Oceans and Coasts


The economics of trawl fishing along the Coromandel coast

Trawling is one of the most efficiently destructive and wasteful fishing techniques known, leading to rapid overharvests of trawled waters. Along the East Coast of India, the fishery keeps itself profitable by finding value in previously discarded trash fish, now used to feed the rapidly growing poultry industry

Trash fishing is a thriving industry

Trawlers have gained global notoriety for the high levels of bycatch they discard. Besides being ecologically unsustainable, the discarded bycatch, is of little value to trawl fishers. However, it serves as the sole source of livelihood and protein to artisanal fishers and millions who throng the coastlines of the developing world.
However, with declining commercial fish stocks and decreasing profits, fishers  in India and other parts of the developing world, find more commercial value in ‘trash fish’ (the previously discarded category of bycatch).

In this project we sought to understand the economics of trawl fishing along the Coromandel Coast in the light of rapid overexploitation.  We monitored trawlers along the Tamil Nadu coastline, documenting operational costs, quantities and prices of target and trash fish. Our data indicate that fishers adopted different strategies, dynamically adapting to local conditions in the struggle to stay profitable. Landing trash was an important part of this strategy, and it supports a thriving industry along the Coromandel that processes trash into poultry feed and includes several middlemen, sorters and finally fishmeal processing plants. 

Our data indicate that trash fishing helps subsidize the trawl fishery, particularly when commercial catch profits are low, fuel prices increase or the catch variability is high. 

Rays of hope: indicators of trawling intensity

Trawling is a largely unmanaged fishery along the coast, driven by market imperatives, technology and resource stocks. This drives a pattern of sequential overexploitation, as benthic waters are first depleted of their large, long-lived carnivores and the fishery shifts to  species lower down the marine food web.  A recent analysis of long-term data series suggests that this trophic decline, termed "fishing down food webs" is also evident in the Indian marine fisheries sector. 

One of the principle difficulties of managing this sector in Indian waters is the notorious unreliability of direct monitoring measures of fishing intensity.  These data are logistically complex to collect, collate and make sense of.  We conducted a study to determine if it were possible to use simple proxies of overfishing along the Coromandel coast.  We explored the use of benthic elasmobranchs (essentially rays and skates) as an indicator of trawling intensity. We recorded at least 19  species (from 7 families),  exhibiting a range of life history characteristics. These species show a clear differential response along a gradient of fishing intensity. The abundances of some species decline exponentially with increasing trawling intensity. In addition, adult body lengths of individuals captured in heavily trawled areas were considerably smaller than those captured in low fishing intensity areas. Taken together our work suggests that this group may be a useful and robust indicator of trawling intensity.