| 英文摘要 |
Fishery data and catch information of the Taiwanese longline fleets in the Pacific and generalized additive model (GAM) to examine the trends of relative abundance index. All the effects considered in the CPUE standardization including year, month, latitude, longitude, and the interactions were statistically significant (P ＜ 0.05). Standardized CPUEs of the Pacific blue marlin showed an increasing trend since 2000, but decreased slightly from 2005 and relatively stabilized in recent two years. The standardized CPUE of North Pacific swordfish decreased during 2002-2005, but increased since 2005. In both the South and North Atlantic Oceans, the standardized CPUE of swordfish sharply dropped in the late 1990s, and then stabilized from 2000 with higher values appeared in recent two years. The results were insensitive to the inclusion of gear configuration as explanatory variables in the model for all analyses of CPUE standardizations. The stock status of Pacific blue marlin and South Atlantic swordfish were assessed using an age-structured production model (ASPM). Results show that the status of Pacific blue marlin was fully exploited (S/SMSY = 1.00) and currently slightly overfishing (F/FMSY = 1.22). The swordfish in the South Atlantic Ocean was assessed to be overfished (S/SMSY = 0.89), but not overfishing (F/FMSY = 0.79). Assessment results for both species in this study suggest that these two stocks should be monitored closely. |
