Abstract
Although, the fishery plays important parts in the nutrient flow of body of waters, these effects have not been clarified appropriately. Thus, we evaluated transportation of nutrient in a case of Lake Kasumigaura, Japan. We first calculated amounts of nutrients exported to the outside of the system via fisheries, then compared with various elements to discuss their position in the valley. As a result, export amounts were estimated at 60,000 kg of total nitrogen and 4,500 kg of total phosphorus. They are equivalent to 1.5 % and 3 % of total pollution load of the valley, respectively. From above, fishery should be regarded as one of the environmental improvement technology.
