Studies on management of abalone stock. I. On Management Policies of Yezo Abalone Population Utilizing Information on Sea Water Temperature.

In this paper, we study the management policy for the Yezo abalone Nordotis discus hannai off the coast of Iwate Prefecture. The abnormally low sea temperatures periodically observed are considered to relate to the mortality rates of the abalone. We propose a management procedure which controls the levels of the fishing mortality and numbers released for re-stocking based on the predicted sea water temperature. Simulations were carried out using the estimated and assumed values of the biological and operational parameters. The simulations suggested that the procedure, which weakens fishing intensity and reduces the released numbers if a higher sea water temperature in the following March is predicted, brings a forvorable status to population size and catch.