Would you consider purchasing starfish or sand dollars instead of lobster or snapper at your local supermarket? In India, shoppers have little choice. A steep population decline of commonly consumed species such as shrimp and grouper — from overfishing — has forced Indian fishermen to land a larger portion of less desirable varieties such as sardines and sea urchins, also referred to as bycatch. Although they used to discard it in the millions of tons, fishermen now sell bycatch for local consumption and poultry feed. And according to new research, Indian fisheries have become reliant on bycatch for turning a profit, a practice that could severely disrupt the entire offshore ecosystem where Indian vessels exhaustively trawl the waters.
Researchers examined changes in catches by Indian trawlers by interviewing fishermen in three locations and reconstructing trends in income, bycatch figures, and catch of marketable species over the past thirty years. The results revealed that the annual catch of more marketable species like shrimp and grouper has declined sharply in the past twenty years while the amount of bycatch sold has steadily increased. They also saw a steady rise in bycatch sales to India’s growing poultry industry, whose rapid expansion coincides with the country’s burgeoning affluence and consequential shift away from vegetarianism. As stocks of more commonly eaten species dwindle, the demand for bycatch from both local consumers and from the poultry industry has become critical to fisheries’ survival.
Aaron Savio Lobo, a Ph.D. candidate who studies ecology at Cambridge University in the U.K., was the lead author of the paper describing the research, which was published in August in the journal Conservation Letters. Bycatch commercialization is “definitely bad news” for the marine environment, Lobo said, with “profound implications” for the health of fish stocks. Fishers “scraping the sea floor and picking up whatever they can possibly get, from the tiniest bivalve shells to massive rays” could lead to “ecological catastrophe,” and may push marketable species beyond their ability to ever recover, Lobo warns.
William Cheung, a marine biologist at the University of East Anglia in the U.K., who was not part of the study, explained that the shift to bycatch targeting is referred to as “fishing down the food web,” or as in the case in India, fishing “down the price list.” As more desirable species become depleted, fishermen target cheaper and cheaper varieties “until we finally develop markets for jellyfish and plankton,” Cheung said. “I don’t think that would be a good way to go.” Moreover, Cheung explained, commercializing bycatch makes it even more difficult for originally targeted species to survive, since the incentive no longer exists for fishermen to move to a new location after marketable fish stocks have been exhausted. Fishers lingering on in a depleted area to collect bycatch leave no window of opportunity for population recovery of marketable species, as the next generation of juvenile fish is scooped up alongside the few remaining adults. As a result, Cheung concluded, fish stocks cannot fully recuperate and some species can even be driven to local extinction.
Lobo hopes his future research, which will concentrate on establishing bycatch figures, can further define the scope of the problem. If successful, his work could contribute to the design of strategies that would strike a balance between the livelihoods of fishermen and the survival of threatened species currently suffering the effects of overfishing. This would ultimately benefit the fishing industry through sustainable management of species populations, Lobo says.
But for now, Lobo says, no easy solution exists. “What are you going to do with all those fishermen? They pick up whatever they can possibly get, just to keep afloat.”