Content area
Full text
Correspondence should be addressed to: S.M. Guimarães, Laboratório ECOPESCA–Biologia do Nécton e Ecologia Pesqueira, Departamento de Biologia Marinha, Universidade Federal Fluminense, Niterói, RJ, Cx. Postal 100.644, Brasil email: [email protected]
INTRODUCTION
Commercial fisheries occur worldwide, affecting target and non-target species, with important impacts on marine ecosystems (Alverson et al., 1994; Gislason et al., 2000). Sea turtles are caught as bycatch (incidental capture of non-target species) in several fisheries. When captured, they are often thrown back into the sea, most of the time injured, drowning or dead (Oravetz, 2000). The impact of bycatches of non-target populations depends on the life history of the impacted species (Alverson et al., 1994). Due to their long lifespan and late maturation (long juvenile period), sea turtle populations, both adult (reproductive) and juvenile individuals, are highly vulnerable to mortality (Crouse et al., 1987).
All sea turtle species are protected by the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES, 2015) and listed as threatened or endangered in the International Union for the Conservation of Nature's Red List (IUCN, 2015). Nevertheless, commercial fisheries continue to threaten sea turtle species due to incidental fishing mortality. Thus, top research and conservation priorities include the identification of areas where sea turtles and fisheries overlap, quantification of the impacts on sea turtle populations and the development of solutions to either reduce capture or increase turtle post-capture survival without causing economic losses to fishery activities (National Research Council, 1990; Domingo et al., 2006; FAO, 2009). Since the 1970s, studies evaluating the mortality of sea turtles in trawl fisheries in South Atlantic and Gulf of Mexico have been conducted, and some estimates indicate that more than 10,000 turtles die from bycatch per year (Roithmayr & Henwood, 1982; Henwood & Stuntz, 1987; National Research Council, 1990). These estimates provided the basis for the development of the Turtle Excluder Device (TED), an inclined metal grid placed in the trawl to prevent large animals from entering the cod-end. A small opening in the trawl is located either above or below the grid, which allows specimens stopped by the TED to escape, relatively unharmed. Targeted species such as shrimp, however, flow to the back of the cod-end (FAO, 2009).
The size of the...