Salmon Steward is the official publication of the Pacific Salmon Foundation in British Columbia, Canada
Issue link: http://digital.canadawide.com/i/300930
Strategic Salmon Health Initiative M ore than 90 per cent of young salmon migrating from fresh water to the ocean will never make it back to spawn. Although disease is suspected to be a significant factor in the high mortality rate, scientists don't know enough about what pathogens or diseases might be involved. And the situation has been gradually growing worse. In particular, many populations of wild Sockeye, Chinook and Coho salmon in the Strait of Georgia have been declining over the last two decades — a few to critically low levels, says Kristi Miller-Saunders, PhD, head of the molecular genetics section at the Pacific Biological Station for Fisheries and Oceans Canada. Meanwhile, public concern has been rising over the potential for "coincident exposure" — the possibility for bi-directional exchange of microbes between sea-pen-raised salmon from the aquaculture industry and their wild brethren, adds Brad Popovich, PhD, chief scientific officer with Genome BC. It was these concerns that inspired the Pacific Salmon Foundation to partner with Genome BC and Fisheries and Oceans Canada in the creation of the Strategic Salmon Health Initiative, a five-year project, with the first phase valued at $930,000 alone. The aim: to find out which pathogens, if any, are key contributors to mortality in Pacific salmon once they leave the freshwater environment. "There is a strong need for information on the role of infectious disease in wild salmon declines and, until now, there have not been technologies capable of resolving these questions," says Miller-Saunders. While traditional methods of monitoring fish health are often not sensitive enough to detect disease in its early stages, "recent advances in molecular and genomic technologies are beginning to revolutionize our understanding of infectious disease across a vast array of species. We will be applying these approaches for the first time in wild migrating salmon." The first step toward achieving this goal was collecting tissue samples from smolts and salmon returning to spawn — more than 23,000 in total. The chief tasks of phase two, which began in January 2014 and will likely take until late 2015, are to develop an efficient genomic tool for assessing samples of wild and cultured salmon, to identify when and where microbes are first detected, and to resolve which may be associated with disease. "Just as in human health, if someone has a virus, it doesn't mean they have a disease," says Popovich. "For example, we have more bacteria in our body than we do cells — we are just walking repositories of bacteria — and on a normal day, it causes us no trouble. So phase three aims to find out whether the microbes that are present actually cause any problems." Finally, phase four will seek to make the study's results readily available to industry and the agencies that have jurisdiction over Pacific salmon. "The project aims to develop a tool that can be used by the industry in a rapid, cost-effective way to screen fish — be they aquaculture fish, hatchery fish or wild fish — to determine if microbes are present or not present," says Popovich. "If infectious disease is found to be a factor in salmon declines, it will be imperative that measures be taken to reduce disease pressures on wild populations, where possible," says Miller-Saunders. "The microbe monitoring platform developed will be a critical element that can be applied to assess and mitigate disease issues in hatchery and aquaculture brood stocks. Moreover, microbe monitoring could be applied to enhance salmon forecasting for management by identifying years and stocks that may be highly affected." In practical application, that translates into a testing platform that can assess the prevalence of up to 47 microbes in hundreds of fish per day. This will allow industry to quickly and efficiently assess the current and future health of salmon populations and act accordingly — whether through vaccination, culling infected populations or other means. Miller-Saunders also points out that, as the microbes being studied by the Initiative will be associated with diseases that affect salmon worldwide, other countries can benefit from the research as well. The study is truly cutting-edge. "I closely follow the human medical research arena for novel technologies, and usually, while my lab is often an early technology adopter for the study of wild populations, we are often a decade behind applications in humans," says Miller-Saunders. "This time, we are at the forefront, adapting a technology that is still being trialed for use in monitoring human diseases." Speaking to Genome BC's involvement in the project, Popovich notes that the independent not-for-profit has spent almost $40 million on salmon research to date — a testament to the value that it and British Columbians place on the salmon industry. "Salmon — be it wild salmon or farmed salmon — is a very important industry to British Columbia. It's part of our culture here. It's also economically important — salmon is our No. 1 food export," says Popovich. "That's why it's so important to help the salmon industries understand what is causing salmon populations to be either healthy or not healthy." n salmon Steward magazine 9 Dr. Kristi Miller-Saunders studies a tube of worms from a salmon liver. Opposite (from left): Miller-Saunders puts samples onto a slide to identify disease- causing microbes; a microarray slide; samples are prepped for monitoring; Miller-Saunders examines a salmon smolt. p08-09Salmon Health.indd 9 14-04-11 2:03 PM