New business in bycatch 'will lead to catastrophe'

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Going to the nearest market to pick up a few lizardfishes and flatheads (fishes traditionally not considered to be good eating) for the dinner table is rapidly becoming a reality in some parts of the world. This is the result of the commercialisation of bycatch (less desirable species that are incidentally caught and traditionally discarded).

This trend has potentially disastrous consequences for the world’s ocean ecosystems, highlighted a study published in a recent issue of the journal Conservation Letters.

Aaron Lobo and co-authors revealed this sad state of affairs along the Coromandel Coast (the southeastern coast of India) after conducting extensive surveys of the bottom trawl fishery of the region and interviewing both trawler owners and trash fish (bycatch) dealers. 

From the information they obtained, the authors reconstructed trends in income, bycatch figures, and the catch of marketable species over the past 30 years.

The authors found a sharp decline in the catches and income from the target species (such as penaeid shrimps, lobsters, groupers, snappers and barracudas) over the last two decades.

At the same time, the cost of operating the trawlers has increased substantially to the point that it almost exceeds the income obtained from target species. This has forced the fishermen to begin selling bycatch (which was traditionally discarded), both for human consumption (e.g. lizardfishes, flatheads and rays) as well as for the production of animal feed (e.g. cardinalfishes, sea urchins and mantis shrimp) to support the region’s rapidly growing poultry industry. 

While reducing waste and improving livelihoods, the increasing reliance on bycatch to sustain the trawl fisheries in the Coromandel Coast has the potential to exploit marketable species to the point beyond economic extinction and from which they may never recover. 

Without sustainable management, the bycatch-supported prolongation of trawl fishing along the Coromandel Coast will lead to an ecological catastrophe for the nearshore marine ecosystems, warn the authors.

For more information, see the paper: Lobo, AS, A Balmford, R Arthur and A Manica (2010) Commercializing bycatch can push a fishery beyond economic extinction. Conservation Letters 3, pp. 277–285.