasing minimum landing sizes and increasing minimum trawl mesh size in the 

commercial fishery since the late-1990s.

Research Vessel Survey Indices

Bottom trawl survey biomass indices from the Massachusetts Division of Marine 

Fisheries (MADMF) spring and fall surveys declined after 1983. The fall survey 

attained a record low in 1986 while the spring reached a record-low in 1994. Between 

1996 and 2000, both survey indices increased. The 2000 spring index was the highest 

on record and the 2000 fall index was the 2rd highest in the 28-year time series 

(Figure 11.4 [Fig 11.4 Data]). However, subsequently the indices have declined. As 

stock biomass declined in the late 1980s, the age structure of the winter flounder 

Figure 11.2

Figure 11.3

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population became truncated, with a low proportion of fish at ages 5 and older (Figure 

11.5 [Fig 11.5 Data]). The age structure has expanded slightly since the mid 1990s. 

Figure 11.4

Figure 11.5

Figure 11.6

 

Figure 11.7 

Figure 11.8 

Figure 11.9 

Assessment Results

The assessment for GOM winter flounder was last updated at the Groundfish Assessment 

Review Meeting (GARM) in 2005 (NEFSC 2005). Average fishing mortality (ages 5-6, 

unweighted) varied between 0.5 and 2.1 during the 1980s and mid 1990s, but declined to 

a record low of 0.13 in 2004 ( Figure 11.6 [Fig 11.6 Data]). Spawning stock biomass 

declined from 4,800 mt in 1982 to 500 mt in 1996 and then increased to 3,400 mt by 2004 

(Figure 11.7 [Fig 11.7 Data]). Recruitment at age 1 declined from 12 million fish in 1982 

to 3 million fish in 1993, ( Figure 11.7 [Fig 11.7 Data]) but has since increased to 18 

million in 2005. Over the 1982-2004 time period, geometric mean recruitment was 5 

million fish. 

Biological Reference Points 

Biological reference points ( Figure 11.8 [Fig 11.8 Data]) were last reviewed by SARC 36 

(NEFSC 2002) and the values are presented in Table 11.2 . The relationship between 

spawning stock biomass and recruitment for winter flounder over the period covering the 

1982-2004 year classes is illustrated in ( Figure 11.9 [Fig 11.9 Data]). The stockrecruitment trajectory suggests that increases in recent SSB have been accompanied by 

improvement in recruitment. The solid horizontal line indicates the geometric mean 

recruitment over the same period. Survival ratios, recruits per unit of spawning biomass 

(Figure 11.10 [Fig 11.10 Data]), illustrate a general increasing trend in the survival rate 

over time. 

Summary

Spawning stock biomass in 2004 was 3,400 mt or about 84% of BMSY = 4,100 mt. Fishing 

mortality in 2004 was 0.13 or about 30% of FMSY = 0.43. Thus, the stock is not in a 

overfished condition and overfishing is not occurring. 

 

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Figure 11.10

Table 11.1 Recreational and commercial landings of Gulf of Maine winter flounder (thousand metric tons). 

 

Table 11.2 Yield and SSB per Recruit and MSY Based Reference Points for Gulf of Maine winter flounder. 

Category 1986-95 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005

Average 

 

 U.S. Recreational 0.4 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1

 Commercial 

 United States 1.0 0.6 0.6 0.6 0.3 0.4 0.6 0.6 0.7 0.5 0.3

 Canada - ----------

 Other - ----------

 Total Nominal 

Catch 1.4 0.6 0.6 0.6 0.3 0.4 0.6 0.6 0.7 0.5 0.3

 

Yield and SSB per Recruit-based Reference Points

 F0.1 = 0.26

 Fmax = 0.69

 F40% = 0.26

 MSY-based Reference Points

 FMSY = 0.43

 MSY = 1,500 mt

 BMSY = 4,100 mt

GEORGES BANK WINTER FLOUNDER

The Fishery 

Commercial landings of Georges Bank winter flounder are predominately from U.S. 

fisheries, but a small percentage (< 12% during most years) is from Canadian 

fisheries ( Table 11.3 , Figure 11.11 [Fig 11.11 Data]). Canadian landings gradually 

increased after 1993, reached a peak of 500 mt in 2001, and subsequently declined to 

200 mt in 2004. During 1965-1977, the USSR also landed winter flounder from 

Georges Bank, with Soviet landings accounting for 23% to 38% of the total harvest 

during 1971-1973. Recreational landings of winter flounder from Georges Bank are 

insignificant. 

After reaching a peak of 4,500 mt in 1972, total landings of Georges Bank winter 

flounder declined to 1,900 mt in 1976. During 1977-1984, total landings ranged 

between 3,000 and 4,000 mt, but thereafter declined to a record low (800 mt) in 1995. 

Total landings increased between 1995 and 2003 then declined to 2,200 mt in 2005. 

Discarding of Georges Bank winter flounder occurs in the Northeast multispecies 

bottom trawl fishery and the sea scallop dredge fishery. However, data from the 

Fisheries Observer Program and Vessel Trip Report databases have been insufficient 

to produce reliable estimates of the magnitude or size and age composition of these 

discards (NEFSC 2002a). 

Research Vessel Survey Indices

Autumn relative abundance and biomass indices declined between 1976 and 1991 to 

reach a record low (Figure 11.12 [Fig 11.12 Data]). Thereafter, biomass increased 

through 2002, then declined to a level near the time series average in 2005. 

Assessment Results

The assessment of Georges Bank winter flounder was last updated in 2005 using a 

surplus production model (Mayo and Terceiro 2005). Model estimates of relative total 

biomass (Bt

/BMSY) and fishing mortality rates (Ft/FMSY) are utilized because they more 

 

Figure 11.11

 

Figure 11.12

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precisely estimated than absolute values (Prager 1994). 

Relative fishing mortality rates (Ft

/FMSY) were highest during 1983-1993, declined 

sharply during 1996-1999, but have since increased to above FMSY during 2000-2004 

(Figure 11.13 [Fig 11.13 Data]). During 1977-1994, relative biomass indices 

consistently declined reaching a record low in 1994. Subsequently, relative biomass 

increased through 2003, but has since declined to a level just below the threshold in 

2005 (Figure 11.13 [Fig 11.13 Data]). 

Figure 11.13

Biological Reference Points 

MSY-based reference points for Georges Bank winter flounder ( Table 11.4 ) were estimated in the 2001 assessment using a 

surplus production model (NEFSC 2002a) and the reference points implemented in May of 2004 (NEFMC 2003). The MSY 

estimate (3,000 mt) does not include discards. FMSY = 0.32 and BMSY = 9,400 mt. Stock status is determined by comparing 

relative estimates of biomass and fishing mortality with a relative biomass threshold (50% of BMSY) of 0.5 and a relative fishing 

mortality rate threshold (FMSY) of 1.0 because these relative metrics are more precise than the absolute estimates of fishing 

mortality rate and biomass (Mayo and Terceiro 2005). 

Summary

Relative fishing mortality has exceeded FMSY since 2000 and was 1.86 in 2004. Relative biomass exceeded the threshold level 

in 2004 but declined below the threshold, to 0.46, in 2005. Therefore, in 2004, the stock was not overfished but overfishing was 

occurring (Mayo and Terceiro 2005). 

Table 11.3 Recreational and commercial landings of Georges Bank winter flounder (thousand metric tons). 

 

Table 11.4 Yield and SSB per Recruit and MSY Based Reference Points for Georges Bank winter flounder. 

Category 1986-95 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005

Average 

 

 U.S. Recreational - ----------

 Commercial 

 United States 1.9 1.3 1.3 1.2 0.9 1.7 1.6 2.1 2.8 2.9 2.1

 Canada <0.1 0.1 0.1 0.1 0.1 0.2 0.5 0.2 0.3 0.2 0.1

 Other - ----------

 Total Nominal 

Catch 1.9 1.4 1.4 1.3 1.0 1.9 2.1 2.3 3.1 3.1 2.2

 

 MSY-based Reference Points

 MSY = 3,000 mt 

 BMSY = 9,400 mt 

 FMSY = 0.32

SOUTHERN NEW ENGLAND/MID-ATLANTIC BIGHT STOCK COMPLEX

The Fishery 

U.S. commercial landings of SNE/MAB winter flounder peaked at 12,000 mt in 1966, 

declined through the 1970s, and then peaked again at over 11,000 mt in 1981 

(Figure 11.14 [Fig 11.14 Data]). Commercial landings subsequently declined during 

the 1980s and early 1990s, falling to 2,200 mt in 1994. Commercial landings then 

increased to 4,700 mt in 2001 but have since declined to 1,200 mt in 2005, a record 

low (Table 11.5 , Figure 11.14 [Fig 11.14 Data]). The principal gear used in the 

SNE/MAB winter flounder fishery is the otter trawl. The recreational rod-and-reel 

fishery for winter flounder historically harvested a significant proportion of the total 

catch, but recreational landings have markedly declined during the last decade. After 

peaking at 5,800 mt in 1984, recreational landings of winter flounder averaged 1,600 

mt annually during 1986- 1995, but have since declined to 120 mt in 2005 (Table 

11.5 ). 

SNE/MAB winter flounder landings in numbers have generally been dominated by 

age 2-4 fish (Figure 11.15 [Fig 11.15 Data]). Since the mid-1990s, the proportion of 

ages 1 and 2 fish in the commercial and recreational landings has been greatly 

reduced by the effects of increasing minimum landed sizes and increases in the 

minimum trawl mesh size in the commercial fishery. 

Research Vessel Survey Indices

Figure 11.14

 

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NEFSC spring and autumn biomass indices for SNE/MAB winter flounder indicate 

peaks in abundance during the mid-1960s, early 1980s, and late 1990s, and have 

exhibited a declining trend since 1999 (Figure 11.16 [Fig 11.16 Data]). As stock 

biomass declined, the age structure of the winter flounder population became 

truncated, with a low proportion of fish at ages 5 and older (Figure 11.17 [Fig 11.17 

Data]). 

Assessment Results

The assessment for SNE/MAB winter flounder was last updated at the Groundfish 

Assessment Review Meeting (GARM) in 2005 (NEFSC 2005). Average fishing 

mortality (F, ages 4-5, unweighted) ranged between 0.5 and 1.5 during the 1980s 

and mid 1990s, but has steadily declined since 1997 and in 2004 was F = 0.4, a 

record low ( Figure 11.18 [Fig 11.18 Data]). Spawning stock biomass declined from 

14,800 mt in 1983 to 2,700 mt in 1994, slowly increased to 5,000 mt in 2001, and 

has since stabilized at about 4,000 mt (Figure 11.19 [Fig 11.19 Data]). Since 1982, 

recruitment at age 1 has ranged from 57 million fish (1982 year class in 1983) to 4 

million fish (2001 year class in 2002) (Figure 11.19 [Fig 11.19 Data]). Over the 

1982-2004 period, the geometric mean recruitment was 16 million fish. 

Figure 11.15

Figure 11.16

Figure 11.17

 

Figure 11.18

Figure 11.19

Figure 11.20

Figure 11.21

Biological Reference Points 

Biological reference points ( Figure 11.20 [Fig 11.20 Data]) were last calculated by the 

2002 Working Group on Re-Evaluation of Biological Reference Points for New England 

Groundfish (NEFSC 2002) and are presented in Table 11.6 . The relationship between 

spawning stock biomass and recruitment for winter flounder over the period covering the 

1981-2004 year classes is illustrated in ( Figure 11.21 [Fig 11.21 Data]). The stockrecruitment trajectory shows that recent levels of SSB and recruitment occur on the 

lower-left side of the plot. The solid horizontal line indicates the geometric mean 

recruitment (16 million fish at age 1) over the same period. Survival ratios (Figure 

11.22 [Fig 11.22 Data]), illustrate fluctuating survival over time. 

Summary

Spawning stock biomass of SNE/MAB winter flounder in 2004 was 3,900 mt, about 13% 

of BMSY (30,100 mt). Fishing mortality was 0.40 in 2004, 25% above FMSY = 0.32. 

Thus, the stock in 2004 was in an overfished condition and overfishing continues to 

occur. 

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Figure 11.22

Table 11.5 Recreational and commercial landings of SNE/MAB winter flounder (thousand metric tons). 

 

Table 11.6 Yield and SSB per Recruit and MSY Based Reference Points for SNE/MAB winter flounder. 

 

Category 1986-95 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005

Average 

 

 U.S. Recreational 1.6 0.7 0.6 0.3 0.3 0.8 0.5 0.3 0.6 0.2 0.1

 Commercial 

 United States 3.9 2.8 3.4 3.2 3.4 3.8 4.7 3.1 2.4 1.5 1.2

 Canada - ----------

 Other - ----------

 Total Nominal 

Catch 5.5 3.5 4.0 3.5 3.7 4.6 5.2 3.4 3.0 1.7 1.3

 

 Yield and SSB per Recruit-based Reference Points

 F0.1 = 0.25

 Fmax = 0.48

 F40% = 0.21

MSY-based Reference Points

 FMSY = 0.32

 MSY = 10,600 mt

 BMSY = 30,100 mt

For further information

Mayo, R. K. and M. Terceiro. 2005. Assessment of 19 Northeast groundfish stocks through 2004. 2005 Groundfish Assessment 

Review Meeting (2005 GARM), Northeast Fisheries Science Center, Woods Hole, Massachusetts, 15-19 August 2005. U.S. 

Dep. Commer., Northeast Fish. Sci. Cent. Ref. Doc. 05-13, 499 p. 

NEFMC [New England Fishery Management Council]. 2003. Final Amendment 13 to the Northeast Multispecies Fishery 

Management Plan Including a Final Supplemental Environmental Impact Statement and an Initial Regulatory Flexibility 

Analysis. 1,660 p. plus Appendices. 

NEFSC [Northeast Fisheries Science Center]. 2002a. Assessment of 20 northeast groundfish stocks through 2001: A report of 

the Groundfish Assessment Review Meeting (GARM), Northeast Fisheries Science Center, Woods Hole, Massachusetts, 

October 8-11, 2002. Northeast Fish. Sci. Cent. Ref. Doc. 02-16. 511 p. 

NEFSC [Northeast Fisheries Science Center]. 2002b. Final Report of the Working Group on Re- Evaluation of Biological 

Reference Points for New England Groundfish. Northeast Fish. Sci. Cent. Ref. Doc. 02-04, 249 p. 

NEFSC [Northeast Fisheries Science Center]. 2003. Report of the 36th Northeast Regional Stock Assessment Workshop (36th 

SAW), Stock Assessment Review Committee (SARC) consensus summary of assessments. Northeast Fish. Sci. Cent. Ref. 

Doc. 03-06, 453 p. 

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Return to Status of Fishery Resources off the Northeastern US

NEFSC [Northeast Fisheries Science Center]. 2006. Report of the 34th Northeast Regional Stock Assessment Workshop (34th 

SAW): Stock Assessment Review Committee (SARC) consensus summary of assessments. Northeast Fish. Sci. Cent. Ref. 

Doc. 02-06, 346 p. 

O’Brien, L., J. Burnett, and R.K. Mayo. 1993. Maturation of nineteen species of finfish off the northeast coast of the United 

States, 1985-1990. NOAA Tech. Report. NMFS 113, 66 p. 

Pereira, J.J, R. Goldberg, J.J. Ziskowski, P.L. Berrien, W.W. Morse, and D.L. Johnson. 1999. Essential fish habitat source 

document: winter flounder, Pseudopleuronectes americanus, life history and habitat characteristics. NOAA Tech. Mem. NMFSNE-138, 39 p. 

Pentilla, J.A., G.A. Nelson, and J.M. Burnett, III. 1989. Guidelines for estimating lengths at age for 18 Northwest Atlantic finfish 

and shellfish species. NOAA Tech. Mem. NMFS-F/NEC-66, 39 p. 

Prager, M. H. 1994. A suite of extensions to a nonequilibrium surplus-production model. Fish. Bull. 92: 374–389. 

http://www.nefsc.noaa.gov/ Search Link Disclaimer webMASTER Privacy Policy (File Modified Dec. 29 2010) 

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1

Last Revised: December 2006 

 

Winter flounder 

by 

Lisa Hendrickson, Paul Nitschke, and Mark Terceiro 

Distribution, Biology and Management 

The winter flounder, blackback, or lemon sole, Psuedopleuronectes americanus, is a demersal 

flatfish distributed in the Northwest Atlantic from Labrador to Georgia. Important U.S. 

commercial and recreational fisheries exist from the Gulf of Maine to the the Mid-Atlantic Bight. 

In USA waters, the resource is assessed and managed as three stocks: Gulf of Maine, Southern 

New England/Mid-Atlantic Bight (SNE/MAB), and Georges Bank (Figure 11.1). Winter 

flounder generally occur in inshore bays and estuaries during the winter, and move to deeper 

water in the summer. Spawning occurs during the winter and spring months (Pereira et al. 

1999). Growth and maturity vary by stock; Georges Bank fish have the fastest growth and reach 

the largest size, and reach maturity at the earliest age and smallest size. Gulf of Maine fish grow 

the slowest and reach the smallest size, and reach maturity at the oldest age and largest size 

(O’Brien et al. 1993). Winter flounder may grow up to 58 cm in total length and attain 15-20 

years of age (Pentilla et al. 1989, Pereira et al. 1999). 

U.S. commercial and recreational fisheries for winter flounder are managed in federal waters 

under the New England Fishery Management Council’s Northeast Multispecies Fishery 

Management Plan (FMP), and in state waters under Atlantic States Marine Fisheries 

Commission’s Fishery Management Plan for Inshore Stocks of Winter Flounder. FMP 

provisions include restrictions on commercial permits, limits on commercial fishery days-at-sea, 

commercial and recreational fishery time-area closures, commercial fishery mesh sizes, 

commercial and recreational fishery fish size limits, and commercial and recreational fishery 

possession limits. The information provided herein reflects the results of the most recent peerreviewed assessments for the Gulf of Maine, Georges Bank, and Southern New England winter 

flounder stocks (Mayo and Terceiro 2005). 

GULF OF MAINE WINTER FLOUNDER 

The Fishery 
2

Commercial landings from the Gulf of Maine (GOM) winter flounder stock increased from an 

annual average of about 1,000 mt during 1964 to 1975 to nearly 3,000 mt in 1982 (Figure 11.2). 

Commercial landings have since declined to 300 mt in 2005. Otter trawls accounted for about 

95% of the GOM commercial winter flounder landings during 1964-1985, but their percentage 

declined to 75% between 1986 and 2001 because of increased landings from gillnets (average of 

20% from 1986-2001). Since 2001, gillnets have accounted for 15% of the landings. The 

recreational rod-and-reel fishery historically harvested a significant proportion of the total 

landings, but recreational catches have sharply declined over the last decade from over 2,500 mt 

in the early 1980s to less than 100 mt during 1997-2005 (Table 11.1). 

GOM winter flounder landings in numbers have generally been dominated by age 3-5 fish 

(Figure 11.3). The proportion of ages 2 and 3 winter flounder in the commercial and recreational 

landings has been greatly reduced by the effects of increasing minimum landing sizes and 

increasing minimum trawl mesh size in the commercial fishery since the late-1990s. 

Research Vessel Survey Indices

Bottom trawl survey biomass indices from the Massachusetts Division of Marine Fisheries 

(MADMF) spring and fall surveys declined after 1983. The fall survey attained a record low in 

1986 while the spring reached a record-low in 1994. Between 1996 and 2000, both survey 

indices increased. The 2000 spring index was the highest on record and the 2000 fall index was 

the 2rd highest in the 28-year time series (Figure 11.4). However, subsequently the indices have 

declined. As stock biomass declined in the late 1980s, the age structure of the winter flounder 

population became truncated, with a low proportion of fish at ages 5 and older (Figure 11.5). 

The age structure has expanded slightly since the mid 1990s. 

Assessment Results

The assessment for GOM winter flounder was last updated at the Groundfish Assessment 

Review Meeting (GARM) in 2005 (NEFSC 2005). Average fishing mortality (ages 5-6, 

unweighted) varied between 0.5 and 2.1 during the 1980s and mid 1990s, but declined to a 

record low of 0.13 in 2004 (Figures 11.6). Spawning stock biomass declined from 4,800 mt in 

1982 to 500 mt in 1996 and then increased to 3,400 mt by 2004 (Figure 11.7). Recruitment at 

age 1 declined from 12 million fish in 1982 to 3 million fish in 1993, (Figure 11.7) but has since 

increased to 18 million in 2005. Over the 1982-2004 time period, geometric mean recruitment 

was 5 million fish. 

 

Biological Reference Points 

Biological reference points (Figure 11.8) were last reviewed by SARC 36 (NEFSC 2002) and the 

values are presented in Table 11.2. The relationship between spawning stock biomass and 

recruitment for winter flounder over the period covering the 1982-2004 year classes is illustrated 

in Figure 11.9. The stock-recruitment trajectory suggests that increases in recent SSB have been 

accompanied by improvement in recruitment. The solid horizontal line indicates the geometric 

mean recruitment over the same period. Survival ratios, recruits per unit of spawning biomass 

(Figure 11.10), illustrate a general increasing trend in the survival rate over time. 
3

Summary 

Spawning stock biomass in 2004 was 3,400 mt or about 84% of BMSY = 4,100 mt. Fishing 

mortality in 2004 was 0.13 or about 30% of FMSY = 0.43. Thus, the stock is not in a overfished 

condition and overfishing is not occurring. 

Table 11.1 Recreational and commercial landings of GOM winter flounder (thousand metric 

tons). 

Category 1986-95 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005

Average

U. S. Recreational 0.4 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1

Commercial

 United States 1.0 0.6 0.6 0.6 0.3 0.4 0.6 0.6 0.7 0.5 0.3

 Canada -----------

 Other -----------

Total Nominal Catch 1.4 0.6 0.6 0.6 0.3 0.4 0.6 0.6 0.7 0.5 0.3

Table 11.2 Yield and SSB per Recruit and MSY Based Reference Points for GOM winter 

flounder. 

Yield and SSB per Recruit-based Reference Points 

F0.1 = 0.26 

Fmax = 0.69 

F40% = 0.26 

MSY-based Reference Points 

FMSY = 0.43 

MSY = 1,500 mt 

BMSY = 4,100 mt 

GEORGES BANK WINTER FLOUNDER 

The Fishery 

Commercial landings of Georges Bank winter flounder are predominately from U.S. fisheries, 

but a small percentage (< 12% during most years) is from Canadian fisheries (Table 11.3, Figure 

11.11). Canadian landings gradually increased after 1993, reached a peak of 500 mt in 2001, and 

subsequently declined to 200 mt in 2004. During 1965-1977, the USSR also landed winter 

flounder from Georges Bank, with Soviet landings accounting for 23% to 38% of the total 

harvest during 1971-1973. Recreational landings of winter flounder from Georges Bank are 

insignificant. 
4

After reaching a peak of 4,500 mt in 1972, total landings of Georges Bank winter flounder 

declined to 1,900 mt in 1976. During 1977-1984, total landings ranged between 3,000 and 4,000 

mt, but thereafter declined to a record low (800 mt) in 1995. Total landings increased between 

1995 and 2003 then declined to 2,200 mt in 2005. 

Discarding of Georges Bank winter flounder occurs in the Northeast multispecies bottom trawl 

fishery and the sea scallop dredge fishery. However, data from the Fisheries Observer Program 

and Vessel Trip Report databases have been insufficient to produce reliable estimates of the 

magnitude or size and age composition of these discards (NEFSC 2002a). 

Research Vessel Survey Indices 

Autumn relative abundance and biomass indices declined between 1976 and 1991 to reach a 

record low (Figure 11.12). Thereafter, biomass increased through 2002, then declined to a level 

near the time series average in 2005. 

Assessment Results 

The assessment of Georges Bank winter flounder was last updated in 2005 using a surplus 

production model (Mayo and Terceiro 2005). Model estimates of relative total biomass 

(Bt/BMSY) and fishing mortality rates (Ft/FMSY) are utilized because they more precisely estimated 

than absolute values (Prager 1994). 

Relative fishing mortality rates (Ft/FMSY) were highest during 1983-1993, declined sharply 

during 1996-1999, but have since increased to above FMSY during 2000-2004 (Figure 11.13). 

During 1977-1994, relative biomass indices consistently declined reaching a record low in 1994. 

Subsequently, relative biomass increased through 2003, but has since declined to a level just 

below the threshold in 2005 (Figure 11.13). 

Biological Reference Points 

MSY-based reference points for Georges Bank winter flounder (Table 11.4) were estimated in 

the 2001 assessment using a surplus production model (NEFSC 2002a) and the reference points 

implemented in May of 2004 (NEFMC 2003). The MSY estimate (3,000 mt) does not include 

discards. FMSY = 0.32 and BMSY = 9,400 mt. Stock status is determined by comparing relative 

estimates of biomass and fishing mortality with a relative biomass threshold (50% of BMSY) of 

0.5 and a relative fishing mortality rate threshold (FMSY) of 1.0 because these relative metrics are 

more precise than the absolute estimates of fishing mortality rate and biomass (Mayo and 

Terceiro 2005). 

Summary 

Relative fishing mortality has exceeded FMSY since 2000 and was 1.86 in 2004. Relative biomass 

exceeded the threshold level in 2004 but declined below the threshold, to 0.46, in 2005. 

Therefore, in 2004, the stock was not overfished but overfishing was occurring (Mayo and 

Terceiro 2005). 
5

Table 11.3 Recreational and commercial landings of Georges Bank winter flounder (thousand 

metric tons). 

Category 1986-95 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005

Average

U. S. Recreational -----------

Commercial

 United States 1.9 1.3 1.3 1.2 0.9 1.7 1.6 2.1 2.8 2.9 2.1

 Canada <0.1 0.1 0.1 0.1 0.1 0.2 0.5 0.2 0.3 0.2 0.1

 Other -----------

Total Nominal Catch 1.9 1.4 1.4 1.3 1.0 1.9 2.1 2.3 3.1 3.1 2.2

Table 11.4 MSY-based reference points for Georges Bank winter flounder. 

MSY-based Reference Points 

MSY = 3,000 mt 

BMSY = 9,400 mt 

FMSY = 0.32 

SOUTHERN NEW ENGLAND/MID-ATLANTIC BIGHT WINTER FLOUNDER 

The Fishery

U.S. commercial landings of SNE/MAB winter flounder peaked at 12,000 mt in 1966, declined 

through the 1970s, and then peaked again at over 11,000 mt in 1981 (Figure 11.14). Commercial 

landings subsequently declined during the 1980s and early 1990s, falling to 2,200 mt in 1994. 

Commercial landings then increased to 4,700 mt in 2001 but have since declined to 1,200 mt in 

2005, a record low (Table 11.5, Figure 11.14). The principal gear used in the SNE/MAB winter 

flounder fishery is the otter trawl. The recreational rod-and-reel fishery for winter flounder 

historically harvested a significant proportion of the total catch, but recreational landings have 

markedly declined during the last decade. After peaking at 5,800 mt in 1984, recreational 

landings of winter flounder averaged 1,600 mt annually during 1986-1995, but have since 

declined to 120 mt in 2005 (Table 11.5) . 

SNE/MAB winter flounder landings in numbers have generally been dominated by age 2-4 fish 

(Figure 11.15). Since the mid-1990s, the proportion of ages 1 and 2 fish in the commercial and 

recreational landings has been greatly reduced by the effects of increasing minimum landed sizes 

and increases in the minimum trawl mesh size in the commercial fishery. 

Research Vessel Survey Indices

NEFSC spring and autumn biomass indices for SNE/MAB winter flounder indicate peaks in 

abundance during the mid-1960s, early 1980s, and late 1990s, and have exhibited a declining 
6

trend since 1999 (Figure 11.16). As stock biomass declined, the age structure of the winter 

flounder population became truncated, with a low proportion of fish at ages 5 and older (Figure 

11.17). 

 

Assessment Results

The assessment for SNE/MAB winter flounder was last updated at the Groundfish Assessment 

Review Meeting (GARM) in 2005 (NEFSC 2005). Average fishing mortality (F, ages 4-5, 

unweighted) ranged between 0.5 and 1.5 during the 1980s and mid 1990s, but has steadily 

declined since 1997 and in 2004 was F = 0.4, a record low (Figures 11.18. Spawning stock 

biomass declined from 14,800 mt in 1983 to 2,700 mt in 1994, slowly increased to 5,000 mt in 

2001, and has since stabilized at about 4,000 mt (Figure 11.19). Since 1982, recruitment at age 1 

has ranged from 57 million fish (1982 year class in 1983) to 4 million fish (2001 year class in 

2002) (Figure 11.19). Over the 1982-2004 period, the geometric mean recruitment was 16 

million fish. 

Biological Reference Points 

Biological reference points (Figure 11.20) were last calculated by the 2002 Working Group on 

Re-Evaluation of Biological Reference Points for New England Groundfish (NEFSC 2002a) and 

are presented in Table 11.6. The relationship between spawning stock biomass and recruitment 

for winter flounder over the period covering the 1981-2004 year classes is illustrated in Figure 

11.21. The stock-recruitment trajectory shows that recent levels of SSB and recruitment occur 

on the lower-left side of the plot. The solid horizontal line indicates the geometric mean 

recruitment (16 million fish at age 1) over the same period. Survival ratios (Figure 11.22), 

illustrate fluctuating survival over time. 

Summary 

Spawning stock biomass of SNE/MAB winter flounder in 2004 was 3,900 mt, about 13% of 

BMSY (30,100 mt). Fishing mortality was 0.40 in 2004, 25% above FMSY = 0.32. Thus, the stock 

in 2004 was in an overfished condition and overfishing continues to occur. 

Table 11.5 Recreational and commercial landings of SNE/MAB winter flounder (thousand 

metric tons). 

Category 1986-95 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005

Average

U. S. Recreational 1.6 0.7 0.6 0.3 0.3 0.8 0.5 0.3 0.6 0.2 0.1

Commercial

 United States 3.9 2.8 3.4 3.2 3.4 3.8 4.7 3.1 2.4 1.5 1.2

 Canada -----------

 Other -----------

Total Nominal Catch 5.5 3.5 4.0 3.5 3.7 4.6 5.2 3.4 3.0 1.7 1.3
7

Table 11.6 Yield and SSB per Recruit and MSY Based Reference Points for SNE/MAB winter 

flounder. 

Yield and SSB per Recruit-based Reference Points 

F0.1 = 0.25 

Fmax = 0.48 

F40% = 0.21 

MSY-based Reference Points 

FMSY = 0.32 

MSY = 10,600 mt 

BMSY = 30,100 mt 

For further information 

Mayo, R. K. and M. Terceiro. 2005. Assessment of 19 Northeast groundfish stocks through 

2004. 2005 Groundfish Assessment Review Meeting (2005 GARM), Northeast Fisheries 

Science Center, Woods Hole, Massachusetts, 15-19 August 2005. U.S. Dep. Commer., 

Northeast Fish. Sci. Cent. Ref. Doc. 05-13, 499 p. 

NEFMC [New England Fishery Management Council]. 2003. Final Amendment 13 to the 

Northeast Multispecies Fishery Management Plan Including a Final Supplemental 

Environmental Impact Statement and an Initial Regulatory Flexibility Analysis. 1,660 p. 

plus Appendices. 

NEFSC [Northeast Fisheries Science Center]. 2002a. Assessment of 20 northeast groundfish 

 stocks through 2001: A report of the Groundfish Assessment Review Meeting (GARM), 

 Northeast Fisheries Science Center, Woods Hole, Massachusetts, October 8-11, 2002. 

 Northeast Fish. Sci. Cent. Ref. Doc. 02-16. 511 p.

NEFSC [Northeast Fisheries Science Center]. 2002b. Final Report of the Working Group on Re-

 Evaluation of Biological Reference Points for New England Groundfish. Northeast Fish. 

 Sci. Cent. Ref. Doc. 02-04, 249 p. 

NEFSC [Northeast Fisheries Science Center]. 2003. Report of the 36th Northeast 

Regional Stock Assessment Workshop (36th SAW), Stock Assessment Review 

Committee (SARC) consensus summary of assessments. Northeast Fish. Sci. Cent. Ref. 

Doc. 03-06, 453 p. 

NEFSC [Northeast Fisheries Science Center]. 2006. Report of the 34th Northeast Regional Stock 

Assessment Workshop (34th SAW): Stock Assessment Review Committee (SARC) 

consensus summary of assessments. Northeast Fish. Sci. Cent. Ref. Doc. 02-06, 346 p. 

O’Brien, L., J. Burnett, and R.K. Mayo. 1993. Maturation of nineteen species of finfish 

off the northeast coast of the United States, 1985-1990. NOAA Tech. Report. NMFS 

113, 66 p. 
8

Pereira, J.J, R. Goldberg, J.J. Ziskowski, P.L. Berrien, W.W. Morse, and D.L. Johnson. 

1999. Essential fish habitat source document: winter flounder, Pseudopleuronectes 

americanus, life history and habitat characteristics. NOAA Tech. Mem. NMFS-NE-138, 

39 p. 

Pentilla, J.A., G.A. Nelson, and J.M. Burnett, III. 1989. Guidelines for estimating 

 lengths at age for 18 Northwest Atlantic finfish and shellfish species. NOAA 

 Tech. Mem. NMFS-F/NEC-66, 39 p. 

Prager, M. H. 1994. A suite of extensions to a nonequilibrium surplus-production model. Fish. 

Bull. 92: 374–389. 
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