(DRAFT) - Taxonomy
Species flounder, winter
Species Id M010016
Date 27 AUG 96
TAXONOMY
NAME - flounder, winter
OTHER COMMON NAMES - winter flounder, blackback flounder, lemon sole and black flounder
ELEMENT CODE -
CATEGORY - Fish
PHYLUM AND SUBPHYLUM - ,
CLASS AND SUBCLASS - Osteichthyes,
ORDER AND SUBORDER - Pleuronectiformes,
FAMILY AND SUBFAMILY - Pleuronectidae,
GENUS AND SUBGENUS - Pseudopleuronectes,
SPECIES AND SSP - americanus,
SCIENTIFIC NAME - Pseudopleuronectes americanus
AUTHORITY - Walbaum
TAXONOMY REFERENCES - 1
COMMENTS ON TAXONOMY -
The family pleuronectidae is a large family of benthic marine fishes
(occasionally found in brackish water; rarely in fresh water), closely
related to the percomorph fishes, inhabiting the Arctic, Atlantic, and
Pacific oceans. Bottom fishes of continental shore waters, often lying
partially concealed in mud or sand. The asymmetry and behavioral life
stages of righteye flounders are similar to those of Bothidae, the lefteye
flounders, the eyes migrating to the right side of the head in righteye
flounders, and the fish commencing to lie on the left side with the right
side (or eyed side) uppermost; sometimes called dextral flounders. Eggs
without an oil globule.
Body oval, sometimes elongated, laterally compressed; the mouth small to
large, asymmetrical, lower jaw more or less projecting; teeth usually small,
obsure, palatines, toothless; normally both eyes on right side of head may
be raised and moved independently; preopular margin free.*258*
Taxonomy - 1 (DRAFT) - Status
Species flounder, winter
Species Id M010016
Date 27 AUG 96
STATUS
Coded Status
Sport Fish
Commercial
REFERENCES FOR STATUS - 1
COMMENTS ON STATUS -
By virtue of its abundance in estuarine and nearshore waters, the winter
flounder is one of the most important commercial and sport fishes in the
Northeastern United States.*1*
Status - 1 (DRAFT) - Distribution
Species flounder, winter
Species Id M010016
Date 27 AUG 96
DISTRIBUTION
Distribution - 1 HABITAT ASSOCIATIONS
NATIONAL WETLAND INVENTORY CODES
NWI NWICLS NWIMOD NWISPEC
Marine UB3
Estuarine FL2
Marine FL2
Estuarine UB2
REFERENCES FOR NWI - 1
COMMENTS ON HABITAT ASSOCIATIONS -
There is evidence that winter flounder north and south of Cape Cod and from
Georges Banks compose three separate groups..*1*
Habitat Associations - 1 (DRAFT) - Food Habits
Species flounder, winter
Species Id M010016
Date 27 AUG 96
FOOD HABITS
TROPHIC LEVEL -
CARNIVORE
REFERENCES FOR TROPHIC LEVEL - 1
LIFESTAGE FOOD FOOD PART
Larva See Comments; Food Not Specified
Adult See Comments; Food Not Specified
General Annelids Not Specified
General Molluscs Not Specified
General Cnidaria Not Specified
REFERENCES FOR GENERAL FOOD - 1
COMMENTS ON FOOD -
Winter flounder primarily feed visually and only during daylight.
In the Bay of Fundy, those in nearshore waters usually feed in the intertidal
zone. They move inshore about 2 h after low tide and return to the
sublittoral zone about 2 h before the next low tide.*1*
When feeding, the winter flounder lies motionless with its head raised off
the bottom, braced by the dorsal fin. When a prey is sighted, the fish
remains motionless, pointing toward the prey, and then lunges forward and
downward to capture it. If no prey is sighted, the fish moves to a new
location, changing position from four to five times per minute.*1*
COMMENTS ON ADULT FOOD -
Adult winter flounder feed largely on organisms of three phyla: Annelida,
Cnidaria, and Mollusca.*1*
COMMENTS ON LARVAE FOOD -
Larvae begin to feed 2 to 3 weeks after they hatch. They first feed on
copepods and phytoplankton, but as they reach metamorphosis, their diet is
composed of copepod nauplii, small polychaetes, nemerteans, and ostracods.
Food density on larval growth and survival was studied. It was found that
larvae died from starvation in 2 weeks at prey (nauplius) densities of
<0.1/ml; critical prey density was about 0.5/ml. Plankton density influenced
survival more than it did growth. It was demonstrated that the density of
prey was probably the most important factor affecting survival.*1*
Food Habits - 1 (DRAFT) - Environment Associations
Species flounder, winter
Species Id M010016
Date 27 AUG 96
ENVIRONMENTAL ASSOCIATIONS
G = General A = Adult
LIM = Limiting RA = Resting Adult
J = Juvenile FA = Feeding Adult
RJ = Resting Juvenile BA = Breeding Adult
FJ = Feeding Juvenile P = Pupae
L = Larvae E = Egg
RL = Resting Larvae
FL = Feeding Larvae
LIFESTAGE ENVIRONMENTAL ASSOCIATIONS
E Water Temperature: Specified in Comments
E
E Bottom Type [Aquatic]: Specified in Comments
E Estuarine habitat zone: specified in comments
L Water Temperature: Specified in Comments
J Water Temperature: Specified in Comments
A Water Level: Specified in Comments
REFERENCES FOR ENVIRONMENTAL ASSOC_ - 1
COMMENTS ON RESTING ADULT ENVIRONMENTAL ASSOC_ -
Water temperature seems to be the most important environmental factor
determining seasonal distribution. In Rhode Island, adult
winter flounder lived in cooler offshore waters during summer and in
shallow inshore waters in winter and early spring. In
Newfoundland, winter flounder remained in shallow water during summer as
long as temperatures did not exceed 15 degrees C. Adult winter flounder
commonly live in salinities of 5 to 35 ppt.*1*
COMMENTS ON RESTING JUVENILE ENVIRONMENTAL ASSOC_ -
After metamorphosis, winter flounder are benthic and seldom lose contact
with the substrate. Most juveniles spend much of their first 2 years in or
near shallow natal waters, where they move in reponse to extreme heat or
cold. After metamorphosis, the juveniles prefer a substrate of sand or sand
and silt. Older juveniles in estuaries gradually move seaward as they grow
larger. Temperature is a less important factor in the distribution of
juveniles, which tolerate higher temperatures than adults.*1*
COMMENTS ON RESTING LARVAE ENVIRONMENTAL ASSOC_ -
At a water temperature of 3.9 degrees C the larvae were about 5 mm TL, and
the yolk sac was absorbed in 12 to 14 days. La Roche (1980) provides a
detailed description of larval development. At a water temperature of 5
degrees C the metamorphosis took 80 days, with the larvae reaching 8 to 9
mm TL. At a temperature of 8 degrees C the metamorphosis took 49 days,
with the larvae reaching 8 to 9 mm TL as well. No metamorphosis was
evident at 2 degrees C.*1*
In aquaria, winter flounder larvae engage in upward swimming bouts and then
sink to the bottom where they remian for a short time.
Environment Associations - 1 (DRAFT) - Environment Associations
Species flounder, winter
Species Id M010016
Date 27 AUG 96
The larvae of other flatfish species are more pelagic.
Winter flounder larvae are continuous, visual, daylight feeders
that cease feeding at night.*1*
COMMENTS ON EGG ENVIRONMENTAL ASSOC_ -
Winter flounder eggs are demersal, and adhesive. Incubation time was 15 to
18 days at 2.8 to 3.3 degrees C, 25 days at 3 degrees C,
and 7 days at 12 to 14 degrees C. Incubation time
was inversely related to water temperature and salinity.*1*
Winter flounder eggs seem to be most abundant in water with a salinity of
10 to 30 ppt; at salinities below 5 ppt or above 40 ppt, some embryos
survive, but are usually deformed. The optimal salinity for
egg survival is 15 to 35 ppt.*1*
Many embryos become inviable or abnormal at temperatures below freezing
(-1.8 to 0 degrees C) and temperatures above 10 degrees C.
The optimum water temperature range for survival is 0 to 10 degrees C. *1*
Environment Associations - 2 (DRAFT) - Life History
Species flounder, winter
Species Id M010016
Date 27 AUG 96
LIFE HISTORY
PHYSICAL DESCRIPTION:
The winter flounder, one of the right-eyed flounder, is oval-shaped and
thick-bodied; the caudal fin and peduncle are broader than those of other
North Atlantic flounders. The anal fin is highest at its midpoint and is
preceded by a short sharp spine. The dorsal fin (60-75 rays) originates
opposite the anterior edge of the eye, and is about equal in height
along its length. The mouth is small, not gaping to the eye. The left
(under) half of the jaw is armed with a series of close-set incisors; the
right (upper) half has only a few teeth.*1*
The winter flounder, like other flatfishes, varies in color, depending
largely on the color of the surrounding substrate. Most adults tend to be
reddish brown, olive-green, or blackish. Smaller fish generally are paler
than larger fish. The blind side is white and, toward the edge, translucent
or occasionally yellowish.*1*
Compared with the yellowtail flounder , Limanda ferruginea, the winter
flounder has a much straighter lateral line, a less concave dorsal head
profile, and fewer fin rays.*1*
The winter founder lacks the mucous pits that are conspicuous on the left
(blind) side of the head of the witch flounder (Glyptocephalus cynoglossus);
it also has three times as many dorsal rays as the witch flounder.*1*
The scales between the eyes are smooth in the smooth flounder (Liopsetta
putnami), but rough in the winter flounder. Between the two, the winter
flounder also has the greater number of anal fin rays.*1*
REPRODUCTION:
The winter flounder spawns in coastal waters as early as December in the
Southern United States and as late as June in Canada. Typically, eggs are
deposited over a sandy substrate at depths of 2 to 80 m.*1*
Most spawning takes place at salinities of 31 to 32.5 ppt in inshore waters,
and on Nantucket Shoal and Georges Bank at slightly higher salinities (32.7
to 33 ppt, respectively). Water temperature during spawning is usually
between 0 and 3 degrees C but may be as high as 6 degrees.
The winter flounder spawns at slightly higher temperatures on
Georges Bank than in inshore waters.*1*
The stage of maturity of the winter flounder is largely governed by size
rather than age. Flounders grow faster and mature at a younger age in the
south than in the north. In Newfoundland, males mature at age VI and
females at age VII; in New York, winter flounder mature at age II or III.*1*
The fecundity of winter flounder ranges from 0.5 to 1.5 million eggs per
female. The following equations for estimating fecundity on the basis of
weight have been published:
Life History - 1 (DRAFT) - Life History
Species flounder, winter
Species Id M010016
Date 27 AUG 96
log F = 2.3894 + 1.2403 log W
log F = 0.0697 + 1.0659 log W
log F = 2.6712 + 1.1383 log W
where F = fecundity in thousands of eggs and W = total weight in grams.*1*
BEHAVIOR:
The seasonal movements of winter flounder differ between populations north
and south of Cape Cod. A 5-year tagging study showed that
winter flounder north of Cape Cod moved about only locally in
inshore waters, while those south of Cape Cod dispersed more than 3 mi
offshore in a southwesterly direction. Adults from Martha's Vineyard and
coastal populations from south of Cape Cod mixed in Nantucket Sound. *1*
Water temperature seems to be the most important environmental factor
determining seasonal distribution. In Rhode Island, adult
winter flounder lived in cooler offshore waters during summer and in
shallow inshore waters in winter and early spring. In
Newfoundland, winter flounder remained in shallow water during summer as
long as temperatures did not exceed 15 degrees C. Temperature is a less
important factor in the distribution of juveniles, which tolerate higher
temperatures than adults.*1*
Indications are that a local population is defined by fish inhabiting
several adjacent estuaries. Although a large percentage
of winter flounder in a tagging study were recaptured at or near
the original tagging locations, apparently the same breeding
area is not always reoccupied each season. On a larger geographic scale,
there is evidence that winter flounder north and south of Cape Cod and from
Georges Banks compose three separate groups.*1*
Adaptive traits. The highly productive estuarine and coastal habitats it
occupies, combined with its omnivorous food habits, tend to reduce
competition. It was suspected that the early spawning
and the short period of time to metamorphosis permit the larvae to reach the
juvenile stage before potential competitors enter the bays and estuaries.*1*
LIMITING FACTORS:
Predators. Adult winter flounder are the prey of many of the larger
estuarine and coastal predators such as striped bass (Morone saxatilis),
bluefish (Pomatomus saltatrix), goosefish (Lophius amercanus), spiny
dogfish (Squalus acanthias), oyster toadfish (Opsanus tau), and sea raven
(Hemitripterus americanus). *1*
Predation is a major cause of mortality in larval and juvenile winter
flounder. The larvae were heavily preyed upon by the small hydromedusa
Saria tubulosa. It was reported that the great cormorant
(Phalacrocorax carbo), the great blue heron (Ardea herodias), and
the osprey (Pandion haliaetus) are also predators of winter flounder.*1*
Life History - 2 (DRAFT) - Life History
Species flounder, winter
Species Id M010016
Date 27 AUG 96
Parasites. The microsporidian parasite Glugea hertwigi is most common
and may cause high mortality among winter flounder less than 30 mm long
(TL).*1*
Disease. About 14% of the winter flounder examined from the New York Bight
have fin erosion. It is not known if the disease is infectious
or noninfectious, but it is not usually fatal.
Although the precise cause of fin rot erosion is not known, its high
incidence in association with high sediment contamination suggests that
contact of the fins with toxic sediment is an important factor in the
development of the disease.*1*
The microsporidian Glugea hertwigi, was found in the digestive tract of
winter flounder. The incidence of infection in samples ranged from 54% in
Martha'a Vineyard to zero on Georges Bank.*1*
Water temperature. An extended period of unusually hot weather caused heavy
mortality in coastal waters of Long Island Sound.
A maximum temperature tolerance of about 30 degrees C was reported.*1*
Salinity. Extremes in salinity may lower egg and larval survival and
hatching success. Adult winter flounder commonly live in salinities of 5 to
35 ppt.*1*
Contaminants. In a study in the Weweantic River, Massachusetts, chlorinated
hydrocarbon insecticides and their breakdown products (DDT, DDE, heptachlor,
heptachlor epoxide, and dieldrin) were found in various tissues of the winter
flounder. Concentrations of DDT, DDE, and heptachlor epoxide were highest
in ripening ovaries. Agricultural runoff was the major source of the
contaminants. It has been reported that this contamination caused high
mortality in the Weweantic River.*1*
In studies of the effects of silver on the eggs and larvae of winter
flounder, it was found that concentrations of silver greater
than 54 micrograms per liter sometimes caused high mortality of the
eggs and yolk-sac larvae, and that exposure to 92 micrograms per liter
significantly increased egg mortalities. In contrast, it was
reported that silver in concentrations up to 166 micrograms per liter did
not increase egg mortality.*1*
POPULATION ATTRIBUTES:
Growth rate. The rate of growth of the winter flounder is rapid until age V
or VI and then decreases, particularly in males. After the first
2 years, females grow faster than males. An exception is in Newfoundland,
where the growth rates of the sexes are similar.*1*
The growth rate also differs between fish from areas relatively close
geographically. Lengths of flounder at the same age were significantly
different among certain bays on Long Island. Flounder
grow to a larger size in the Georges Bank population than in
inshore populations.
Life History - 3 (DRAFT) - Life History
Species flounder, winter
Species Id M010016
Date 27 AUG 96
There is no typical growth rate for the winter flounder because the
populations may be exposed to different rates of exploitation or live under
different environmental conditions. In addition, the extended spawning
period (up to 4 months) can make comparisons difficult between age groups
and locations.*1*
Population dynamics. The age and size of winter flounder recruited into the
fishery varies with the location and the type of fishery. It was
reported that flounder recruited into the sport fishery at South Shore Bay,
Long Island, were from 200 to 260 mm TL. In Nova Scotia, recruits into the
commercial fishery were 3 to 4 years old and weighed an average of 363 g.
In Narragansett Bay, Rhode Island, winter flounder were fully
recruited into the commercial catch at age III (250 mm TL).*1*
Estimated natural mortality rates of winter flounder ranged from 50% to 54%
and total annual mortality (natural and fishing) ranged from 72% to 78%.
Total annual mortality rates estimated on the basis of age composition for
two different Long Island populations were 56% for males and 65% for
females in one population, and 51% for males and 58% for females
in the other. The instantaneous mortality rates of winter
flounder in Nova Scotia were 0.321 (natural) and 0.475 (fishing).
South of Cape Cod, instantaneous mortality rates of 0.1125 (natural) and 0.2
445 (fishing) were reported.*1*
Two important factors affecting mortality are translocation of larvae out of
the estuary by drift and predation. Winter flounder abundance
in Narragansett Bay may be partially governed by annual or seasonal changes
in climate. Because each population does not usually disperse beyond local
waters, the degradation of an estuary may have a drastic effect on the
abundance of recruits in nearby coastal waters.*1*
REFERENCES FOR LIFE HISTORY- *1*
Life History - 4 (DRAFT) - Management Practices
Species flounder, winter
Species Id M010016
Date 27 AUG 96
MANAGEMENT PRACTICES
RESULT MANAGEMENT PRACTICE
Beneficial Controlling pollution [thermal, chemical, physical]
Adverse Applying insecticides
Adverse Applying other toxicants
REFERENCES FOR BENEFICIAL MANAGEMENT PRACTICES - 1
REFERENCES FOR ADVERSE MANAGEMENT PRACTICES - 1
COMMENTS ON MANAGEMENT PRACTICES -
Chlorinated hydrocarbon insecticides and their breakdown products (DDT, DDE,
heptachlor epoxide, and dieldrin) were found in various tissues of the
winter flounder. Concentrations of DDT, DDE, and heptachlor epoxide were
highest in ripening ovaries.*1*
Management Practices - 1 (DRAFT) - References
Species flounder, winter
Species Id M010016
Date 27 AUG 96
References
1* Buckley, J. 1989. Species profiles: life histories and
environmental requirements of coastal fishes and invertebrates
(North Atlantic)--Winter flounder. U.S. Fish and Wildlife
Service Biol. Rep. 82(11.87):12 pp.
242 * Grimes, B.H, M.T. Huish, J.H. Kerby, D. Moran. 1989.
Species Profiles: Life Histories and Environmental Requirements
of Coastal Fishes and Invertebrates (Mid-Atlantic) --Summer and
Winter Flounder. Species Profile Series 82(11.112) (ed.). Fish
and Wildlife Service Washington, DC:18.
References - 1