尖头塘鳢(Eleotris oxycephala Temmiuck et Schlegel)的年龄、生长和生活史类型的研究

本文采用胸鳍第二支鳍骨为研究东江尖头塘鳢的年龄鉴定材料。胸鳍第二支鳍骨(远侧部)长的骨(R)与体长(L)的关系L=10.6565 54.3848R。用von Bertalanffy生长方程可表达体长、体重与年龄的关系:L=298.6(1-e~(-0.2313(t 0.3028))];W_t=577.4(1-e~(-0.2313(t 0.3028))]~3。根据r-选择和K-选择的典型特征以及渐近体长(L_∞)、渐近体重(W_∞)、生长系数(K)、瞬时自然死亡率(M)、初次生殖年龄(T_m)、最大年龄(T_(max))和性腺指数(GI)等7个生态学参数值,可以判断尖头塘鳢偏向r-选择。应用平衡产量模式计算改变瞬时捕捞死亡率(F)和渔业补充年龄(t_c)时的产量变化,同样证实尖头塘鳢生活史偏向r-选择。作为渔业管理对策,尖头塘鳢的捕捞年龄可定为2—3龄,以2龄为主,这样既能保护资源,又能获得较好的经济效益。

STUDY ON AGE, GROWTE AND LIFE-HISTORY PATTERN OF (ELEOTRIS OXYCEPHALA TEMMINCK ET SCHLEGEL)

The second radial of left pectoral fin is selected for the age determination material of Elentris oxycephala in the Dongjiang river, Guangdong. The relationship between length of the second pectoral radial (R, mm) and body length (L, mm) is expressed as L- 10.6565 54.3848R(r = 0.9939). The relationship between body length or body weight (W, g) and age can be described by the von Bertalanffy growth equation.Lt = 298.6 (1-e-0.2313(t 0.28)) Wt =577.4(1-e-0.213(t 0.028))3.According to the typical characteristics of r and K selection and the given values of 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),it is concluded that the life-history pattern of E. oxycepiala tends to be r-selected. Equilibrium yield model is applied to calculate the fish yield. When the instantaneous fishing mortality (F) is changed, the yield curve has a weaker peak at relatively low value of F, and beyond the value of F, the yield curve declines slowly with increasing F. When the fishery recruit age(tc) is changed, the yield increases to a maximum value at tc = 1.5 years and then decreases greatly with raising t. Analysis of yield curves also demonstrates that the life- history pattern inclines to r-selection. As a strategy of fishery management, the harvesting age can be decided at two to three years of age in which the chief is two years eld, in this way, a greater economic profit might be gained and the fish resourses can be preserved.