鲢、鳙、草鱼摄食节律和日摄食率的初步研究

本文报道了鲢、鳙和草鱼的昼夜摄食节律和日摄食率，并对影响摄食节律和摄食强度的环境因子进行了初步探讨。试验的结果表明，这三种鱼都有明显的摄食节律。鲢、鳙鱼的饱满指数在每天4时最低，天亮前后开始升高，8时起明显升高，12时至20时是一天中的最高阶段，20时以后逐渐下降，午夜24时后，大约有6小时停食。草鱼的饱满指数也是以每天4时最低，12时和20时分别出现两个摄食高峰，两个高峰之间，即16时左右摄食强度有一个低落的阶段。试验也揭示了这三种鱼的日摄食率，即每天按单位体重的进食量。按日平均饱满指数法测计，鲢鱼日摄食率的最低值为5．6％，最高值为16．8％，平均为11．4％；鳙鱼的日摄食率最低值为2．5％，最高值为16．4％，平均值为6．7％；草鱼的日摄食率的最低值为26．3％，最高值为49．9％，平均值为38．6％。在全年中三种鱼的日摄食率都以在7、8月份为最高，这就是鲢、鳙、草鱼一年中摄食的最旺盛期。

PRELIMINARY RESEARSH ON DIURNAL FEEDING RHYTHM AND THE DAILY RATION FOR SILVER CARP,BIGHEAD CARP AND GRASS CARP

The work was conducted during the growing season of fishes (from April to Octo-ber) in 1978, in Xiamen. The total number of fish studied was 1,596. The preliminary study indicated that the silver carp (Hypophthamichthy molitrix),the big head carp (Aristichthys nobilis) and the grass carp (Ctenopharyngoden idellus)all show the diural rhythm of feeding. The peak of feeding lies at 12:00--20:00. Thegrass carp usually retreats for a certain extent at 16: 00. Seasonally these three fishes takefood vigorously in July and August comparatively greater than in other months. By the method of daily average fullness index, the daily ration (the relation of thetotal weight of food taken in a day to the weight of tbe fish) is 36.2% for grass carp,11. 4% for silver carp and 6. 6% for big head carp, and the duration of feeding withina day is about 20 hours for the grass carp, and 18 hours for silver carp and big headcarp. The rhythm of feeding seems to be influenced by the following factors: the intensityof illumination, the amount of dissolved oxygen, and the temperature of the water. Illu-mination plays a very important role, both directly and indirectly, since it affeclswater temperiture and the amount of dissolved oxygen.