Ocean Harvest

As a major science, oceanography is young, and to most nations a relatively remote business of water-temperature graphs or current lines on a chart. But last week Japanese fishing vessels, trailing long, baited lines off the Canary Islands, hauling dragnets along banks off Kamchatka, were providing a dramatic demonstration of how skillful interpretation of those graphs and lines can pay off.

Japan has always depended on the sea; 80% of the protein in the Japanese diet comes from seafood. Before World War II it was the leading fishing nation. But after the war the U.S., the U.S.S.R., Canada, Red China, Korea and Australia excluded Japanese fishermen from many of their traditional fishing grounds.* Something had to be done to make up for the loss.

In the early 1950s, Japan's Board of Fisheries began an elaborate campaign to find new fishing grounds. Systematically, its scientists collected data on water temperatures, current flows, plankton and weather conditions all over the world's oceans, including the North and South Atlantic and Antarctic waters. Its survey ships cruised everywhere, watching for clues that pointed to fish.

Currents for Tuna. Main target was tuna, a surface fish that is usually found far from land and therefore is not claimed as the property of any nation. Japanese scientists found that the different species of tuna inhabit different ocean currents. So the bureau's ships started at known tuna-fishing grounds and followed the currents. At intervals they fed out buoyed lines. Usually they caught little or nothing; most of the vast ocean is poor in fish. Then, suddenly, the water would come alive with tuna. Hungry Japan acquired another source of food.

Nine new tuna grounds have been found so far, including one in the Atlantic west of the Canary Islands. Japanese fishermen that work that remote area figure they will be away from home for at least six months at a time. Since the ocean currents often shift (carrying the tuna with them), the board's survey ships keep constant vigil, reporting their findings to the fishing boats lest they travel 10,000 miles only to find no fish.

New Bottoms. Japan's oceanographers have also spotted new places to drag for bottom fish such as cod and halibut. To find them, a survey ship cruises in likely places until it is in water of the right depth (no more than 750 ft.). Then its scientists study the bottom with electronic sounding gear, test the currents with meters. If the bottom is rocky or too steep, it will damage the fishermen's dragging apparatus. If a fast current flows near the bottom, fish will be scarce. A fast current at higher levels may make dragging difficult. In the past few years, Japanese survey ships have discovered four new dragging grounds off Kamchatka and the Aleutians.

Overall, Japan's new fishing methods have produced spectacular results. The 1958 catch (latest for which figures are available) came from all over the earth and exceeded the biggest prewar catch by 900,000 tons.

* The tuna fishing ground most recently denied them: the Russian rocket target area southwest of Hawaii.

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