Abstract

Knowledge of life history and fish reproduction is essential to understand the population dynamics of exploited shark populations. We provide information regarding the length, weight, and sex ratio of Carcharhinus longimanus (oceanic whitetip shark), Galeocerdo cuvier (tiger sharks), and Alopias superciliosus (bigeye thresher sharks) from longline boats based on Manzanillo (39–45 m longline vessels), Colima, Mexico, from 1986 to 2001. We analyzed a total of 264 oceanic whitetip sharks with 107 females (86-186 cm FL) and 157 males (68-184 cm FL); 67 tiger sharks with 36 females (105-193 cm FL) and 31 males (103-207 cm FL) and 67 bigeye thresher sharks with 22 females (131-209 cm FL) and 45 males (138-204 cm FL). The sex ratio for the whole sample differed significantly from the expected 1:1 in the oceanic whitetip shark and bigeye thresher shark, probably due to the mobility nature of the species. The length-frequency distribution of the bigeye thresher shark revealed a high frequency of individuals of large size in the catches. This shark is, on average, larger and heavier than the oceanic whitetip shark and the tiger shark. Factors affecting the catch susceptibility of this particular group of species and their lengths (or ages) are discussed.
 Keywords: Length-frequency, life history, Mexican Pacific, pelagic sharks

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