东海区小黄鱼种群生物学特性的分析

Analysis of population biology of small yellow croaker Pseudosciaena polyactis in the East China Sea region

本研究以 196 3、1983和 2 0 0 1年东海区渔业资源监测调查资料为依据 ,对小黄鱼 (Pseudosciaenapolyactis)的种群结构、生长和死亡等主要种群生物学特征进行了动态分析。结果表明 ,目前东海区小黄鱼种群的个体小型化、低龄化现象相当突出 ,平均年龄仅为 0 .92 3龄 ;生长加快 ,生长参数k值达 0 .5 5 ;体重生长的体重生长的拐点年龄变小 ,仅为 1.6 7龄 ;性成熟提前 ;死亡率提高 ,残存率减小。尽管小黄鱼近年来产量有所恢复 ,但资源利用对象主要以当年生补充群体为主 。

Little yellow croaker Pseudosciaena polyactis is warm-temperate and economic fish of bottom layer, distributed in the Bohai Sea, the Yellow Sea and the East China Sea. It is the mainly catching target of fishery in China. Since the 1950’s, the resource amount and fishery yield of small yellow croaker have changed greatly. Its fishery resources have experienced four phases such as prosperity, stabilization, decline and restoration. After the 1990’s , because the measures of forbidden fishing zone, forbidden fishing period and summer close season were brought into effect, in the East China Sea the spawning ground and recruitment of small yellow croaker received effective maintenance, and the output obviously went up later on, achieving the historical supreme record of the output of small yellow croaker in the East China Sea region in 2000, which was (15.95×10~4 t,) and the output was 12.50×10~4 t in 2001, which is in relatively high level in history. In fact, the increase of little yellow croaker’s output was not due to the ultimate mending but the commanding fishing intensity. Negatively, the increasing output made the miniaturization and early-maturation more distinct. The catches mainly consisted of young fish and the population structure was low-aged. So in this research, some important population biological parameters of species dynamics such as the composing of body length and weightiness, age structure, growth and death, remaining ratio and gonad maturing were compared and analyzed according to time sequence in order to master the changing rule of small yellow croaker and to provide theoretic guidance for reasonable use and scientific management. According to the data obtained from the fishery resources monitoring in the East China Sea in 1963, 1983 and 2001, the results of analysis indicated that the resource of small yellow croaker in the East China Sea was in a poor state. Miniaturization of population structure and trend of low age were quite distinct; the average body length reduced from 224.23 mm of 1963 and 152.31mm of 1983 to 120.97 mm of 2001; the average age reduced from 5.66 and 1.99 in 1963 and 1983 to 0.923 in 2001; the growth rate increased and growth parameter rose to 0.55 in 2001 from 0.44 in 1983 and 0.24 in 1963; the inflexion age became small, which reduced from 3.80 years of 1963 and 1.95 years of 1983 to 1.67 years of 2001; at the same time the maturation advanced. On the other hand, the total mortality rate increased to 0.520 of 2001 from 0.334 of 1983 and (0.151) of 1963; the survival rate decreased from 0.849 of 1963 and 0.666 of 1983 to 0.480 of 2001. Although the output of the small yellow croaker showed a sign of recruit, the object utilized was mainly focused on the recruitment population one-year old and the over-fishing was sharpening.