EFFECTS OF TURTLE EXCLUDER DEVICES (TEDS) ON LOGGERHEAD SEA-TURTLE STRANDINGS WITH IMPLICATIONS FOR CONSERVATION

All five species of sea turtles in United States waters are listed und er the Endangered Species Act as threatened or endangered. A major sou rce of mortality for these turtles is drowning in shrimp trawls; 70-80 % of strandings of dead turtles on beaches are related to interactions with this fishery. In the late 1980s, the state and federal governmen ts began requiring turtle excluder devices (TEDs) in trawl nets; TEDs allow turtles to escape the nets before they drown. To date, the effec tiveness of Thus in reducing sea turtle strandings has not been quanti tatively assessed. In this paper, we report on a statistical analysis of strandings data for loggerhead sea turtles on South Carolina beache s from 1980-1993. These data are long term, based on excellent beach c overage and include eight years before TEDs were required, two years o f intermittent use, and four years with TED regulations in place. Regr ession analysis of the natural log-transformed strandings data showed a good fit to the model (R(2) = 0.88). The model had significant linea r and squared trend terms suggesting the trawlers were sampling from a declining population (-5.3% per year), but the rate of decline has di minished. The analysis shows significant effects of the shrimp fishery in increasing strandings. The effect of TEDs in reducing strandings w as also significant; TEDs reduce strandings by about 44% relative to t he estimated effects of shrimp trawls without TEDs. If reductions in s tage-specific mortality rates are at all similar to the observed reduc tions in strandings due to TEDs and other mortality sources do not int ervene, population model predictions suggest that the outlook for logg erhead population recovery is good.