印度洋长鳍金枪鱼资源评估

本研究运用年龄结构资源评估模型ASAP,利用最新的渔业数据和生物学研究成果,对印度洋长鳍金枪鱼资源进行了评估。结果显示,主要资源变量捕捞死亡系数(F)、产卵亲体生物量(SSB)和生物学参考点受亲体-补充量关系的陡度参数(h)的影响很大。假设陡度参数h=0.7、0.8、0.9时,最大持续产量(MSY)分别为25 268t、27 414t、51 924t,当前(2010年初)F与FMSY之比分别为2.85、2.32、1.11,当前渔获量与MSY之比分别为1.65、1.52、0.80。1984年以来,F总体处于上升趋势,SSB处于下降趋势。基本模型条件下(h=0.8),当前资源状况为"趋向于过度捕捞"(Overfishing),且已接近于"过度捕捞"(Overfished)。若h=0.7、h=0.9,当前资源状况分别为"捕捞过度"、"趋向于过度捕捞"。

Stock assessment of albacore Thunnus alalunga in the Indian Ocean

Albacore Thunnus alalunga is one of the main tuna species in the Indian Ocean （IO）. The stock status of IO albacore was uncertain due to the lack of reliable data. We as- sessed the albacore based on the most recent available fishery data and biological information u- sing an age-structured assessment program （ASAP）. The estimated fishing mortality （F）, spawning stock biomass （SSB） and biological reference points were sensitive to the assumed steepness （h） in stock-recruitment relationship. At the assumption of h=0.7, 0.8 （base-case） and 0.9, the maximum sustainable yield （MSY） was 25 268 t, 27 414 t and 51 924 t; the ratio of current （year 2010） F to FMsyWaS 2. 85, 2. 32 and 1. 11; and the ratio of current catch to MSY was 1.65, 1.52 and 0.80, respectively. The F value has been increasing and SSB value has been decreasing since 1984. At the base-case（h=0.8）, the current stock status was ＂overfishing＂ and approaching to ＂overfished＂. At the sensitivity analyses of h = 0.7 and 0.9, the current stock status was ＂overfished＂ and ＂overfishing＂, respectively.