doi:10.1111/j.1365-2664.2008.01507.x Impacts of fisheries bycatch on loggerhead turtles Blackwell Publishing Ltd worldwide inferred from reproductive value analyses

• Main Authors: Bryan P. Wallace, Rebecca L. Lewison, Shaleyla Kelez, Larry B. Crowder
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Subjects: Pacific; North Atlantic
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.374.9582; http://imina.soest.hawaii.edu/PFRP/reprints/Wallace_etal_JApplEcol2008.pdf

1. Fisheries bycatch has been implicated in declines of many long-lived marine vertebrate populations, but bycatch impacts on these populations vary according to spatio-temporal overlap in fisheries operations and critical ontogenetic habitat, as well as to characteristics of fishing gear. 2. To provide a framework for comparing the relative impacts of different fisheries on populations of loggerhead sea turtles Caretta caretta, we compiled published data on sizes of individual loggerheads taken as bycatch in North Atlantic, North Pacific and Mediterranean fisheries, and used Leslie matrix models to calculate reproductive values (RVs) for bycatch samples of loggerheads within these basins. 3. Sizes and RVs of loggerheads varied significantly based on spatial overlap in fisheries and ontogenetic habitat as well as on fishing gear. Thus, fisheries operating in areas occupied by larger, older turtles (e.g. trawls in neritic areas) tended to interact with more reproductively ‘valuable’ turtles than fisheries that operated in areas occupied by smaller, younger turtles (e.g. oceanic and pelagic longlines). 4. We also found evidence of size-selectivity among different fishing gears (e.g. wider size variation among loggerheads taken in driftnets and trawls than in longlines) and gear configuration (e.g.