藤森康澄, 塩出大輔, 馬場紀彦, 清水晋, 三浦汀介
日本水産学会誌 65 1 26 - 32 The Japanese Society of Fisheries Science 1999年
[査読有り] 小型水槽においてスケトウダラ稚魚の活動性への時刻と照度の影響を調べるため, 明暗(LD), 恒常暗(DD), 恒常明(LL)の3種類の条件下での行動と数種の照度下(0.1,1.0,100lx)における対網行動を記録した。スケトウダラ稚魚の活動量は, LD条件の下で消灯する18 : 00以後に減少し, 点灯する6 : 00から増加した。しかし, 同様のリズムは他の条件では認められず, 概日リズムは確認されなかった。対網行動から推定された網の通過率の照度にともなう減少はゆるやかであった。活動リズムに着目し, 曳網類による昼夜での採取率も推定した。The following two behavioral experiments were conducted in a small water tank (90×45×30cm) to examine the characteristics of activity of juvenile walleye pollock. 1) Locomotor activity was observed with an infrared ray sensor under the different light-dark conditions, 12h light (100lx) and 12h dark (<0.1lx) cycles (LD), 24h constant dark (DD) and 24h constant light (LL). 2) Fish behavior to net under different illuminance (0.1,1.0,100lx) was recorded by a CCD camera. The activity of juvenile walleye pollock showed clearly a diurnal rhythm under the LD condition, which gradually decreased after 18 : 00 and increased after 6 : 00. However, the particular rhythms such as circadian rhythm were not shown in other conditions. The activity of juvenile walleye pollock was considered to largely depend on illuminance condition. In the experiment with relation to behaviors toward a net, the linear regression coefficient between the cumulative number of passing through the net and elapsed time was nearly constant with various illuminance, while the regression coefficient of the approach to it increased with illuminance. The passing rate, the coefficient of passing/the coefficient of approach decreased gently as illuminance increases. The probability of capture for juvenile walleye pollock by a mid-water trawl was estimated separately at day and night based on the method of Barkley.