Jellyfish swarm northward in warming world

Michael Casey in the Seattle Times: … 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.

T…his year's jellyfish swarm is one of the worst …. 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.

The gelatinous seaborne creatures are blamed for decimating fishing industries in the Bering and Black seas, forcing the shutdown of seaside power and desalination plants in Japan, the Middle East and Africa, and terrorizing beachgoers worldwide, the U.S. National Science Foundation says.

A 2008 foundation study cited research estimating that people are stung 500,000 times every year - sometimes multiple times - in Chesapeake Bay on the U.S. East Coast, and 20 to 40 die each year in the Philippines from jellyfish stings.

…The invasions cost the [Japanese fishing] industry up to 30 billion yen ($332 million) a year, and tens of thousands of fishermen have sought government compensation, said scientist Shin-ichi Uye, Japan's leading expert on the problem.

…He concluded China's coastal waters offered a perfect breeding ground: Agricultural and sewage runoff are spurring plankton growth, and fish catches are declining. The waters of the Yellow Sea, meanwhile, have warmed as much as 1.7 degrees C (3 degrees F) over the past quarter-century. "The jellyfish are becoming more and more dominant," said Uye, as he sliced off samples of dead jellyfish on the deck of an Echizen fishing boat. "Their growth rates are quite amazing."…

Cassiopea jellyfish, shot by Jacopo Werther, Wikimedia Commons