Fisheries management by spawning per recruit analysis for Pagrus major around the coastal waters of Ishima Island, Tokushima Prefecture [Japanese]

摘要

Fisheries management of Pagrus major around Ishima Island on the Pacific coast of Tokushima Prefecture was examined based on spawning per recruit (SPR) analysis. % SPR of the present stock is 11.97% and the lower limit status for a sustainable yield is 20%. A SPR of 20% can be attained by reducing mainly the fishing coefficient by 20% on small trawls which raise the fishing pressure around Ishima Island and by more than 60% on fish younger than one year old by fixing the minimum size limit to a total length of 14 cm. The ideal status (% SPR = 30%) can be attained by reducing the fishing coefficient by 20% on small trawls and by 60% on fish younger than one year old, and 40% on one year old fish by fixing the minimum size limit to a fork length of 20 cm. The fish younger than one year old are caught by small trawl fishery, and one year old fish by pole line and set net fishery. Stock management can be attained by reducing the fishing coefficient of small trawls and releasing the fish caught under the minimum size limit.