| 英文摘要 |
一、Biology and fishery of Pacific Bluefin tuna Biology of Pacific bluefin tuna (Thunnus orientalis) was described including its external morphology, taxonomy, distribution, life history, growth, reproduction, migratory route of larvae and juveniles, and physiological ecology. Two spawning areas (Western North Pacific and the Sea of Japan) were investigated to reflect the problematic evaluation of stock status and issues of identification of birth place, the proportion of migration northward of juveniles from Nasei Shoto waters, the migratory routes of juveniles and the relationship to their environmental factors, the understanding of migration routes from eggs, larvae and juveniles of Pacific Bluefin tuna as occurrence of recruitment, introduction of numerical method to simulate the migratory routes, and evaluation of the separated proportion of juveniles migrated into either side of Pacific Ocean or the Sea of Japan by using the preference of their swimming direction. Pacific Bluefin tuna is harvested along the regime of Kuroshio Current, juveniles of small sized (about 1-3 cm SL) and medium sized (2-8 cm SL) is caught in the waters of western area of Okinawa main island and Amami Islands, respectively. Juveniles of Pacific bluefin tuna grow when they migrate northward along regime of Kuroshio Current. Besides, the mechanism of separation of juveniles into either the Sea of Japan or Pacific side was not known. The report was also dealing with the description of Pacific bluefin tuna fishery and evaluation outlook of stock status assessed recently. 二、Trial estimation of standardized catch per unit effort of yellowfin tuna by Taiwanese longline fishery in the tropical waters of Atlantic Ocean The trial standardized catch per unit effort (CPUE) of Atlantic yellowfin tuna caught by Taiwanese longline fishery was estimated by delta general linear models. For the manipulation, several factors were used including year, quarter, subarea, vessel category and the two-way interactions. Before estimating CPUE, historical catch and effort data were selected and re-examined by spatial and temporal distribution; then the 1990-2011 catch and effort data within the tropical area (15oN – 20oS) were selected and stratified into 5 subareas to make the nominal CPUE homogeneous as possible among subareas. The GLM and Delta-GLM were used to standardize yellowfin tuna CPUE for Taiwanese longline fishery in the Atlantic tropical waters from 1990 to 2011. The results obtained are very similar trend but the displacement of peaks in the series; and different trends were occurred between Japanese longline CPUE series and anyone of the Taiwanese 3 series. |
