Bycatch impacts on the health and conservation of endangered north pacific loggerhead turtles (Caretta caretta): turning science into policy

At Baja California Sur, México (BCS), the overlap of an important juvenile loggerhead foraging area with intense, local small-scale fisheries results in amongst the highest sea turtle bycatch rates documented globally, which... [ view full abstract ]

At Baja California Sur, México (BCS), the overlap of an important juvenile loggerhead foraging area with intense, local small-scale fisheries results in amongst the highest sea turtle bycatch rates documented globally, which in turn fuels equally high stranding rates. Additional factors may also contribute to regional loggerhead mortality including bycatch in undocumented fisheries, directed hunting for the illegal trade and consumption, and natural factors including predation and disease. From 2007 to 2013, we assessed baseline health parameters of loggerheads in the region and established a comprehensive strandings program during the fishing seasons to determine causes of sea turtle mortality. Over 60 turtles were captured alive and unharmed using snorkel. All were diagnosed as clinically healthy. On the other hand we collected, 1,121 loggerhead carcasses along a 43km stretch of coastline in Playa San Lázaro BCS since 2007. In 2014, 705 turtles were stranded. However, very few turtles were in fresh condition. Fully trained veterinarians performed necropsies and a board-certified pathologist did histopathological analyses on 12 turtles that were grossly in relatively fresh condition. A subset of these turtles exhibited liver, renal and lung lesions compatible with biotoxin poisoning. Further testing is required to determine if domoic acid or a similar biotoxin is involved in exacerbating loggerhead strandings related to bycatch fisheries. Multifactorial etiologies have been identified as a cause of mortality of the endangered loggerheads by scientists appointed by the federal government in 2011 suggesting that disease may result in high morbidity and mortality. Our studies concluded that exceedingly high local mortality is the result of fisheries bycatch. In 2014, the International Sea Turtle Society and many other NGOs sent letters to President Peña Nieto to take action. In the last year, the federal government has designated loggerhead habitat, where fishing is not allowed, to be protected long term.