| 英文摘要 |
The aims of this project include (1)studying on age and growth of albacore in South Pacific and (2) asses the Indian albacore stock. About the studying on age and growth of South Pacific albacore, the 1st dorsal spines and the last caudal vertebrae were used to study the age and growth of South Pacific albacore, by mean of character reading. A total of 373 spines and 135 caudal vertebrae were collected from 373 albacore specimens which were sampled by observers from Taiwanese distant water fishing boats operated in South Pacific, from June/2009 to February/2013. Since the central portion of the spines will become vascularized when fish gets older, the earlier rings will inevitably become obscured. Both spines and vertebrae collected from 135 individuals were used to calibrate the ring counts. From the results, the relationship between first ring of spine (R1) and the difference of ring counts on vertebra and spine (ΔCi = Vno - Sno) was obtained as ΔCi = -2.2523+2.9682 R1. All justified ring counts and fork length data set were then used to estimate the parameters of the von Bertalanffy growth equation by using non-linear regression method, and the results thus obtained were: L∞ = 142.9 (cm); k = 0.1371 (1/Yr); and t0 = - 1.40 (Yr). About the stock assessment, Age Structured Production Model (ASPM) with stochastic recruitment was applied to assess stock status of Indian albacore. For the selection of Base case, yields, indices of abundance and the needed biological parameters are made. A series of model fits related to different assumptions or parameters to examine the sensitivity of the results to these choices were also carried out. The status of Indian albacore resource and risk analysis were assessed by the best run of Base case and sensitivity tests.The results indicated that: (1)the annual yields were closed to or over MSY in recent years; (2)all the estimates of depletion are higher than 0.2, but decreased to the level of 0.4 about in recent years; (3)the fishing mortalities (F) were closed to the mortality at MSY (FMSY) in recent years, even was larger than FMSY in 2010; (4)though the mature biomass (Bmat )is still larger than the mature biomass at MSY (B mat MSY) in all the years, the value of Bmat 2011 was very closed to it. And the result of risk analysis indicated that only the yield decreased 20% thus could keep the fishing mortalities lower than F2011 and make the mature biomass (Bmat ) raised and closed to the mature biomass at MSY (Bmat MSY) in the further 14 years. |
