| 英文摘要 |
A production model (ASPIC) analyses were conducted for evauating Atlantic yellowfin tuna. The estimate of MSY derived using ASPIC was 146,600 t. The estimate of relative fishing mortality was 0.891, and for relative biomass was 0.826. The ASPIC estimates indicate that there has been both overfishing and an overfished status in recent years, but that overfishing was not occurring in 2006. Examination of the distribution of these estimates shows that about 40% indicate a sustainable situation, in which the stock is not overfished and overfishing is not occurring.
For Indian bigeye tuna stock, the von Bertalanffy growth parameters were estimated by FiSAT software, natural mortality was estimated by Pauly empirical formula, totoal mortality was computed by length converted catch curve and finally, the length based yield per recruit model analysis was pursued. The results show that the exploitation ratio estimated using 2006 sampling size frequency data were smaller than the estimated biological reference points that displayed as target biological reference point ( ) and limited biological reference point ( ). The stock of Indian bigeye tuna is in healthy stock status. The Indian yellowfin tuna was evaluated by ASPM and indicates that the maximum sustainable yield was estimated about 390 thousand tons, the estimate of relative fishing mortality was 0.5, and for relative biomass was 1.3. Results shows that the stock was in reasonable status.
The results of Pacific bluefin tuna by ASPIC indicate that the estimated maximum sustainable yield (MSY) is between 19,000 ~ 26,000 metric tons with corresponding to the optimal fishing mortality about 0.589/year. Without considering the uncertainty, it is suitable to recommend that the total allowable catch (TAC) of Pacific bluefin tuna be around 18,000 metric tons annually.
Stock Synthesis (SS) software was applied to Pacific bigeye and yellowfin tuna assessments in parallel with MULTIFAN-CL. Two parallel assessments of the current WCPO bigeye and yellowfin assessments, which were conducted by Secretariat of the Pacific Community using MFCL. Differences in these underlying model structures and comparisons between the results of MFCL and SS applied to WCPO bigeye and yellowfin assessments were noted. |
