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Effects of summer close season and rational utilization on redlip croaker( Larim-ichthys polyactis Bleeker) resource in the East China Sea Region

2004; Science Press; Linguagem: Inglês

1005-8737

Longshan Lin,

Marine Bivalve and Aquaculture Studies

Redlip croaker ( Larimichthys polyactis Bleeker) was a traditional fishery resource in history.Be-fore 1970 s, L. polyactis , L. croceus , Trichiurus japonicus and Sepiella maindronide were regarded as the four important commercial fishery resources in the East China Sea Region. However, the stock of redlip croaker was decreased badly because of overfishing after 1980's,and the average fishery resources were de-creased from 7.6 × 104 t in 1950's to 0.9 × 104 t in 1980's. The state paid much attention to it,and carried out the Action of Spring Close Season in Lusi fishing ground which is the largest spawning ground of redlip croaker from 1981. The fishery resources of redlip croaker were resuscitated slowly in the East China Sea after 1980' s and increased from 1. 7 × 104 t in 1991 to 5.0 × 104 t in 1994. The effect was embodied especially after 1995 when the Summer Close Season was carried out in the round,and the fishery resource increased rapidly from 7.6 × 104 t in 1995 to 16.0 × 104 t in 2000, which set up the greatest record in the resource of redlip croaker in the East China Sea Region. The conserving effect and the limitation of Summer Close Season on redlip croaker were analyzed based on the survey data conducted by Fishery East China Sea Region Fishery Resources Dynamic and Monitor Net during 1991 to 2002. In addition, the maximum sustainable yield (MSY) was calculated with Ricker Reproduction Modei based on the present resource status,and the management to consolidate the effects of Summer Close Season was also discussed. It was shown that the conserving effect of Summer Close Season on redlip croaker was significant; the resource was increased 1.71 times and the relative resource density was the greatest in a year after Summer Close Season. However, the effect of Summer Close Season did not work after fall and winter. In December, the remained resources were only 11% of the resources at the end of Summer Close Season. The stock structure of redlip croaker changed qualitatively and was more unreasonable at present. The proportion of young-of-the-year ( YOY) stock was increased from 43.14% before Summer Close Season to 74.64% in recent years after Summer Close Season, and the proportion of remained stock was decreased from 56.86% before Summer Close Season to 25.36% in recent years. The expected effect of Summer Close Season on restoration of redlip croaker is hardly achieved due to the overfishing, and the preservation and restoration of redlip croaker will be realized if annual yield is controlled at 10 × 10 t of the MSY for redlip croaker in the East China Sea Region.