Information on reproductive biology is presented for the grey sharpnose shark Rhizoprionodon oligolinx Springer, 1964 (Chondrichthyes: Carcharhiniformes), collected off the north-west coast of India in the Arabian Sea. A total of 711 individuals, of 27.0 to 93.0 cm total length (TL), 180 to 2600 g total weight (TW) were used for the study. The lengthweight relationships were significantly different between the sexes. The size-at-maturity (Lm 50 ) for females and males was estimated to be 62.3 and 59.5 cm TL respectively. Number of embryos ranged from 1 to 7 and the size at birth was estimated between 25 to 30 cm TL. Overall sex ratio favoured the females slightly at the rate of 1.27:1. There was significant positive correlation between maternal TL and number of embryos (p<0.001). Dietary analysis of stomach contents (%IRI) revealed that R. oligolinx feeds primarily on teleosts (95.5%), cephalopods (3.2%) and crustaceans (1.2%). This study presents the first detailed biological observation on size, sex composition, size-at-maturity (Lm 50 ) and length-weight relationship of R. oligolinx from the northern Arabian Sea.

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SummaryThe length weight relationships (LWRs) of ten tropical finfish species from north eastern Arabian Sea, India were studied. Specimens were caught using a wide range of fishing gear mainly trawl nets (20-25 mm), dol nets or bag nets (20-40 mm) and gill nets (80-270 mm) operated in Maharashtra maritime waters during 2012-2016. The specimens were measured for total length, and weight, then dissected and the sex confirmed. Previously unavailable in FishBase, the detailed LWR of Polydactylus mullani is reported for the first time. Maximum total lengths presented for six species in this study are new records. The existence of a differential growth between male and female was confirmed for five species, which was not known earlier. The LWR data will be useful for deriving future sustainable management and conservation strategies.

Biological information was collected from 214 individuals of the broadfin shark Lamiopsis temminckii measuring 418 to 1782 mm total length, L . Size at maturity (L ) for females and males was estimated at 1430 and 1368 mm L , respectively, while mature and gravid females were observed from 1350 mm L with litter sizes 2-8 and size at birth 418-650 mm L . Analysis of stomach contents revealed a variety of prey, primarily crustaceans (54·0%), teleosts (42·7%) and cephalopods.