貝桁網の漁獲效率の推定について

抄録

An attempt was made to estimate the catch efficiency of a dredge, used for capturing Scapharca subcrenata from the analysis of data obtained on catch. In the fishing experiment using the dredge, the hauls were repeated many times, each haul for a short duration of time, within the limited area of the fishing ground. The catch per haul decreased gradually with each subsequent haul though it fluctuated considerably. Under the assumption that the catch per haul is approximated by a binomial distribution, an analysis was made with the data on catch obtained in the experiments and gave 0.18-0.29 as the estimates of the catch efficiency for the species in consideration. In addition, it seemed that the gear efficiencies a of the dredge to S. subcrenata and S. broughtonii, which were obtained from an analysis on catch statistics, were nearly proportional to the catch efficiency estimated in the experiments and sweep area per unit effort, and inversely proportional to the area of the fishing ground. Here, the catch efficiency was defined as the probability that the species in the area swept by a haul was caught by the haul.