By Ian Roberts
Can a flu shot that is commonly used for farm-raised salmon help improve the survival of native coho salmon? It’s a question that’s about to be answered, thanks to the collaboration of a group of researchers, aquaculture companies and Campbell River businesses.
Over the past 30 years, Strait of Georgia coho returns have declined significantly and researchers are keen to find out why.
One factor believed to have a negative effect on salmon survival is increasing water temperatures – a concern highlighted as a major factor in the recent Cohen Commission Report that investigated the decline of Fraser River sockeye.
Because an increase in water temperature can trigger disease in fish, juvenile salmon entering the marine environment in the warming spring become quite susceptible.
Vaccinating a Coho salmon
So a group of fisheries biologists and veterinarians put their collective heads together and hypothesized that the occurrence of vibriosis, a naturally occurring bacterial disease found in fish in the marine environment, may be amplified by warming water temperatures and negatively affecting coho survival.
Fisheries and Oceans Canada, which operates dozens of salmon enhancement and conservation hatcheries in British Columbia, uses bath vaccination against vibriosis for Chinook salmon, but has never injection vaccinated coho to help protect against the disease.
Dave Ewart, manager at Campbell River’s Quinsam River Hatchery, was aware of the major success that salmon farmers have using injection vaccination to protect their fish from common diseases such as vibriosis, and was keen to trial Quinsam River coho with a similar vaccine.
So this past December about 40,000 coho salmon (weighing 12 grams each) were injected with a vibriosis vaccine. The trial includes a control group – another 40,000 salmon injected with an innocuous saline solution. All 80,000 salmon have been tagged with a coded wire so when the salmon return as adults (some early maturing males will return in the fall of 2013 and the rest in the fall of 2014), the survival rates of the two groups can be compared.
“Typically, Quinsam Hatchery produces up to 800,000 Coho smolts per year with a current survival rate of only 2%. If vaccinating increased this to 4%, it would double the adult return,” says Ewart. “By increasing survival
Coho receive a vaccine and coded tag
rate we could decide to keep smolt releases the same and provide fishers with many more adult salmon to be caught, or decrease releases and maintain the same number of adult returns, thus saving significant dollars and reducing competition in the Strait of Georgia.”
The trial will run for three consecutive years and is funded by the Campbell River Salmon Foundation ($9200 cash), Centre for Aquatic Health Sciences ($8000 of in-kind support for fish health monitoring services), Fisheries and Oceans Canada ($8000 for in-kind services), and Northwest Marine Technology ($4000 for coded wire tags). Donations were also presented to the Campbell River Salmon Foundation in support of this project by Mercury Marina and Trailer Park ($2000 cash), Marine Harvest Canada ($1000 cash), Novartis Animal Health ($700 for vaccine) and Syndel Labs ($200 for anesthetic).