Reproduction, diet and growth of silky shark Carcharhinus falciformis in the eastern Arabian Sea are described based on 473 specimens collected from the gillnet-cum-longline landings at the Cochin fisheries harbour during 2012–2014. The reproductive biology of 215 males and 258 females was examined while 113 stomachs were sampled to study the diet. The von Bertalanffy growth parameters estimated using length-based models were asymptotic length (L∞) = 309.80 cm, growth coefficient (K) = 0.10 year−1 and age at zero length (t0) = −2.398 year. The sex ratio was significantly skewed to females. Seasonality in reproduction was not evident and in males, sexual maturity was attained at 201–223 cm total length (LT) with the size at maturity (LT50) occurring at 217.0 cm, whereas in females sexual maturity was attained at 224–231 cm LT and LT50 occurs at 226.5 cm. In total 114 embryos, in the length range of 12.2–65.1 cm were recovered from 15 pregnant females. Numbers of embryos in females were in the range of 3–13, averaging 7.6. Silky sharks of the eastern Arabian Sea feed primarily on swimming crab Charybdis smithii, with juveniles feeding principally on swimming crabs, while adults feed on actively swimming prey like squids and teleost fishes. This preliminary information on the reproduction, diet and growth should be useful to identify management strategies for silky sharks in the eastern Arabian Sea.

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.

No abstract

Documentation of fish parasites is important in describing the biodiversity of a given water body. In this study, the first record of metazoan parasite fauna of long snouted lancetfish (Alepisaurus ferox) and swordfish (Xiphias gladius) of the eastern Arabian Sea is presented. Three cestodes (Pelichnibothrium speciosum, Tentacularia coryphaenae and Hepatoxylon trichiuri) and one trematode (Botulus microporus) were collected from the lancetfish. Parasite prevalence was 98.04 % and the average intensity was 9.58. In the swordfish, all the samples were infected, and the average parasite intensity was 51.4. Five cestodes (Hepatoxylon trichiuri, Fistulicola plicatus, Nybelinia bisulcata, Nybelinia lingualis and Tentacularia coryphaenae), at least two species of nematodes (Hysterothylacium incurvum and unidentified nematodes), one species of copepode (Pennella instructa), and a trematode (Hirudinella ventricosa) were collected from the swordfish.

Where it is read in the published text (p. 8, Table 4, last row) 'Eastern Arabian Sea 218.