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Thread: Mass Bycatch Mortality of Sea Snakes, Goa

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    Default Mass Bycatch Mortality of Sea Snakes, Goa

    Bycatch – the incidental, unintentional take of non-commercial, non-target species or undersized animals in fishing gear — has been an ever-increasing threat to the planet’s marine life, and is today considered one of the major threats to marine biodiversity the world over. The problem of bycatch is now a widely recognised and well-documented menace to threatened wildlife, including marine mammals, sea turtles, sharks and rays, and endangered seabirds such as the wandering albatross. Witnessing first-hand the devastation caused even by a relatively small-scale fishery is, however, something I had not anticipated during a stroll on the beach.

    I was out exploring a beach in Goa close to where I stay, and having seen a live sea snake on the beach the day before, I was half-expecting a similar find. Soon enough, I glimpsed the familiar form of a sea snake close to the tide line, but on getting closer, I found that it was dead. It was a juvenile Hook-nosed Sea Snake (Enhydrina schistosa), one of the commonest of sea snakes along the west coast, and the same species I had seen the previous day. As I walked on, I saw another of the same kind, also dead. To my surprise, more of them lay ahead.As I walked further on, a whole shocking sight revealed itself, and it was of a much greater scale than I had ever imagined. There were several of these snakes scattered over a 20-30 metre stretch of the beach. A few were bone dry, one had been fed upon by crows, but a great majority of them seemed fresh enough to have died very recently. I counted a staggering eighty-one sea snakes in the area, eighty of which were juveniles of approximately 1.5 feet in length; one was an adult of the same species. Only one of these snakes was still alive, and despite almost having dried up in the baking sun, it was healthy enough to swim away when I left it below the tide line. A couple of days later, I went to take a look at the same area again and once again found a similar scene — this time there were sixty-nine dead, and once again, all but two were juveniles. Most were scattered in the same area as on the previous occasion.

    The area happened to be a part of the beach where shore seines are hauled and the catch landed, which led me to guess the connection between the fishery and this mass mortality of sea snakes. My hunch was confirmed by a few local children I met on the beach the same evening, as well as by local fishermen I spoke to the following morning. Shore seines are long wall-like nets that are set in an arc in near-shore waters, and hauled towards shore by teams of fishermen pulling the two ends in. The net completely encloses the area between itself and the shore, gathering up all the animals within this area, including the sea snakes in this case.

    In the course of a brief chat with the fishermen, they claimed that mass sea snake bycatch events happened multiple times a year, but they did not know much about the exact times of year when these events were expected to occur. Sea snakes are also intentionally killed for the same reason other snakes are- the fear that their mere existence and presence is a threat. On one of my excursions, I saw fishermen pick out a three-foot-long adult from their net and promptly proceed to bludgeon it, justifying the act by saying the snake was “poisonous” and “too dangerous to be released alive”. Hook-nosed sea snakes can remain active when stranded (as compared to the generally sluggish behaviour of most other sea snakes on land, barring the sea kraits), often thrashing about when handled, and it is possible that this feisty nature, in addition to the well-known toxicity of its venom, contributes to their reputation as a menace. From one fisherman’s point of view, releasing a sea snake would be a bad idea as it would continue to live there, continue to turn up in his net and hence continue to be a threat to his life.

    It is clear that this problem can effectively be solved only by aiding fisher folk to alter their perception of sea snakes, understand more about the lives of these animals and acknowledge their role in maintaining the integrity of a marine ecosystem as a whole — an ecosystem which ultimately forms the very basis of their livelihood.

    [A special thank you to Dr. Aaron Savio Lobo for a lot of valuable learning and for encouraging me to probe deeper into this phenomenon.]
    - Abhishek
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    Another image of juveniles mixed with other bycatch
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    I agree only creating awareness about this species with the fishermen folk can help. So many snakes might be getting killed daily. Twice you counted and the number was above 50 daily. So in a month roughly 1000 snakes might be getting killed or atleast 500. Is any action taken locally to educate these fishermen folk? Thanks for sharing the details and the photographs.

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    Mrudul- I did not find large numbers in the following days, just a few isolated snakes. One possibility (though not sure) is that most of that local juvenile congregation was fished out in those few days.
    There is no education being done. It would be a challenge, but it certainly needs to be done. Always open to ideas!

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    Sad to see one more example of the devastation caused by our species. People often say that humans are a superior species however greed and fear and ignorance drive most of our actions.

    They don't fear authorities because no one ever cares. They fear snakes, so they kill. One needs to spend a time with these folk to educate them. Knowing the local language will be of help.

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    Sabyasachi- I do speak the language. I met them three or four times to speak to them. Some fishermen see the bycatch as something they can't avoid since they can't predict the aggregations. This is pertaining to the accidental capture of juveniles. About the release of adults- this would be harder to achieve. When one encounters a deadly animal (that too a snake with aggressive habits) regularly in the course of a days work, it would be hard not to fear it. When I spoke to them about releasing snakes rather than killing them, it seemed a ridiculous topic to them, and to be frank I understand why. That is the reason I find this hard to deal with. The only way i see education being effective in this case is if the cause is endorsed by one of their own. Laws and enforcement won't help as that would imply loss to livelihoods.

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    I agree with you that it is a tough proposition for the fishermen to even think of safely handling the snakes for release. I am not sure if there can be a way of ensuring that the snakes don't get caught. Fishermen were even reluctant to use TEDs for a much more benign species like turtle. Ofcourse that fishing technique is different and in deeper seas. Apart from the snakes, other species that are not in demand are just thrown away and not released into the water. I think more interaction with the fishermen and observing their techniques may help us in finding an answer.

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    Sabyasachi- Exactly, I don't know how bycatch reduction devices (BRDs) could work on these nets. Given the small size of the fish these nets catch, there seems to be no scope of allowing smaller animals to escape, as can be achieved with wider mesh size nets. Given the very structure of the sea snake's body, entanglement would happen very easily.
    It is also difficult to study the lives of sea snakes... Otherwise, a proper understanding of their life cycle could possibly help avoid human conflict with them, at least at times of mass aggregations.
    I have not had a chance to observe the operation of large shore seines (sometimes several kilometres long). Have been repeatedly watching the smaller ones, but haven't found many sea snakes in them on any of my surveys- the occasional one or two. Of course, they do contain other bycatch. Have seen bottom-dwelling sharks and skates in them for instance.

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    Update- Found another 18 dead juveniles yesterday, following the day a large shore seine was in operation.

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    That's a horror story for a whole set of species playing out, a ticking time bomb of sorts if one factors in death & depletion of so many species (flora / fauna) all across the world, every day.

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    Hi Abhishek,
    This is very distressing , was not aware shore seine are creating this much trouble. I have seen some shore seine used locally which have a wider mesh and did not result in as much by catch as compared to the shrimp nets used in trawlers. They are used in specific seasons for specific catch. Even the nets used in the traditional boats called vanchee used to have a wider mesh compared to the nets used on trawlers and hence much less by catch. By and large sea snakes seemed to figure much less in the bycatch list compared to fish with less or no commercial value and other crustaceans, turtles and marine mammals.

    Most fishermen in these parts used to agree that sea snakes caught in the nets were simply thrown back into the water and I remember seeing this many times. However the snakes which got entangled in the nets are usually killed and cut free from the net as trying to free an entangled sea snake is considered risky, but the free ones are usually thrown back into the sea and I have even seen some being handled with bare hands. These creatures are considered harmless by the fishermen as they rarely bite. The interesting part is that in the smaller boats while most of the fish and other creatures died due to suffocation, the snakes usually survived and ended up in the water once again. It has been sometime since I have gone out into the sea on these boats, im not sure if this has changed around here.
    How prevalent is this wanton killing of sea snakes is matter which needs be looked at as in some coastal cultures killing of these reptiles is considered a sin. This might again not apply to some communities and also might have changed in the recent generations with the demand and competition increasing, catch reducing and patience and tolerance wearing. Sea snakes have a market in china and some other far eastern countries and are actively netted for. This demand does not seem to have yet reached the Indian shores unlike the shark fin. If and when it does this will turn into a much bigger problem.

    TFS
    Roopak

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