The Salmon Farm Monitor
An rud bhios na do bhroin, cha bhi e na do thiomhnadh
"That which you have wasted will not be there for future generations"

Home | The Problems with Salmon Farms | About Us | Contact Us | Links | What You Can Do
| Latest News | Media and Docs Archive | Press Releases | Rod McGill | Guest Column

'Northern Climes, April 2003'


I make no apology for reproducing here Professor Frazer's masterly paper on the link between fish farm sea lice and the collapse in wild salmon. It follows the devastation of pink salmon in the fish farm riddled Broughton Archipelago in Canada, where, in the last two years, pink salmon runs have fallen from 3.6 million to 147,000.

Here in Scotland, as is the case in Ireland and Norway, fish farm sea lice have wiped out many distinct, irreplaceable, populations of wild salmonids. And, as is the case in Canada, our government officials and their fishery scientists, and the fish farmers they protect, still deny that there is conclusive evidence that fish farm sea lice are responsible for this catastrophe.

By the time you read this the Scottish Executive will have published its Aquaculture Strategy. This spurious piece of propaganda on behalf of the fish farmers does nothing whatsoever to save remaining stocks of wild salmon and sea-trout from extinction. How long are we anglers going to accept the deception and obfuscation of government civil servants and fishery scientists who, to protect themselves from ridicule, refuse to act to save our wild fish?

From Neil Frazer, Professor, School of Ocean and Earth Science and Technology, University of Hawaii at Maona, Honolulu:

"For at least a decade salmon farming industry representatives and government officials have maintained that 'There is no evidence that wild fish get [whatever infection] from farm fish.' They follow industry officials, such as Don Noakes, Director, Pacific Biological Station, or cite pseudoscience such as BC's Salmon Aquaculture Review and, admittedly, proof is missing when the obviously needed research has not been done, but still science has something to offer. Let's review the facts using sea lice as an example.

(1) Sea lice cannot survive in fresh water for more than a few weeks (e.g., Hahnenkamp and Fyhn 1985, Finstad 2002). (2) Hatchery salmon are raised in fresh water before they are put into the ocean. From 1 and 2 it follows that...

(3) Farm salmon are free of sea lice when they are put into the ocean. Some other facts: (4) Most wild salmon carry some sea lice most of the time. (5) Farm salmon have been plagued by sea lice infestations almost since salmon farming began (e.g., Brandal and Egidius 1979).

(6) The species of sea lice infesting farm salmon are those that infect wild salmon. Lepeophtheirus salmonis, in particular, has troubled the salmon farming industry since its beginning (e.g., MacKinnon 1997), and in the wild, L. salmonis is largely restricted to salmon hosts. From 3,4,5 and 6 it seems unarguably clear that farm salmon get sea lice from wild salmon. Even salmon farmers would not dispute that.

Now some other facts...

(7) Every species of sea louse is free swimming during the part of its life cycle prior to host attachment (e.g., Kabata 1979). (8) Farm smolts stocked alongside older fish carrying sea lice quickly become infested (e.g., Grant and Treasurer 1993). (9) Control of sea lice on salmon farms by fallowing is greatly improved if all farms in a single loch (inlet) are simultaneously fallowed (e.g., Grant and Treasurer 1993).

From 7 and 8 it seems overwhelmingly probable that... (10) Sea lice are transmitted from one farm to another through the water. Even salmon farmers would not dispute this. Accepting the above, we may conclude, with as much certainty as science ever has to offer, that sea lice are transmitted from wild salmon to farm salmon and that sea lice are transmitted from salmon on one farm to salmon on other farms. Isn't it then absurd to suggest that these same sea lice will not be transmitted from farm salmon back to wild salmon--when wild salmon are their original host species?

From elementary epidemiology we know. (11) In the transmission of any infection the probability of transmission increases with source strength. (12) In the transmission of any infection the probability of transmission increases with proximity to the source. We also know that... (13) Salmon farms can have very high levels of sea lice infestation. (14) Many salmon farms are located on the migration routes of adult and juvenile wild salmon.

Taking 11 and 13 together, and 12 and 14 together, leads ineluctably to the conclusion that transmission from farm salmon back to wild salmon is overwhelmingly probable. Overwhelming probability is not proof, but it's the way to bet until experiments have been done.

Accordingly, since 1993 at least, it has been scientifically irresponsible for any technical person to mislead the non-technical public by saying 'There is no evidence' that wild salmon get sea lice from farm salmon. A responsible scientist would have said 'It is likely that wild salmon get sea lice from farm salmon, just as farm salmon get sea lice from wild salmon, but the matter has not been studied.'

I think it is particularly irresponsible and unfair to mislead elected officials in this way, as it is their job to make difficult policy decisions with consequences far into the future. The word 'irresponsible' does not seem to me to be too strong a description in view of the public trust enjoyed by scientists and the fact that most of our education and professional activity is paid for by the public.

With regard to sea lice, at least, the problem of transmission from farms to wild fish is now being studied because it has become impossible for governments to ignore, though they have certainly tried (Frazer 2001, 2002; Noakes 2002).

The spring 2001 sea lice epizootic on pink salmon fry in the Broughton Archipelago (Morton and Williams, submitted) and the subsequent 98% drop in 2002 pink salmon recruitment in the Broughton--unpublished DFO data indicate 3.5M - 5M missing pinks!--underscore the consequences of ignoring the elementary scientific thinking outlined above.

Research by catastrophe, one could call it. By coincidence and poor husbandry most farms in the Broughton simultaneously held lice-infested Atlantics, and thus very few pink fry survived their passage down the inlets (Morton and Williams submitted). If only a few farms had held fish with lice many pink fry would still have perished, but the decline would have been regarded by DFO as within the normal range of fluctuation for pinks.

Absent clear evidence to the contrary, the above remarks and conclusion apply, mutatis mutandis, to any pathogen or parasite of wild salmon that has also been shown to infect farm salmon. Put plainly, any scientist who tells you that 'There is no evidence that wild salmon get [whatever disease] from farm salmon,' is not technically lying - but I cannot think of a better word for it."