By Ines Min
Contributing Writer
Clusters of up to 500 giant Nomura jellyfish found in many locations off Korean shores are frustrating fishermen, who are complaining of a double-digit reduction in fish they catch around this time of the year.
The recent overpopulation has also led to added labor, a decrease in profits and damaged nets.
The National Fisheries Research and Development Institute reported that out of the world's 350 known jellyfish species, 40 to 50 of them have been spotted in the Southern and Yellow seas .
The jellyfish overpopulation is attributed to rising ocean temperatures that provide advantageous breeding grounds.
The government updates weekly its tracking of the surging number of jellyfish, whose recent overpopulation has become a source of problems for fisheries.
Nets often break from the added weight of the unwanted prey, which can also bruise or kill fish. Overall, the jellyfish have hurt profits and led to extra labor needed to remove them from fishing nets.
Nomura jellyfish make up the majority of the population and are one of the largest types of jellyfish. They can grow up to two meters in diameter and weigh up to 220 kilograms.
The Agriculture, Forestry and Fisheries Department is working on a comprehensive national program to cut the jellyfish numbers, including the removal and utilization of by-products, for cosmetics and pharmaceuticals.
A fishing net specially designed to efficiently remove unwanted jellyfish was tested on Aug. 17 in Busan.
A public demonstration was held on the net, which has three different stainless steel wiring grids inside, which slice and kill larger jellyfish while allowing other catch to pass through.
"It seemed to work well," said Kim Tae-gi, an official from the National Fisheries Research and Development Institute. "Now it's being used everyday" on fishing boats, he said.
Japan and China are also concerned about the overpopulation, which has caused profit losses and inhibited commercial growth on waterfronts.
The Japanese use collagen from the jellyfish in cosmetic products and the government is encouraging more public consumption. Jellyfish ice cream, cookies and other edibles have been sold for several years.
Consumption has not been advocated in South Korea because Nomura jellyfish have a high toxicity level and a strong flavor, which is difficult to market, a government official said. Instead, jellyfish for consumption in South Korea are largely imported.
The National Fisheries Research and Development Institute reported that in 2008, 8,383 tons of imports were brought in from countries such as China, Thailand and Indonesia, while 8,595 tons were imported in 2007.
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