For over a year now, TeMI has been advising and supporting Abhishek Jamalabad, an independent research associate, to conduct research on dolphin interactions with purse-seine fisheries off Karwar. Fisheries interaction with cetaceans (includes dolphins, whales, and porpoises) is a complex topic and a global conservation problem that has plenty of challenges and often, few solutions. However, with any conservation problem, it is critical to collect scientific evidence before mitigative solutions can be proposed. Socio-economics and risk management strategies need to be interwoven with any such scientific investigation. We are just beginning to learn about the biology and behavior of cetaceans, the threats they face, and the socio-economics of commercial and traditional fisheries in Karwar and nearby waters. While early results are exciting and promising, there are significant data gaps, which we hope to fill in the near future with the support of the local fishing community and research partners. Read on to learn more about Abhishek’s work and the beguiling problem of dolphin interactions with purse-seine fisheries.
By Abhishek Jamalabad
*All images copyrighted Abhishek Jamalabad. Images not for commercial use.
I am out at sea on a purse seiner looking for fish shoals. As soon as one is sighted, the net is set. Not long after the hauling process begins, the fishermen notice humpback dolphins approaching the net, and diving under just as they reach its margin. I watch and photograph as the incident unfolds, while an assistant takes notes. There are dolphins to be seen, splashes and bangs to be heard, some frantic net-hauling to be watched, and in the end, the net comes up riddled with holes and with less fish than the fishermen expected.
This happens several times over the season, and there are more cases to be heard of than I have witnessed. Amidst all our current knowledge about human-wildlife conflicts, the marine side of this issue has not been investigated in India. Considering the burgeoning fisheries on our coasts and the fact that we know little about the status of marine mammals in our seas, this issue is indeed a pressing one.
In 2015, I took up an independent project in Karwar to study the anecdotally-known interactions between coastal cetaceans and the very busy purse seine fishery in this region. At the time, the exact nature and extent of interactions were not clearly known. Based on primary observations from active fishing vessels, I found that catch depredation by dolphins is the dominant type of interaction between the animals and most fisheries in the area. A little over 40% of all monitored fishing events involved depredation (the act of deliberate removal of fish from fishing nets) by dolphins. This results not only in a loss of fish and less pay for the fishermen but also damage to the nets – sometimes considerable enough to require fishermen to put off fishing until the net is mended.
Why depredation happens here, at the scale at which it does, is a question that can only be answered by long-term studies, which would help paint a more complete picture of the dolphins’ foraging behaviour in the region. The two most likely possibilities are (a) that some sub-population of dolphins have learnt how to get an easy meal from the nets, and/or (b) food scarcity created by overfishing may limit the choices available for dolphins. Regardless of the reason(s) for depredation, humpback dolphins are not favourably viewed by fishermen, resulting in varying degrees of conflict between the fisheries and the dolphins. While no fisherman wants to deliberately harm dolphins, there is certainly frustration and angst over lost catch and damage to fishing nets. But if left unchecked, then this strained interface, along with fishers’ perceptions of declining fish catches, could possibly lead to more direct conflict between man and cetacean. Stealing fish from nets can prove costly to the dolphins as well since it makes them vulnerable to gear entanglement resulting in injury or death. The more we investigate and understand the type, extent, and nature of fisheries-cetacean interactions, the more equipped we will be to propose constructive solutions to mitigate such events.
In conjunction with my primary project, I initiated a sighting-reporting exercise with some of the offshore fishing crews. The waters beyond the coastal strip are hard to access on a regular basis for researchers, and the marine mammal life here is barely known. With the help of simple identification charts in the vernacular language, and using the GPS and depth sounding systems that every boat is already equipped with, fishermen were able to report a number of marine mammal sightings with relevant data, on a few occasions even with videos. They reported Bryde’s whales, Arabian common dolphins, unidentified delphinids, and orcas (killer whales), and they continue to do so as and when they have sightings. The presence of some of these species could be verified personally and photographed during the few opportunistic offshore surveys I conducted with these crews. It is clear that systematic sighting reports by fishing crews (and other sea-going personnel) on a consistent and larger scale could contribute greatly to our knowledge of offshore cetacean diversity, which remains largely inaccessible and unknown to most researchers.
In addition, some more valuable cetacean records came up as a result of my semi-structured interviews of fishermen. The finless porpoise, a cryptic and largely understudied species, became one of the focal points of interviews, and a lot of information about this animal in the region could be obtained from querying fishermen. The many anecdotal accounts and historical narrations that came up during these interviews helped project a rough picture of the changing relationship between marine mammals and fisheries over the decades – again, a useful insight into a region with no prior baseline data on this subject.
This project provides a baseline for studying marine mammals in the region, with a focus on the fisheries-interactions. Furthermore, my additional field observations and the outcomes of my interviews suggest the potential for important conservation-oriented research in the directions of fisheries management and socio-economics as well. The next step is to conduct fisheries-independent dolphin studies to investigate dolphin and porpoise behaviours in the absence of fishing vessels, and to continue fishery-dependent surveys to monitor consistency or changing trends in dolphin-fishery interactions.
*Additional funding for this project was provided by the Ravi Sankaran Fellowship and Rufford Small Grant. Requisite research permits and permissions were obtained for conducting this project.