John West Tuna

"A win for consumers" ... John West will be phasing out fishing practices that involve "by-catch". Photo: Louise Kennerley

IT'S the sharks, manta rays and critically endangered sea turtles that John West rejects that should eventually make it sustainable.

The canned tuna company said on Tuesday that fishing practices that involve significant ''by-catch'', such as purse seine netting and using fish aggregation devices, or FADs, would be phased out by 2015.

The announcement follows a six-week campaign by Greenpeace that aimed to use consumer pressure to make the company change its ways.

''In six weeks 20,000 Australians demanded John West respect fisheries science and change their tuna,'' a Greenpeace oceans campaigner, Nathaniel Pelle, said. ''This is a win for consumers and a win for the oceans. It shows that when Australians take action together, we can bring about real change.''

The company's decision builds on earlier commitments to minimise by-catch and stop catching juvenile tuna.

The transition is unlikely to lead to higher tuna prices. John West said that ''following recent proactive engagement with Greenpeace'' it had ''clarified its sustainability goals''. The company had already been working to improve its fishing practices with WWF, it said.

Purse seine fishing deploys nets with a row of rings along the bottom that can swiftly draw a net tight around a school of fish to stop them escaping. Fish aggregation devices are usually tethered buoys that attract a high number of fish to one place, sometimes by using sonar signals.

John West joins other Australian brands Greenseas, Safcol and Sirena in making a commitment to sustainable fishing methods. For the purposes of measuring tuna numbers, ''sustainability'' is defined as fishing at a rate that does not impair a fish population's ability to replenish itself and does not adversely impact on other species within an ecosystem.

The move comes as the future of fishing in the Pacific is being decided at a meeting of the Western and Central Pacific Fisheries Commission, of which Australia is a member, in the Philippines.

Daniel Pauly, a professor of fisheries at Canada's University of British Columbia, delivered a speech at NSW Parliament on Tuesday warning that as Australia tried to preserve most of its ocean resources it would come under increasing pressure from international fishing operations.

The focus should be on small fishing operations, not supertrawlers such as the former FV Margiris, which had planned to fish in Australian waters and would ''punch holes in the food web'', Dr Pauly said.

The Environment Minister, Tony Burke, moved to stop Seafish Tasmania operating the 142-metre FV Margiris to catch redbait and jack mackerel off Australia's east and west coasts in September, pending research into the impact on fish stocks.

Dr Pauly said overfishing had already removed about half the world's table fish population in the oceans.

with AAP