Latest Scientific Reports

Sea Lice Found on Juvenile Sockeye & Herring as Well as Pinks & Chums Near Fish Farms in Northern Georgia Strait

The latest scientific paper on sea lice reports that infestations have spread to juvenile pink, chum, and sockeye salmon as well as juvenile herring near Campbell River fish farms in the northern Georgia Strait. The study was published online by the North American Journal of Fisheries Management. Alexandra Morton R.P.Bio. (Salmon Coast Field Station) and Dr. Richard Routledge (Simon Fraser University) and Dr. Martin Krkosek (University of Alberta) looked at 4,700 young wild salmon near and distant to fish farms in 2005 and 2006 throughout the Discovery Islands.

"We found four times as many wild juvenile salmon were infected with sea lice near fish farms than distant from the farms," says Alexandra Morton. "Then in 2006 when most of the farms were empty, the sea lice declined". "This is the same pattern we see in the Broughton Archipelago," added Dr. Routledge, "Where there are farm fish the young wild salmon are infested with lice. Remove the farm fish and the sea lice problem disappears." The study looked at other variables, including salinity and temperature, but found that farm fish were the only significant factor contributing to the infestations. The study was made possible through the dedication of several commercial fishermen who did the sampling. Pink and chum salmon were the primary study focus, but juvenile herring were also examined and found infested with lice. The herring were tiny and still lacking scales suggesting high vulnerability. This is the first report of sea lice on herring this young.In addition, juvenile sockeye were discovered to be infested near the farms. Last summer, commercial salmon fishing was closed on the south coast because so many of the Fraser River sockeye failed to come home. Some of the sockeye that went "missing" last year were likely infested with sea lice in 2005 when they migrated to sea. "We did not test the DNA of the sockeye we examined," explains Dr. Martin Krkosek. "However, we know that many Fraser River sockeye migrate through our study area." The report concludes there is urgent need to implement policy that protects wild salmon from farm fish.

Currently Minister Pat Bell has called for more drug use to control lice. But Morton disagrees, saying that using drugs creates concerns for environmental and human health. The drug (Slice) has not been approved for use by Health Canada and may impact important stocks of crab, shrimp, and prawns. Morton concluded: "The only measure that is going to work is separating the farm and wild salmon. This can only be achieved by completely closed containment technology or moving the farms. If nothing is done now, I worry that Canadian salmon stocks will suffer the same fate as European salmon stocks that have declined dramatically in fish farming regions.”

Read the full study (29 page pdf).

Declining wild salmon populations in relation to parasites from farm salmon, by M. Krkosek, J.S. Ford, A. Morton, S. Lele, R.A. Myers, and M.A. Lewis, published in the peer-reviewed journal Science in December 2007.

“Declining wild salmon populations in relation to parasites from farm salmon”, a study conducted by a team of biologists, fisheries scientists, and mathematicians from Dalhousie University and the University of Alberta and published in the December 14, 2007, edition of peer-reviewed Science magazine, investigates the impacts of sea lice from fish farms on wild salmon abundance.

Results show:

• Recurrent sea-lice outbreaks cause 33 per cent to over 99 per cent annual mortality of pink salmon on the central British Columbia coast
• Under current conditions, the population is expected to decline to regional extinction, with 99 per cent loss predicted in the next four salmon generations (eight years).

Read the full report in Science (subscription required).

Estimated Sea Louse Egg Production from Marine Harvest Canada Farmed Atlantic Salmon in the Broughton Archipelago, British Columbia, 2003–2004. Craig Orr, North American Journal of Fisheries Management, Volume 27, Issue 1 (February 2007) pp. 187–197. (pdf)

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