Large sharks have the potential to help structure ecosystem dynamics through top-down impacts on their prey, including sea turtles. Studies of interactions between large sharks and sea turtles, however, are practically nonexistent along the Brazilian coast. Between September 2002 and May 2011 we examined 655 sea turtles – including green turtles Chelonia mydas (n = 607), olive ridleys Lepidochelys olivacea (n = 10), hawksbills Eretmochelys imbricata (n = 33), and loggerheads Caretta caretta (n = 5) – that stranded on Paraíba coast, northeastern Brazil. A total of 63 green turtles (10.4%), two olive ridleys (20.0%) and one hawksbill (3.0%) had shark-inflicted bites. Most bites could not be definitively attributed to scavenging or attacks on living turtles, but the presence of healed shark bites and freshly bleeding bites suggests that some attacks occurred pre-mortem. Bite characteristics suggest that tiger sharks Galeocerdo cuvier were responsible for most bites that could be identified to a particular species. Within green turtles, the only species with sufficient sample size, the probability of carcasses having been bitten increased with carapace length but did not vary across seasons and years. However, there was spatial variation in the probability of a carcass having been bitten by sharks. Our estimates of the minimum proportion of turtles attacked while alive (∼4%) and bitten overall are similar to other areas where shark-turtle interactions have been studied. Turtles likely are an important food for tiger sharks in northeastern Brazil, but further studies are needed to determine the relative frequencies of scavenging and predation.
Avaliação do estado de conservação da tartaruga marinha Chelonia mydas (Linnaeus, 1758) no Brasil.
Data on the food of juveniles Tiger Shark, Galeocerdo cuvier (Péron and Lesueur) (Elasmobranchii, Carcharhinidae), from southern Brazil.
Pan-Am. J. Aquat. Sci.2:
Shark scavenging and predation on cetaceans at Abrolhos Bank, eastern Brazil.
J. Mar. Biol. Assoc. UK. DOI:10.1017/S0025315412001154.
State-dependent risk-taking by green sea turtles mediates top-down effects of tiger shark intimidation in a marine ecosystem.
J. Anim. Ecol.76:
White shark predation and scavenging on cetaceans in the eastern north Pacific Ocean. In:
Great White Sharks: The Biology of Carcharodon carcharias p.
KlimleyA.P.AinleyD.G. Eds Academic PressNew York, NY.
Avaliação do estado de conservação da tartaruga marinha Eretmochelys imbricata (Linnaeus, 1766) no Brasil.
Biodiversidade Brasileira. Ano I1:
20-27. Instituto Chico Mendes de Conservação da Biodiversidade.
Green turtles (Chelonia mydas) foraging at Arvoredo Island in Southern Brazil: Genetic characterization and mixed stock analysis through mtDNA control region haplotypes.
Genet. Mol. Biol.32:
Avaliação do estado de conservação da tartaruga marinha Caretta caretta Linnaeus, 1758 no Brasil.
Nesting biology and conservation of the olive ridley sea turtle (Lepidochelys olivacea) in Brazil, 1991/1992 to 2002/2003.
J. Mar. Biol. Assoc. UK87: