Title: By-catch mortality of beaked Sea Snake Hydrophis schistosus (Daudin, 1803) by entanglement in shore-seine operation in Goa-India
Authors: Gangadhar Tambre, Sambhaji Mote, Kalyan De, Deepa Yogi, Mahesh Jadhav, Baban Ingole, Tapas Chatterjee, and Mandar Nanajkar
Journal Article: Acta Biologica
Link: https://wnus.edu.pl/ab/en/issue/1195/article/18975/
On the Caranzalem-Miramar coast within the Mandovi estuary, the authors would go out to the beach twice a week from August-September of 2017-2018 to count every entangled sea snake brought in as by-catch. They would release the live snakes and take back the deceased snakes to their lab for analysis. A total of 1,448 individuals of H.schistosus, or the beaked nose sea snake, were caught in shore-seine nets. About 90% of those snakes were juveniles or sub-adults. Every operation of shore-seine practices had a very high by-catch rate of sea snakes with about 20-60 H.schistosus individuals entangled. This study showed an exceptionally high by-catch rate of sea snakes compared to similar studies conducted within 100 km of the research area. The authors also performed gut content analysis and found that about 80% of H. schistosus had recently fed on the catfish A.jella, indicating a prey preference. The researchers implied that H.schistosus would follow A.jella into the estuary to feed on as well as take advantage of the nursery properties of the habitat. These catfish were also recorded as a big by-catch species for the area. The article stated that this rate of by-catch for the beaked nose sea snakes could possibly mean a broad-scale scale effect on the entire ecosystem, the benthic food chain, commercial fishermen, and local subsistence fishers. The beaked nose sea snake is a top predator that has very little scientific literature about population ecology, mortality, or environmental influences. This study indicated that this estuary was a very important habitat for this species, especially the juveniles. Which are crucial for the population control of the A.jella who otherwise would dominate the local Gao-Indian waters. This means that the economically important species would diminish in the face of the "voracious feeding" catfish, which would cost fishing companies a lot of money. This article adds to our understanding of reptiles because it shows not only that the commonly known sea turtle by-catch is going on worldwide, but the by-catch of other reptiles such as sea snakes is occurring. One would think that a sea snake would easily escape entanglement, but the results of mostly juveniles who recently fed on also captured species show that this assumption is not true. Looking at the picture below shows just how many sea snakes are brought in as by-catch and that there is a need for change. This research is valuable because it highlights this atrocity and the necessity of awareness. Local fishermen and commercial fishing companies need to be aware that this is a problem that could affect the whole marine ecosystem that they depend on for survival or profit. Also, this brings a call for regulations and policies on nets, mesh size, seining practices, and speedy releases of by-catch.
2 comments:
Wow, I had no idea sea snakes were such common bycatch. Did the article happen to mention whether juveniles account for such a high percentage of the sample because they're more easily trapped or are they just that much more abundant than other life stages?
Yeah, I had no idea about this occurrence either. The article mentioned that the juveniles made up such a large percentage of sea snakes as by-catch because of the habitat that the shore-seine practices occurred. Estuaries were stated as nurseries for the sea snakes and the adults would come in for little amounts of time to breed, rest, and feed. Whereas, the juveniles lived there until they reached maturity.
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