Abstract
We developed an expanded DeLury's method that adjusted to the diving fishery exploiting abalones along the coast of Shirahama in Shizuoka Prefecture. In the early phase of the fishery, which started in 1982, an increase in catch per unit effort was observed with fishing season. Assuming that this was caused by a change in effectiveness in fishing effort, we applied the expanded DeLury's method allowing for such change to the catch-effort from 1982 to 1997. We assumed some mathematical models for on the change in effectiveness of fishing effort. The parameters were estimated by the maximum likelihood procedure. Several models with different constraints were compared using the Akaike information criterion (AIC). The model with the lowest AIC suggested that the effectiveness of fishing effort increased linearly during the fishing season. Modifications of the model were also discussed.
