(DRAFT) - Taxonomy
Species flounder, summer
Species Id M010006
Date 27 AUG 96
TAXONOMY
NAME - flounder, summer
OTHER COMMON NAMES - flounder, fluke, plaice fish, plaice, plaise, splaice, chicken halibut, brail, turbot, flatfish, long-toothed flounder, flounder of New York and common flounder
ELEMENT CODE -
CATEGORY - Fish
PHYLUM AND SUBPHYLUM - ,
CLASS AND SUBCLASS - Osteichthyes,
ORDER AND SUBORDER - Pleuronectiformes,
FAMILY AND SUBFAMILY - Bothidae,
GENUS AND SUBGENUS - Paralichthys,
SPECIES AND SSP - dentatus,
SCIENTIFIC NAME - Paralichthys dentatus
AUTHORITY - Linnaeus
TAXONOMY REFERENCES - 185 and 190
COMMENTS ON TAXONOMY -
The preferred common name is summer flounder. Other common names include:
flounder, fluke, plaice fish, plaice, plaise, splaice, chicken halibut,
brail, turbot, flatfish, long-toothed flounder, flounder of New York, common
flounder.*185*
Family bothidae is a large family of benthic marine fishes, closely related
to percomorph fishes, inhabiting continental shore waters in tropical and
temperate zones of Atlantic, Pacific and Indian oceans.
Flatfishes are one of the most clearly defined and distinct orders of fishes
because of their asymmetry. They commence life swimming in the normal
manner, but early in life strange changes take place in their behavior
pattern and instead of swimming upright they commence to lie and swim on one
side. The eye on the blind side (underside) migrates to the upper side (to
the left in lefteye flounders, the fish lying on its right side), a change
that involves complex modification of the skeltal structure of the head and
also of the nervous and muscle tissues. Reversal does occur occasionally,
and is especially apparent in Pacific species. Flounders usually live on
the bottom and are often almost entirely covered with a thin layer of mud or
sand. Some species of lefteye flounders exhibit sexual dimorphism; the eyes
in males may be farther apart than in females, and pectoral fins of males
longer.*258*
Taxonomy - 1 (DRAFT) - Status
Species flounder, summer
Species Id M010006
Date 27 AUG 96
STATUS
Coded Status
Sport Fish
Game (Consumptive Recreational)
Commercial
Commercial/consumption
Existing, FMP exists
REFERENCES FOR STATUS - 185 and 171
COMMENTS ON STATUS -
The summer flounder is an important commercial and recreational fish along
the Atlantic seaboard of the United States, but the commercial fishery is
not substantial in the South Atlantic Bight (south of Cape Hatteras to
Florida). The Pamlico Sound estuarine complex in North Carolina is believed
to be a major nursery area for young from the Middle Atlantic (Cape Hatteras
northward to Cape Cod) and South Atlantic stocks, but this is uncertain
because little is known about dispersal. The eventual contribution of fish
using smaller nursery areas scattered along the South Atlantic Bight to
adult stocks along other portions of the Atlantic coast is not known.*185*
In 1982 the Atlantic States Marine Fisheries Commission prepared a Fishery
Management Plan for summer flounder which provided a comprehensive
description of the stocks including habitat, general biological data, a
description of fishing activity, the economic characteristics of the
fishery, and recomendations for management. The plan was reviewed in 1987,
and was found to still be appropriate. Updated information and
recommendations were added to the plan at the time of review.*171*
Status - 1 (DRAFT) - Distribution
Species flounder, summer
Species Id M010006
Date 27 AUG 96
DISTRIBUTION
Distribution - 1 HABITAT ASSOCIATIONS
NATIONAL WETLAND INVENTORY CODES
NWI NWICLS NWIMOD NWISPEC
Estuarine FL2
Estuarine UB3
Marine FL2
Marine UB3
Estuarine FL2
Estuarine UB3
Marine FL2
Marine UB3
Estuarine FL2
Estuarine UB3
Marine FL2
Marine UB3
Estuarine FL2
Estuarine UB3
Marine FL2
Marine UB3
REFERENCES FOR NWI - 185
Habitat Associations - 1 (DRAFT) - Food Habits
Species flounder, summer
Species Id M010006
Date 27 AUG 96
FOOD HABITS
TROPHIC LEVEL -
OMNIVORE
REFERENCES FOR TROPHIC LEVEL - 185
LIFESTAGE FOOD FOOD PART
Larva Crustaceans Not Specified
Larva Chondrichthyes See Comments
Larva Osteichthyes See Comments
Adult Chondrichthyes See Comments
Adult Osteichthyes See Comments
Adult See Comments; Food See Comments
REFERENCES FOR GENERAL FOOD - 185
COMMENTS ON ADULT FOOD -
No data exist for other areas in the South Atlantic Bight, but adults north
of Cape Hatteras feed primarily on fish and large invertebrates in
estuaries and shelf water. Olla et al. (1972) showed that summer
flounder are visual feeders and are adept at feeding on the bottom and in
the water column. Laboratory studies and field collections indicate that
summer flounder are active primarily during daylight hours.*185*
The role of summer flounder in ecosystem function and community dynamics has
not been adequately addressed, but the adults are generally regarded as top
or nearly top predators. Because the flounder undergoes pronounced
seasonal migrations, its influences on prey populations and its interactions
with other predatory species are expeceted to vary with season, depth, and
habitat type.*185*
COMMENTS ON LARVAE FOOD -
The larval and postlarval feeding ecology of summer flounder is not well
documented; it is only inferred that they initially feed on zooplankton and
then utilize small crustaceans. Juveniles longer than 80 mm in Pamlico
Sound consumed progressively larger prey items as they grew. They initially
fed on mysid shrimp and small fish and shifted to decapod crustaceans and
larger fish as they reached adulthood.*185*
Food Habits - 1 (DRAFT) - Environment Associations
Species flounder, summer
Species Id M010006
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
G Water Temperature: Specified in Comments
G Dissolved Oxygen: Specified in Comments
G Bottom Type [Aquatic]: Specified in Comments
G
REFERENCES FOR ENVIRONMENTAL ASSOC_ - 185
COMMENTS ON ENVIRONMENTAL ASSOCIATIONS -
Temperature: It was shown that increased temperature within a range of
5 degrees to 21 degrees C promoted faster development of embryos and
yolk-sac larvae. Temperatures below 11 degrees C were lethal to larvae
during development, but at higher temperatures all larvae were the same
length at yolk-sac absorption.
Data for the Middle Atlantic Bight and Cape Hatteras areas indicate that
adults spawn where bottom water temperatures are 12 degrees C to 19 degrees
C, but most eggs were collected where temperatures were 18 degrees C to 19
degrees C. Evidence indicates that the offshore limits of migration and
spawning of summer flounder in the Middle Atlantic Bight coincide with the
inshore edge of the mass of cold bottom water, but it is not known if this
relationship exists in the South Atlantic Bight. Smith (1973) proposed
that temperature changes caused by mixing of the cold water upper layers
during late summer and fall storms affected year-class success in the
Middle Atlantic Bight. Temperature has a pronounced effect on growth
efficiency feeding rate, and assimilation efficiency of juveniles held in
laboratory conditions.*185*
Salinity: Laboratory studies have shown that growth rates increase with
increasing salinity. Maximum growth rate and efficiency occurred at
salinities greater than 10 ppt, corresponding with salinities at which
young summer flounder are most abundant in estuaries.*185*
Dissolved oxygen: Effects of dissolved oxygen concentration on summer
flounder has not been investigated, but the closely related southern
flounder (Paralichthys lethostigma) prefer water with dissolved oxygen
concentrations exceeding 3.7 ml/l (or 5.3 mg/l).*185*
Substrate and Vegetation: Juvenile summer flounder occur more frequently
over sandy substrates than mud or silt bottoms in Pamlico Sound, North
Carolina. During daylight hours, the fish tend to occupy areas in
Environment Associations - 1 (DRAFT) - Environment Associations
Species flounder, summer
Species Id M010006
Date 27 AUG 96
estuaries that have submerged vegetation. Effects of turbidity have not
been reported.*185*
Environment Associations - 2 (DRAFT) - Life History
Species flounder, summer
Species Id M010006
Date 27 AUG 96
LIFE HISTORY
Morphology and Identification Aids:
The following description was provided by Gutherz (1967): dorsal rays,
80-98; anal rays, 60-78; pectoral rays, 10-13; gill rakers on upper arch,
3-7; gill rakers on lower arch 13-18; body laterally flattened with margin
of preopercle free and eyes on left side as in other bothids; bases of both
pelvic fins short. Summer flounder longer than 18 mm standard length (SL)
can be separated from southern flounder (P. lethostigma) and gulf flounder
(P. albigutta) by using gill raker counts (P. dentatus) usually has more
than 14 rakers on lower arch) and sometimes by body coloration. Specimens
shorter than 18 mm SL can be separated from southern and gulf flounders by
using vertebrae counts (40-42 for summer flounder, fewer than 38 for others)
and pigment patterns.
Color in life: ocular side is tannish to dark brown with numerous ocellated
spots, five of which are arranged in two triangles with a common apex on the
lateral line. Spots generally are absent in larger specimens. Paralichthys
spp. can readily match the apparent texture and, to a lesser degree, the
color of bottom substrates on which they live.*185*
Reproduction:
Spawning times and habitats of summer flounder in the South Atlantic Bight
are poorly documented. Available information consists of limited offshore
collecions of newly hatched larvae, observations of reproductive cycles at
Beaufort and Pamlico Sound, North Carolina, and seasonality of newly arrived
young in estuaries.*185*
Adult summer flounder spend the warmer months in nearshore shelf waters and
coastal embayments. They migrate offshore during cooler months and spawn
during late fall, winter, or early spring on or near the bottom in shelf
waters ranging from 30 to 200 m deep. Summer flounder begin a spawning
migration as they near the peak of their gonadal development cycle, with the
oldest and largest fishing migrating first each year (Morse 1981).*185*
The major spawning period in the waters between Virginia and Cape Lookout,
North CArolina, begins in November and continues for 2 or 3 months; newly
hatched larvae have been collected in the open shelf water of the South
Atlantic Bight in late January and early February (Smith 1973). In the
Middle Atlantic Bight, the spawning cycle and offshore limits of migration
are strongly correlated with the fall-winter cooling of coastal waters and
with the inshore limits of cold bottom water intrusion (see ENVIRONMENTAL
REQUIREMENTS section for spawning temperatures). The timing of offshore
spawning migrations apparently is a southward progression of a cycle that
begins in the northern part of the Middle Atlantic Bight in early September
and ends in the South Atlantic Bight by December (Eldridge 1962; Smith 1973;
Morse 1981). Powell (1974) noted peak gonadal development during December
and January for individuals collected from the Cape Hatteras area; and all
fish collected during April and May at Beaufort, North Carolina, were spent
(Hildebrand and Schroeder 1928). Therefore, a progressively later peak of
spawning activity is likely for the South Atlantic Bight, starting in mid-
to late-November in the Cape Hatteras area and ending in early spring in
south Georgia and Florida. There is good evidence to indicate that summer
flounder are serial spawners, continuously shedding mature eggs during the
Life History - 1 (DRAFT) - Life History
Species flounder, summer
Species Id M010006
Date 27 AUG 96
protracted spawning season (Morse 1981). It is likely that year-to-year
variation in migratory distances is governed by variation in the extent to
which coastal waters are cooled each winter. Morse (1981) suggested that
"the reproductive strategy of the summer flounder tends to maximize
reproductive potential and avoid catastrophe" by combining a protracted
spawning season of variable duration with early maturation, high fecundity,
serial spawning, and extensive migrations across the shelf.*185*
Adult summer flounder move inshore after spawning in late spring and show
peak abundance in coastal waters from July to September. Individuals in
Middle Atlantic stocks tend to use the same spawning and wintering areas in
successive years, but similar behavior has not been documented for stocks in
the South Atlantic Bight. This behavior provides a mechanism by which
adjacent stocks can be reproductively isolated (Wilk et al. 1980; see THE
FISHERY section). Tagging studies in the Middle Atlantic Bight indicate a
tendency for older and larger fish to move toward the northeastern limit of
the fishery's range.*185*
BEHAVIOR:
Seasonal migration patterns of adult fish have been deduced from (1)
collecions of newly hatched larvae (which provide information only on the
reproducing segment of the population); (2) commercial catch rates in the
Cape Hatteras area; and (3) generalized coastal and shelf trawling surveys.
The studies cited above plus information from the Middle Atlantic Bight on
seasonality of the commercial catch and tagging studies provide data that
may be applicable to population in the South Atlantic Bight.
It should be recognized, however, that subpopulations north and
south of Cape Hatteras may be genetically distinct, a possibility which
could lead to differences in behavior, habitat requirements, and other
factors.*185*
Young flounder generally emigrate from North Carolina's estuarine waters
during their second fall of life, but this emigration may occur earlier in
the north. Some individuals of a given year class probably remain in
Pamlico Sound, North Carolina, for 18 to 20 months following their arrival
in the nursery area.*185*
SPECIES ORIGIN WITHIN STATE:
The commercial summer flounder fishery in the South Atlantic Bight consists
of an offshore otter trawl fishery in the Cape Hatteras area and small
incidental catches associated with shrimp trawling throughout the region.
There is no fishery for summer flounder throughout most of the open shelf
waters of the South Atlantic Bight. The Cape Hatteras winter trawl fishery
was initiated in the late 1920's as trawlers from northern ports moved south
to exploit flounder and other species. Fishing occurs during two
major time periods. Trawling effort is concentrated north of Cape
Hatteras from November through late December ("fall") in waters 40 to 100 m
deep and just south of Cape Hatteras from December through March or April
("winter") in waters 20 to 60 m deep (Pearson 1932). About 60% of the
annual North Carolina flounder landings occur during the fall fishery
(outside of the South Atlantic Bight), and 20% is taken from the northern
limit of the South Atlantic Bight during the winter fishery, according to
the U.S. Department of Commerce (USDC), National Marine Fisheries Service
Life History - 2 (DRAFT) - Life History
Species flounder, summer
Species Id M010006
Date 27 AUG 96
(1978, 1980a).*185*
LIMITING FACTORS:
Temperatures below 11 degrees C were lethal to larvae during development,
but at higher temperatures all larvae were the same length at yolk-sac
absorption.*185*
Dissolved oxygen. Effects of dissolved oxygen concentrations on summer
flounder has not been investigated, but the closely related southern
flounder (Paralichthys lethostigma) prefers water with dissolved oxygen
concentrations exceeding 3.7 ml/l (or 5.3 mg/l) (Deubler and Posner
1963).*185*
Environmental contaminants. Arsenic, copper, and zinc residues were
somewhat high in summer flounder collected in the South Atlantic Bight, but
information on acceptable or safe levels of these trace metals was not
reported (Hall et al. 1978). Mean and maximum values for mercury
concentrations were below United States Food and Drug Administration
"action" levels. Certain polynuclear aromatic hydrocarbons were detected at
low levels in summer flounder collected from the Baltimore Canyon in the
Middle Atlantic Bight (Brown and Pancirov 1979). Toxic levels of most
contaminants to summer flounder have not been quantified.*185*
POPULATION ATTRIBUTES:
Growth characteristics. Considerable controversy exists regarding the
validity of using otoliths to age summer flounder. Authors have
variously stated that the first "annulus" forms at ages II through VII,
indicating that length-at-age information is subject to considerable error.
Only one growth study (Powell 1974) has been done in the South Atlantic
Bight (at Pamlico Sound). Powell showed that growth began in the spring and
ended in the fall as the water temperature reached an approximate 7 degrees
C threshold. Flounder were 111 to 219 mm TL at the end of their first
growing season. Maximum sizes of males collected from New York were about
600 mm TL and 2200 g, and females reached 800 mm and 5500 g.
Summer flounder may live about 10 years; all fish older than 7 years of age
collected by Eldridge (1962) were females. Growth rates published for fish
collected outside the South Atlantic Bight were summarized by Smith et al.
(1981).*185*
Total annual landings for 1974 through 1978 in North Carolina averaged about
18.5 million lb, valued at $9.7 million (USDC 1980b). Harvest and economic
value for other parts of the South Atlantic Bight have not been reported,
probably because abundance elsewhere is too low to support a major
commercial fishery.*185*
The recreational catch of summer flounder in the South Atlantic Bight is
minor compared to catches in the Middle Atlantic and Gulf of Mexico
regions. Numbers caught (in 1000's) by anglers in 1979 were: Middle
Atlantic region - 12,653; Gulf of Mexico - 1,882; South Atlantic - 988; and
North Atlantic - 571 (USDC 1980c). The South Atlantic catch was comprised
of 72% from North Carolina, 19% from Florida, 7% from South Carolina, and 2%
from Georgia.*185*
Life History - 3 (DRAFT) - Life History
Species flounder, summer
Species Id M010006
Date 27 AUG 96
No information exists on the age and size composition of the summer flounder
catch in the South Atlantic Bight. The commercial and recreational catch in
the Middle Atlantic Bight consists mostly of fish younger than age
five.*185*
Subpopulations. Since a genetically distinct stock can have unique rates of
recruitment, growth, and mortality (Cushing 1968), identification of the
stocks (= subpopulations) and stockspecific biological traits is necessary
for proper management. There is evidence provided that suggests
the existence of separate stocks of summer flounder in North
Carolina and in the Chesapeake-Delaware Bay areas. Smith (1973)
proposed the existence of three spawning populations (New York/New Jersey;
Delaware Bay to Cape Hatteras; Cape Hatteras to Cape Lookout). Wilk et al.
(1980) demonstrated significant differences in meristic and morphometric
characteristics of summer flounder collected in the Middle and South
Atlantic Bights and showed little intermixing between the groups. They
concluded that individuals from both groups use the Pamlico Sound estuarine
complex as a nursery area, but use separate spawning grounds each
winter.*185*
LIFE HISTORY CODES -
Periodicity: Active in day
REFERENCES FOR LIFE HISTORY- 185
Life History - 4 (DRAFT) - Management Practices
Species flounder, summer
Species Id M010006
Date 27 AUG 96
MANAGEMENT PRACTICES
RESULT MANAGEMENT PRACTICE
Beneficial Regulating harvest of species being described
Existing Regulating harvest - setting size limits
Existing Regulating commercial harvest gear types
Beneficial Developing/maintaining/protecting wetlands
Beneficial
Beneficial Controlling pollution [thermal, chemical, physical]
Beneficial Controlling sedimentation
Adverse Draining wetlands, marshes, ponds, lakes
Adverse Dredging
Adverse Wastewater disposal/assimilation
Adverse Water supply, flow withdrawl
Adverse Shoreline modification/development
Adverse Migration barriers
REFERENCES FOR BENEFICIAL MANAGEMENT PRACTICES - 185 and 98
REFERENCES FOR ADVERSE MANAGEMENT PRACTICES - 98
REFERENCES FOR EXISTING MANAGEMENT PRACTICES - 171
COMMENTS ON MANAGEMENT PRACTICES -
Without question, yield per recruit and long-term yield can be increased
significantly by increasing the minimum size of fish caught and by reducing
fishing mortality. Biological benefits accrued from increasing the mean
size of fish could include a reduction in mortality, an increase in yield
per recruit and an increase in the long term yield which would provide
stability to the fishery, through inclusion of more than one-year class in
the catch. Economically, the fishery benefits from larger, more valuable
fish in both the commercial and recreational fisheries.*171*
Recommendations for FMP as of 1988:
It is the feeling of the plan review sub-committee that the summer flounder
plan should be updated once the draft summer flounder management plan
prepared by the Mid-Atlantic Fishery Management Council is accepted.
However, prior to a major re-write of the summer flounder plan, the
management recommendations of the original plan (1982) should be
implemented. Specifically option 3A which allows U.S. fishermen
unrestricted catches of summer flounder but imposes a 14-inch total length
size limit (and if warranted following completion of stock discrimination
studies) and 3C which imposes a mesh regulation in a directed summer
flounder fishery, the size of which shall allow undersize summer flounder to
escape according to the size limit options listed in the plan (ASMFC).
Complimentary to this is the need for regional council agreement on minimum
size of fish and mesh which will accomplish the above.*171*
Habitat preservation, protection and restoration recommendations:
(For more complete description of recommendations, see p.29 of *98*)
1. All available or potential natural habitat for migratory summer flounder
Management Practices - 1 (DRAFT) - Management Practices
Species flounder, summer
Species Id M010006
Date 27 AUG 96
should be preserved by encouraging management of conflicting uses to assure
access by the fish to essential habitat and maintenance of high water
quality standards to protect summer flounders migration, spawning, nursery,
overwintering and feeding areas.
2. Filling of wetlands should not be permitted in or near nursery summering
areas.
3. Best engineering and management practices should be employed for all
dredging and in-water construction projects.
4. The disposal of sewage sludge, industrial waste, and contaminated
dredged material in summer flounder habitat including the New York Bight
should not be allowed.
5. The siting of industries requiring water diversion and large volume
water withdrawals should be avoided in summer flounder nursery areas.
6. Dechlorination facilities or lagoon effluent holding facilities should
be used to destroy chlorine at sewage treatment plants and power plants.
7. No toxic substances in concentrations harmful to humans, fish, wildlife,
and aquatic life should be discharged.
8. The EPA and States should review their water quality standards relative
to summer flounder nursery areas and make changes as needed.
9. The EPA and States should establish water quality standards for the
coastal zone specifically with respect to the habitat requirements of summer
flounder migratory passage and feeding.
10. The EPA should establish water quality standards for the EEZ sufficient
to maintain edible summer flounder.
11. Water quality standards in nursery, feeding, and areas of migratory
passage should be enforced rigidly by State or local water quality
management agencies, whose actions should be carefully monitored by the EPA.
12. Appropriate measures must be taken as soon as possible to reduce acid
precipitation and runoff into estuaries and nearshore waters.
13. EPA and appropriate agencies must establish and approve criteria for
vegetated buffer strips in agricultural areas adjacent to summer flounder
nursery areas to minimize pesticide, fertilizer, and sediment loads to these
areas critical for summer flounder survival.
14. It is necessary that scientific investigations be conducted on summer
flounder to emphasize the long-term, synergistic effects of combinations of
environmental variables on, for example, reproductive capability, genetic
changes, and suitability for human consumption.
15. Recommendations for furture habitat studies are listed here (see *98*).
Management Practices - 2 (DRAFT) - References
Species flounder, summer
Species Id M010006
Date 27 AUG 96
References
98* Anonymous. 1987. Fishery Management Plan for the Summer Flounder
Fishery. 11.9.87. Mid-Atlantic Fishery Management Council pp 159.
*171* Street, Mike (ed.), Eric Smith, Joseph McGurrin, Paul Perra.
1988. Atlantic States Marine Fisheries Commission: Fisheries
Management Plans for American Lobster, Atlantic Menhaden,
Northern Shrimp, Red Drum, Shad and River Herrings, Spotted
Seatrout, Summer Flounder, Weakfish. (11). Atlantic States
Marine Fisheries Commission:83.
*185* Rogers, S., M. Van Den Avyle. 1983. Species Profiles: Life
Histories and Environmental Requirements of Coastal Fishes and
Invertebrates (South Atlantic) -- Atlantic Menhaden. U.S. Fish
and Wildlife Service Biol. Rep. 82(11.11) pp 20.
190 * Robins, C.R., R.M. Bailey, C.E. Bond, J.R. Brooker, E.A.
Lachner, R.N. Lea, and W.B. Scott. 1980. A list of common and
scientific names of fishes from the United States and Canada.
American Fisheries Society, Special Publ. No. 12, 4th edition
(computerized version):65 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