| 英文摘要 |
This study will analyze the fishing logbook and observer data of Taiwanese tuna fishing vessels in South Atlantic Ocean. First transfer 1982-2001 Catch-at-size data into Catch-at-age to estimate age-structure and evaluate the recruitment of South Atlantic Albacore. And then use GLM to standardize CPUE trend, analyze the relation between Albacore catch and the marine environmental conditions. Finally, use Age Structured Production Model (ASPM) to assess the current stock status, find the optimal fishing strategy and implement risk analysis of South Atlantic albacore stock to provide crucial information of fishery management need. The results of this project will offer effective benefits for sustainably utilizing the South Atlantic albacore resources, ensuring the rights and interests of Taiwanese South Atlantic albacore fishery. The results obtained as follows: (1) Based on the dominancy of albacore in their different oceanic habitats, summarized and pictorically shown their size distribution characters respectively, there are 3 subregions in the South Atlantic ocean: in which big-size in the subregion 1＆2,and small ones in the 3. And we found out there have been a circular fluctuations occurred in subregion 1 might imply some biological phenomena had arisen. (2) The most significantly related to sea surface temperature is average weights of albacore catch with a correlation coefficient 0.688,and to chlorophyll is the numbers of albacore catch with a correlation coefficient 0.707,however there is no significant relationship between salinity and all albacore catch factors.(3) According to the standardized CPUE trend ,we see a continuous decline from the beginning of Taiwanes longline fishery to 90s, then increase till the mid 90s, and leveled off since 2003 up to 2011.And factor “subregion” played the most important role in explanation of the model.(4) Evaluated by ASPM , with a the criteria 24,000mt as a constant TAC(Total allowable catch), we can assure that there appears a risk of smaller than 50% chance that the prospecting SSB/SSB2011 will reach the value always greater than 1 in-5years. |
