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Rational management is required for the profitability of the Japanese aquaculture industry and to promote investment in the industry. Although bioeconomic modeling could facilitate rational aquaculture management, it has not been applied in Japanese marine aquaculture. In the present study, we developed a bioeconomic model for oyster farming in Miyagi prefecture, Japan, and determined the optimal harvest schedules under labor constraints. Low, moderate, and high temperature scenarios were simulated to investigate the effects of changes in seawater temperature on farm productivity. Early initiation of harvest, particularly from late October or early November, achieved the maximum profit under the environmental and economic conditions in the present study. The moderate temperature scenario (current temperature conditions) had a high total profit (962,890 JPY) when harvest was initiated on October 29. The high temperature scenario had lower profits than the profits under current conditions, indicating that climate change could have adverse effects on oyster farming profitability in Miyagi prefecture.

This study aims to clarify the distribution of marine products from the Batan Estuary in Panay Island, the Philippines, and the relationships between actors in this distribution system. To achieve these objectives, we interviewed 24 seafood distributors located around the Batan Estuary and in Kalibo, using a structured questionnaire, in March and October 2013 and in September 2015. The results showed that the food system of raw marine products from the Batan Estuary is completed within the country. The results of distributors' proˆt margins indicated that the distributors had not established a monopoly or an oligopoly. They experienced di‹culties in procuring and selling products owing to increased competition during product collection. Theˆndings suggested that the rising domestic demand for marine products has led to overˆshing, causing resource depletion and consequent decrease in the supply of these products, and that this situation might have deteriorated following intensifying competition among distributors.

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