根据2006年10月至2007年9月南海北部大陆架海域4个航次底拖网调查资料,分析了该海域渔业资源的种类组成、种类丰富度和渔获率的空间分布.结果表明,渔获种类数以湛江断面最多(405种),汕头断面最少(337种).种类数随水深变化呈非对称正态分布,以40-80m水深组种类数最多.物种丰富度指数D的空间分布与种类数基本一致.在总渔获物中,鱼类、头足类和甲壳类3大类群重量组成比例为80:12:8,在断面分布上,组成比例鱼类以珠江口断面最高,头足类以湛江断面最高,甲壳类以阳江断面最高.在水深分布上,鱼类占比随水深的增加而增加,头足类占比在40-100m水深较高,甲壳类在10-20m浅水区最高.鱼类最主要的优势种有6种,其中,深水金线鱼主要在90-120m水深占优势,黄鳍马面鲀在60-90m水深占优势,条尾绯鲤在60- 120m水深占优势,单棘豹鲂鮄在120-200m水深占优势,六指马鲅在30-60m水深占优势,龙头鱼在10-30m水深占优势.鱼类渔获率断面分布以珠江口和粤西海域较高,汕头海域最低；水深分布渔获率随水深的增加而增加.头足类渔获率以粤西和珠江口海域较高,粤东海域较低；在100m水深范围内,渔获率随水深的增加而增加,100m以深渔获率减少.甲壳类渔获率以阳江断面最高,其他断面均较低；10-20m浅水区渔获率最高.通过与历史资料比较,南海北部渔业资源衰退后种类更替现象十分明显,大型优质种类数量大幅减少,小型低值鱼类和头足类数量明显上升,受近海捕捞压力较大影响,鱼类的渔获率呈现随水深增加而增加的分布趋势.%in fish. Of the dominant species, Nemipterus bathybius was dominant in 90-120m depth, while Navodon xanthopterus in 60-90m, Upeneus bensasi in 60-120m, Daicocus peterseni in 120-200m, Polynemus sextarius in 30-60m, and Harpodon nehereus in 10-30m. For transect distribution, high catch rate of fish was found in the Zhujiang estuary and western Guang-dong waters, and the lowest was found along Shantou transect. For depth distribution, fish catch rate increased with water depth. Catch rate of cephalopoda was found higher in western Guangdong and Zhujiang estuary than in eastern Guangdong waters. Cephalopoda catch rate increased with water depth within 100m and decreased below 100m. The highest catch rate of crustacean was found along Yangjiang transect, and was distinctly lower along other transects. By comparison with the exist-ing data, succession of species was distinct after the decline of fishery resources in the northern South China Sea. While the resource of large-scale and well quality species substantially decreased, the resource of small-scale and bad quality species increased obviously. Under the pressure of fishing catch power in coastal waters, the distribution of fish catch rate showed the trend of increasing with depth.
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