中西太平洋金枪鱼围网黄鳍金枪鱼渔获时空分析

中西太平洋的金枪鱼围网渔业目前的年产量约在1×106t左右,其中黄鳍金枪鱼占有很重要的地位。本文通过对围网捕获的黄鳍金枪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,20世纪70年代以来,随着渔船数的增加,中西太平洋围网捕获的黄鳍金枪鱼渔获量分布,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,到80年代在145°E左右,90年代在152°E左右,近年在155°E左右。而黄鳍金枪鱼渔获量纬度重心位于赤道区域,70年代在3°30′N附近,80年代在0°30′N左右,90年代在0°40′S左右,近年在1°20′S左右。经纬度5°×5°小区范围内10年内的最高总产量则从70年代的8×104t,增加到90年代超过20×104t。渔获量空间分布除了随着渔业发展向外海扩展以外,还受到被称为南方涛动的ENSO现象的明显影响,一般来说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,渔获量纬度重心在厄尔尼诺年或次年比较偏南,在拉尼娜次年比较偏北。此外,黄鳍金枪鱼渔获量经度重心在厄尔尼诺年变化比较大,渔获量纬度重心在厄尔尼诺年或次年变化比较大。

Analysis on distribution of yellowfin tuna purse seine catches in the Western Central Pacific Ocean

The total tuna catches by purse seine in the Western Central Pacific Ocean(WCPO) have reached about 1 million tons in recent years and yellowfin tuna(Thunnus albacares) is one of the important targets of the fishery.The spatial-temporal analysis of the yellowfin tuna catch data by purse seine in WCPO was made to describe the trend and development of the fishery.The results revealed that with the increase of the fishing vessels from the beginning of the 1970s,the distribution of yellowfin tuna catches has expanded from the off-shore of Pacific Islands to the central tropical Pacific.The catch center of gravity in longitude has spread with a eastward shifting from around 128°E in the 1970s to around 145°E,152°E and 155°W in the 1980s,1990s and 2000s,respectively.The center of gravity in latitude has varied around equator from around 3°30′N in the 1970s to around 0°30′N,0°40′S and 1°20′S in the 1980s,1990s and 2000s.The highest total catches within a unit region(5°×5°in longitude and latitude) have increased from 8×10~4t in the 1970s to over 20×10~4t in the 1990s.The distribution of yellowfin tuna catches not only has spread to offshore area with the development of the fishery,but also affected by El Nin~o Southern Oscillation.In general,the catch center of gravity in longitude tended to shift eastward during El Nin~o years and westward during La Nin~a years.And the catch center of gravity in latitude tended to shift southward after several months of El Nin~o periods and northward after several months of La Ni(n~)a periods.Furthermore,greater changes have been found in the yellowfin tuna catch center of gravity in longitude during El Ni(n~)o years and those of the catch center of gravity have been found after several months of La Ni(n~)a years.