Huge volumes of captured fish go to waste either because they鈥檙e non-target species or because fishing fleets make no effort to record and manage non-target species sustainably.
That鈥檚 the conclusion of an (pdf) by , which estimates how much of the fish harvest goes to waste as bycatch, the species thrown back dead into the sea or used for other purposes, such as feed for aquaculture.
WWF says the study reinforces the need for a complete paradigm shift in how fisheries are managed, so that everything taken from the sea is accounted for. What鈥檚 also needed is a clear and consistent new definition of bycatch to avoid existing disparities in how 鈥渨aste鈥� fish is recorded and accounted for.
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鈥淲e want to see everything taken out to be managed in some way to make sure we are fishing within the limits of what鈥檚 sustainable,鈥� says study author, Robin Davies of WWF International.
Davies suggests that from now on, bycatches should include fish that are either unused and thrown back, or fish that are caught but are not currently monitored to check for any species in danger.
Mass waste
Two earlier landmark studies cited by Davies estimated that between 7 and 27 million tonnes of fish go to waste as bycatch.
Davies new study estimates that 38 million tonnes go to waste, some 40 per cent of the total tonnage landed.
鈥淚f 40 per cent of the global catch is unused or unmanaged, how can we make sure it鈥檚 fished sustainably?鈥� says Davies, whose study will appear in Marine Policy later this month.
Davies arrived at the estimates by analysing public fisheries data from 2000 to 2003, covering 44 countries, two oceanic regions (the northeast Atlantic, and the Mediterannean and Black Sea) and global tuna and sharkfin fisheries.
The waste was greatest in sharkfin fisheries, which typically discarded 92 per cent of non-target species.
There were also disparities in what counted as bycatch. In some parts of the world, non-target fish were still utilised. In prawn fisheries in Asia, for example, owners paid their deck-hands in bycatch fish.
Davies also found that the use of technology to allow non-target fish to escape 鈥� such as in the prawn fisheries of Europe 鈥� was patchy on a global basis.
Monitor system
Equally, there were big differences in how and whether independent observers were allowed on boats to keep records of the species caught, and their fate.
Such a system has been operating in Europe for at least 20 years, and WWF argues that the latest estimates justify installing such systems everywhere. Even in Europe, for example, too many skates and rays are caught and discarded but not recorded.
鈥淢onitors are so important, to show that fisheries are implementing technologies they should, and to get accurate data on bycatch,鈥� says Giles Bartlett, fisheries policy officer at WWF-UK. 鈥淭he key is that they鈥檙e in place, and part of overall fisheries management plans everywhere,鈥� he said. Otherwise, fisheries will continue to collapse.
Mark Tasker, head of marine advice at the , which advises the UK government on nature management, says the new study is useful and sound. 鈥淚t keeps the spotlight on the major environmental impact of fisheries, and it鈥檚 a reasonable attempt to make bycatch estimates with good conclusions,鈥� he says.
鈥淲e know that 40 to 50 per cent of catches are being killed by being thrown back, and that鈥檚 not a good thing,鈥� says Tasker.
He applauds the attempt to re-define bycatch, but wonders whether management of stocks will itself be difficult to define and implement. 鈥淚 agree recording of total catch is a good thing, and then you could think about preserving rarer fish caught by accident,鈥� he said. 鈥淎nd we all agree that unused fish count as bycatch.鈥�
