Description
The black sea bass occurs along the Atlantic Coast of the United
States from Cape Cod to Florida, reaching greatest abundance between
the Capes of New Jersey and North Carolina. This species generally
does not occur in the Gulf of Maine, but it is an important groundfish
west and south of Cape Cod
Black sea bass are fairly stout-bodied fish, with a long dorsal
fin, and large pectoral and pelvic fins. The rounded tail sometimes
has a long streamer trailing out from the top edge. Each gill
cover has a flat spine near the outer edge. Mature males have
a fleshy dorsal hump just anterior to the dorsal fin.
The background color of the black sea bass (smokey gray, brown,
or bluish black) is mottled with darker patches and light speckles.
The belly is only slightly lighter than the sides. The dorsal
fin is marked with whitish mottling, while all other fins have
dark spots, Young sea bass are green or brown with a dark lateral
stripe running from the head to the tail.
The largest black sea bass caught by an angler in Massachusetts's
waters weighed 8 pounds. However, most adults do not exceed 1.5
pounds. A 12-inch fish generally weighs 1 pound, while an 18 to
20-inch fish weighs about 3 pounds.
The black sea bass has an unusual life cycle: most individuals
are hermaphroditic, reproducing both as female and a male at some
time in their lives. Although some fish are males from the time
they reach sexual maturity, most produce eggs when they first
mature. At some subsequent point the ovary tissues in these fish
become non-functional, while at the same time testes commence
production of sperm. The age at which individuals "switch"
from female to male is variable, although most fish have done
so before they are 6 years old. In heavily exploited populations
in which larger, older males are selectively harvested, the resulting
death of males causes females to change sex at a younger age and
smaller size than would be the case in populations less depleted
by fishing. The effects of reduced abundance of males and reduced
average size of females on the reproductive capacity of sea bass
populations is not fully understood.
Habits
Black sea bass generally overwinter at depths from 240 to
more than 600 feet, with fish inhabiting deeper waters in the
New Jersey-New York region than in the mid-Atlantic region to
the south. Few fish occur north of Cape May (New Jersey) in the
winter, although some are known to travel extensively between
Nantucket Shoals and Cape Hatteras at depths to nearly 1,100 feet.
In the spring, this species displays a general northward and inshore
movement, expanding its range as far north as Cape Cod from May
to October. During the summer, adult sea bass gather around rocky
bottoms, sunken wrecks, old pilings, and wharves. At this time
of year they are most abundant at depths of less than 120 feet.
Young-of-the-year and yearlings tend to summer in estuaries, which
are critically important nursery grounds for this species. In
southern Massachusetts, young-of-the-year start to enter estuaries
in August and move offshore to depths of 180 to 360 feet during
the fall. The largest adults in southern New England tend to begin
their annual offshore and southerly migration as early as August,
while juveniles and smaller adults migrate later in the fall.
Black sea bass reproduce from February to July, with the spawning
season starting earliest in the southern portion of their range
and progressing northward as spring passes. Off the southern New
England coast, they reproduce from mid-May until the end of June.
The eggs are buoyant, floating in the water column until they
hatch 1 ½ to 5 days after fertilization. The larvae drift
in bays, inlets, and offshore areas; they become bottom-dwelling
when they have grown to about ½ inch in length.
Juvenile and adult black sea bass feed upon a variety of benthic
(bottom-dwelling) invertebrate's suck as rock crabs, hermit crabs,
squids, and razor clams.
Management
The general abundance of black sea bass along the East Coast
has been declining for over three decades. Further more, the average
size fish harvested both commercially and recreationally has been
decreasing since about 1950, indication that larger, older fish
have become increasingly scarce.
Commercial harvests have been based upon otter trawl and wooden
pot (similar to a lobster trap) fisheries, although hook and line
is an important local gear type. Annual landings from trawlers
are typically greatest from September to March, when black sea
bass are distributed in more offshore waters. The total annual
catch from trawl fisheries peaked in the early 1950's. Yearly
landings for the entire mid-Atlantic region peaked at nearly 21,000,000
pounds in 1952, and then plummeted to less than 5% of that level
by 1970.
Pots are fished from spring through late fall, enabling fishermen
to harvest sea bass in areas where rugged underwater terrain makes
trawling ineffective. Pot fisheries developed rapidly along much
of the East Coast in the 1950's and more locally in the 1980's.
The recreational fishery has added to the decline in population
abundance along the Atlantic Coast. In 1965 over half of the total
catch of black sea bass was credited to recreational fishing.
One survey indicated that, by 1970, the recreational catch was
at least several times as great as the commercial harvest. Angling
pressure increased markedly in the mid 1980's. In the north Atlantic
region, including Cape Cod, recreational harvest increased nearly
500 percent between 1981 and 1986. Over the same time period,
recreational harvest increased about 1400 percent in the mid-Atlantic
region. From Cape Hatteras to Nova Scotia, harvest increased from
8,100,000 to 31,200,000 fish between 1985 and 1986. Local recreational
harvest has averaged 18,500 fish over the past 10 years.
Both commercial and recreational harvests are now controlled
through a coast-wide management plan. Commercial harvests are
now controlled through a quota system, which holds annual harvests
to approximately 3 million pounds. Recreational fisheries are
managed with minimum sizes and bag limits adjusted as needed to
achieve target harvest levels. Both local commercial and recreational
harvests have risen dramatically in the past few years despite
management constraints. These increased harvests appear due to
an increase in local abundance.
