中西太平洋金枪鱼围网鲣鱼渔获量时空分布分析

中西太平洋的金枪鱼围网渔业目前的年产量约在100×104t左右,其中鲣鱼占有很重要的地位。本文通过对20世纪70年代以来围网捕获的鲣鱼渔获数据进行时间序列以及空间位置变化等时空分析,试图找出其变化规律以及趋势。结果表明,从20世纪70年代以来,随着渔船数的增加,中西太平洋的围网捕获的鲣鱼渔获量分布,从太平洋岛屿近海逐渐向太平洋热带中部海域扩展。渔获量经度重心随着中西太平洋金枪鱼围网渔业的发展有向东移动的趋势,70年代在128°E附近变化,80年代在144°E左右,90年代在153°E左右,近年在158°E左右变化。而鲣鱼渔获量纬度重心位于赤道区域,70年代在2°N附近,80年代在1°30′S左右,90年代在2°50′S左右,近年在2°55′S左右变化。经纬度5°×5°单个小区范围内10年内的最高总产量则从70年代的11×104t,增加到90年代超过了69×104t。渔获量空间分布除了随着渔业发展向外海向赤道以南扩展以外,还受南方涛动(ENSO)现象的明显影响,一般来说在相邻的数年中渔获量经度中心在厄尔尼诺年比较偏东,在拉尼娜年比较偏西。

Analysis on spatial-temporal distribution of skipjack tuna catches by purse seine in the Western and Central Pacific Ocean

The total tuna catches by purse seine in the Western and Central Pacific Ocean(WCPO) have reached about 1 million tons in recent years and skipjack tuna(Katsuwonus pelamis) is the most important target of the fishery.The spatial-temporal analyses on the skipjack tuna catch data by purse seine in WCPO were made to determine the trend and development of the fishery.The results revealed that the distribution of skipjack tuna catches has expanded from the offlying sea of Pacific Islands to the tropical Western and Central Pacific with the increase of the fishing vessels from the beginning of the 1970's.The center of catch in longitude has spread with a eastward shift from around 128°E in the 1970's to around 144°E in the 1980's,to around 153°E in the 1990's and around 158°W in recent years.The catch center in latitude has varied near equator from around 2°N in the 1970's to around 1°30′S in the 1980's,to around 2°50′S in the 1990's,and around 2°55′S in recent years. The highest total catches in a unit region(5°×5°grid in longitude and latitude) increased from 11×10~4t in the 1970's to over 69×10~4t in the 1990' s.The distribution of skipjack tuna catches not only was spread to offshore area with the development of the fishery,but also was affected by El Nin~ o Southern Oscillation.In general,the center of catch in longitude will shift eastward during El Nin~ o periods,but it will shift westward during La Nin~ a event.