The yellowtail flounder, Limanda ferruginea,
is a demersalflatfish distributed from Labrador to Chesapeake
Bay generally at depths between 40 and 70 m (20 to 40 fathoms).
Off the U.S. coast, three stocks are considered for management
purposes (Cadrin 2003): Cape Cod/Gulf of Maine, Georges Bank,
and Southern New England/ Mid-Atlantic (Figure
7.1). Yellowtail flounder have been described as relatively
sedentary, although evidence exists for off bottom movements (Walsh
and Morgan 2004; Cadrin and Westwood 2004), limited seasonal movements
(Royce et al. 1959; Lux 1963; Stone and Nelson 2003), and transboundary
movements (Stone and Nelson 2003; Cadrin 2005).
Spawning occurs during spring and summer,
peaking in May (Cadrin 2003). Eggs are deposited on or near the
bottom and after fertilization float to the surface. Larvae drift
for approximately two months, then change form and settle to the
the northeast United States, yellowtail flounder grow to 55 cm (22
in.) total length and attain weights of 1.0 kg (2.2 lb). Growth
is sexually dimorphic, with females growing at a faster rate than
males (Lux and Nichy 1969; Cadrin 2003). Yellowtail flounder appear
to have variable maturity schedules, with age two females 40% mature
during periods of high stockbiomass to 90% mature during periods
of low stock biomass (NEFSC 2005).
The principal fishing gear used to catch yellowtail flounder is
the otter trawl. Total landings of yellowtail flounder by the U.S.
in 2005 were 4,118 mt, a 43% decline from the 7,202 mt landed in
2004. An additional 30 mt was landed by Canada from Georges Bank
in 2005. Recreational landings of yellowtail are negligible.
United States fisheries for yellowtail flounder are managed under
the New England Fishery Management Council's Northeast Multispecies
Fishery Management Plan (FMP). Under this FMP, yellowtail flounder
are included in a complex of 15 groundfish species managed by time/area
closures, gear restrictions, minimum size limits, and, since 1994,
by direct effort controls including a moratorium on permits and
days-at-sea restrictions. Amendment 9 established initial biomass
rebuilding targets and defined control rules which specify target
fishing mortality rates and corresponding rebuilding time horizons.
Amendment 13 implemented formal rebuilding plans within specified
time frames based on revised biomass and fishing mortality targets
derived by the Working Group on Re-Evaluation of Biological Reference
Points for New England Groundfish (NEFSC 2002). The goal of the
management program is to reduce fishing mortality to allow stocks
to rebuild above minimum biomass thresholds and, attain and remain
at or near target biomass levels. In addition, a formal quota sharing
agreement was implemented in 2004 between Canada and the U.S. to
share the harvest of yellowtail in the transboundary Georges Bank
management unit. The agreement includes total allowable catch quotas
for each country as well as in-season monitoring of the U.S. catch
of yellowtail on Georges Bank. The information provided herein reflects
the results of the most recent peer-reviewed assessments for the
Cape Cod-Gulf of Maine, Georges Bank, and Southern New England-Mid
Atlantic yellowtail flounder stocks (NEFSC 2005, Legault et al.
COD-GULF OF MAINE YELLOWTAIL FLOUNDER
Cape Cod-Gulf of Maine yellowtail
are generally caught in multi-species groundfish fisheries (principally
by otter trawls) from late fall to spring, with some landings
by gillnets in the winter and spring. Historically, landings from
the stock were a small portion of the total U.S. yellowtail landings.
However, during the collapse of Georges Bank and southern New
England stocks in the early 1990s, landings from the Cape Cod-Gulf
of Maine stock accounted for the majority of U.S. yellowtail harvest.
Annual landings from the stock increased from less than 1,000
mt in the mid 1930s to a peak of 5,600 mt in 1980 (Figure
7.2 Data]).Landings decreased to approximately 1,200 mt per
year in the late 1980s, but increased to 3,200 mt in 1990 due
to recruitment of the strong 1987 yearclass. Landings declined
to 800 mt in 1993, remained low through the 1990s, increased to
greater than 2,400 mt in 2000 and 2001, but declined to 700 mt
in 2005 (Table 7.1). Discards constitute
about 20% of the total catch.
Survey biomass indices are somewhat
variable, but generally indicate high biomass in the late 1970s
and early 1980s, a decline in the 1980s, a rapid increase in the
late 1990s, and a recent decrease (Figure
7.3 Data]). Age structure for this stock became severely truncated
during the 1980s. Despite increases in the proportion of age 4
fish during 1990s, very few fish now survive beyond this age (Figure
The 2005 stock assessment indicated
that that F on ages 3+ decreased from high levels in the late
1980s to 0.28 in 1993, but gradually increased to an average of
0.9 since 2000 (Figure
7.5 Data]). With the exception of the strong 1987 year class
(29 million at age-1), recruitment was stable from 1985 to 2001,
averaging 10 million at age 1, but has been below average since
7.6 Data]). Spawning biomass averaged 1,000 mt during the
late 1980s, peaked at 3,800 mt in 1991 as the 1987 cohort matured,
decreased to 1,600 mt in 1997, gradually increased to 2,700 mt
in 2000, but has subsequently declined (Figure
The overfishing threshold, FMSY
is approximated as F40%MSP (0.17). The SSBMSYproxy is 12,600 mt, calculated as the product of 40% MSP (1.192
kg spawning biomass) and average long-term recruitment (10.5 million).
The MSY proxy is 2,300 mt, derived as the product of yield per
recruit at F 40% (0.213 kg) and average recruitment (Table
The Cape Cod-Gulf of Maine yellowtail
stock is overfished, because the 2004 SSB is far below the SSBMSY.
Overfishing is occurring because the 2004 fishing mortality exceeds
Exploitation of the Georges
Bank stock began in the mid-1930’s by the US trawler fleet.
Landings increased from 400 mt in 1935 to 9,800 mt in 1949, then
decreased in the early 1950s to 2,200 mt in 1956, and increased
again in the late 1950s (Figure
7.7 Data]). The highest landings occurred during 1963-1976
(average: 14,100 mt) and included modest landings by foreign fleets.
No foreign catches of yellowtail have occurred since 1975. In
1985, the stock became a transboundary resource under both Canadian
and US jurisdictions. Landings averaged about 2,600 mt between
1985 and 1994, then dropped to a record low of 877 mt in 1995
when fishing effort was drastically reduced to allow the stock
to rebuild. The US fishery has been constrained by spatial expansion
of Closed Area II in 1994 and by extension to year-round closure
in 1995, as well as by gear regulations and limits on days fished.
In 2004, a Yellowtail Special Access Program (SAP) in Closed Area
II allowed a US bottom trawl fishery in the area for the first
time since 1995 generating US landings of 6,200 mt, the highest
US harvest since 1983. This SAP did not continue in 2005. A directed
Canadian fishery began on eastern Georges Bank in 1993, pursued
mainly by small otter trawlers (< 20 m). Total combined landings
by both countries increased (with increasing quotas) from a record
low of 877 mt in 1995, when the stock was considered to be in
a collapsed state, to 6,705 mt in 2001 (Table
7.3). In 2005, combined landings were 3,358 mt resulting from
the US nearly filling their portion of the quota but Canada unable
to catch their portion (Table 7.3). Since
1973, discards have accounted for about 20% of the total catch.
Georges Bank yellowtail flounder
landings are generally dominated by ages 2-4 fish, by number (Figure
[Fig 7.8 Data]). The proportion of age 1
flounder in the landings has been reduced via increases in the
minimum trawl mesh size since the mid-1990s. The proportion of
age 3 and older fish in the landings has increased since the mid-1990s.
NEFSC spring and autumn biomass
indices for yellowtail flounder have exhibited similar trends
throughout the survey time series (Figure
7.9 Data]). A survey conducted by the Canadians in spring
on Georges Bank also shows a similar pattern. Total biomass indices
declined through the late 1970s into the early 1990s, increased
in the mid 1990s and late 1990s, peaked in the early 2000s, but
have since declined. The age structure of the yellowtail flounder
population has become truncated as the stock has declined, with
a low proportion of fish at ages 5 and older (Figure
Average (age 4+, unweighted)
fishing mortality was close to or above 1.0 between 1973 and 1994,
fluctuated between 0.6 and 0.9 during 1995 to 2003, increased
in 2004 to 1.92, and then declined in 2005 to 1.37 (Figure
7.11 Data]). Spawning stock biomass of yellowtail
flounder increased from a low of 2,648 mt in 1995 to an average
of 10,100 mt from 1999-2003 before declining in 2004 and 2005
to 6,377 mt and 5,441 mt, respectively (Figure
7.12 Data]). Recruitment averaged 23.5 million fish at age
1 during 1998 to 2001 but has since declined to 9.2 million in
2005, well below the median of 18.3 million during the assessment
time period (Figure
Yield and spawning stockbiomassbiological reference points (Figure
7.13 Data]) were last calculated in the Working Group on Re-Evaluation
of Biological Reference Points for New England Groundfish (NEFSC
2002) and reported in the 2002 and 2005 GARM assessments (NEFSC
2002, 2005). The overfishing threshold, FMSY is approximated
as F40%MSP (0.25). The SSBMSYproxy is 58,800
mt, calculated as the product of 40%MSP (1.0925 kg spawning biomass
per recruit) and average long-term recruitment (53.8 million using
VPA estimates for 1973 onward and hindcast recruitment estimates
from the 1963-1972 period). The MSY proxy is 12,900 mt, derived
as the product of yield per recruit at F40% (0.240 kg) and average
recruitment (Table 7.4).
The fishing mortality rate used by the Transboundary Management
Guidance Committee as the target value, Fref, is 0.25.
NEW ENGLAND/MID ATLANTIC YELLOWTAIL FLOUNDER
A fishery for yellowtail flounder
developed off southern New England in the 1930s, coincident with
the increased use of otter trawls, a decline in winter flounder
abundance, and demand for food products during World War II. Landings
increased during the 1930s and early 1940s and the fishery expanded
to the Mid Atlantic in the early 1940s. During this period, landings
peaked at 28,000 mt in 1942 (Figure
7.16 Data]). Annual landings were around 10,000 mt during
1943 to 1948 with approximately 10% from the Mid Atlantic. A domestic
industrial fishery developed in the late 1940s, but landings decreased
to less than 2,000 mt in the mid 1950s. Landings increased again
in the late 1950s and 1960s. A distant water fishery developed
in the late 1960s and total annual landings exceeded 20,000 mt
between 1963 and 1970. The distant water fisheries were eliminated
in the early 1970s, and landings generally decreased with temporary
increases in the early 1980s and early 1990s. Landings in 1995
were a record low 200 mt, and the proportion of landings from
the Mid Atlantic increased from approximately 10% in the early
1990s to greater than 20%. Landings increased to greater than
1,000 mt per year at the turn of the century but declined to 220
mt in 2004 (Table 7.5). Discards accounted
for about 30% of total annual catches until 1995. Since then,
discards have been very low (e.g. 150 mt or less).
Indices of abundance and biomass
were high in the 1960s and early 1970s, but declined sharply in
the mid 1970s (Figure
[Fig 7.17 Data]). Biomass indices increased in the early and
late 1980s, with the recruitment of the strong 1980 and 1987 cohorts,
but have since been extremely low. Age distribution of yellowtail
in surveys indicates abundant cohorts in the 1960s and early 1970s,
strong year classes in 1980 and 1987, and little recruitment and
a relatively truncated population age structure since the mid
[Fig 7.18 Data]).
The 2005 stock assessment indicated that
the stock was abundant in the early 1970s but subsequently markedly
declined. Fishing mortality has been high through the three decades
of the assessment, 1973-2004 (Figure
7.19 Data]). Recruitment was generally strong in the 1970s
and moderate during the 1980s, with two exceptional year classes
in 1980 and 1987, but has been low since (Figure
7.20 Data]). Spawning biomass was high in
the early 1970s, decreased in the late 1970s, and increased briefly
in the early and late 1980s with recruitment of the 1980 and 1987
cohorts. Spawning biomass was high in the early 1970s, decreased
in the late 1970s, increased briefly in the early and late 1980s,
but declined in the early 1990s and has thereafter remained low
The overfishing threshold, FMSY
is approximated as F40%MSP (0.26). The SSBMSYproxy is 69,500 mt, calculated as the product of 40%MSP (1.129
kg spawning biomass per recruit) and average long-term recruitment
(61.57 million using hindcast estimates for 1963 onward). The
MSY proxy is 14,200 mt, derived as the product of yield per
recruit at F40% (0.230 kg) and average recruitment
The Southern New England-Mid
Atlantic stock is overfished, because the 2004 spawning biomass
is far below SSBMSY. Overfishing is occurring, because
the 2004 fishing mortality exceeds FMSY.
Cadrin, S.X. 2003. Stock structure of
yellowtail flounder off the northeastern United States.
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Cadrin, S. 2005. Yellowtail flounder, Limanda
ferruginea. pp. 15-18 in Proceedings of a Workshop
to Review and Evaluate the Design and Utility of Fish
Mark-Recapture Projects in the Northeastern United States.
NEFSC Ref Doc 05-02.
Cadrin, S.X. and A.D. Westwood.
2004. The use of electronic tags to study fish movement: a case
study with yellowtail flounder off New England. ICES CM 2004/K:81.
Legault, C.M., H.H. Stone, and
K.J. Clark. 2006. Stock Assessment of Georges Bank Yellowtail
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Lux, F.E. 1963. Identification of New
England yellowtail flounder groups. Fish. Bull. 63: 1-10.
Lux, F.E. and F.E. Nichy. 1969. Growth
of yellowtail flounder, Limanda ferruginea (Storer),
on three New England fishing grounds. ICNAF Res. Bull.
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2002. Final report of the Working Group on Re-Evaluation
of Biological Reference Points for New England Groundfish.
Northeast Fisheries Science Center Reference Doc. 02-04.
249 p. + appendices.
NEFSC (Northeast Fisheries Science Center).
2005. Assessment of 19 Northeast Groundfish stocks through
2004. Northeast Fisheries Science Center Reference Doc.
Royce, W.F., R.J. Buller, and E.D. Premetz.
1959. Decline of the yellowtail flounder (Limanda ferruginea)
off New England. Fish. Bull. 146:169-267.
Stone, H.H. and C. Nelson. 2003. Tagging
studies on eastern Georges Bank yellowtail flounder. Can.
Sci. Advis. Sec. Res. Doc. 2003/056, 21p.
Walsh, S.J. and M.J. Morgan. 2004. Observations
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