Abstract

The purpose of this study is to find the light intensity which induces maximum gathering rate and to observe the variation of the gathering rate both in daytime and at night by using marbled sole, Limanda yokohamae (Gunther). An experimental tank ($360L{\times}50W{\times}55H\;cm$) was set up in a dark room. An illumination system was attached to the end of one side of the tank to control horizontal light intensity. Six artificial light sources were prepared by combination of two light bulbs (5W, 150W) and seven filters. During the experiment water depth was maintained 50 cm level in the tank. The tank was marked into six longitudinal sections each being 60 cm long to observe the distribution of fish. The fish were acclimatized in dark condition for 50 minutes prior to the main experiment. Upon turning on the light, the number of fish in each section was counted 40 times every 30 seconds, and the gathering rate was obtained from the average number of fish in each section. The light intensity inducing maximum gathering rate was 1.9 lux ($1.2{\sim}2.9\;lux$) in the daytime and 0.7 lux ($0.5{\sim}1.1\;lux$) at night. The variation of the gathering rate of fish in illumination time was small and comparatively fluctuated with stability.

백색광에 대한 문치가자미 Limanda yokohamae의 행동을 조사하기 위하여, 빛의 세기가 서로 다른 6가지 백색인공광원으로 광자극을 주어 그에 대한 반응을 주간과 야간으로 구분 조사한 결과는 다음과 같다. 1. 광자극에 대한 수조내의 구간별분포곡선은 대체로 W우형이 되었으나, 빛의 세기에 따라 그 형태가 다소 차이가 있었다. 2. 수중조도가 높아짐에 따라 광원에서 멀리 떨어지는 경향을 나타냈으며 주야간의 차이가 다소 있었다. 3. 집어율이 최대가 되는 수중조도(적정조도)는 주간에 1.9 lux($1.2{\sim}2.9lux$), 야간에 0.7lux ($0.5{\sim}1.1lux$)로서 주간에 더 높았다. 4. 조명시간의 경과에 따른 집어율의 변화는 적어 안정하게 변동하였으며, 주간보다 야간의 집어율이 더 높았다.

Keywords