This Oct. 14, 2009 photo shows a giant jellyfish drifting off Kokonogi in western Japan. Once considered a rarity occurring every 40 years, jellyfish swarms are now an almost annual occurrence along several thousand kilometers (miles) of Japanese coast, and far beyond Japan, decimating local fishing industries from the Japan Sea to the Black Sea. (AP Photo / Junji Kurokawa)

By MICHAEL CASEY, AP Environmental Writer KOKONOGI, Japan – A blood-orange blob the size of a small refrigerator emerged from the dark waters, its venomous tentacles trapped in a fishing net. Within minutes, hundreds more were being hauled up, a pulsating mass crowding out the catch of mackerel and sea bass. The fishermen leaned into the nets, grunting and grumbling as they tossed the translucent jellyfish back into the bay, giants weighing up to 200 kilograms (450 pounds), marine invaders that are putting the men’s livelihoods at risk. The venom of the Nomura, the world’s largest jellyfish, a creature up to 2 meters (6 feet) in diameter, can ruin a whole day’s catch by tainting or killing fish stung when ensnared with them in the maze of nets here in northwest Japan’s Wakasa Bay. “Some fishermen have just stopped fishing,” said Taiichiro Hamano, 67. “When you pull in the nets and see jellyfish, you get depressed.” This year’s jellyfish swarm is one of the worst he has seen, Hamano said. Once considered a rarity occurring every 40 years, they are now an almost annual occurrence along several thousand kilometers (miles) of Japanese coast, and far beyond Japan. Scientists believe climate change — the warming of oceans — has allowed some of the almost 2,000 jellyfish species to expand their ranges, appear earlier in the year and increase overall numbers, much as warming has helped ticks, bark beetles and other pests to spread to new latitudes. …

Jellyfish swarm northward in warming world