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Researcher Responds To Pacific Salmon Forum
(In the following open letter, Alexandra Morton responds to a Pacific Salmon Forum press release issued earlier this week.)
Dear Colleagues:
Yesterday, Dec. 18, 2007 the Pacific Salmon Forum (PSF) issued a press release suggesting that 80 per cent of the Broughton juvenile salmon were not infected with sea lice in 2007. I am a co-investigator on the study that generated the PSF number “80 per cent.”
For the past two years, Drs. Brent Hargreaves, Simon Jones and I have worked together on the PSF funded project to monitor sea lice and salmon in the Broughton.
We have been trying to resolve some differences of opinion for some weeks about using the number (80 per cent).
Since the PSF has gone ahead and released the figure under debate I feel compelled to tell you where it came from.
We know that juvenile salmon migrate through the Broughton from their rivers, towards fish farms, past fish farms and out to sea.
We also know that surface currents in Knight and Kingcome inlets generally flow in the same direction as the fish.
This means we can identify areas where sea lice from fish farms are highly unlikely to drift into and that these are the same areas where young salmon will not yet have encountered a fish farm. This roughly divides the Broughton Archipelago into areas exposed and not exposed to fish farms.
Many of us have published on this, showing both the difference in lice abundance and prevalence between exposed and unexposed areas and also a finer scale examination of the transition between these zones.
The PSF chooses to ignore all of this work when they use the number 80 per cent to challenge the recent paper in Science.
The number 80 per cent not infected with sea lice includes fish from areas exposed and not exposed to fish farms.
This includes fish caught in lower Knight Inlet east of Tribune, Kingcome Inlet and the estuarine environments of the Kakweikan and the Ahta.
As well, this number includes the Wells Passage area where there were no farm salmon, except for one pen for a few days in March. It includes fish that have been in the saltwater for hours, days, and months.
But we know juvenile salmon move generally west, passing fish farms in the channels of the Broughton like water through a coffee filter.
You are only going to find brown water at the outcome of the funnel.
To learn how many salmon got infected by sea lice from fish farms you need to understand where the fish came from.
One of my co-investigators did not want to offer a more detailed analysis on the grounds that measuring impact of fish farms was not an objective of the study and that we need to understand the natural processes involved before we can understand any farm effects.
I don’t see how anyone can study natural effects in the most perturbed sea louse habitat we know of in BC.
It is my impression that if we want to know what percent of juvenile salmon were infected with sea lice in the Broughton, we need to look at the fish as they leave the archipelago.
In both my own study and the PSF study, the site that best represents the product of the Broughton Archipelago is Wicklow.
At the peak of the 2007 out-migration, 83 per cent of the salmon I examined in my own study at Wicklow were infected with sea lice.
If the PSF study was not designed to tell us anything about impact of fish farms on sea lice infections of juvenile salmon, why is the PSF using it to challenge the Science paper on this subject?
As I write this the Cliff Bay fish farm is being stocked resulting in more stocked fish farms on the Tribune – Fife salmon migration route than in the history of fish farming.
Science reports sea lice from these exact fish farms are rapidly driving wild salmon to extinction and John Fraser chooses to publicly challenges Science using a study that was not even designed to speak to this subject.
I think it is time that the relationship between the fish farming industry and our governments be investigated and reported to the Canadian public.
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