Data/hora: 01/06/2024 03:08:08

Provedor de dados: | Ocean Docs: e-repository of  publications
País: | Belgium

Título:

Ecología y conservación de los grandes tiburones costeros de Bahía Anegada, provincia de Buenos Aires, Argentina.

Ecology and conservation of large coastal sharks from Anegada Bay, Buenos Aires province, Argentina.

Autores: | Lucifora, L.O.
Data: | 2007-01-09
Ano: | 2003
Palavras-chave: | Reproductive behaviour; Feeding behaviour; Age; Growth; Exploitation; Shark fisheries; Reproductive behaviour; Feeding behaviour; Growth; Age; Http://aims.fao.org/aos/agrovoc/c_37902; Http://aims.fao.org/aos/agrovoc/c_10778; Http://aims.fao.org/aos/agrovoc/c_3394; Http://aims.fao.org/aos/agrovoc/c_186.
Resumo: | Reproduction, age, growth, feeding habits and population dynamics of four large temperate sharks (sand tiger shark Carcharias taurus, school shark Galeorhinus galeus, copper shark Carcharhinus brachyurus, and broadnose sevengill shark Notorynchus cepedianus) were studied in Anegada Bay (between 39°50' and 40°40'S), Argentina. Data were gathered from 1089 individuals examined during a three-year study period. Age and growth were studied through examination of vertebral centra only in the first three species. Population dynamics was modeled through stage matrix population models. Most sand tiger sharks examined were adults and evidence indicates that they use the study area as a mating ground. Sand tiger males mature at 193 and females at 223 cm total length (TL), which corresponds to ages of 4.5 and 7.7 years, respectively. Both sexes differed significantly in growth patterns. The population of sand tiger sharks appears to be stationary in the absence of human exploitation. When the most likely current exploitation rate was added to the model, the population decreased by 11.  per year. Male school sharks are mature at 119 and females at 124 cm TL. Three stages of mature females were observed confirming previous observations in S Brazil that the female reproductive cycle lasts 3 years. The patterns of occurrence and embryonic development indicate that school sharks migrate between S Brazil and Patagonia every year. The school shark population is stable without exploitation but it diminishes at a rate of 6-12.  annually with the most likely current exploitation rates. Most copper sharks from Anegada Bay are large juveniles and subadults. Males mature at 216 and females at 222 cm TL, which corresponds to ages of 20 and 21.7 years, respectively. Growth patterns were significantly different between sexes. With the most likely current exploitation the copper shark population decreases at 3-13. annually. Broadnose sevengill sharks were mature at 170 (males) and 224 (females) cm TL. Neonates were present in the area during February. The four species had food habits that barely overlap each other. There were differences even in food habits of a particular species along ontogeny. This indicates that the effect on the community differs among species and ontogenetic stage.
Tipo: | Theses and Dissertations
Idioma: | Espanhol
Identificador: | http://hdl.handle.net/1834/1441

Formato:

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