北部湾西北部近海鱼类资源的时空分布特征研究

根据2012年1月(冬季)、4月(春季)、8月(夏季)、11月(秋季)在北部湾西北部广西近海4个航次的渔业资源调查资料,进一步结合同步测定的水文情况,探讨北部湾西北部广西近海的鱼类资源分布特征和季节变化及其影响因素。调查结果表明,该调查海域共鉴定鱼类125种,鱼类资源质量密度夏季(402.46kg/km^2)>春季(343.22kg/km^2)>秋季(145.13kg/km^2)>冬季(53.99kg/km^2);尾数密度春季(84.34×10~3尾/km^2)>夏季(51.54×10~3尾/km^2)>秋季(26.53×10~3尾/km^2)>冬季(16.81×10~3尾/km^2);平均体长、体质量分别在春季和夏季最大,分别为7.15cm和7.65g;幼体比在夏季最高,为85.86%。从时间上看,春、夏季的鱼类资源密度大于秋、冬季,从空间上看,沿岸水域的资源密度大于近海水域,这与该水域各水团随季节变化的消长密切相关。依据相对重要性指数确定各季节的优势种,二长棘鲷是夏季最重要的优势种,同时也是春、夏、秋3季的共有优势种。通过贡献率β值可知,该区域鱼类总密度变化与主要优势种变化关系密切,且调查海域多为规格较小的幼鱼,其为北部湾渔场重要的产卵场、育幼场和索饵场,对整个北部湾鱼类资源的补充具有重要的作用。

Temporal-spatial Distribution Characteristics of Fish Stocks in North-west Coastal Waters of Beibu Gulf

The distribution characteristics and seasonal quantitative changes in fish stocks as well as their influential factors were studied by the data from four oceanographic surveys in Guangxi offshore in the Northwest Beibu Gulf in spring(April),summer(August),autumn(November)and winter(January)in2012,along with synchronous hydrological features.The results showed that there were 125 fish species in the waters,and the density of fish in terms of weight was the maximum in summer(402.462kg/km^2),followed by spring(343.22kg/km^2)and autumn(145.13kg/km^2),and least in winter(53.99kg/km^2).By contrast,the density of fish in terms of number was the maximum in spring(84.34×10~3 ind/km^2),intermediate in summer(51.54×10~3 ind/km^2)and autumn(26.53×10~3 ind/km^2),and least in winter(16.81×10~3 ind/km^2).The maximal average body length of fish was observed in spring(7.15cm),while the maximal average body weight in summer(7.65g).The proportion of juvenile was the highest in summer(as high as 85.86%).From the time,the fish density was obviously higher in spring and summer than that in autumn and winter.In spatial distribution,the fish of density was higher in coastal waters than those in offshore waters,which was closely related to the changes in different water masses during four seasons.According to the index of relative significance(IRI),Paerargyrops edita was the most important dominant species in summer,and the common dominant species in spring,summer and autumn.Based on theβvalue,the seasonal change in fish density was closely correlated with the dominant species,and had the same distribution characteristics.In the survey area,foraging juveniles were predominant.This area was the important spawning,nursing and feeding grounds in Beibu Gulf fishing ground and played an important role in the supplement of the entire Beibu Gulf fish resources.