The cobia,
Rachycentron canadum, is a fairly common offshore
finfish species, highly prized by both recreational and commercial
fishermen. They are excellent table-fare and usually appear
on everyone’s list of favorite fish to eat.
Cobia
are the only living species in their family and they have
no close relatives. Found almost worldwide in tropical, subtropical
and warm temperate waters, they are open-water fish, but tend
to locate around pilings, buoys or drifting objects. They
even orient themselves under sea turtles and floating boats.
Cobia also appear to be attracted to noise. They range from
saline bays inshore to offshore waters 4,000 feet deep. They
are found over mud, sand, and gravel bottoms, over coral reefs
and in mangrove sloughs.
In the
Gulf of Mexico, cobia winter in the Florida Keys and move
north and west along the Gulf coast to Louisiana and Texas
in the spring. The cobia fishery reflects these migratory
habits. In south Florida, cobia are fished mostly in the winter.
Off of Louisiana, the fishery takes place in spring and summer.
Some research indicates that cobia also move offshore to deeper
waters during cooler months.
Male cobia
mature earlier than females, at 21 inches and 2.5 pounds in
their second year. Females begin to mature in their third
year at 27 inches and about 7 pounds. Cobia form spawning
groups in the northern Gulf of Mexico between May and August.
Egg counts made from 6 females from the Atlantic Coast ranged
from 1.9 to 5.4 million eggs per female.
Fertilized
eggs are buoyant and are kept afloat by a large oil globule
in the egg until they hatch in 36 hours. Highest hatching
rates occur in full-strength seawater at temperatures of 80°F.
Cobia grow rapidly, reaching 7 inches in a matter of months
and 13 to 15 inches by one year old. Cobia are known to live
at least 10 years and may reach 15 years of age. The world
record for rod-and-reel-caught cobia is a 135 pounder from
Australia, although 150-pound fish have been reported.
Cobia
are aggressive feeders, chasing down food from the top to
the bottom of the sea. Fishermen targeting cobia with natural
baits almost always use some form of finfish. From this practice,
it would be easy to assume that finfish are the most preferred
food item by cobia. But when scientists check cobia stomachs,
they usually find swimming crabs, such as blue crabs, dominate.
A food habits study done in the lower Chesapeake Bay bears
this out. The researcher found 28 different species of animals
in the 78 cobia stomachs he examined, but swimming crabs were
by far the number one item in volume and number, making up
78% of Cobia diet. This was true even in large cobia. The
researcher did find one interesting thing that no one had
seen before – some of his cobia had eaten cownose rays,
a very common species in the Gulf as well as the Atlantic.
Download:
cobia.pdf (65KB)
