Fishery management and environmental preservation in marine culture in Southeast Asia

本研究旨在对海水鱼类养殖影响日益增大的东南亚沿海海域的环境保护进行基础研究。我们与印度尼西亚政府机构合作，进行了实地观察和长期环境监测。主要研究结果如下：1.尽管受热带气候影响，该海域层结较弱，但极易形成缺氧水团，容易受到鱼类养殖的影响。低氧水团可能是由于水温高，有机物降解速率高，耗氧量大，氧饱和度低所致。2.雨季暴雨过后，有关地区经常发生甲藻、原甲藻和Bahamenes赤潮，导致养殖鱼类发病和大量死亡。3.对两种有代表性的养殖鱼类进行了鱼病调查和两种病毒的检测。低氧水团和赤潮对病毒和应激的感染可能是引起鱼类疾病的原因。4.在有关地区和陆上养鱼设施中检测到多溴二苯醚(PBDEs)的污染，但有机氯(OCS)或丁香化合物的污染并不严重。5.检验了所开发的估算温带海域养鱼指标的物质循环模型与热带地区的可行性。结果表明，由于水温的稳定，模式系数在热带地区更为适用，模式可以利用有关海域的面积、水深和水交换率来估算指标值。

The present study aimed at conducting basic research on the environmental preservation of Southeast Asian coastal seas where impacts by marine fish culture are increasing. We carried out field observations and long-term environmental monitoring in cooperation with the Indonesian governmental institutions. The major results are as follow.1.Even though stratification of the concerned sea area is weak due to tropical climate, hypoxic water mass is easy to be formed and hence the concerned sea area is vulnerable to impacts of fish culture. The hypoxic water mass is supposed to be caused by high rates of organic degradation and oxygen consumption and low oxygen saturation concentration which are due to high water temperature.2.Red tides of dinoflagellates Protoperidinium and Pyrodinium bahamense often occur in the concerned area after heavy rain in rainy season, leading to diseases and mass mortalities of cultured fish.3.Fish diseases for two representative species of cultured fish were studied and two species of virus were detected. Infection with the viruses and stresses by hypoxic water mass and red tides were supposed to be caused the fish diseases.4.Pollution by polybrominated diphenyl ethers (PBDEs) was detected in the concerned area and fish culture equipments on land, but that by organochlorines (OCs) or butiltin compounds was not so serious.5.Availaility of the material cycling model developed to estimate fish culture guideline in temperate sea area to that in tropical one was examined. It was revealed that model coefficients are more available in the tropical area due to the stable water temperature and the guideline can be estimated by the model using the area, water depth and water exchange rate of the concerned sea area.