东太平洋赤道海域茎柔鱼(Dosidicus gigas)小型群体资源分布及其渔场环境特征

DISTRIBUTION AND ENVIRONMENTAL DEPENDENCY OF SMALL SCHOOLS OF SQUID DOSIDICUS GIGAS AND IN THE EQUATOR OF EASTERN PACIFIC OCEAN

茎柔鱼(Dosidicus gigas)是我国远洋渔业的重要捕捞对象。当前针对茎柔鱼渔场分布及其与环境关系的研究多集中于秘鲁海域,而在赤道海域则研究较少。根据2019年12月至2020年2月在赤道海域获取的茎柔鱼生物学数据,以及同期的渔业生产和环境数据,运用胴长-体重关系拟合、Arcgis地统计插值、广义可加模型(GAM)探究其资源分布及渔场环境状况。结果表明:东太平洋赤道海域茎柔鱼胴长范围为136~407 mm,体重范围为117~1557 g;2019年12月~2020年4月各月渔获量呈先增加后减小趋势,2月渔获量最高;CPUE(单位捕捞努力量渔获量)除2月增加外,总体呈下降趋势;渔场集中分布于0°~3°S、105°~114°W海域,不同月份渔场中心经向变化明显;渔场最适SST范围是24.5~25.5℃,最适chl a范围是0.16~0.20 mg/m^(3),月份是影响茎柔鱼CPUE的主要因子。进一步分析表明:该海域茎柔鱼渔获主要为小型群体;小型群体生长发育期(2~3月)对渔场分布有重要影响,生长发育期前茎柔鱼集群度高,生长发育期后逐渐分散活动;单一影响因子与茎柔鱼CPUE相关性不显著,综合考虑其他环境因素及其交互影响是今后的研究方向。

Dosidicus gigas is one of the most important fish in China’s ocean fishery.At present,research on the distribution of the squid and its fishing ground and environment dependency focused on the waters of Peru,and those of specific population of D.gigas in the equatorial waters remain unclear.Based on the biological data and the production and environmental data obtained from fishing during December 2019 to February 2020,the population composition and resource distribution of D.gigas were investigated using mental length-weight relationship fitting,geostatistical interpolation and generalized additive model(GAM).Results show that the mantle length range of D.gigas in the equatorial in the eastern Pacific Ocean was 136~407 mm,and the weight range was 117~1557 g.The monthly catch from December 2019 to April 2020 displayed a trend of first increasing and then decreasing,and peaked in February.The CPUE showed a general downward trend except for the increase in February.The center of fishing grounds distributed in the area of 0°~3°S and 105°~114°W,and the longitudinal direction of the center of the fishing grounds changed obviously in different months.The optimal range of SST was 24.5~25.5℃,and the optimal range of chl a was 0.16~0.20 mg/m^(3).Therefore,the month was the main factor affecting CPUE.In addition,the catch of D.gigas was mainly from small schools;their growth and developmental period(from February to March)determined the distribution of the fishery resource,which the degree of schooling was high before the developmental period,and which they gradually dispersed after the developmental period.Correlation between CPUE and any single factor is not significant.Therefore,study in the future shall focus on other environmental factors and their interactions.