东海带鱼渔获量变动原因分析

利用1951~1984年东海带鱼年渔获量和捕捞努力量资料,以及降雨、风速和海表温度等的时间系列,分析了带鱼渔获量年际变化与捕捞努力量及环境因素的关系,并建立了渔获量对捕捞努力量和环境变量的回归模型。带鱼渔获量随捕捞努力量的变化可用Fox模型拟合(R=0·89,P<0·01),1951~1974年期间,渔获量随着捕捞努力量的增长而不断提高,但自1974年后,随着捕捞努力量的持续增长,渔获量开始下降。排除捕捞效应后的带鱼渔获量波动还与环境因素显著相关,分析结果表明,长江流域和东海沿岸地区年降水量、渤海海域年均风速、长江口年均风速、黄海和东海海表温度(2月)、东海中部年平均海表温度及南部冬季月平均海表温度等环境因子都与之显著相关。包含捕捞努力量和环境变量的渔获量模型的回归系数为0·97,其置信水平达到99%以上。运用1951~1984年的回归模型对1985和1986年的渔获量作出了预测,其预测值与实际渔获量的相对误差均小于5%,验证了其可靠性。研究的结果表明,带鱼渔获量变动不仅与捕捞作用有关,同时还受环境因素的影响,是两者综合作用的结果。

An analysis of interannual variations of hairtail catches in East China Sea

Using annual hairtail catch and fishing effort data between 1951 and 1984, as well as time series of precipitation, wind speed, and sea surface temperature (SST), interannual trend and variation of hairtail catch in East China Sea (ECS) were analyzed and a regression catch model incorporating fishing effort and environmental variables were established. Hairtail catches showed a significant trend with fishing effort (R=0.89,P< 0.01), which can be well fitted by Gulland-Fox model. Catch increased with fishing effort between 1951 and 1974, but declined with further effort growth after 1974. After removing this trend with fishing effort, variation in catch can be significantly correlated to environmental variables. This includes annual precipitation in Yangtze River Valley and coastal East China, annual wind speed around Bohai, annual wind speed in Yangtze River estuary, February SST in ECS and Yellow Sea, annual average SST in central ECS, as well as winter monthly average SST in southern ECS. The regression catch model incorporating fishing effort and selected environmental variables has a correlation coefficient of 0.97 and a level of confidence of 99%. Regression model of catches between 1951 and 1984 was used to predict catch in 1985 and 1986 with less than 5% relative error. The analysis and modeling suggested that catch of hairtail in ECS was jointly influenced by fishing and environmental variations.