繁殖期におけるニゴロブナの行動と地理的環境

概要

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An acoustic telemetry by a manual tracking receiver was used to observe the behavior of 4 adults of Nigorobuna Carassius auratus grandoculis, in the south basin of Lake Biwa, Japan from 7 May through 4 June, 2008. The fish were implanted with acoustic transmitters and were released. Positions of the individuals during daytime were recorded for 7, 8, 3 and 2 days, respectively. Ambient water temperatures of individuals were recorded during tracking simultaneously. In addition, water temperatures in 9 sites of the south basin were continuously recorded at an interval of 30 minute by data loggers and contours of the lakebed of tracking area were recorded by an echo sounder. Maps of geographical environments including temperature and depth were made by GIS software and compared to the fish positions. The fish moved according to the horizontal graduation of water temperature. The ambient water temperatures of fish distributed in narrower range rather than the water temperatures recorded by data loggers in the south basin. These results suggest that Nigorobuna prefer certain temperature range (18-20℃) and move to the preferred temperature area during the spawning season.
2013-07-15