Nomura's jellyfish may strike Japan this year the same way they did in 2005. (Photo: C. Reports/Stock File)

Jellyfish invasion imminent

JAPAN
Tuesday, July 14, 2009, 02:00 (GMT + 9)

Japanese researchers fear that the giant Nomura’s jellyfish found in waters off the Chinese coast will exceed recent trends and grow to an unprecedentedly massive invasion.

Unusually high numbers of these jellyfish were detected by Hiroshima University’s marine surveys conducted late in June in the Yellow and East China Seas. Nomura’s jellyfish (Nemopilema nomurai) can reach 2m in diameter and a colossal weight of 220kg, Asahi reports.

Ocean currents are expected to pull the jellyfish into Japanese waters in overwhelming numbers. Over the past few years, Japan has experienced similar plagues by this species, which have adversely impacted the domestic fishing industry.

The Fisheries Agency has already notified fishers throughout the country, who may have to refrain from venturing into open waters to fish as a result of the plague. The jellyfish tend to damage nets due to their high weight, harm harvested fish with their toxins and sting fishers when the latter attempt to remove the jellyfish from the nets.

June’s marine survey predicts that early this month jellyfish will reach the sea off Tsushima Island.

In 2005, hundreds of millions of dollars’ worth of damage was caused by an invasion of jellyfish. Scientists fear the upcoming invasion will match the former’s level of destruction.

Professor of biological oceanography Shinichi Ue at Hiroshima University has been leading the marine survey. He chairs a governmental research committee that works to create technology that will predict and help control jellyfish plagues.

In 2006, Ue began surveilling Nomura’s jellyfish population density in the southern Yellow Sea and the northern East China Sea.

Ue’s team found abundant amounts of these animals with umbrellas 10-50 cm long across and estimated an average distribution of 2.14 jellyfish per 100 sqm between 20-24 June. Compared to the 2008 figures of 0.01 jellyfish per 100 sqm, the June numbers are over 200 times higher.

"The arrival (of a large number of the jellyfish) is inevitable. A huge ’jellyfish typhoon’ will hit the country," Ue said.

The June numbers are also almost triple the 0.77 jellyfish per 100 sqm calculated in 2007. The fishing industry struggled with extensive damage that year in the Sea of Japan; the government received 15,500 complaints.

"The situation is quite similar to that when a large number of these jellyfish came to Japan’s coastal waters in the past," said Hideki Akiyama, head of the Fisheries Research Agency’s East China Sea Fisheries Oceanography Division.

Also more alarmingly, the jellyfish currently in Chinese waters are moving southward and directly toward Japan. In 2007, they had moved rather northward and thus reached the Sea of Japan from the side of Korea.

The Pacific Ocean coast will be hit by record amounts of jellyfish, say researchers.

As to the option of fighting back, attacked or killed jellyfish release billions of offspring, reports Earthweek.

By Natalia Real
editorial@fis.com
www.fis.com 

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