Abstract
Many studies on fishery management assume that the objective of the fishery management is to maximize their economic rent and the fisherman operates to maximize their respective net profits. In order to confirm these assumptions, this paper tries to evaluate the net profit and the marginal net profit of the scoop net fishery in Lake Biwa, which is a main fishery for ayu Plecoglossus altivelis. Here, the net profit is defined as the landing in value terms minus the operating cost. This paper calculates the net profit per boat and the marginal net profit per boat using two cost functions. One includes only the variable cost, and the other is the opportunity cost including the estimated family wages.
The net profit and the marginal net profit have the negative value specially at the end of the fishing season of the scoop net fishery, using a cost function including the estimated family wages. This does not support the above assumptions. This suggests that the fisherman's behavior depends not only on the net profit but also on other factors in the scoop net fishery. This is due to the less adjustability of labor power in the fishery. Under this economical condition of the fishery, it is difficult to maximize the economic rent as an objective of the fishery management.
