太湖梅梁湾生物控藻围栏内鲢、鳙比肠长和比肝重的动态变化

为了解滤食性鱼类的消化生理指标及其生态适应性,2005年1-10月,调查了太湖梅梁湾生物控藻围栏中鲢(Hypophthalmichthys molitrix)、鳙(Aristichthys nobilis)在不同生长阶段的比肠长和比肝重指数的动态变化,分析了比肠长和比肝重与温度、体长、体重以及饵料组成的关系。结果表明,鲢、鳙比肠长和比肝重的季节变化都非常明显,比肠长均值分别为9.66和5.73,夏季的比肠长均明显增大。总的来看,鲢的比肠长和季节变化幅度均大于鳙,表明在滤食和消化浮游植物上,鲢具有更强的环境适应能力;鲢、鳙的比肠长与水温显著正相关(鲢P<0.01;鳙P<0.05),而与体长、体重以及饵料组成的相关性不显著;温度导致的摄食强度变化应是鲢、鳙比肠长季节变化的主要原因。鲢、鳙的比肝重均值分别为1.57%和1.91%,鳙的比肝重明显大于鲢,这可能与鳙摄食更多的浮游动物有关;鲢、鳙的比肝重与温度、体长、体重以及饵料组成均有显著的相关性(P<0.05),表明生物个体的形态特征与其所利用的资源环境有非常紧密的联系。

Relative Gut Length and Hepato-somatic Index of Silver and Bighead Carp in the Biomanipulation Fish Pens in Meiliang Bay of Lake Taihu

The relative gut length and hepato-somatic index of silver and bighead carp were investigated in the biomanipulation fish pens in Meiliang Bay of Lake Taihu during January to October 2005.Our results showed that the relative gut length and hepato-somatic index of silver and bighead carp greatly changed over time.The average relative gut length of silver and bighead carp was respectively 9.66 and 5.73,which significantly increased in summer.The variation of gut length of silver carp was more significant than that of bighead carp,suggesting a stronger ability of feeding phytoplankton.There were significant positive correlations between the relative gut length of silver and bighead carp and water temperature,while,no significant correlations were found between the relative gut length and bogy length,bogy weight and food composition.Relative gut length of silver and bighead carp should mainly be influenced by the temperature-controlled feeding intensity.The average hepato-somatic index of silver and bighead carp was 1.57% and 1.91%,respectively.Bighead carp usually had a higher hepato-somatic index than silver carp,which maybe attribute to more zooplankton in its diet.Hepato-somatic index of silver and bighead carp were significantly correlated with temperature,bogy length,bogy weight and food composition.Environmental variation can induce dramatic changes in the traits of organisms.