효과적인 자원관리를 위한 어업관리수단의 생물경제학적 분석

Abstract

In this study, the bioeconomic modeling method was used for the effective analysis of fishery management to estimate optimal yield of hairtail. In addition, the purpose of this study is to present an optimal yield standard considering both the resource biological and economic aspects simultaneously when determining the annual TAC level and to provide a sustainable management implication for hairtail stocks. The catch level of hairtail was relatively high with maximum of 166 thousand tons in 1974 and 153 thousand tons in 1983. However, it decreased to one third of the level recently which remains at almost 50 thousand tons. As for the catch between 2006-2019 on annual basis, various fishing types of catch has been used including offshore longline, offshore stow net fishery, large powered purse seine, large powered pair trawl, and coastal complex fishery and majority of the fishing was done by offshore fishing except the coastal complex fishery. In particular, the offshore longline catch has been consistently high every year. From the fisheries business evaluation of the five major fisheries, the fixed ratio, a typical ratio for verifying capital allocation, was over 100% which showed poor financial condition. Especially, the offshore stow net fishery showed highest at 144.2%. In that respect of debt ratio, the large powered purse seine fishery showed the highest of 116.6% and other 4 fisheries showed lower than 100%. In the case of owner's asset, it was found somewhat stable with the ratio of more than 50% of four other fisheries except the large powered purse seine fishery which showed at 46.2%. Recent 3 years of the profit rate for each fisheries based on the fisheries income, costs, and profits, which are directly related to the change in the amount of catches, showed the highest with the offshore longline fishery at 31.0%, followed by the offshore stow net fishery(26.6%), large powered trawl fishery(21.0%), large powered pair trawl fishery(14.2%), and large powered purse seine fishery at–5.3%. Last 3 years of the hairtail yield in each fisheries showed the highest of offshore longline fishery at 79.2%, followed by offshore stow net fishery(19.3%), large powered pair trawl fishery(7.0%), large powered purse seine fishery(5.1%), and large powered trawl fishery at 1.1% and the profit of offshore longline fishery was the highest at 317 million KW. Reference points of hairtail management derived from major parameter of State-space production model were estimated to be 0.382 of intrinsic rater(r), 442,738 tons of carrying capacity(k), 42,108 tons of maximum sustainable yield(MSY), 221,369 tons of Biomass(BMSY), and 0.190 of fishing mortality(FMSY/year). From this model results, the estimated hairtail stock biomass was recorded the highest in 2000 at 364,664 tons and decreased continuously from 2016 for 3 years which stayed at 64% of BMSY with 141,692 tons in 2018. The biomass is expected to be decreased gradually as the catch amount was higher than the estimated ABC. Bioeconomic analysis that combined both biological model and economic model using yield of hairtail as well as production costs targeted management regulations such as size limit, closed season/time, and TAC for effective hairtail stock management. If the result of bioeconomic analysis applies in each fisheries management in 15 years or 20 years, target stock biomass(BMSY) can be achieved with size limit below 25cm, closed season/time from June-October, TAC which is averaged from 2016-2018, and TAC1.2. Therefore, in the future, it is appropriate to choose one of the above regulations for the recovery of hairtail stocks and its management. From the aspects of stock recovery for 20 years, the most effective way is to expand the closed season/time from June to October. However, if excessive fishing efforts are put after the closed season/time, additional measures which can control the catch amount should be implemented together because the effects of closed season/time may be offset.