As Japan's Seaweed Forests Die Under Multiple Impacts, Abalone & Fish Vanish As Well - Asahi

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Fisherman Hideo Kawamura recalls how the Suruga Bay seabed full of kelp and other sea grasses gave him an eerie feeling as a novice abalone catcher. "I went down to find grasses dancing as if they were the long hairs of a woman. It was scary," the 75-year-old says, but he could harvest "lots of large abalones." That was more than 50 years ago.

The rich seaweed beds stretching 8,000 hectares and brimming with fish in the western coast of the bay off Shizuoka Prefecture have been transformed into a barren wasteland. The sea grasses began to disappear around 1985; by 1994, almost all were gone. So were the fish and abalones. "After the seaweed beds died off, horse mackerels and striped pigfish quickly swam away," says fisherman Mitsugi Tomita, 70.

The area's annual catch of abalones, which feed on sea grasses, has plummeted from 23.5 tons in 1992 to less than 1 ton. At an area 10 minutes by boat from Sakai-Hirata port in Makinohara, the seabed 10 meters deep had nothing but rocks and stones covered by a thin layer of mud. Few signs of marine life were seen during a 20-minute dive.

Seaweed beds are called the "cradle of the sea" because they provide fish with oxygen, as well as places to hide and lay eggs. The symbol of marine biodiversity, however, is fast disappearing from Japan's coastal regions in a phenomenon called isoyake, or denudation of rocky shores. In 1991, an Environment Agency survey found 200,000 hectares of rich seaweed beds around the nation. The Marine Ecology Research Institute in Tokyo estimates about 20 percent had been lost by 2008. The underwater deforestation is attributed to overgrazing by herbivorous fish, pollution and other factors, but the exact causes have not been determined.

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http://www.asahi.com/english/TKY201002070166.html