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Studies on reproduction in sharks are important for their management, since the attainment of sexual maturity has a
substantial impact on their distribution, behaviour and biology. However, reproductive biology of large oceanic sharks is
poorly studied in the Indian seas. In this study, the size structure, sex and maturity of pelagic thresher (Alopias pelagicus),
bigeye thresher (A. superciliosus), oceanic whitetip shark (Carcharhinus longimanus), tiger shark (Galeocerdo cuvier),
shortfin mako (Isurus oxyrinchus), longfin mako (I. paucus) and blue shark (Prionace glauca) in the eastern Arabian Sea
are described based on 1449 specimens collected from gillnet-cum-longline landings at the Cochin fisheries harbour during
2013–2014. Sex ratios of sampled specimens were biased to males in pelagic thresher, bigeye thresher, tiger shark and
blue shark, while females dominated in the specimens of oceanic whitetip shark. Females matured at greater lengths than
males in all species except oceanic whitetip shark. Lengths at maturity for males were in the range of 189.05–286.56 cm,
whereas those of females were in the range of 187.74–310.69 cm. Litter sizes of both the thresher shark species were
always two, while in oceanic whitetip shark, litter size was 3–9 and 22–51 in tiger shark. Seasonal reproduction was
noticed in oceanic whitetip shark and tiger shark. Pregnant females were not found in the blue shark, shortfin and longfin
makos sampled during the study period. Reproductive aspects of pelagic thresher, bigeye thresher, oceanic whitetip shark,
tiger shark, shortfin mako, longfin mako and blue sharks in the eastern Arabian Sea are generally consistent with earlier
reports from other regions of the world’s oceans. These preliminary findings should be useful to identify suitable management
measures for the above shark species.
