The winter flounder, blackback, or lemon sole,
Psuedopleuronectes americanus, is a demersalflatfish
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).
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
Commerciallandings 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
[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
GOM winter flounder landings
in numbers have generally been dominated by age 3-5 fish (Figure
[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.
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
[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 population became truncated,
with a low proportion of fish at ages 5 and older (Figure
[Fig 11.5 Data]). The age structure has expanded slightly
since the mid 1990s.
Commerciallandings of Georges Bank winter flounder are predominately
from U.S. fisheries, but a small percentage (< 12% during
most years) is from Canadian fisheries (Table
[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.
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
[Fig 11.13 Data]). During 1977-1994, relative biomassindices 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
[Fig 11.13 Data]).
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).
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
U.S. commerciallandings 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
[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
[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
[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
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
[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
[Fig 11.17 Data]).
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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