Nomura Jellyfish in Oki Japan

By SEBASTIAN MOFFETT of the WSJ online

Invasion of Jellyfish Envelops Japan In Ocean of Slime

Fisherman Ryoichi Yoshida pulled in his nets before dawn one morning, hoping for lots of yellowtail and mackerel. But the fish were overwhelmed by a heaving mass of living pink slime.

The creatures, called Nomura jellyfish, can measure six feet across and weigh up to about 450 pounds. They have been drifting en masse to places like Oki, a small island 40 miles off the coast, bobbing beneath the surface of the water like pink mines. They rip holes in fishermen's nets, and they poison fish.

"Normally, we just bring up the nets and it takes about an hour," said the weather-beaten Mr. Yoshida, 61 years old, after his crew had cleared the jellyfish out of the nets using long poles and hooks. "Now it takes two or three hours. And some of the fish escape."

Until 2002, these giant creatures were seen only occasionally in Japanese waters. But for the past five years, they have been swarming every year into the Sea of Japan, the water that separates Japan from mainland Asia. During the biggest invasion so far, in 2005, an estimated 500 million jellyfish -- not yet mature -- drifted in each day.

It's hard to calculate financial damage to fishermen, but the Japanese government last year counted about 50,000 incidents of jellyfish trouble. Fish poisoned by jellyfish tentacles die with their mouths agape. That mars their appearance and reduces their value by as much as 20%. "When their mouths are wide open, it means they've died going, 'I'm in pain! I'm in pain!' " explains Mr. Yoshida.

Scientists have various ideas about what causes the outbreak. One has devised a computer model of ocean currents that suggests the jellyfish are breeding off the Chinese coast near the mouth of the Yangtze River. One theory is that pollution, perhaps linked to industrialization in China, is helping create more algae in the sea. The algae are food for plankton, which is food for jellyfish.

Then, too, there is speculation about a link to the Three Gorges Dam, the world's largest hydroelectric-power project under construction in the Yangtze, which could be changing water flows to the sea. A dam in a section of the Danube that runs between Serbia and Romania completed in 1972 changed the river flow, after which the jellyfish population of the Black Sea exploded.

Chinese officials and scientists deny that Chinese pollution has caused the outbreaks.

"No research evidence in China supports a connection between pollution and jellyfish," says Li Qi, a dean of the Ocean University of China. "Floating jellyfish are mostly in the Sea of Japan....That's Japan and Korea's problem."

Eager for a solution, slasher squads of fishermen went out last year armed with barbed poles to attack jellyfish that were jamming up nets. If the jellyfish are cut into three or more bits, they usually die and get eaten by other sea creatures.

Fishermen have also taken a trawl net and added a wire grill like a large potato masher at the trailing end: When the net is pulled through a swarm of jellyfish, they float through and are sliced up.

The Japanese government is doing what it can. It tracks the progress of jellyfish as they swarm through the Sea of Japan, urging trawlers to steer clear of them. The Japanese harvest some jellyfish to eat. Jellyfish can be boiled and added to salads -- though smaller varieties are said to be more tender and tasty. Trying to win converts, the fisheries ministry has drawn up a manual with tips on cooking with giant jellyfish. Menus include jellyfish-flavored biscuits, jellyfish soaked in rum and a dessert of jellyfish chunks in coconut milk.

One coastal firm, Tango Jersey Dairy, has for the past three years produced 2,000 or 3,000 cartons of vanilla-and-jellyfish ice cream. The jellyfish is soaked overnight in milk to reduce its smell, and is then diced. Fumiko Hirabayashi, a director of the dairy, says the jelly cubes are slightly chewy. Jellyfish is also getting publicity in women's magazines because it contains collagen, a protein used in cosmetics.

"We think it's important to use local ingredients," says Mrs. Hirabayashi. "And this has now become a local ingredient." (more)