大津漁業協同組合地先漁場における外来魚の漁獲動向にっいて-2003~2015年度漁期を例に-

摘要

In the western part of south-basin fishing ground of Lake Biwa,13 fyke-nets had been operated under the supervision of the Otsu Fishery Association to capture invasive alien species. Almost all invasive alien species catch are Lepomis macrochirus. In 2006, the maximum catch (total of monthly mean) reached about 2,000 kg. Afterwards, the amount of catch indicated a basically decreasing trend reaching less than 1,000 kg in 2015. The amount of catch was closely related with the ambient water temperature in the area, with low temperatures resulting in bigger catch. When catch was low during the previous fiscal year, the following year also indicate low level catch. The catch of invasive alien species has been continuously decreasing, however, their impact on the native species remains a serious problem.