#8: 今年もか！長崎・対馬沖で大量のエチゼンクラゲ

今年もか！長崎・対馬沖で大量のエチゼンクラゲ
This year too? A large number of Nomura jellyfish in the sea around Tsushima, Nagasaki.
2009年7月8日09時15分 読売新聞

　網に入り込むなど漁業に深刻な打撃を与えるエチゼンクラゲが長崎・対馬沖で大量に見つかり、巨大化した群れが３年ぶりに鳥取県沖に流れてくる恐れが高まったとして、鳥取県は７日、各漁協や境海上保安部を交えた緊急の対策会議を開いた。

Large numbers of Nomura (also known as Echizen) jellyfish, which cause serious damage to the fishing industry by entering nets etc., have been discovered in the sea near Nagasaki. There is rising fear that, for the first time in 3 years, that an enormous group will drift into the sea near Tottori prefecture, so on 7 July both the prefecture fishery cooperative and the Sakai marine preservation department joined together for a meeting to discuss emergency counter-measures.

　過去には網を揚げようとした底引き網漁船がクラゲの重みで転覆する被害も起きているが、被害防止の“決定打”は見つかっていない。漁業者は「昨年の燃油高に続いて、今度はクラゲか」と戦々恐々としている。

In the past, trawlers, having started to haul up their nets, have capsized due to the weight of the jellyfish. However, no "sure-fire" way has been found to prevent this damage. A fisherman, filled with trepidation, said "Continuing on from last year's fuel price rise, this year we have jellyfish?"

　この日の会議には、漁協関係者や県水産試験場の職員、鳥取海上保安署長ら約２０人が出席。県の担当者が、対馬沖で今月、傘の直径が１５〜３０センチのエチゼンクラゲが多い日には約２０００匹確認されていることを報告した。海流に乗って鳥取県沖では８、９月には大量漂流が続く恐れがあり、その頃には８０〜１００センチ、重さ１００〜２００キロにまで成長しているという。

At today's meeting there were representatives from the fishery cooperative, employees from the marine products laboratory, the chief of the Tottori prefecture marine preservation department and others, in all about 20 people attended. The person in charge reported that this month, in the sea around Tsushima, it was confirmed that on some days there were up to 2,000 Nomura jellyfish with heads 15 to 30cm in diameter. There is a fear that, after riding the ocean current, in the sea off Tottori prefecture in August and September there will be a large number drifting about. By that time, they will have grown to 80 - 100 cm and weigh 100-200kg.

　エチゼンクラゲは前回、０５、０６年に大量発生。県内でも定置網漁が大打撃を受け、県沖合底曳(そこびき)網漁協の生越日出夫会長は「底引き網漁でも、クラゲのいない海域を探すのに一苦労。網を揚げてもクラゲを取り除くのに時間がかかり、魚も傷んで漁にならんかった」と振り返る。

The last time there was an outbreak of large numbers of Nomura jellyfish was in 2005/06. The fixed fishing nets in the prefecture also incurred serious damage. The prefecture Coastal Trawler Cooperative president, Mr Hideo Namakashi, looking back on that time, said that "Even for fishing trawlers, it was difficult to search for an area of sea which did not have jellyfish. Even if the nets could be raised, it took time to remove the jellyfish, the fish were damaged, so it did not amount to a catch".

　０２年８月には、岩美町沖で底引き網にクラゲが大量に入り、重みで小型漁船が転覆、船長が海に投げ出され、約４時間後に救助される事故も起きた。

In August 2002 in the sea near Iwami village an accident occurred where, a large number of jellyfish were in a trawlers net, the weight made the small boat capsize, the captain was thrown into the sea and it took about 4 hours for him to be rescued.

　会議では、ワイヤで編んだ網を２隻の船で引き、クラゲを切断したり、定置網に魚を誘導する網の目を大きくし、クラゲをすり抜けさせたりする対策も紹介された。

At the meeting several counter-measures were introduced, to slice the jellyfish by pulling a net made from wire between two boats, or to guide the fish into a fixed net, then make the mesh of the net larger and let the jellyfish slip through.

　しかし、ワイヤの網は作業で船体を傷めるほか、駆除目的の航行となるため燃油負担が大きいのが難点。目の大きい改良網も、結局は漁獲が減るため、普及が進みにくいという。

However, apart from the wire net damaging the boat's hull when in use, a weakness of the cruise designed to exterminate the jellyfish would be the large fuel costs. Also, an improved net with large mesh would, after all, reduce the catch, so it was said that it would be difficult to progress its uptake.

　大量発生の原因は、中国の経済発展に伴う東シナ海の富栄養化などが指摘されているが、よく分かっていない。県水産課は「改良網の普及支援や処理費の補助で漁業者の負担を減らしたい」としている。

The cause of the outbreak is not well understood, but it is pointed out that China's economic development has led to increases in chemical nutrients, and the like, in the East China Sea. The prefecture fisheries department is "supporting the spread of improved nets and by assisting with processing costs wants to reduce the burden on fishermen".

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