After analysing over a decade's worth of statistics from fish farms, a team led by Gary Marty, a veterinary pathologist at the University of California, Davis, suggests that the farmed fish instead seem to pick up the lice from wild salmon - and, in any case, the lice don't seem to have been responsible for the 2002 population crash.
The pernicious effect of lice from fish farms became a generally accepted fact after studies seemed to connect them to declines in wild salmon populations. In 2007, a study ... showed that the numbers of pink salmon in rivers exposed to farmed fish declined after 2001, when the lice were first noticed. ...
Marty's co-author, Terrance Quinn, from the Juneau Center at the University of Alaska Fairbanks, says that their model does include "a residual term for other unexplained variability". "The relationship [with lice] could indeed be there," he adds, "but if it is, it is swamped by other unexplained variation."
Read more at Nature and at CBC News.
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