Every fall, when kids go back to school, epidemics of lice skyrocket. It’s simply a case of more bodies in one place at one time; where the little critters can spread from one kid to another.
And every year when wild juvenile salmon migrate from freshwater lakes and rivers to the open ocean, the same phenomenon seems to occur when they come into fairly close range of farmed salmon. Sea lice are not at all related to the dry-land versions, but they can be just as aggravating. Unfortunately for the salmon, they can cause severe damage to both wild and farmed populations.
In December two apparently contradictory reports were published regarding salmon and sea lice.
The first, written by Gary Marty, UC-Davis and Sonja Saksida, University of Alaska, and published in the Proceedings of the National Academy of Sciences (PNAS), seems to show that salmon farming did not cause a crash in the population of wild pink salmon in the Broughton Archipelago of western Canada. Salmon farming produces nearly 1.5 million tons of fish annually and the sea lice were suspected to have migrated from the farms to infect wild populations. Marty’s conclusion:
The data from Broughton Archibelago pink salmon populations and sea lice experiments best fit the conclusion that the majority of pink salmon deaths are caused by something other than sea lice…
The second report, published in Aquaculture Environment Interactions, written by Martin Krosek , University of Washington, Seattle, and Andrew Bageman, University of Cambridge, concludes in the discussion section of the report:
The rapid growth of sea-cage salmon aquaculture in coastal seas has triggered the emergence of infestations of parasitic copepods (sea lice) that challenge aquaculture productivity. …(T)he exposure of wild juvenile salmon to lice during spring, and the productivity of local wild salmon populations, is likely dependent on the dynamics of outbreaks and control of louse populations on farms.
Those research reports were published just about the time that the Canadian First Nations won the right to pursue a class-action suit against salmon farms in the Broughton Archipelago. You can be sure both of these research reports – and many more – will be called into evidence as the First Nations, who asked for permission to file suit nearly a year ago, allege sea lice infestations on farms raising Atlantic salmon infect juvenile pink salmon on their way to open water in the Pacific Ocean.
We’ll be watching for the developments around this issue. Stay will us!