Fishery management and environmental preservation in marine culture in Southeast Asia

本研究的目的是进行基础研究的环境保护的东南亚沿海地区的海洋鱼类养殖的影响越来越大。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。主要结果如下：1.尽管受热带气候影响，该海域层结较弱，但易形成缺氧水团，因此该海域易受鱼类养殖的影响。分析认为，高水温引起的有机物降解速率和耗氧速率加快以及氧饱和度降低是造成缺氧水体的主要原因。2.在雨季暴雨后，巴哈马甲藻原多甲藻和甲藻赤潮发生频繁，3.对两种有代表性的养殖鱼类进行了鱼病研究，并检测到两种病毒。病毒感染和缺氧水团、赤潮等环境胁迫可能是导致鱼类疾病的主要原因。4.在调查海域和养殖设施中检测到多溴联苯醚（PBDEs）污染。但有机氯化合物（OCs）5.所建立的估算温带海区鱼类养殖指标的物质循环模型对温、海、渔、水产品的适应性较好，在热带一个进行了检查。结果表明，热带海域水温稳定，模型系数更容易获得，可利用该海域的面积、水深和水交换率等参数估算该海域的指导值。

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.