Page 235 - NS-2 Textbook

230 NAUTICAL SCIENCES

A U.S. Coast Guard helicopter inspects a Russian fish-factory ship operating in the Gulf of Alaska.

hooks every few feet. They seek mainly to catch marlin, An adult oyster can produce as many as 100 million
sailfish, and tuna. eggs at one laying! But only a few oysters per million
The trawler fleets of the world have greatly in- eggs survive in their natural environment. Each egg de-
creased, especially under Eastern European and Asian velops into a zooplankton larva and floats about for two
flags, and they fish the continental shelves throughout to three weeks before settling down on a rock or other
the world. Trawlers generally stay at sea for several surface. People have traditionally cultivated oysters by
months and bring in a catch of up to 250 tons of fish providing old oyster shells for the larvae to settle on;
that have been automatically cleaned and stored in ice. these old shells are called the clutch. Predators, such as
The Japanese and Russians have developed huge fish- starfish, are cleared out, and the area is fenced off. In a
factory ships that process and can the catch at sea. TIley few years the oysters are ready to be harvested.
serve as "mother ships" to a fleet of trawlers. They This method has been improved upon, however" be-
deliver their products directly to foreign markets at cause it was too slow. Previously, only the food that fell
prices that cannot be matched by fishermen with less so- to the bottom could be eaten by the growing oysters.
phisticated equipment. Now most oyster beds have been replaced by suspension
cultures in which the clutch is hung from ropes attached
to floating frame rafts, or to stakes driven into the bot-
AQUACULTURE
tom. This way, the oysters have access to plankton float-
The oceans are a good source of food now, but their poten- ing by in all depths, and they are safe from their bottom-
tial is even greater. The seas alone could provide enough dwelling enemies. Using this method, it is possible to
protein for the entire world population of more than 6 bil- harvest 6AOO tons of oyster meat per square kilometer in
lion people. At the present tinle, however, only about 1 per- about two years. French oyster farms near Bordeaux pro-
cent of tile protein in the human diet comes from the sea. A duce 500 million oysters armually for the European mar-
change in people's eating habits, careful conservation and ket. The Japanese have increased productivity of oysters
harvesting practices, and cultivation of selected kinds of from 600 pounds per acre lmder natural conditions to
marine plant and animal life could increase food produc- well over 30 tons per acre under culture.
tion from the sea. We must be very careful, however/ not to Even more productive is aquafarming the common
deplete the breeding stock of fish 01' to overfish given areas. mussel. Mussel cultivation near Vigo, Spain, on the At-
If we do, the disaster of extinction that has occurred with lantic Ocean, nets an unbelievable 27,000 tons of mussel
some land animals may be repeated. meat from each square kilometer of floating farms!
A term used today to identify marine ilfanning" is Fish farming has had a high record of success for
aquaculture, the cultivation or raising of marine plants centuries in Southeast Asia, the Philippines, Indonesia,
and animals for food. Sea farming has existed for many and China. The raising of milkfish in shallow fish ponds
centuries. The ancient Romans in the Mediterranean and filled with brackish water has reaped some 200 tons per
the Chinese and Japanese have raised oysters for more square kilometer using commercial fertilizers and more
than 2,000 years. Oyster bed cultivation remains one of than 500 tons using human sewage as the nutrient fertil-
their main commercial marine projects. Today most of izer. In the open ocean, 7 tons is the natural production.
the world's oysters come from such beds. The United Nations has figured that, in Southeast Asia