Wednesday, 28 June, 2000, 17:51 GMT 18:51 UK
Fish farms 'devastate' wild stocks

By BBC Science's Corinne Podger
Fish farms might seem a sensible alternative to over-fishing the world's
oceans but a new report says they have a disastrous impact on both the
environment and on stocks of wild fish.

Fish farming, also known as aquaculture, has been widely promoted as a smart
way to feed the world's surging population.

But an international team of scientists writing in the journal Nature say it
is contributing to the global collapse of the world's wild fish stocks.

This is because huge quantities of wild fish, especially anchovies and
mackerel, are being scooped up and ground into meal to feed farmed fish.

The authors of the report say fish farming also harms the environment, by
converting wetlands into artificial farms, and with the escape of farmed
species which can interbreed with wild fish and pass on weak or specially
inbred genes.

This is especially true of farmed salmon species, which now account for up to
two-fifths of salmon caught in the north Atlantic.

China praised

But the report singles out China for praise, for embracing a centuries-old
sustainable technique of keeping different kinds of carp species in the same
pond to create a balanced mini-ecosystem.

To make fish farming more sustainable worldwide, the authors recommend that
farmed fish should be fed vegetable protein instead of fishmeal.

And they say tighter controls are needed to lessen the impact of farms on
natural habitats. Otherwise, they say, fish farming is not the harmless
alternative to ocean fishing that its advocates would claim.

Scotland has a large number of fish farms and Kevin Dunion, Director of
Friends of the Earth Scotland, said: "This important piece of work clearly
shows that the intensive farming of fish such as salmon and trout is
inherently unsustainable. It can take up to three tonnes of wild fish to
produce a single tonne of farmed fish."