Biological aspects of sea snakes caught incidentally by commercial trawlers off Goa, west coast of India

Vinay P Padate,Lalita V Baragi,Chandrashekher U Rivonker

doi:10.11609/jott.o2253.609-16

Abstract

Sea snakes occur in trawl hauls as by-catch, incurring mortality in populations inhabiting commercial fishing grounds (< 20 m depth) along the coastal inshore waters of Goa. Observations of this incidental catch show that true sea snakes inhabiting inshore waters comprise two species: Enhydrina schistosa and Lapemis curtus, contributing 65 and 35 % of the population respectively. 70 trawl operations over a period of 17 months with a total fishing effort of 110 hours yielded 43 individuals, all females, which numerically contributed ~ 1 % to the total trawl catch. Seasonal variations indicate that there is an increasing trend in abundance from post-monsoon to pre-monsoon season. The capture of a gravid female from the estuarine inshore waters during January suggests parturition and recruitment among sea snakes during the post-monsoon season. An assessment of the food composition in the stomach content revealed completely digested prey in smaller individuals, whereas in larger-sized individuals these items were either undigested or semi-digested. Qualitative assessment of gut content of sea snakes revealed the dominance of finfish (Ariidae, Engraulidae, Clupeidae). A biological assessment of a gravid female and the association of sea snakes with a barnacle species (Octolasmis grayii) are described.

Highlights

Coastal ecosystems exhibit high variability in ecological parameters that are largely influenced by land use patterns and runoff, resulting in seasonal anomalies
Commercial fishing grounds are of great concern as they are subjected to indiscriminate removal of non-target species (Kumar & Deepthi 2006) as by-catch, including sea snakes
The present paper addresses the taxonomic composition of the assemblage of true sea snake species, seasonal variations in trawl catches and certain biological attributes such as feeding habits, reproduction and symbiotic associations, based on observations made using commercial trawlers along the fishing grounds of Goa

Summary

Introduction

Coastal ecosystems exhibit high variability in ecological parameters that are largely influenced by land use patterns and runoff, resulting in seasonal anomalies. The present paper addresses the taxonomic composition of the assemblage of true sea snake species, seasonal variations in trawl catches and certain biological attributes such as feeding habits, reproduction and symbiotic associations, based on observations made using commercial trawlers along the fishing grounds of Goa. OPEN ACCESS | FREE DOWNLOAD

Results

Conclusion