In this study, the mass-flow of material in individual industries in fishing area is analyzed to show material balance, and to extract the problems in establishment of the recycling-based society. The analysis counting nitrogen as the index material results in following facts. The material flow in this area is not like closed-cycle caused by 3 problems, input mass exceeds shipment in agriculture, inflow material exceeds catch and outflow in lake Saroma, a larger part of raw material changed into wastes in marine product processing industry. To establish the society, 6 ways of measures are thought up, such as fertilizer and feed production from scallop viscera, fishing field development, promotion of lake water exchange and so on. The approximate costs to balance in lake Saroma is estimated and compared to the benefits (losses in case no measure were taken).
