A preliminary study on the sea snake bycatches (Serpentes: Hydrophis) across time and space in the Coromandel Coast of southeastern Indiae potential population decline

Abstract

We examined the dynamics of sea snake bycatches in two locations in the Coromandel Coast of southeastern India, namely, Chennai and Puducherry, with an emphasis on two variables — time and space. For the time variable, we conducted multiple surveys in Chennai for both long (3650 days apart, 2009–10 vs. 2019–20) and short (45 days, May–June 2024) timelines. For the space variable, we surveyed a relatively lower intensity fishing site of Puducherry (150 km south; January–April 2023). We recorded a total of 98 bycatches representing nine snake species, over a period of 189 days. Rate of snake bycatches per day saw a reduction in long-term timeline: 33/49 days (67.3% in 2009–10) vs. 22/40 days (55% in 2019–20), in short-term timeline: 16/39 days (41% in fishing ban period) and in space: 27/61 days (44.2%). Number of snake mortalities was relatively similar everywhere: 14/33 snakes (42.4% in 2009–10), 10/22 snakes (45.4% in 2019–20) in Chennai, 11/27 snakes (40.7% January–April 2023) in Puducherry, except during the fishing ban period: 5/16 snakes (31.2% May–June 2024). Bycatch rates with respect to various types of fishing gears and vessels are major avenues for future improvements. This preliminary study warrants much more detailed investigations to find out the bycatch frequencies and mortality rates of sea snakes in the Coromandel Coast.