Population trends and fishery closure impacts on sea turtles in the northwest Atlantic

Sea turtle populations have shown dramatic declines from historical abundances and there is considerable concern about the possible extinction of loggerhead and leatherback sea turtles. In this thesis I analyzed for the first time current trends in sea turtle abundance from pelagic longline bycatch data. I also modelled the effects of an existing area closure on turtle bycatch in that fishery.; A closure of the Grand Banks area to the U.S. pelagic longline fishery has been implemented to reduce loggerhead and leatherback turtle bycatch by this fishery. Simple closed area models were used to evaluate the direct effects that this management action and subsequent reallocation of effort may have on sea turtles as well as on 20 other bycatch species which are of conservation concern. Empirical data from U.S. swordfish longline observer and logbook data (1992–1999) were used in the analysis. Effort was reallocated under two assumptions: (i) total fishing effort remained constant and (ii) total swordfish catch remained constant. (Abstract shortened by UMI.)...