山东半岛南部三疣梭子蟹增殖放流群体贡献率

Contribution of Releasing to Stock Quantity of Swimming Crab Portunus trituberculatus in Waters off Southern Shandong Peninsula

根据2010—2016年每年5—8月在山东半岛南部海域对三疣梭子蟹增殖放流前后进行的3个航次的跟踪调查结果,定量分析三疣梭子蟹自然群体和增殖放流群体的数量,并根据三疣梭子蟹放流苗种数量和放流后捕捞产量以及增殖放流群体的贡献率和回捕率,对三疣梭子蟹近年的增殖放流结果进行分析。研究结果表明,2010—2016年的5月,山东半岛南部三疣梭子蟹增殖放流前自然群体资源量较少,相对资源密度为0.20~17.17尾/(站·h),平均资源密度为3.46尾/(站·h);放流苗种数量逐年增加,平均放流苗种数量为14 367.78万尾,放流后约10d的跟踪调查结果表明,三疣梭子蟹的资源量有了较大提高,相对资源密度为6.7~53尾/(站·h),平均资源密度为16.65尾/(站·h),放流群体贡献率的均值为85.82%;8月进行的相对资源量调查,其相对资源密度为0.75~6.72尾/(站·h),均值为1.76尾/(站·h);秋汛期间的回捕产量为2332.91~10 410.77t,平均产量为5308.66t,根据各年秋汛期间调查获得的三疣梭子蟹的平均体质量,得出的放流群体回捕率为5.76%~21.18%,平均回捕率为12.16%。总体上,放流群体在山东半岛南部海域三疣梭子蟹的资源群体中起到了很重要的补充作用,放流群体贡献率较稳定,且相对处于较高水平。

We conducted a quantitative analysis to assess the recapture rates and releasing contribution of swimming crab Portunus trituberculatus in waters off southern Shandong peninsula using survey data collected in May,June,July,and August of 2010-2016 via comparison of survey results before and after the releasing of swimming crab in the waters off southern Shandong Peninsula.It was found that there was very low population size,with the relative resource density of 0.20 to 17.17 individuals per site per hour,and average resource density of 3.46 individuals per site per hour.The swimming crab was released at increasing rate year by year,with average number of 14.37778 million per year,and the amount of resources of swimming crab was found to be increased 10 days after releasing,with average resource density of 16.65 individuals per site per hour,and the average population contribution rate of 85.82%.In August,the relative resource quantity survey showed that there were average resource density of 16.65 individuals per site per hour,relative resource density of 0.75 to 6.72 individuals per site per hour,and an average of 1.76 individuals per site per hour.The annual production of swimming crab was estimated to be from 2332.91 to 10410.77 t,with average value of 5308.66 t.Measurement of body weight of swimming crab caught during the autumn of the year revealed that the recapture rate was varied from 5.7 6%to 21.1 8%,with average value of 12.16%.The findings indicate that the released population has played an important role in the stock of swimming crab in the southern part of Shandong peninsula,with relatively stable and high recapture rate.