Notes on the Bull shark Carcharhinus leucas in the lagoon region of Cananéia, Brazil

Abstract

Ninety one young specimens and 3 adult females of BulI shark ("cação cabeça chata") caught in the lagoon region of Cananéia were examined, their tooth formula being 27/25 and the number of pre-caudal vertebrae ranging from 109 to 115. The proportion between the 1st and 2nd dorsal fins were found to be 2.3 and 2.8 for the young,and 2.9 to 3.1 for the adults. These data confirm that the studied form belongs to C. leuoas. Young occur regularly but in limited numbers.As regards the adults, however, females only appear during the short parturition period, i.e., from November to February. The number of embryos in the litters were from 7 to 9, their sizes ranging between 768-812 mm. The length of the smallest free young found was 697 mm, but young presumably 9 to 12 months old had 98 to 112 cm; between 21 and 24 months they were reaching 124 to 128 cm, that is, the same size they have when they start migrating to the open sea. The feeding inhibition phenomenon during the period of parturition was not observed in the female specimens caught in the lagoon. The more abundant species found in the stomach contents were: Arius spixii; Chloroscombrus chrysurus; A. grandicassus; A. barbus; Felichtys marinus; Genidens genidens; Chanophorus tajacica and Carcharhinus porosus.

Guiana dolphins, Sotalia guianensis (Cetacea: Delphinidae), in the Paranaguá Estuarine Complex: insights on the use of area based on the photo-identification technique

“…The wound had already healed when the cataloged dolphin was sighted for the first time and no clues were available regarding where the attack took place. Sharks are known to occur in coastal waters with occasional incursions into inner estuarine waters (SADOWSKY 1971, HEITHAUS 2001. Surveys along the coast would be interesting in order to check for dolphin displacements to outer waters.…”

Diet of the bull shark, Carcharhinus leucas, and the tiger shark,Galeocerdo cuvier, in the eastern Pacific Ocean

“…The species is considered a generalist predator, consuming any type of available prey (Baughman and Springer, 1950;Casey, 1964;Tuma, 1976). The bull sharks, C. leucas, have been found to eat echinoderms (e.g., sea urchins), mollusks (e.g., cephalopods), arthropods (e.g., crustaceans and crabs), elasmobranchs (e.g., sharks, rays, and sawfish), teleosts, marine mammals (e.g., cetaceans, porpoises, and whale remains), terrestrial organisms (e.g., dogs, cats, rabbits, and human remains), birds, and reptiles; various items like plant remains, paper, bottles, garbage, fish waste, and plastic (Nichols, 1917;Bell and Nichols, 1921;Gudger, 1932;Darnell, 1958; Schuwartz, 1960;Springer, 1960;D' Aubrey, 1964;Clark and Schmidt, 1965;Sadowsky, 1971;Tuma, 1976;Snelson et al, 1984;Cliff and Dudley, 1991;Tillett et al, 2014); and even members of their own species (cannibalism) (Snelson et al, 1984). This study agrees with observations made in previous studies, reporting similar dietary components (e.g., rays, cephalopods, teleosts, and sea turtles).…”

Bioecology and movements of bull sharks, Carcharhinus leucas , caught in a long-term longline survey off northeastern Brazil

“…The maturation size of the female C. leucas caught in this study agrees with the estimates of CruzMartínez et al (2004), since all mature females were larger than 204 cm L T . Although mature specimens were largely represented in C. leucas catch and were mostly sampled during the austral summer, which reportedly corresponds to the parturition period of the species at the Brazilian southeastern coast (Sadowsky, 1971), no pregnant females were noted and no signs of recent mating activity were detected either (Clark, Schmidt, 1965;Pratt, Carrier, 2001). Further research comprising a greater number of specimens sampled, probably adopting a different fishing strategy, is required to better understand several important aspects of C. leucas bioecology in the southwestern Atlantic Ocean, including reproduction, age and growth, diet and habitat use.…”

“…Despite a considerable amount of published literature, little is yet known about the bioecology of C. leucas in the Southwestern Atlantic. The parturition period in Cananéia lagoon, in the São Paulo State, has been reported to occur from November to February (Sadowsky, 1971). Off Recife, in the Pernambuco State, the bull shark occurs occasionally but with much less frequency than other medium to large-bodied species such as the blacknose (Carcharhinus acronotus), the nurse (Ginglymostoma cirratum) and the tiger (Galeocerdo cuvier) sharks .…”