Description
Perhaps more than any other member of Massachusetts' rich array
of natural resources, the Atlantic cod is recognized as a symbol
of the Commonwealth's natural heritage. This species, so entwined
in the early history of settlement of coastal Massachusetts that
a model (referred to as the "Sacred Cod") hangs in the
statehouse, is native to most of the North Atlantic Ocean. In
the northwest Atlantic it inhabits waters from western Greenland
south to Cape Hatteras, North Carolina, and is most abundant from
the coast of northern Labrador to the Nantucket Shoals region
off Massachusetts.
Cod are easily distinguished from most other marine fish by their
three rounded dorsal fins and two anal fins that are mirror images
of the second and third dorsals. They also have a prominent barbell
("whisker") on the chin.
Cod lack the large dark blotch on the side that is characteristic
of the closely related haddock. The square or indented outline
of the cod's tail differs from the rounded tail of the tomcod.
The cod also lacks the slender, elongate extensions of the pelvic
fins characteristic of the tomcod.
Individuals vary widely in color. Most cod are grayish green
to reddish brown of their backs and sides, and white on their
bellies. They are speckled on the upper portion of their bodies,
the sides of their heads, and their fins and tails. The lateral
line, a series of pores that allows fish to detect disturbances
in the water, is conspicuously lighter than the dark sides of
the body.
Cod occasionally reach lengths in excess of 5 to 6 feet. The
heaviest fish on record, caught off the Massachusetts coast by
a commercial vessel, weighed over 200 pounds. The Massachusetts
angling record was set by a fish weighing 85 pounds 10 ounces
boated on Jefferys Ledge in 1984. In recent years, harvested cod
very rarely weigh more than 100 pounds, with 50-60 pound fish
normally the largest sizes taken. Offshore cod tend to be larger
than inshore ones, the former frequently reaching sizes of 25
pounds and 40 to 42 inches in length while the latter usually
weigh 6 to 12 pounds and measure 27 to 34 inches in length. One-year-old
fish are typically 7 to 12, 2-year-olds 14 to 17 and 3-year-olds
19 to 22 inches length.
Both sexes usually reproduce for the first time when 5 or 6 year
old. The fecundity (number of eggs produced in a given year) of
females increases with age and size. A 40-inch female may lay
about 3 million eggs and a 50-inch female up to 9 million eggs
in one spawning season.
Habits
Atlantic cod live in a variety of habitats but generally are
found in depths of 200 to 360 feet with temperatures ranging from
34 to 46 degrees F in the summer, and depths of 295 to 440 feet
with temperatures of 36 to 39 degrees F in the winter. They seldom
are found deeper than 660 feet.
Cod undergo seasonal migrations in the more northerly and southerly
reaches of their range in the northwest Atlantic. Those fish inhabiting
polar waters in the summer and autumn migrate to more southerly
and deeper waters in winter and spring, while fish summering in
the Nantucket Shoals region overwinter along the New Jersey coast.
Fish inhabiting the region between coastal Nova Scotia and Cape
Cod do not exhibit predictable seasonal migrations. Some move
considerable distances in search of food or in response to overcrowding
at certain spawning grounds, but generally adults in our region
remain within limited areas of uniform physical conditions. Cod
do not swim about in large schools, but they do travel in small
groups when searching for food.
The cod is a winter spawner. It reproduces from November to December
along the coast of southern New England. Spawning takes place
at depths of 3 to 350 feet, with the greatest activity occurring
in about 200 feet of water. Adults inhabiting inshore areas generally
move offshore to reproduce.
Larvae measuring about 0.2 inches hatch from 10 to 40 days after
spawning, depending upon water temperatures. The larvae inhabit
the open water column feeding upon microscopic copepods for 2
to 3 months after hatching. Then they move to the bottom where
they die and feed among rocks and algae until they are large enough
to swim away from predators.
The smaller bottom-dwelling cod feed mainly upon small crustaceans
such as shrimp and amphipods. Adults will eat almost anything
small enough to fit into their mouths, including clams, cockles,
mussels, and other mollusks, as well as crabs, lobsters, and sea
urchins. Adults also pursue schooling fish, eating substantial
numbers of herring, capelin, shad, mackerel, silver hake, young
haddock, and other species. Voraciously pursuing a variety of
potential foods, cod will occasionally dine upon some very exotic
items: ducks, shoes, jewelry, and rope have been found in the
stomachs of captured cod.
Young cod are eaten by many species of fish, including pollock
and larger cod. Once juvenile cod grow to about 8 inches, they
can effectively swim away from many of their potential predators.
Adult Cod occasionally fall prey to spiny dogfish and sharks.
Management
The cod has been an extremely valuable resource for several
centuries in Massachusetts. Its extensive use as a food dates
back to the earliest period of European settlement in coastal
New England. In colonial times, it was deemed so important that
in 1693 the General Court of the Massachusetts Nay Colony ordered
that farmers could no longer use cod as fertilizer. This action
was one of the first recorded attempts at natural resource conservation
and management on this continent.
Although one of the earliest fisheries resources to be broadly
utilized after European settlement in New England, cod populations
along the US coast proved to be very resilient. Cod apparently
withstood more than 3 centuries of harvest without displaying
major, long-term regulations in abundance. However, mid-twentieth
century advances in fishing technology and the introduction into
the northwest Atlantic of distant-water foreign fishing fleets
during the late 1950's led to a period of reduced abundance and
major annual fluctuations in population size. During the mid-1980s
commercial vessels captured mostly 3 to 5 year old fish, indication
that few larger, older individuals remain along the North American
coast.
Recreational harvest constitutes a modest portion of the total
cod landed. From 1979 to 1984, recreational harvest averaged about
13% of the total cod harvest in the Gulf of Maine and about 10%
on George's Bank and areas to the south.
Cod harvest in the Fishery Conservation Zone (FCZ: 3 miles to
200 miles from the shoreline) falls under the Northeast Multispecies
Fishery Management Plan of the New England Fisheries Management
Council. Regulations under this plan include minimum legal size
regulations for commercial and recreational harvest (17 inches
for the latter), area closures, and mesh size regulations for
commercial trawl nets. In Massachusetts territorial waters, the
Massachusetts Division of Marine Fisheries has established minimum
legal size limits (23 inches for recreational fishing and 22 inches
for commercial fishing for 2002) to protect the spawning potential
of cod populations.
