OSLO — Freshwater fish can be introduced more safely than
expected to new regions for farming with fewer than 10 percent damaging wildlife
in their new homes, a scientist said on Tuesday.
Many countries wrongly view alien fish species – such as
trout, catfish, perch or salmon – as posing a big risk when put in new rivers
and lakes, said Rodolphe Gozlan, a French scientist who works at Bournemouth
University in Britain.
"We shouldn’t exaggerate the risks of non-native species,"
Gozlan, who also advises the European Commission on the safety of fish farming,
told Reuters.
"The risk of ecological impact after the introduction of a
freshwater fish species is less than 10 percent for the great majority of fish
species introduced," he wrote in the March edition of the journal Fish and
Fisheries.
Some types, such as the perch or catfish, were more likely to
cause disruptions. But many nations had accepted the view that all alien fish
was "guilty until proven innocent", he said.
A study of 103 introduced fish species in an aquaculture
database by the UN’s Food and Agriculture Organization showed that 54 were
reported with no adverse impact on their new habitats, he said.
"Fish farming will expand around the world in coming years,"
Gozlan said. "Overfishing at sea is not sustainable and we will have to rely
more on farmed fish."
That meant it made more sense for governments to assess the
risks of new species rather than seek to ban them.
Gozlan said widespread worries about alien species of animals
and plants marked a shift from a view common in the 19th century that new
species were beneficial.
France set up group to encourage introduction of new species
in 1854, for instance, and Britain followed in 1860 with the "Society for
Acclimatization of Animals, Birds, Fishes, Insects and Vegetables".
With time, many species had blended in. Rainbow trout
introduced from North America, catfish from Africa and carp from Asia were
widely viewed as beneficial in Europe. "After a while people widely accept them
as native species," he said.
Even the widely accepted villains among alien species, such
as zebra mussels in the Great Lakes of North America or the Nile perch in Lake
Victoria in Africa, might be less damaging than expected, Gozlan said.
The mussels, brought accidentally from the Black Sea, are
blamed for clogging inlet pipes of power stations for instance, but are a new
food source for some species of fish and birds.
The Nile perch, introduced to Lake Victoria about 60 years
ago as a new food source for local people, is widely blamed for eating other
fish.
But the perch created a big new fishery that attracted ever more fishermen,
often using smaller-mesh nets. The fishermen also chopped down trees around the
lake to smoke the perch, helping wash more sediment into the waters. –
Reuters
