The decline of fish stock the world over is gravely affecting the balance of things in our seas. In India too, with the ever-rising, unregulated fishing, things aren’t looking too good.

Mayuresh is a PhD candidate with our Oceans and Coasts Programme and works on understanding impacts of overfishing on fish populations in India’s west coast. He talks to us about what brought him here.

Let’s go back a little. What got you interested in working on marine fisheries?

For my masters dissertation (which was on seagrass), I was staying in Mandapam, a fishing town in Ramnathpuram district of  Tamil Nadu. It was then that I saw indiscriminate fishing for the first time. It kind of hit me very hard. And then I thought that fisheries might be the research/conservation area where I would like to invest most of my time.

We’re hearing a lot about the problem of overfishing in the country, and how we’re affecting the natural balance of many species and entire marine ecosystems. How do we tell when fishing becomes overfishing? What really goes into making sure that our fisheries are sustainable?

Imagine you have a bank account and you have deposited some money in it. The amount will grow every year with some interest. Now as long as you are just spending the interest, the amount you started off with will not reduce and that is sustainable use of your money. But if you spend more than the amount of interest then the starting amount will reduce and the interest for subsequent years will also reduce. That is unsustainable use of your money.

Overfishing works in the same way. Suppose we have 100 fish in the water. In a year’s time they might reproduce and become 110. Now as long as we are just taking 10 fish out from the water there will still be 100 fish in water. But if we take more than 10 fish, the overall population will be lower than the starting population and that’s basically overfishing.

Typical bottom trawling haul (a mix of catch and discards)

One of the ways to address the problem of overfishing is to monitor fish that are being caught, right? How does one collect information about fish catch? It seems like there would be so many logistical challenges in doing this—with so much of fishing going unreported in the country.

Yes, one big logistical challenge is that the oceans are so huge. Fish populations are also huge and there is no way we can count all the fish.

One crude, but reliable way to understand the state of fishing is to look at the Juvenile/Adult Ratio in the catch. Now if the Juvenile to Adult Ratio in the catch is skewed towards adults—that’s a sign of a healthy population, but if that ratio is skewed towards juveniles, that means that there are not enough adults and that’s why the proportion of juveniles is higher in the catch. This is a clear sign of overfishing and leads to a dangerous situation because with more juveniles getting caught, less remain into water to mature, become adults and lay eggs.

Tell us a little about your journey, when did you start working on fisheries?

I started working on coastal and marine fisheries back in 2011. With Divya Karnad, I worked on a project which explored whether fishermen from Tamil Nadu and Maharashtra are perceiving a decline in their fish catch.

Later on to explore the more ecological side of fisheries, I thought of monitoring the juvenile/adult ratio of catch on the coast of Maharashtra. I applied for a Rufford Grant and started working on collecting this baseline data from two villages along the Konkan coast—Malvan and Harne over two years. We examined catch from different fishing gear like gill nets, trawlers, shore seine, purse nets.

And that brought you to your PhD, right?

Yes, actually a big drawback in that work kind of lead me to my current PhD topic. While doing this project, we realised that there was a problem in analysing the data. Fisherfolk in the two coastal villages of the study—Malvan and Harne—were going all over the coastline and bringing back fish. So there was no way to tell whether the fish catch we had in hand was coming from one population or multiple populations. And if it was coming from multiple populations, analysing the state of fisheries based on the proportion of juveniles becomes a bit meaningless. I realised that to deal with this issue we needed to demarcate different populations across the west coast of India. Then we could do the population-wise age structure analysis which would make our work more meaningful.

By the time we started learning more about how fisheries in Maharashtra function, we realised that since each state has different fishing laws, all of the existing boundaries in the ocean are political, manmade boundaries. Fish of course adhere to completely different, natural boundaries in the water.

This mismatch often leads to mismanagement. States may share populations, so what one state does can have implications for fisheries of neighboring states. I found this population question interesting—and I’m now working on this with the help of genetic tools.

So that’s what brought me to my PhD. I’m now working on questions like:  do the biological boundaries and political boundaries of these fish being caught match? Does state policy take into account biological clues?

This is interesting! And I can see how useful this information will be in conserving fish, especially if it’s weaved into policy.

Yes, certainly.

What are current state policies like with respect to overfishing?

Fisheries are a renewable natural resource. At the time of India’s Independence, among the known natural resources, the management regime that could have come biologically or ecologically closest to capture fisheries was forestry or silviculture. But maybe because of the underexploited nature of fisheries back then, as Rohan Arthur put it,  “Fisheries was perceived as a mineral resource—something which is static, out there for us to get”. So the whole approach to fisheries was to find and exploit fish. Seven decades since that time, things in the water have changed rapidly but the approach has remained largely the same.

Shark catch at the port of Malvan

You’re also working on some other projects apart from your PhD. Tell us something about those?

I’ve been working on a small project in Mumbai that deals with collecting basic ecological information on sharks, since the city is a hub for shark fishing. We’ve been looking at demographic data on shark catch. Sharks are becoming rare now and we’re not getting enough samples to make inferences, so hopefully this project will help with baseline information.

Students from St. Xaviers College to go to Sassoon Dock every weekend and sample sharks in the catch—so far, we’ve documented around 22-24 species.

Where do you plan to go from here?

Well my immediate goal is to complete the PhD, but after that I might want to involve myself more in outreach and policy and undertake research questions that point towards conservation interventions.