Proceedings of the 27th Annual ISTS: Sea turtle bycatch and terrestrial ecology: A review of the interactions between strandings, scavengers and terrestrial ecosystems

Elena M. Finkbeiner and Wallace J. Nichols. 2008. Sea turtle bycatch and terrestrial ecology: A review of the interactions between strandings, scavengers and terrestrial ecosystems. In: Rees, A.F., M. Frick, A. Panagopoulou and K. Williams., compilers. Proceedings of the Twenty-Seventh Annual Symposium on Sea Turtle Biology and Conservation. NOAA Technical Memorandum NMFS-SEFSC-569, 262 p.

Sea turtle mortality results in the occurrence of carcass strandings on coastlines all over the world, the extent of which is established from international stranding networks and research efforts. For example, the Sea Turtle Stranding and Salvage Network reports 16,879 strandings on the shorelines of all states between Texas and Maine between 1998-2002 (STSSN). In addition, various research studies are underway in an attempt to understand the leading causes of mortality in sea turtles, including fisheries observing, PIT tagging (Spotila et al. 2000), satellite telemetry (Hays et al. 2003), and carcass assessment (Panagopoulos et al. 2003; Koch et al. 2006; Balazs 2006). Studies suggest the deployment of gillnets, longlines, trawls, and hook and line gear as the main cause of sea turtle mortality. As strandings accumulate on beaches, coastal ecosystems are the recipient of this resource allocation. The terrestrial implications of sea turtle strandings have yet to be studied; therefore, this preliminary review is a compilation of data regarding scavenger and stranded turtle interactions, obtained through literature review and personal communication with field researchers. Among other species, black vultures (Coragyps atratus), turkey vultures (Cathartes aura), ghost crabs (Ocypode quadrata), dogs (Canis lupus familiaris), fire ants (Solenopsis invictiva), crocodiles (Crocodylus sp.), coyotes (Canis latrans) (Nichols, pers. obs.) and black bears (Ursus americanus) have all been observed feeding on stranded turtles (eg: J.P. Martinez, pers. comm.; P. Plotkin, pers. comm.; S. Murphy, pers. comm.; M. Lamont, pers. comm.). At some locations, the majority of strandings are due to anthropogenic causes, and an unnatural accumulation of carcasses on coastlines may have an ecological effect. For example, an increasing number of scavengers in coastal areas may affect ecosystem equilibriums by altering species interactions or through the reallocation of resources. Future studies in this theme should be considered in order to understand the ecological relationship between scavengers and stranded turtles, and to distinguish any resulting ecosystem impacts.