Biological aspects of sharks caught off the Coast of Pernambuco, Northeast Brazil

Abstract

One hundred seventeen specimens of sharks were caught along the coast of Pernambuco State, Northern Brazil, between May 2004 and May 2007, among which 86 were blacknose sharks, Carcharhinus acronotus, enabling a more detailed study of the species. Blacknose sharks were caught in the 2 study areas along the Boa Viagem/Piedade and Paiva beaches, accounting for the highest relative abundance among the species caught (73.5% of total). Potentially dangerous sharks, tiger and bull sharks, were also caught in the same areas, whereas hammerhead and blacktip sharks were only captured off Boa Viagem/Piedade. Concerning the blacknose shark, the total length (TL) ranged from 39.0 to 180.0 cm. Among the 38 females analysed, 32 were juveniles, 11 were maturing, 2 were pre-ovulatory and 21 were pregnant. Sexing was possible for 75 of the 83 embryos, 38 of which were males and 37 were females, with a sex proportion of 1:0.9 and total length ranging between 6.4 and 63.5 cm. Ovarian fecundity ranged from 5 to 10 and uterine fecundity from 1 to 3, with an estimated gestational period of 9 months. Among the 48 males, 6 were juveniles and 42 were adults. Both males and females seem to reach sexual maturity at about 105.0 cm TL. Among the 86 stomachs analysed, only 22.1% had contents, with teleosts as the most frequent item.Keywords: biology, abundance, sharks, Pernambuco. Aspectos da biologia dos tubarões capturados na Costa de Pernambuco, Brasil ResumoEntre maio de 2004 e maio de 2007, foram capturados 117 exemplares de tubarões na costa de Pernambuco. Desses, 86 eram tubarões-flamengo, Carcharhinus acronotus, possibilitando um estudo mais detalhado da espécie. Esta espécie foi capturada nas duas áreas estudadas, nas praias de Boa Viagem/ Piedade e Paiva, apresentando a maior abundância relativa entre os tubarões capturados (73,5% do número total). Tubarões potencialmente perigosos (tigre e cabeça-chata) foram também capturados nas duas áreas, enquanto os tubarões-martelo e galha-preta foram capturados apenas em frente à Boa Viagem/ Piedade. O comprimento total (CT) dos tubarões-flamengo variou de 39,0 a 180,0 cm CT. Das 38 fêmeas analisadas, 32 eram jovens, 11 em maturação, 2 pré-ovulatórias e 21 prenhes. Dos 83 embriões, foi possível a sexagem de 75, dos quais 38 eram machos e 37 fêmeas, com proporção sexual de 1:0,9, e CT entre 6,4 e 63,5 cm. A fecundidade ovariana variou entre 5 e 10 e a uterina entre 1 e 3, com período gestacional estimado em 9 meses. Dos 48 machos, 6 eram jovens e 42 adultos. Tanto machos quanto fêmeas parecem alcançar a maturação sexual em torno de 105,0 cm CT. Dos 86 estômagos de tubarões-flamengo analisados apenas 22,1% apresentavam conteúdo, com teleósteos sendo o item mais frequente.Palavras-chave: biologia, abundância, tubarões, Pernambuco.Fischer, AF. et al.

Age and growth of the tiger shark, Galeocerdo cuvier (Péron & Lesueur, 1822) from the equatorial South Atlantic Ocean

“…The tiger shark is a relatively rare species (Fischer et al 2009;Harry et al 2011;Afonso et al 2012b;Coelho et al 2012;Holmes et al 2012) probably due to its top predator position in the food chain, which leads to their populations being generally comprised of a small number of individuals (Ebert et al 2013;Sulikowski et al 2016). As in the current study, age and growth assessments of G. cuvier are usually based on a small amount of samples, mostly below 50 (De Crosta et al 1984;Branstetter et al 1987).…”

Ictiofauna das piscinas de maré da praia do paiva: um registro anterior à exploração imobiliária

“…A região metropolitana do Recife (RMR) possui uma linha de costa com aproximadamente 60 km, que engloba as praias do Paiva, Candeias, Piedade, Boa Viagem e Pina, entre outras, com temperatura da água variando entre 24 e 30ºC, durante o verão (FISCHER et al, 2009). A praia do Paiva (Erro!…”

Regional movements of the tiger shark, Galeocerdo cuvier, off northeastern Brazil: inferences regarding shark attack hazard

“…Since 1992, the metropolitan region of Recife, Brazil, exhibits one the highest shark attack rates per unit of area in the world, accounting for 53 attacks which resulted in 20 fatalities. Relative abundances assessed off Recife (Fischer et al 2009), together with forensic analysis (Gadig andSazima 2003, Hazin et al 2008) indicated the tiger shark, Galeocerdo cuvier, and the bull shark, Carcharhinus leucas, to be responsible for most of the attacks. Both species are considered potentially aggressive and have been frequently implicated in attacks on humans worldwide (International Shark Attack File, http:// www.flmnh.ufl.edu/fish/Sharks/ISAF/ISAF.htm.…”