Northeast Fisheries Science Center Reference Document 03-02
A Report of the 36th Northeast Regional Stock Assessment Workshop
Stock Assessment of Yellowtail Flounder
in the
Southern New England - Mid-Atlantic Area
by Steven X. Cadrin
National Marine Fisheries Serv., Woods Hole Lab., 166 Water St.,
Woods Hole, MA 02543
Print
publication date February 2003;
web version posted February
20, 2003
Citation: Cadrin, S.X. 2003. Stock assessment of yellowtail flounder in the Southern New England - Mid-Atlantic area. U.S. Dep.
Commer. Northeast Fish. Sci. Cent. Ref. Doc. 03-02; 101 p.
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Abstract
Southern New England and Mid Atlantic yellowtail flounder resources
were previously assessed separately, but are combined for this assessment.
The combined stock is overfished and overfishing is taking place. The
current estimate of fishing mortality is high, much greater than the
proposed FMSY proxy (F40%MSP = 0.26). Spawning
stock biomass is low (2001 SSB = 1,900 mt), well below the proposed SSBMSY proxy
(69,500 mt SSB). Recruitment has been poor for more than a decade. The
age structure of the stock is truncated in comparison to MSY conditions.
INTRODUCTION
Yellowtail flounder, Limanda ferruginea, inhabit relatively shallow
waters (20-100 m) of the northwest Atlantic from Labrador to Chesapeake
Bay (Bigelow and Schroeder 1953, Scott and Scott 1988, Collette and Klein-MacPhee
2002). 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 (Scott 1954, Royce et al. 1959).
The available information on yellowtail flounder stock structure off
the northeast U.S. indicates separate stocks on Georges Bank, off Cape
Cod, and from southern New England to the Mid-Atlantic Bight. Distributional
analyses indicate a relatively continuous distribution from the Mid Atlantic
Bight to Nantucket Shoals, a concentration on Georges Bank, and a relatively
separate concentration off Cape Cod (Royce et al. 1959). Geographic
patterns of landings over time suggest that yellowtail resources on Georges
Bank on off southern New England are separate harvest stocks (McBride
and Brown 1980). Geographic variation indicates that yellowtail off
Cape Cod comprise a separate phenotypic stock than resources to the south
(Begg et al. 1999). Tagging data indicate low dispersion from Cape Cod,
Georges Bank and southern New England fishing grounds, but substantial
movement from the Mid Atlantic to southern New England (Royce et al.
1959, Lux 1963). Descriptive information on early life history stages
and circulation patterns suggest that yellowtail spawn in hydrographic
retention areas, but there may be some advection of eggs and larvae from
Georges Bank and Cape Cod to southern New England and the Mid Atlantic
Bight (Sinclair 1988). In sumary, yellowtail flounder on Georges Bank
appear to be a separate harvest stock, yellowtail off Cape Cod can be
considered a separate phenotypic stock (with some question on the northern
boundary of the stock area), but there is little evidence supporting
separate stocks in southern New England and the Mid Atlantic Bight.
Management
History
From 1950 to 1977,
the International Commission for the Northwest Atlantic Fisheries managed
yellowtail flounder resources in southern New England, Georges Bank and
the Gulf of Maine (i.e., in ICNAF subarea 5). Gear restrictions and
total allowable catch were the primary management strategies of ICNAF,
but minimum fish size, fishing effort and closed area and season regulations
were also regulated. Minimum trawl mesh size was 114 mm in the 1950s
and 1960s. National catch quotas were implemented for southern New England
yellowtail flounder from 1971 to 1976, but these were exceeded in most
years.
Following the implementation of the Magnuson Fisheries Conservation
and Management Act (FCMA) in 1976, U.S. yellowtail resources have been
managed by the New England Fisheries Management Council (Table
1). Groundfish regulations included minimum cod end mesh size, minimum
fish size, seasonal area closures, mandatory reporting, trip limits and
annual quotas. Minimum size for yellowtail was increased from 28cm in
1982 to 30cm in 1986 and 33cm in 1989. Minimum mesh size increased from
140 mm in 1991 (diamond and square mesh) to 140mm diamond-152mm square
in 1994 and to 165mm in 1999. A large area south of Nantucket Shoals
was closed to fishing since December 1994. Scallop dredge vessels were
limited to possession of 136kg of yellowtail flounder since 1996. Scallop
dredge vessels were limited to possession of 136kg of yellowtail flounder
since 1996, and in 1999 minimum twine top mesh was increased from 203mm
to 254mm to reduce yellowtail bycatch.
Assessment History
The first quantitative stock assessment of yellowtail flounder was on
the southern New England - Mid Atlantic resource and fishery. Royce
et al. (1959) evaluated landings, length and age composition, effort,
and tagging data to conclude that fishing mortality was approximately
0.30 in the 1940s. However, retrospective estimates of F during the
1940s were substantially greater (approximately 0.6, Lux 1969). Lux
(1964) concluded that the stock was not overfished during the 1950s,
but age-based mortality estimates for the 1960s were high (Lux 1967[1] ,
1969).
Subsequent assessments of yellowtail flounder in the southern New England
area excluded Mid-Atlantic catch and survey data, but indicated increasing
F and declining stock size in the late 1960s (Brown and Hennemuth 1971a,
1971b; Pentilla and Brown 1973). Starting in 1974, Mid Atlantic and
southern New England yellowtail resources were treated as separate assessment
and management units, but analyses for each area indicated high mortality
and low stock size in the 1970s (Parrack 1974, Sissenwine et al. 1978,
McBride and Sissenwine 1979, McBride et al. 1980, Clark et al. 1981). In
the early 1980s, there was indication of strong recruitment of yellowtail
from surveys and commercial catches in both southern New England and
Mid Atlantic areas, but discard rates were high and F exceeded Fmax in
southern New England (McBride and Clark 1983, Clark et al. 1984, NEFC
1986).
Assessment methods used for southern New England yellowtail progressed
to a calibrated VPA in the late 1980s. The 1988 assessment indicated
high F in the 1970s and early 1980s and a strong 1980 cohort (F=0.60-1.48;
NEFC 1989). Later stock assessments showed another dominant cohort spawned
in 1987, but F continually increased through the 1980s, and the stock
was depleted to record low biomass in the early 1990s (Conser et al.
1991, Rago et al. 1994). The VPA-based assessment of southern New England
yellowtail was updated annually from 1997 to 1999, and assessments indicated
a reduction in F in the late 1990s, but little rebuilding of stock biomass
(NEFSC 1997, 1998; Cadrin 2000). In 2000, an updated VPA was attempted,
but was rejected as a basis for management advice because sampling in
1999 was inadequate to estimate catch at age reliably (Cadrin 2001b). Therefore,
recent assessments of southern New England yellowtail have been based
on projections of observed catch from the 1999 VPA (Cadrin 2001b, NEFSC
2002). An updated assessment of the southern New England yellowtail
flounder stock was prepared concurrently with this assessment for the
Groundfish Assessment Review Meeting (Cadrin 2002b).
An analytical assessment of Mid Atlantic yellowtail flounder has not
been developed, and management advice has been based on descriptive summaries
of landings and survey data. Assessments of the Mid Atlantic yellowtail
resource indicated similar trends in catch and survey indices as in southern
New England (NEFC 1987, 1988; NEFSC 1991, 1992, 1993; Rago 1995; Overholtz
and Cadrin 1998). Based on survey biomass and exploitation ratios, the
Mid Atlantic yellowtail resource was 2% of the BMSY proxy,
and the exploitation rate greatly exceeded the FMSY proxy (Cadrin
2001a). An updated assessment of the Mid Atlantic yellowtail flounder
stock was prepared concurrently with this assessment for the Groundfish
Assessment Review Meeting (Cadrin 2002a).
1. Although Lux (1967) is titled, “Landings
per unit effort, age composition and total mortality of yellowtail
flounder (
Limanda ferruginea) in subarea 5Z,” the southern New
England analyses also include catch and effort data from statistical
area 6.
FISHERY
DATA
Commercial Landings
Commercial statistics for southern New England yellowtail
flounder are from statistical areas 526, 537, 538, and 539, and mid Atlantic
yellowtail are from statistical areas 611-623 (Figure
1). U.S. commercial landings of yellowtail flounder were derived
from dealer weighout reports and canvas data according to historical
assessment reports (Royce et al. 1959, Brown and Hennemuth 1971, Sissenwine
et al. 1978, McBride et al. 1980, McBride and Clark 1983, NEFC 1986,
McBride 1989, Rago et al. 1994). Total Mid Atlantic landings from canvas
data were allocated to market category according to annual proportions
in the weighout database. Previous to 1994, landings were allocated
to statistical area, month, and gear type according to interview data
collected by port agents (Burns et al. 1983). For 1994, landings reported
by dealers were allocated to stock area using fishing vessel logbook
data, by fishing gear, port, and season (Wigley, et al. 1998). For 1995-1997,
dealers’ reported landings were prorated to stock area using a modified
proration that included dealer codes (NEFSC 1998).
Landings generally increased in southern
New England during the 1930s and early 1940s and the fishery expanded
to the Mid Atlantic in the early 1940s, with landings of 28,000mt in
1942 (Table 2, Figure 2). Annual
landings were around 10,000mt from 1943 to 1948 with approximately 10%
from the Mid Atlantic. A domestic industrial fishery developed in the
late 1940s. Landings decreased to less than 2,000mt in the mid 1950s. Landings
increased in southern New England in the late 1950s and again expanded
to the Mid Atlantic in the 1960s. A distant water fishery developed
in the 1960s and total annual landings were greater than 20,000mt from
1963 to 1970. The industrial and foreign fisheries were discontinued
in the early 1970s. Landings generally decreased since the 1970s, 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 generally increased from approximately 10% in the early
1990s to greater than 20% (e.g., in 1997, 70% of landings in the stock
area came from the Mid Atlantic). Landings slightly increased to greater
than 1,000mt per year since 1999.
A summary of port samples (each consisting
of approximately 100 lengths and 1 age sample per cm) are listed in Table
3. Landings at age were derived by geographic region, half-year
and market category, when possible. Landings at age of southern New
England yellowtail flounder are described in previous assessment documents
(Conser et al. 1991; Rago et al. 1994; NEFSC 1997, 1998; Cadrin 2000;
Cadrin 2002b). Mid Atlantic landings were not sampled in several half-year
periods, and age distributions of southern New England landings were
assumed for Mid Atlantic landings in those periods by quarter and market
category (2nd half of 1975, 2nd half of 1981, 2nd half
of 1986, 2nd half of 1987, 2nd half of 1988, 1st half
of 1989, 2nd half of 1990), or by half and market category
for 2000 and 2001. Landings at age and landed mean weights at age are
reported in Table 4. In the early 1970s a substantial
portion of landings were from older fish (e.g., 17% of 1973 landings
were age-6 or older), but the age distribution of landings rapidly truncated,
and the portion of age 6+ fish has generally been less than 3% since
1977.
Discarded
Catch
Estimates of discards for the southern New England – Mid
Atlantic yellowtail fishery for 1963-1969 were derived from interviews
with vessel captains; historical discards were approximated by Brown
and Hennemuth (1971a) from the 1963-1969 average discard rate (Table
5). Discards for 1970-1977 were also based on interview data, however
yellowtail interview data were suspect from 1978 to 1982 when trip limits
were imposed (McBride et al. 1980, Clark et al. 1981). Discards during
1978-1982 were estimated from observer data when available (Sissenwine
et al. 1978), derived directly from field selectivity studies (McBride
et al. 1980), or from application of selectivity estimates to survey
size frequencies (McBride and Clark 1983). Discards for 1983 were from
interview data (Clark et al. 1984). Discards at age from southern New
England, 1984-1993 were from a combination of sea sampling, interviews
and survey data (Conser et al. 1991, Rago et al. 1994). Discards for
1994-2001 were derived from vessel logbooks (NEFSC 1997, 1998; Cadrin
2000). Updated discard estimates for southern New England are listed
in Table 5a. Discards of Mid Atlantic yellowtail were from interview
data for 1984-1993. Mid Atlantic discards for 1994-2001 were derived
from logbook data by gear for all trips that reported discards of any
species (NEFSC 1998, Table 5b).
Discarded catch accounted for an average of 30% of total catch annually,
but appears to have decreased to approximately 10% since 1995. In 1969,
discards peaked at 24,000mt, 40% of the total catch that year. A substantial
portion of recent discards are from the scallop dredge fishery.
Discards at age were estimated from observer lengths
(Table 3) and survey ages 1994-2001. Discards at
age of southern New England yellowtail flounder are described in previous
assessment documents (Conser et al. 1991; Rago et al. 1994; NEFSC 1997,
1998; Cadrin 2000; Cadrin 2002b). Age distribution of discards in southern
New England were assumed for Mid Atlantic discards for 1973 to 1993 (Table
6). Discards were primarily ages 1 and 2 during from the 1970s through
the early 1990s, but shifted to age 2 and 3 in the early 1990s, coincident
with regulated mesh size increases.
Estimates of total catch at age reflect
the landings at age in that they indicate a relatively wide age distribution
in the catch in the early 1970s (e.g., approximately 10% of the catch
was age-6 or older from 1973 to 1975; Figure 3, Appendix
A). Subsequent catch at age was dominated by the 1980 and 1987 cohorts,
but few fish older than age-6 contributed to the catch. Mean weights
at age of older fish (age 4+) generally increased in the mid 1970s, were
relatively light during the mid 1980s, and generally increased in recent
years (Figure 4). Mean weight of age-1 yellowtail
generally decreased in the 1990s, presumably from discards of small yellowtail
in the scallop fishery.
ABUNDANCE AND BIOMASS INDICES
Stock Abundance and Biomass Indices
The NEFSC spring and autumn bottom trawl surveys have
sampled offshore strata since 1963 and 1968, respectively (Despres et
al. 1988). However, the southern–most offshore strata (61-76) were not
sampled until 1967. Therefore southern strata were included in the spring
survey index, 1968-2002 and the winter survey index 1992-2002 (strata
1, 2, 5, 6, 9, 10, 69, 73, 74; Figure 5), but excluded
from the fall survey index, 1963-2001 (strata 1, 2, 5, 6, 9, 10). Nearly
all yellowtail caught by the survey in the southern New England – Mid
Atlantic stock area (99%) are in the spring and winter strata sets. The
strata set for the NEFSC scallop survey was determined as all strata
that were consistently sampled in the stock area (14, 15, 18, 19, 22-28,
30, 31, 33, 35, and 46).
Indices
of abundance and biomass indicate relatively high stock size in the 1960s
and early 1970s, followed by a rapid decrease in the mid 1970s (Table
6, Figure 6). Stock biomass increased temporarily
in the early and late 1980s with the recruitment of the strong 1980 and
1987 cohorts. Recent distributions of yellowtail catches in surveys
are illustrated in Figure 7. The average portion
of yellowtail biomass in the Mid Atlantic region has been 45% of the
total southern New England – Mid Atlantic yellowtail biomass (Figure
8). Age distribution of yellowtail in surveys indicates abundant
cohorts in the 1960s and early 1970s, strong year classes in 1980 and
1987, and relatively truncated age structure since the early 1970s (Table
7, Figure 9).
Correspondence among survey indices
was assessed using correlations among normalized observations for the
VPA time series 1973-2001 [Ln(x/mean); Table 8]. Normalized
indices of catch per tow at age are illustrated in Figure
10. Correlations among survey series were generally low for the
winter survey, particularly for older ages, presumably because it is
a short series with little contrast. Correlations between spring and
fall survey series were strongest at ages 2-4 (r=0.71-0.82).
MORTALITY AND STOCK SIZE
Virtual Population Analysis
Abundance estimates from virtual population analysis
of catch of age-1 to age-7+, 1973-1997, were calibrated using an ADAPT
algorithm (Gavaris 1988) that estimated age 2-5 survivors in 2002 and
survey catchability coefficients (q) using nonlinear least squares
of survey observation errors. Abundance at age was calibrated with survey
indices of abundance: spring survey indices (age-1 to age-7+) and winter
indices (age-1 to age-5) were calibrated to January abundance, and fall
survey indices (age-1 to age-7+) were calibrated to mean abundance. The
instantaneous rate of natural mortality (M) was assumed to be 0.2 based
on tag returns (Lux 1969), relationships of Z to effort (Brown and Hennemuth
1971a), and the oldest individual sampled in the stock area (age-14). Although
catches of yellowtail older than age-8 are rare in commercial or research
catches, the stock has been heavily exploited for seven decades. Maturity
at age for southern New England yellowtail flounder was reported by O’Brien
et al. (1993) from 1985-1990 NEFSC spring survey samples. Calibration
output is reported in Appendix A. Model Residuals
are plotted in Figure 11.
Results show that the stock was
abundant in the early 1970s with a relatively wide age structure (11%
of the population in 1973 was age 6 or older), but was quickly truncated
by the late 1970s (<2% age 6+ from 1978 to 2001; Figure
12c). Fishing mortality generally increase in the 1970s and 1980s
to a peak of 2.3 in 1991 and 1992, averaged 1.6 during the 1990s, and
appears to have decreased to 0.68 in 2000 and increased to 0.91 in 2001
(Figure 12a). Recruitment was generally strong
in the 1970s and moderate during the 1980s, with two exceptional year
classes in 1980 and 1987. Recruitment has been low during the 1990s. 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 decreased to a record low 622mt
in 1994, gradually increased to 2,100mt in 2000, and decreased to 1,900mt
in 2001. Retrospective analysis indicates a strong pattern of underestimating
F, and overestimating SSB in recent years (Figure 13).
Biomass
Dynamics
Given the problems in estimating recent catch at age in the southern
New England area (Cadrin 2000) an age-aggregated production model (ASPIC,
Prager 1994) was fit to total catch and survey biomass indices. Results
are reported in Appendix B. Initial trials did
not fit the winter survey biomass series, presumably because it is relatively
short and does not have much contrast, nor did the model fit the catch
rate data from Lux (1969). Alternative analyses that assumed that stock
biomass was at the carrying capacity in 1935 had very similar results.
Results of the biomass dynamics model indicate that
biomass decreased during the 1960s and early 1970s to about 10% of the
biomass estimated for the early 1960s (Figure 14). Similar
to the age-based analysis, the biomass dynamics model indicates brief
periods of rebuilding in the early and late 1980s and a further decrease
to extremely low biomass in the mid 1990s. However, the biomass dynamics
model indicates a slightly faster rate of rebuilding in recent years
than indicated by the age-based analysis.
Biological
Reference Points
Yield and biomass
per recruit were calculated assuming the observed partial recruitment
and mean weight at age for 1994-2001 (Thompson and Bell 1934). Results
are reported in Table 9 and illustrated in Figure
15. A comparison of recently observed age distributions with the
age distribution expected at F40% shows a relative truncation
in current age structure (Figure 16).
Applying the approach used to estimate MSY proxies for southern New
England yellowtail (NEFSC 2002), FMSY is approximated as F40% (0.26). The
SSBMSY proxy is 69,500mt, calculated as the product of 40%MSP
(1.129 kg spawning biomass) and average long-term recruitment (61.57
million). The average long-term recruitment was derived as the fall
survey age-1 index divided by the catchability coefficient estimated
by ADAPT (8.08E-5). The MSY proxy is 14,200mt, derived as the product
of yield per recruit at F40% (0.230 kg) and average recruitment.
Such MSY reference point proxies
are highly sensitive to the assumed value of recruitment. For example,
different periods of observed recruitment produce a wide range of SSBMSY and
MSY proxies (Figure 17). Alternatively, SSBMSY and
MSY can be approximated using stochastic long-term projections assuming
recent average weights at age and partial recruitment (1994-2001), and
the distribution of long term recruitment. Results suggest that at an
F of 0.26, the long-term average catch is 13,100mt, and long-term average
SSB is 64,500mt (Figure 18). For comparison, the
estimate of BMSY from biomass dynamics analysis is 104,700mt
of total biomass, FMSY is 0.19 on total biomass, and MSY is
20,300mt.
Projections
Stochastic age-based projections that assume a 15%
reduction in F from 2001 to 2002 and recruitment similar to that experienced
in the last decade suggest that the stock cannot rebuild to BMSY by
2009 even if F in 2003-2010 is zero. If the same hindcast recruitment
values used to derive the reference points are assumed for projections,
there stock is expected to have approximately a 50% chance of rebuilding
to SSBMSY by 2009 with an F of 0.08 (Figure
19, Appendix A). However, long-term recruitment
levels are not likely in the short-term, because SSB is extremely low,
and retrospective patterns indicate that projections may be overly optimistic.
DISCUSSION
Although estimation of catch at age from Mid Atlantic area is independent
of the estimation for southern New England waters, and the Mid Atlantic
area is well sampled by the surveys, temporal patterns of abundance and
mortality for the combined area is similar to previous assessments of
the Southern New England stock, though scaled up to account for Mid Atlantic
catches. However, the estimate of 2001 fishing mortality for the southern
New England assessment (Cadrin 2002b) is half of the F estimated for
the combined southern New England-Mid Atlantic stock area.
Unlike stocks of yellowtail flounder that have recently rebuilt from
low stock sizes on Georges Bank and the Grand Banks, fishing mortality
on southern New England-Mid Atlantic yellowtail has not been substantially
reduced and is still well above the rate that will allow rapid rebuilding. Accordingly,
the rate of rebuilding has been slow. Projections suggest that fishing
mortality should be reduced to near zero to achieve rebuilding by the
specified management target of 2009.
Some difficulties in the assessment of southern New England yellowtail
(e.g., the retrospective pattern of the VPA) also persist in this assessment
of the combined southern New England-Mid Atlantic area. However, the
overfished and overfishing status is not affected by the retrospective
bias. The retrospective pattern suggests that the VPA is not well calibrated. It
appears that the surveys do not monitor small differences in relative
abundance at such low densities. Perhaps the winter survey, which samples
yellowtail more efficiently than the spring and fall surveys, will help
to monitor stock rebuilding as more contrast is observed in the relatively
short series.
ACKNOWLEDGMENTS
Tom Nies compiled information on management history. Vaughn Silva
provided age determinations for recent years. Jay Burnett and Paul Kostovick
helped to restore historical age data. Ralph Mayo assigned areas to
commercial length samples and provided software for observer data. Susan
Wigley provided software for survey and logbook data. Paul Nitschke
offered input on discard estimation. Mark Terceiro provided input on
many assessment decisions and chaired the Working Group meeting, and
drafted the Working Group discussion. Kathy Sosebee served as rapporteur
for the assessment meeting. Andrew Payne chaired the Stock Assessment
Review Committee. I thank all Working Group and Review Committee participants.
REFERENCES
Begg, G.A., J.A. Hare, and D.D. Sheehan 1999. The role
of life history parameters as indicators of stock structure. Fish. Res.
43: 141-163.
Bigelow, H.B. and W.C. Schroeder. 1953. Fishes of the Gulf of Maine.
Fish. Bull. 53: 1-577.
Brown, B.E. and R.C. Hennemuth. 1971a. Assessment of the yellowtail
flounder fishery in subarea 5. ICNAF Res. Doc. 71/14.
Brown, B.E. and R.C. Hennemuth. 1971b. Prediction of yellowtail flounder
population size from pre-recruit catches. ICNAF Res. Doc. 71/115.
Cadrin, S.X. 2000. Southern New England yellowtail flounder. In Assessment
of 11 Northeast Groundfish Stocks through 1999. NEFSC Ref. Doc. 00-05:
65-82.
Cadrin, S.X. 2001a. Mid Atlantic yellowtail flounder. In Assessment
of 19 Northeast Groundfish Stocks through 2000. NEFSC Ref. Doc. 01-20:
190-194.
Cadrin, S.X. 2001b. Southern New England yellowtail flounder. In Assessment
of 19 Northeast Groundfish Stocks through 2000. NEFSC Ref. Doc. 01-20:
54-66.
Cadrin, S.X. 2002a. Mid-Atlantic yellowtail flounder. In Assessment
of 20 Northeast Groundfish Stocks through 2001. NEFSC Ref. Doc. 02-16:
293-297.
Cadrin, S.X. 2002b. Southern New England yellowtail flounder. In Assessment
of 20 Northeast Groundfish Stocks through 2001. NEFSC Ref. Doc. 02-16:
83-103.
Clark, S.H., L. O'Brien, and R.K. Mayo. 1981. Yellowtail flounder stock
status. NEFC Lab. Ref. Doc. 81-10.
Clark, S.H., M.M. McBride and B. Wells. 1984. Yellowtail flounder assessment
update - 1984. NEFC Lab. Ref. Doc. 84-39.
Collette, B.B. and G. Klein-MacPhee. 2002. Bigelow and Schroeder's Fishes
of the Gulf of Maine. Smithsonian Press, Washington, D.C.
Conser, R.J., L. O'Brien, and W.J. Overholtz. 1991. An assessment of
the southern New England and Georges Bank yellowtail flounder stocks.
Appendix to NEFSC Ref. Doc. 91-03.
Despres, L. I., T. R. Azarovitz, and C. J. Byrne. 1988. Twenty-five
years of fish surveys in the northwest Atlantic: the NMFS Northeast Fisheries
Center's bottom trawl survey program. Mar. Fish. Rev. 50(4): 69-71.
Gavaris, S. 1988. An adaptive framework for the estimation of population
size. CAFSAC Res. Doc. 88/29.
Lux, F.E. 1964. Landings, fishing effort, and apparent abundance in
the yellowtail flounder fishery. ICNAF Res. Bull. No. 1: 5-21.
Lux, F.E. 1967. Landings per unit effort, age composition, and total
mortality of yellowtail flounder (Limanda ferruginea) in subarea 5Z.
ICNAF Res. Doc. 67/28.
Lux, F.E. 1969. Landings per unit effort, age composition, and total
mortality of
yellowtail flounder, Limanda ferruginea (Storer), off New England. ICNAF Res.
Bul. 6:47-69.
McBride, M.M. and B.E. Brown 1980. The status of the marine fishery
resources of the northeastern United States. NOAA Tech. Mem. NMFS-F/NEC-5.
McBride, M.M. and S.H. Clark. 1983. Assessment status of yellowtail
flounder (Limanda ferruginea) stocks off the northeastern United States.
NEFC Lab. Ref. Doc. 83-32.
McBride, M.M. and M.P. Sissenwine. 1979. Yellowtail flounder (Limanda
ferruginea) status of the stocks, February 1979. NEFC Lab. Ref. Doc.
79-06.
McBride, M.M., M.P. Sissenwine, B.E. Brown and L.M. Kerr. 1980. Yellowtail
flounder (Limanda ferruginea) status of the stocks, March 1980. NEFC
Lab. Ref. Doc. 80-20.
NEFC (Northeast Fisheries Center) 1986. Report of the second NEFC stock
assessment workshop (second SAW). NEFC Ref. Doc. 86-09.
NEFC (Northeast Fisheries Center) 1987. Status of the fishery resources off
the northeastern United States for 1987. NOAA Tech. Mem NMFS-F/NEC-50.
NEFC (Northeast Fisheries Center) 1988. Status of the fishery resources
off the northeastern United States for 1988. NOAA Tech. Mem NMFS-F/NEC-63.
NEFC (Northeast Fisheries Center) 1989. Report of the seventh NEFC stock
assessment workshop (seventh SAW). NEFC Ref. Doc. 89-04.
NEFC (Northeast Fisheries Center) 1991. Status of the fishery resources
off the northeastern United States for 1990. NOAA Tech. Mem NMFS-F/NEC-81.
NEFSC (Northeast Fisheries Science Center) 1991. Status of the fishery
resources off the northeastern United States for 1991. NOAA Tech. Mem
NMFS-F/NEC-86.
NEFSC (Northeast Fisheries Science Center) 1992. Status of the fishery
resources off the northeastern United States for 1992. NOAA Tech. Mem
NMFS-F/NEC-95.
NEFSC (Northeast Fisheries Science Center) 1993. Status of the fishery
resources off the northeastern United States for 1993. NOAA Tech. Mem
NMFS-F/NEC-101.
NEFSC (Northeast Fisheries Science Center) 1997. 24th northeast regional
stock assessment workshop (24th SAW). NEFC Ref. Doc. 97-12.
NEFSC (Northeast Fisheries Science Center) 1998. 27th northeast regional
stock assessment workshop (27th SAW). NEFC Ref. Doc. 98-15.
NEFSC (Northeast Fisheries Science Center). 2002. Final report of the
Working Group on Re-Evaluation of Biological Reference Points for New
England Groundfish. 19 March, 2002.
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. Rep. NMFS 113.
Overholtz, W. and S.X. Cadrin. 1998. Yellowtail flounder. NOAA Tech.
Rep. NMFS-NE-115: 70-74.
Parrack, M. 1974. Status review of ICNAF subarea 5 and statistical area
6 yellowtail flounder stocks. ICNAF Res. Doc. 74/99.
Pentilla, J.A. and B.E. Brown 1973. Total mortality estimated from survey
cruise data for two groups of yellowtail flounder in the southern New
England and Georges bank Areas (ICNAF Subarea 5). ICNAF Res. Bul. 10:
5-14.
Prager, M.H. 1994. A suite of extensions to a nonequilibrium surplus-production
model. Fish. Bull. 92: 374-389.
Rago, P. 1994. Yellowtail flounder. NOAA Tech. Rep. NMFS-NE-108: 64-68.
Rago, P.J., W.L. Gabriel, and M.C. Lambert. 1994. Assessment of southern
New England yellowtail flounder (Pleuronectes ferrugineus), 1993. NEFC
Ref. Doc. 94-02.
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.
Sinclair, M. 1988. Marine populations: an essay on population regulation
and speciation. Univ. Washington Press, Seattle.
Sissenwine, M.E., B.E. Brown, and M.M. McBride. 1978. Yellowtail flounder
(Limanda ferruginea): status of the stocks. NEFC Lab. Ref. Doc. 78-02.
Thompson, W. F. and F. H. Bell. 1934. Effect of changes in intensity
upon total yield and yield per unit of gear. Report of the International
Fisheries Commission 8:7-49.