At-vessel and post-release mortality of the dusky (Carcharhinus obscurus) and sandbar (C. plumbeus) sharks after longline capture

摘要: Abstract Since the mid 1990’s, stock assessments of shark populations in northwest Atlantic by National Marine Fisheries Service (NMFS) have indicated that sandbar (Carcharhinus plumbeus) and dusky (C. obscurus) are overfished. In response to these assessments, bottom longline fishery was closed 2000, followed 2005. A common management strategy is mandate release prohibited species if caught as bycatch. However, a major assumption most released sharks survive, which may not be case. Longline operations were conducted during 2011 2012 capture tag sharks, order assess (1) at-vessel mortality, (2) post-release (3) investigate effects soak-time on each variables for species. Our findings show experience high with mortality occurring more frequently after 3–5 h line. While time-on-the-line (TOL) increased (16% when less than 3 h TOL; 27.5% TOL) (11% 42% TOL), low (0% TOL). Nonetheless, apparently hardier did exhibit 29% TOL. The total (at-vessel + post-release, including moribund individuals) 97% being captured demersal TOL surpassed 3 h. These data clearly elucidate an interspecific difference vulnerability gear between