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Halibut
The Pacific halibut (Hippoglos-sus stenolepis) was called “haly-butte”
in Middle English, meaning the flatfish to be eaten on holy days.
Halibut belong to a family of flounders called
Pleuronectidae.
Most halibut are torpedo-shaped and symmetrical, the width being about
one-third the length. While Flounders are similar being "flat" they have both
eyes evenly on one side of the head; halibut usually have both eyes on the
right side. On the top side, the color varies from olive green to dark brown
or black with lighter, irregular blotches that are similar to the pattern of
the ocean floor. This protective coloration makes the fish less conspicuous to
predators and prey. The bottom or blind side is white with occasional
blotching and faces the ocean bottom. When viewed from below, the fish blends
with the lighter water. They are about he width being about one-third the
length.
Halibut are strong swimmers and carnivorous feeders. Larval or baby
halibut feed on plankton. Halibut one to three years old are usually
less than 12 inches in length and feed on small shrimp-like organisms
and small fish. As halibut grow, fish become a more important part of
the diet. The species of fish frequently observed in stomachs of large
halibut include cod, sablefish, pollock, rockfish, turbot, and other
flatfish. Halibut will often leave the bottom to feed on fish such as
sand lance and herring. Octopus, crabs, clams and an occasional smaller
halibut also contribute to their diet. Crabs with a carapace width of
up to seven inches have been found in the stomachs of halibut, although
halibut do not appear to be a primary predator of crab. The size,
active nature, and bottom dwelling habits make halibut less vulnerable
to predation than other species. Halibut are occasionally eaten by
marine mammals and are rarely found as prey for other fish.
Pacific halibut can be found along the continental
shelf in the North
Pacific and Bering Sea. They have flat, diamond-shaped bodies and are
able to migrate long distances. Most adult fish tend to remain on the
same grounds year after year, making only a seasonal migration from the
more shallow feeding grounds in summer to deeper spawning grounds in
winter.
Halibut spawn in deep water, where the eggs are fertilized. The number of eggs
produced by a female is related to its size. A 50-pound female will produce
about 500,000 eggs, whereas a female over 250 pounds may produce 4 million
eggs. Fertilized eggs hatch after about fifteen days. Free-floating eggs and
larvae float for up to six months and are transported up to several hundred
miles by currents of the North Pacific.
During development, the larvae drift
great distances with the ocean currents in a counter-clockwise direction
around the Northeast Pacific Ocean. By the time the young fish settle to the
bottom in the shallow feeding areas, a significant journey awaits. Following
two to three years in the nursery areas, young halibut tend to counter-migrate
and move into more southerly and easterly waters.
Maturity varies with sex, age, and size of the fish. Females grow
faster but mature slower than males. Most males are mature by the time
they are eight years old, whereas the average age of maturity for
females is about 12 years. From November to March, mature halibut
concentrate annually on spawning grounds along the edge of the
continental shelf at depths from 600 to 1,500 feet.
Halibut live quite a long time, but their growth rate varies
depending on locations and habitat conditions. Females grow faster and live
longer than males. The oldest recorded female was 42 years old and the oldest
male was 27 years old. Halibut are the largest of all flatfish. The largest
ever recorded for the northern Pacific was a 495-pound fish caught near
Petersburg, Alaska.
Commercial fishing:
Commercial halibut
fishing probably began about 1888 when three sailing ships from New
England fished off the coast of Washington state. As the industry grew,
company-owned steamers carrying several smaller dories, from which the
fishing was actually conducted, dominated the halibut fishery.
Subsequently, smaller boats of schooner design in the 60- to 100-foot
class were used in the fishery. These boats carried crews of five to
eight and, specifically designed for halibut fishing, were very
effective. Today, many types of boats are used in the halibut fishery.
Resource management is much the same as for the sablefish industry.
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