东海、黄海不同生长时期鳀鱼的胃排空率

The gastric evacuation rate of anchovy Engrauli japanicus in different growth stages in Huanghai Sea and East China Sea

采用现场和室内模拟方法,测定了东海、黄海不同时期鳀鱼的胃排空率,比较了3种常用数学模型对其排空曲线的拟合程度.统计结果表明,3种数学模型均可较好地描述鳀鱼的胃排空曲线,其中当鳀鱼个体较小或实验温度接近于适温下限时,排空曲线较接近于一条直线,随个体增大和温度升高,则逐渐演变为典型的指数曲线;综合评价结果表明,指数模型最适于定量描述其胃排空曲线,平方根模型次之,直线模型较差.在本研究的生长期范围内,近岸觅食高温期的当年生鳀鱼个体较小,胃排空率相对较低;随后温度虽然降低,但个体有较大幅度增大,排空率明显增大;当温度继续降低至越冬温度时,个体继续增大引起的变化被温度效应所掩盖,排空率降低到最低点;越冬后洄游至近岸海域进行生殖之前,温度和体重与越冬阶段项比较,都有较大幅度增长,且测定时卵巢已发育至Ⅳ期,卵巢发育增大了体内能量消耗,故这一时期鳀鱼的胃排空率远大于其他各时期.

On the basis of the ecological features of anchovy in the Huanghai Sea and the East China Sea, the GERs of 4 main developing periods were determined. The gastric evacuation rate curve was close to a beeline when the fish individual was smaller or the experiment was carried out under over-wintering temperature. With individual increase and temperature rise, the above-mentioned curves gradually changed from linearity to typical exponential ones. The further synthetic assessment indicated that the exponential model was best suitable for describing the gastric evacuation rate curves, square root model came second. During high temperature of seeking food inshore, the GER was lower for small individual. Then, in spite of temperature decrease, the GER still obviously increased with body mass increment. When temperature was continuously declined to over-wintering one, the change brought by body mass was covered up by temperature and the GER declined to the lowest in all of 4 growth stages. After over-wintering, the fish migrated back to inshore waters for spawning. Because both of body mass and temperature significantly increased and sex gland of the determined fish had developed to Ⅳ or Ⅴ stage, which would increased demand to nutrition, the GER in this stage was larger than that of other 3 stages.