Английский язык: Сборник текстов и упражнений для студентов специальностей "Промышленное рыболовство". Дьякова Н.П. - 52 стр.

been a traditional favorite. Catfish farming is also practiced in various other states,
though the farther north one goes, the shorter the growing season and consequently,
there are few catfish producers in the north. Besides Mississippi, some of the key cat-
fish producing states are Arkansas, Louisiana and California. The catfish industry is
presently valued at over $ 400 million annually.
Over 90% of the trout produced for human consumption in the United States are
grown in the immediate vicinity of Twin Falls, Idoho. The water from under ground
rivers in this area is of excellent quality and nearly ideal temperature for trout produc-
tion. The trout industry is somewhat smaller than the catfish industry at the present
time and does not appear to be growing appreciably, though there is significant po-
tential for growth if new markets for the product can be developed.
Atlantic and coho salmon have been produced in net-pens in Puget Sound, Washing-
ton for a number of years, and a complementary Atlantic salmon industry is rapidly
developing in the northeastern United States. Salmon net-pen culture has developed
into a major industry in Norway, and Norwegian fishes are being air freighted to the
United States markets where they command a high price. Spurred by that success,
Scotland, Chile and Canada have been actively developing salmon culture industries,
Oysters are cultured on inter tidal or sub tidal beds. Larval oysters, called spat, are
either produced in hatcheries or collected in the wild on substrates to which the spat
attach when they leave the zooplankton and become benthic. In hatcheries, spat are
allowed to settle on dead oyster shell, called cultch, which is then placed on the sea
bed. United States oyster farming is best develop in the state of Washington, which
currently ships a large percentage of its production to the east coast and Gulf of Mex-
ico regions, where disease and pollution problems have severely limited the availabil-
ity of local oysters. Most of the oyster production in Washington is based upon the
Japanese oyster, which is not native to the Pacific North-west but was brought to
Washington, Oregon and California from Japan many years ago.
Freshwater shrimp culture received a great deal of attention in the United States dur-
ing the 1970s. On the basic of culture of the so-called Giant Malaysian prawn, fresh-
water shrimp culture was most successful in Hawaii, though a good deal of research
and development took place in South Carolina, Texas and a few other states. Fresh-
water shrimp are relatively easy to produce in hatcheries, after which the post larvae
are stocked into culture ponds. In tropical climates, aquaculturists can potentially
produce two crops per year. However, there are some major problems associateed
with freshwater shrimp culture. For example, freshwater shrimp are cannibalistic.
When
a shrimp molts sheds its ecoskeleten to provide an opportunity for qrawth it is vulner-
able to attack by other shrimp for a period of several hours until the new exockeleton
hardens. Cannibalism can cause significant losses. Other problems involve short life
of the product after harvest, and the difficulties in marketing have caused many
shrimp culturists to moveaway from fresh water shrimp and toward marine species.



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