英文摘要 |
Based on the length data of 5,160 fish (731 males, 4,225 females, and 204 sex-unknown) randomly collected at Shinkang Fish Market of Taitung during July 2004 to May 2007, the age composition of black marlin (Makaira indica) in the waters off eastern Taiwan were estimated using growth parameters derived from dorsal spine, and the mortalities, per-recruits, and biological reference points were estimated and evaluated. Male black marlin data were not presented in this study due to the lack of enough samples. The estimated instantaneous rate of total mortality (Z) was 0.52 yr-1, natural mortality (M) was 0.20 !O 0.03 yr-1 (mean !O standard error), fishing mortality (F) was 0.32 !O 0.03 yr-1, and the exploitation rate (E) was 0.25. Based on the per-recruit analyses, current instantaneous rate of fishing mortality (FCUR = 0.32 yr-1) was higher than the target reference points (F0.1 = 0.22 yr-1, FSSB40 = 0.19 yr-1) and the limit reference point (FSSB25 = 0.36 yr-1). The results suggested that the fishing mortality should not be increased and the stock condition and developments in the fishery need to be monitored close |