The summer flounder, or "fluke", a flatfish noted for
its fighting ability and flavor, is found in coastal waters from
the southern Gulf of Maine to Florida. Important recreational
and commercial fisheries for this species occur from Cape Cod
to Cape Hatteras, North Carolina.
Like other species of flatfish, the fluke has both eyes on one
side of its head and rests on the ocean floor on its side. The
fluke is called a left-handed flatfish because its eyes are on
the upper surface of the head when the fish is facing left. The
species has a very large mouth that extends below and beyond it
Summer flounder are called the chameleons of the sea because
of their ability to change color to match the bottom on which
they are found. Generally they are white below and darker above,
but they can turn various shades of gray, blue, green-orange,
and almost black. The upper part of the fluke's body is marked
with scattered spots that are darker than the general body color.
The angling record for summer flounder in Massachusetts is 21
pounds 8 ounces. Although the largest fluke may weigh up to 26
pounds, the average adult weighs 2 to 5 pounds and measures 17
to 25 inches long. A 15 to 16-inch fish, which is only 2 to 3
years old, weighs about 1 to 1 1/4 pounds. A 20-inch fish is about
3 to 3 ½ pounds, a 30-inch fish would be 10 pounds, and
a 37-inch fish would be approximately 20 pounds. Females may live
up to 20 years and weigh more than 20 pounds, while males rarely
exceed 7 years of age and 3 to 5 pounds in weight.
Both males and females become sexually mature at the age of 3.
The fecundity (number of eggs produced in a single spawning season)
of females increases with size and weight. A 14-inch female produces
about 460,000 and a 27-inch female about 4,200,000, eggs in a
Summer flounder inhabit inshore areas of Massachusetts during
the warmer periods of the year. Fluke prefer eelgrass beds and
wharf pilings because of the protection they offer. When threatened,
they quickly bury all but their beady eyes in the sand or escape
at surprisingly high speeds. In the summer, small and medium-sized
adults are found on the sandy and muddy bottoms of bays, harbors,
and along the open coastline. Most of the larger fish tend to
stay in somewhat deeper water (50 to 60 feet). With the approach
of fall, summer flounder migrate to more offshore waters in depths
from 150 to more than 500 feet.
Reproduction takes place in the fall, as soon as the fish begin
to migrate to wintering grounds, Peak spawning activity occurs
from early September through early November in water temperatures
of 53 to 66 degrees F and at depths of 60 to 160 feet. The center
of spawning activity occurs off the coasts of New York and New
Jersey, with less concentrated activity occurring in southern
New England waters.
The eggs float in the water column, hatching 72 to 75 hours after
being laid. After hatching, the larvae are carried into bays and
estuaries where they will spend the early portion of their lives.
Autumn water-circulation patterns in southern New England tend
to distribute surviving larval fish southward along the coast,
resulting in the virtual absence of young summer flounder in Massachusetts
The summer flounder, which depends upon sight to capture its
food, feeds most actively during daylight hours. Juveniles feed
upon small shrimp and other crustaceans, while adults eat a variety
of fish, including small winter flounder, menhaden, sand lance,
red hake, silversides, bluefish, weakfish, and mummichogs, as
well as invertebrates such as blue crabs, squid, sand shrimp,
opossum shrimp, and mollusks. Adult are very active predators,
often chasing schools of small fish to the surface and leaping
out of the water in pursuit of them. This behavior clearly distinguishes
the summer flounder from the other more sluggish species of inshore
Historically, the summer flounder has been among the most
important commercial and recreational flatfishes on the East Coast.
The commercial catch in Massachusetts has been modest compared
to catches along the mid-Atlantic states, but the population summering
in Massachusetts coastal waters faces an intensive offshore otter
trawl fishery in the winter and spring. Commercial catches in
the southern part of the fluke's range were stable from the 1950s
to the early 1970s, while those in the northern portion of its
range persistently declined over the same time period. In 1974
it was estimated that total commercial and recreational harvests
exceeded a level that should be sustained for any extended period
of time. Despite this caution, total harvest has exceeded the
1974 level in the 1980s.
Recreational fishing has always been a major component of the
total fluke harvest, often exceeding commercial catches in the
Mid-Atlantic States. The recreational catch ranged from 26 to
60% of the total harvest from 1979 to 1984 on a coast-wide basis.
Certain regions have historically supported tremendous recreational
fishing. One such region, the Great South Bay of Long Island,
reported as many as 2,000,000 fluke landed yearly during the late
1950s and early 1960s. The total coastal recreational catch from
1979 to 1984 ranged from 5,000,000,000 to 18,900,000,000 fish.
Although populations' levels in the 1980s have been somewhat
higher than they were in the 1960s and 1970s, persistently high
harvest levels may once more reduce this species' abundance. The
Atlantic States Marine Fisheries Commission developed a Summer
Flounder Management Plan that was adopted by coastal states from
Massachusetts to North Carolina in 1982. This plan established
a minimum legal size limit of 14 inches to protect this important
coastal fishery resource.