杏吧原创

ATLANTIC salmon that have escaped from fish farms on Canada鈥檚 Pacific coast
have successfully spawned in at least one British Columbian river, according to
a government memo leaked to Canadian conservation groups. The memo, from the
British Columbia Ministry of Fisheries, describes 鈥渢he first verified report of
successful reproduction for introduced Atlantic salmon, anywhere in the
飞辞谤濒诲鈥�.

During the past decade, more than 100 000 farmed Atlantic salmon (Salmo
salar) have escaped from their net cages along the coast of British
Columbia. Conservationists are concerned that the commercially grown fish will
compete with native Pacific salmon of the genus Oncorhynchus, which are
already in decline as a result of logging and other disturbances to their habitat
(This Week, 17 January, p 22).
Provincial fisheries officials, however,
have long maintained that Atlantic salmon can鈥檛 reproduce in Pacific coast
rivers.

That view changed dramatically in August, after Canadian government
biologists found a dozen juvenile Atlantic salmon in Tsitika River on Vancouver
Island. DNA analyses confirmed that the fish were Atlantic salmon. Adults have
been sighted in the river before, says Eric Taylor, a zoologist at the
University of British Columbia in Vancouver who conducted the DNA tests. As
there are no net cage salmon farms nearby, the most likely explanation is that
Atlantic salmon are spawning in the Tsitika River, he says.

Conservationists fear that the faster-growing Atlantic salmon may oust native
species. 鈥淭he consequences are potentially devastating,鈥� says Jim Fulton,
executive director of the David Suzuki Foundation, an environmental group based
in Vancouver.