No loss of wild salmon to sea lice
Previously described by this author as a "ficticious enemy", Broughton Archipelago sea lice (or salmon lice- Lepeophtheirus salmonis) was deemed not to have caused the death of wild out-migrating juvenile salmon in 2007 and 2008, according to the BC Pacific Salmon Forum. In its final report, the Forum explains the findings of a combination of laboratory experiments and studies in the field.
In laboratory trials, a level of 7.5 sea lice per gram of fish weight (3-4 sea lice on a 0.5 g pink salmon smolt) was reported to be lethal. This is in stark contrast with research findings in Europe, where Norwegian scientists have found that levels of their version of the L. salmonis can be lethal for Atlantic salmon smolts at levels as low as 1.3 lice per gram of fish. Pink salmon juveniles in excess of 1g also seemed to be capable of a considerable degree of shedding of lice.
Intensive field monitoring programs in the Broughton in 2007 and 2008 measured levels of sea lice on juvenile pink and chum and, "using the same threshold level, found no lice levels on pink salmon juveniles that would produce fish mortality". The Forum explains that some fish may have died from sea lice infections before they were detected, but this doesn't appear to have been a problem in other studies, where large numbers of sea lice-infected fish have been reported. The Forum also cautions readers that the extrapolation of laboratory-obtained data to the field may be problematic.
The BC Pacific Salmon Forum was established in December 2004, and spent most of its CAD$5 million (~€ 3.1 million) budget on research around sea lice and its potential effect on wild salmon in the Broughton Archipelago. Researchers were summoned from a wide range of interests, from Governmental regulatory agencies as well as from the scientific community usually critical of salmon farming in its presently practised form.
