东江七种鱼类的生活史类型研究

本文通过渐近体长(L∞)、渐近体重(W∞)、生长系数(K)、初次生殖年龄(Tm)、最大年龄(Tmax)、瞬时自然死亡率(M)和性腺指数(Gl)等7个生态学参数来分析鱼类种群生活史类型。根据r-选择和K-选择的典型特征以及各参数间相互关系的显著性,性腺指数、瞬时死亡率和生长系数是判断东江7种鱼类种群偏向rF)和改变渔业补充年龄(tc)时的产量变化,分析产量变化曲线可知,作为偏向r型的种群,提高捕捞强度不能增加渔业产量,适当的捕捞强度可以取得较高的产量;在低龄阶段提高起捕年龄能增加一定产量,但到达一定年龄后再提高起捕年龄,反而引起产量大幅度下降。只有合理控制捕捞强度和起捕年龄,才能获取最大持续产量。  

STUDY ON LIFE-HISTORY PATTERN OF SEVEN FRESHWATER FISHES IN THE DONGJIANG RIVER, GUANGDONG

Life history of fishes may l,e divided into two patterns, i.e. r-selection and K-selection. In this paper, seven ecological parameters, namely, asymptotic body-length (L∞), asymptotic body-weight (W∞), growth coefficient (K), instantaneous natural mortality (M), primary reproductive age (Tm), maximum age (Tmax) and genital gland indices (GI) are used for the analyses of lifehistory patterns of fishes. Seven fishes from Dongjiang River, Guangdong, viz., Cyprinus carpio L, Carassius auratus L., Squaliobarbus curriculus R., Xenocypris davidi B., Cirrhina molitorella C. et V., Siniperca kneri G., Eleotris oxycephala T. et S. seem to have their strategy inclined to r-selection and the genital gland indices (GI), instantaneous natural mortality (M) and growth coefficient (K) have been used as the main basis for this opinion.Equilibrium yield formula is applied to calculate the catch when the instantaneous catching mortality (F) and fishery recruit age (tc) of a particular fish population are changed. Analysis of catch curves demonstrates that for the fish populations of r-selection, higher catch can be obtained through a moderate increase of fishing strength, yet a reckless increase in fishing effort is harmful. Moreover, fish yield may have a certain increase by raising harvesting age when fishes are young, but fish yield will decline greatly by continuously raising harvesting age after fishes reach a certain age. If the decline is due to catching, fish populations will easily recuperate and the maximum sustained fish yield can be expected as long as harvesting strength and harvesting age are regulated reasonably.