Demographics and reproductive biology of Hydrophis schistosus may make it more resilient to bycatch effects than other sea snakes

Dsouza, S and Rao, C (2021) Demographics and reproductive biology of Hydrophis schistosus may make it more resilient to bycatch effects than other sea snakes. In: Regional Studies in Marine Science, 47 .

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Abstract

Mortality in fisheries bycatch is a threat to marine taxa globally. True sea snakes are viviparous marine reptiles found throughout tropical coastal waters, with varying reproductive strategies that differ from their terrestrial counterparts. Hydrophis schistosus and H. curtus are both caught frequently in large numbers as bycatch in gillnets, shore seines and trawlers on the west coast of India. In this study, we aimed to describe the population of H. curtus and H. schistosus in bycatch in terms of developmental stages; compare mortality rates across developmental stages and sexes; and discuss their breeding cycle and reproductive strategies in the context of fisheries threats. We sampled fishing nets for sea snakes from 2016 to 2019. The population structure of H. schistosus consisted primarily of breeding adults and did not change in the four years of sampling. However, the proportion of breeding adults of H. curtus in bycatch declined steadily. Gravid female H. schistosus appear to carry young from November to May, giving birth in April. We did not encounter any gravid H. curtus during our sampling. While the number of eggs increased with female snout to vent length in H. schsitosus, the overall reproductive effort remained the same and investment per embryo reduced. Bycatch - induced mortality of H. curtus was significantly higher than H. schistosus. Adult H. curtus were most vulnerable to bycatch mortality of all demographic groups in both species. Reproductive strategies along with other ecological and life history differences may give H. schistosus an advantage compared to other taxa in the face of anthropogenic threats. © 2021 Elsevier B.V.

Item Type:	Journal Article
Publication:	Regional Studies in Marine Science
Publisher:	Elsevier B.V.
Additional Information:	The copyright for this article belongs to Elsevier B.V.
Department/Centre:	Division of Biological Sciences > Centre for Ecological Sciences
Date Deposited:	21 Sep 2021 09:32
Last Modified:	21 Sep 2021 09:32
URI:	http://eprints.iisc.ac.in/id/eprint/69776

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