南沙群岛重要珊瑚礁水域鱼类资源数量分布

1998年3—5月和1999年5—6月．采用手钓、延绳钓和流刺网3种作业方式在南沙群岛的渚碧、南薰、东门、美济、赤瓜、永署和华阳等7座珊瑚礁水域进行了2个航次的鱼类资源调查。结果表明，7座珊瑚礁水域不同作业方式的鱼类资源相对丰盛度差别较大，其中刺网以永暑礁最高，手钓以华阳礁最高，延绳钓以南薰礁最高；同时．刺网和手钓不同水深区域鱼类资源的相对丰盛度也不相同．其中刺网以11～30m区域最高．手钓以10m以浅和51～80m区域较高；分析认为，造成礁区之间鱼类相对丰盛度差异的主要原因不是初级生产力．而是生态环境因素，主要是礁盘形态和大型海藻的数量。另外．各礁区水域的优势类群有明显不同．这主要与洞穴的大小和数量、大型海藻及珊瑚的种类和数量等生物和非生物环境有关。

Quantitative distribution of fish resources in main coral reef waters of Nansha Islands

DuringMarchtoMay1998and MaytoJune 1999, twosurveycruises were carried out insevencoral reef waters of Nansha Islands : Zhubi , Nanxun , Dongmen , Meiji , Chigua , Yongshu and Huayang reefs using three fishing methods , namely handlining , longlining and gillnetting. The results show that there are obvious differences in relative abundance of fish resources between different reefs surveyed with respect to the three fishing methods , the highest relative abundance of fish resources for gillnetting being in Yongshu reef , for handlining in Huayangreef,andforlonglininginNanxunreef. Andforgillnettingandhandlining,therearealsovariationsin the relative abundance in different depth waters , the biggest value observed for gillnetting occurring in 11 -30m depth waters , and for handlining in less than 10m. The cause leading to the differences is not primary productivity but ecological conditions, mainly related to reef shape and macroalgal biomass. In addition, the dominant taxonomic groups caught in the reefs surveyed are of manifest discrepancy , and this is directly related to such biotic and abiotic environment factors as size and number of grotto , macroalgal biomass and species and quantity of coral polyp etc.