饵料鱼大小对乌鳢捕食的影响

测量了乌鳢口裂形态,以泥鳅(Misgurnus anguillicaudatus)作为饵料鱼,估算了不同规格乌鳢的摄食率,研究了饵料鱼大小对乌鳢捕食的影响.乌鳢口宽(M_w,cm)、口高(M_H,cm)和口面积(M_A,cm~2)与其全长(T_L,cm)的回归方程分别为:M_W=1.65~(e0.0242TL);MH=1.64 ~(e0.022TL);MA=2.12e~(0.0465TL).当水温保持在22～23℃时,4个规格组的乌鳢对泥鳅的摄食率无显著的差别(ANOVA,P>0.05),均值为1.68%.乌鳢对泥鳅的捕食具有明显的大小选择性,乌鳢最喜欢捕食猎物/捕食者大小比为0.25的泥鳅,很少捕食或不捕食猎物/捕食者大小比小于0.06或大于0.45的泥鳅.

Effect of Prey Fish Size on Predation of Snakehead(Channa argus)

Mouth morphometrics, consumption rate, and size-selectivity predation of prey fish by piscivorous snakehead (Channa argus ) were studied by using mud loach (Misgurnus anguillicaudatus)as prey. The regressive equations of mouth width(M_W, cm), mouth height (M_H, cm) and mouth area (M_A,cm~2) based on total length(L, cm) for snakehead were as follow: Mw = 1. 65~(e0.0242L),MH =1.64~(e0.022L),MA = 2. 12~(e0.0462L) respectively. The consumption rates of snakehead were not significantly different among four body size treatments, with mean value of 1.68% at water temperature ranging from 22℃ to 23℃. The size-selective predation behavior of snakehead was found:when prey to predator size (total length) ratio was 0. 25, the prey were most susceptible to predation by snakehead. However, when the size ratio was less than 0. 06 or more than 0. 45, the prey were less or even not susceptible to snakehead predation. Such information was useful for further study on the effects of predation by snakehead on small-sized fish population in natural waters.