Samantha Donovan reported this story on Wednesday, June 17, 2015 08:26:59

MICHAEL BRISSENDEN: It's depressing news for fish lovers but a new study has found dwindling fish stocks will mean consumption patterns will have to dramatically change within a decade.



The University of Tasmania research found nations and industries are competing for fish and it will soon no longer be viable to use the resource for both food and products like fertiliser.



Samantha Donovan explains.



SAMANTHA DONOVAN: For the last decade, Professor Reg Watson from the University of Tasmania has been mapping global fish catches.



He's found fishing practices have changed dramatically over the last 60 years.



REG WATSON: In the 1950s, with the exception of a few things like Atlantic cod, most people fished in their own waters but if they wanted to go further away you could go anywhere, pretty well.



And then as things progressed some of those in-shore waters get fished more and more.



SAMANTHA DONOVAN: Professor Watson's detective work has involved matching up UN records of fish exports and imports to work out who is eating what.



He says many European and African fisheries in particular are seeing stocks plummet because of overfishing and fleets are having to travel further to get their catch.



REG WATSON: Certainly around Europe where the North Sea can't sustain all of the fishing that European fleets want, they have moved further out and now use areas off Africa.



All of the Pacific in Asia has been fished heavily and is subject to claim and counter-claims, and now the Chinese fleet travel a long way and they do a lot of fishing off the African coast.



SAMANTHA DONOVAN: Professor Watson says historically many of the world's poorest people have relied on fish for protein; now it's increasingly a food of the wealthy.



And at the other end of the scale about a third of the world's catch is ground into powder to be used in food production.



REG WATSON: And even at times they've even been used for fertiliser. They've been a very good, cheap source of protein for growing other kinds of food.



We don't value eating those smaller fish from further down the food web, you know, which unfortunately they are some of the most valuable fish in terms of health benefits and they're also some of the easiest on the ecology if we eat those kinds of fishes.



SAMANTHA DONOVAN: How long then can fish-based feeds be used at the current levels in aquaculture?



REG WATSON: There is a limitation to that so what we're actually looking at is ways in which you can reduce that quantity coming from the wild fisheries and make the seafood we produce through farming go further to complement what's coming from the wild, which unfortunately seems to be pretty well all caught.



SAMANTHA DONOVAN: The University of Tasmania research is being published today in the journal Nature Communications.



MICHAEL BRISSENDEN: Samantha Donovan reporting there.