Johnston Strait

Fish farms underreport sea lice when not being audited, study says

“Our results suggest that sea-louse counts reported by the salmon farming industry are lower than the true abundance of parasites on their fish. When the federal government audited a sea-louse count, the industry’s mean counts for that month increased by a factor of 1.18 for L. salmonis and by 1.95 for C. clemensi.” – Sean Godwin et al, Bias in self-reported parasite data from the salmon farming industry.

Dr Sean Godwin is the lead author of eight of the fifteen scientific papers listed on his website. The bulk of these explore interactions between wild and farmed salmon. One of the most troubling, published in the journal Ecological Application, is a survey that showed fish farms underreport sea lice when they are not audited by Fisheries and Oceans Canada.

The study

“The period of study in that paper was 2011 to 2016. It involved every salmon farm that operated in British Columbia during that time. What we found was that when DFO Auditors were there to check in on the salmon farm counts, the industry counts were higher …,” he said. 

Godwin said that while this is not true in every single case, it is the overall trend.  

“Once we took into account all these other things that upset sea lice numbers –  like temperature, salinity, location and all these things – there was this really obvious effect across the board. When DFO Auditors were there, the accounts were higher and when DFO Auditors were not here, the counts were lower.”

Industry Response

The BC Salmon farmer’s Association emailed a previously published statement, “ …The report by Sean Godwin et. al is presented as a direct comparison of sea lice data collected by salmon farmers and submitted to the DFO with audits conducted by the DFO. However, that’s not what it actually does. Rather, the study’s authors created a complex model themselves to try and estimate what sea lice counts should have been in the past, and report on variance from their own model to actual sea lice counts. The model feels rushed, and is based on assumptions that aren’t clear in the study and don’t reflect a number of complex variables including the reality of ocean conditions.”

the degree salmon farms underreport sea lice

Same underreporting in raw data

To which Godwin responded, also by email,“The same trend we identified is present in the raw, publicly-available count data (i.e. -absent any modelling).  The average industry louse counts are still ~15% less for L. salmonis and ~50% for C. clemensi when auditors are not present.”

“ … This analysis began in 2017 as part of my PhD thesis, and has taken the better part of 3.5 years to complete to our satisfaction and go through the thorough peer-review process in a leading scientific journal (to which we first submitted the manuscript last October).”

“ … Our study does not compare industry counts during audits to DFO audit counts, nor do we ever present it as doing so – we know DFO already does this … We were instead curious about what happens to industry’s own counts when auditors are not present. Our use of a statistical model (fit to real industry counts) was designed to account for factors known to affect sea lice (e.g., treatments, seasonality, etc). Our use of a statistical model was in-part an honest attempt to find explanations other than industry bias.”

Study says salmon farms underreport sea lice like these

How big is the sea lice problem? 

Godwin said that a lot of the research that would allow scientists to gage the overall impact sea lice are having on salmon migrations ‘either has not been done or hasn’t been allowed to be done.’

“There is a lot of evidence that shows fish with sea lice don’t survive as well. They don’t compete for food as well. Their behaviour changes. They take more risks, which means more are eaten by predators,” he explained.

Studies in the Broughton Archipelago found that in years when there has been high sea lice numbers in Pink Salmon, “there has been added mortality of up to 80%.” When sea lice numbers are low, that number has dropped to as little as 3%. 

“It is probably similar in other species and in other regions, but we do not have the research for that yet,” said Godwin.

Consequently, people advocating the precautionary principle take this data seriously. 

Others point to the lack of correlational studies in their areas and say’ ‘Why should we take out this industry?’  

Industry numbers are always going to be lower

Q/ How would you explain the difference between, for example, the sea louse counts that Alexandra Morton and the industry did in the Broughton during 2020?

 “Those two numbers aren’t really comparable. Alexander’s numbers include both the sea lice species … Whereas the industry ones separate those two species.  You’d have to add the two industry numbers to get one that is kind of comparable. Even then, Alexandra’s numbers come from sites after the fish have been exposed to salmon farms. Whereas the industry numbers include sites all around the Broughton, including before the fish are exposed. So the industry numbers are always going to be lower,” said Godwin. 

Having worked with both groups in the Broughton, Godwin believes the goal of the industry field team seems to be getting in and out as quickly as possible, “which can be at odds with their accuracy given how easily lice jump off of fish.”  

In the Broughton Archipelago

Godwin started spending his summers at the Salmon Coast Field Station, in the Broughton Archipelago, in 2009 and became one of the Directors on December 15, 2020. He is also the expert consultant for the First Nations in that region. 

This would seem to indicate he is in an excellent position to comment on a situation in the Broughton Archipelago. Some critics of the industry suggest the drop in sea lice numbers in 2020 is linked to the phasing out of fish farms. In response, a BC Salmon Farmer’s Association spokesperson emailed that “last year, some of the highest levels of sea lice were found in the Broughton area where salmon farms have been removed.” 

“I do not know if I buy that comment about last year’s sea lice numbers, but certainly there is more to the situation than just the number of farms,” said Godwin. 

Study suggests fish farms underreport sea lice like these

The Broughton Agreement

He thinks there were about 18 salmon farms in the Broughton Archipelago prior to a landmark decision by the province. Industry has until 2022 to obtain First Nations consent for any farms to remain in their territories. About 7 farms have already been removed as a result of this agreement and Godwin believes that the total number of farms will be reduced to about 7. 

“I do not think I should be speaking for the Nations in any way, on that process, but that is my understanding,” he said. 

“It seems that last year, removing those seven farms did a good thing. We saw the second lowest sea lice numbers since 2014. But this year we are finding that the salmon farms that remain, especially the important ones near the start of the salmon migration, have been unable to control their sea lice numbers. It doesn’t matter how many farms there are, if the farms cannot control their sea lice. So we are finding higher sea lice numbers on the wild salmon.”

Q/ Are those sea lice coming off the salmon farms?

Godwin reiterated, “A couple of the salmon farms have been unable to control their sea lice numbers. Their numbers are higher than you would want them during the migration. They broke their regulatory threshold, where they have to treat the salmon to get rid of the sea lice and those treatments haven’t really brought the number of sea lice down in a couple of cases. What we are seeing is: when there is more sea lice in the salmon farms, there is more sea lice on the wild salmon. No one can argue with that.”

The Discovery Islands

Q/ What do you think of Alexandra Morton’s report that sea lice levels have dropped 95% in the Discovery Islands, now that so many farms have gone fallow?

“I can’t comment first hand on that. I should have a better idea later in the season, once I see the data myself,” said Godwin. 

Links of interest:

Photo Credits: (top) Taken in the Johnston Strait (2016) by Sean Godwin; (podcast) photo of salmon pen by Tavish Campbell; Video “Running the Gaunlet; BC Salmon’s Journey to the High Seas” – courtesy Hakai Institute ; Fig. 3 from Bias in Parasite Data from Salmon Farms; A wild juvenile sockeye salmon, caught in Johnstone Strait, BC, during its migration from the Fraser River, infested with parasitic sea lice (Lepeophtheirus salmonis). Credit: Tavish Campbell; Video: Dr. Sean Godwin discusses new research on the temperature-dependent effects of parasitic sea lice at the 2020 North American Congress for Conservation Biology (NACCB) – courtesy Sean Godwin; Wild juvenile pink salmon from Nootka Sound, BC, covered in and scarred by parasitic sea lice (Lepeophtheirus salmonis) in 2020. Credit: Tavish Campbell; A salmon farm at Sonora Pt in the Discovery Islands of BC. Credit: Tavish Campbell

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