山东近海高眼鲽种群结构及资源分布

根据秋(2016年10月)、冬(2017年1月)、春(2017年5月)和夏(2017年8月)4个季节在山东近海的底拖网调查数据,对高眼鲽(Cleisthenes herzensteini)种群结构和资源分布的季节差异进行研究。结果表明,高眼鲽的平均体长在秋、冬季较大,而平均体质量则在夏、秋季较大。当体长大于15 cm时,体质量呈现较大的季节变化,体质量增长率在夏季最大。采用von Bertalanffy生长方程表示其生长特性,生长参数L∞为37.85 cm、K为0.28、t0为-0.57。通过Pauly经验公式求得高眼鲽的自然死亡系数为0.54。体长转换的渔获曲线求得总死亡系数为1.69,进而求得现阶段的捕捞死亡系数为1.15,开发率高达68.05%,并求得开捕年龄为1.48龄,开捕体长为12.68 cm。年龄组成为1~5龄,其中1龄与2龄个体分别占总数的45.15%与40.23%。各季节中,只有夏季样品的雌雄性比与1∶1差异显著(p<0.05),且雌性的数量显著多于雄性。50%性成熟体长为22.35 cm,性成熟比例和平均性成熟系数最高的季节出现在夏季。高眼鲽主要分布在底层水温为6.45~19.06℃、底层盐度为31.82~33.10和50 m等深线以深的海域,其平均渔获量在秋季远多于其他季节,在冬季陡然下降,随后缓慢上升。山东近海高眼鲽显现出体长分布狭窄、饵料条件恶化、产卵期延迟和过度捕捞等现象,休渔期前后资源量变化剧烈。

Population structure and spatial distribution of Cleisthenes herzensteini in Shandong coastal waters

Based on the survey data from the bottom-trawl surveys in Shandong coastal waters in autumn(October2016), winter(January 2017), spring(May 2017) and summer(August 2017), the seasonal variations of population structure and spatial distribution of Cleisthenes herzensteini were studied. The results showed that the average length of C. herzensteini was larger in autumn and winter, while the average mass was larger in summer and autumn. When the length is more than 15 cm, the seasonal variation of mass is larger, and the growth rate of mass is the biggest in summer. The ages of C. herzensteini ranged from 1 to 5 years old, in which individuals of 1 and 2 years old accounted for 45.15% and 40.23% of the population, respectively. The parameters of the von Bertalanffy growth equation, L∞, K and t0, were 37.85 cm, 0.28 and-0.57, respectively. The Pauly empirical formula evaluated the natural mortality to be 0.54. The total mortality, the fishing mortality, the exploitation ratio, the age of first capture and the length of first capture were 1.69, 1.15, 68.05%, 1.48 years old and 12.68 cm, respectively. In each season, only the ratio of male to female in summer was significantly different from that in 1:1(p<0.05), and the number of females was significantly higher than that of males. 50% of the length of sexual maturity is 22.35 cm. The highest ratio of sexual maturity and the highest average coefficient of sexual maturity occur in summer. C. herzensteini mainly distributes in areas with bottom water temperature of 6.45-19.06℃, bottom salinity of 31.82-33.10 and depth of more than 50 m. Its average catch in autumn is much more than that in other seasons, which declines sharply in winter and then rises slowly. The C. herzensteini in Shandong coastal waters showed some phenomena,such as narrow length distribution, deterioration of food supply, delayed spawning period and over-exploited stock.The resources changed dramatically before and after the forbidden fishing period.