Salmon Steward

salmon Steward magazine 5 CHINOOK & ORCAS Tag, Chinook Are It! Watching What They Eat N obody knows exactly how much Chinook salmon Resident Killer Whales need to survive, but finding out is integral to helping the Southern Resident population. The Pacific Salmon Foundation is part of a larger program involving the University of British Columbia, with funding from the Department of Fisheries and Oceans, and the National Sciences and Engineering Research Council of Canada, proposing to repurpose tagging technology initially used in the Salish Sea Marine Survival Project. The idea is to put receivers at the bottom of the ocean where orcas are known to feed, and then implant Chinook with predator tags. When the orcas feed on tagged Chinook, the receivers will register a change of frequency emitted by the tags as the cold-blooded salmon are consumed by the warm-blooded mammal. "It's an attempt to estimate the consumption rate of orcas on a target group of salmon," says Brian Riddell, CEO of the Pacific Salmon Foundation. In the Salish Sea Marine Survival Project, acoustic tags and receivers were used to track juvenile salmon leaving the Fraser River and migrating north through Johnstone Strait. Says Riddell of adapting this technology: "The metabolic demand of orcas in the cold ocean is high, so they are very sensitive to the loss of food availability. We hope the information gained from our project will help us develop recovery and management goals for Chinook to support recovery of orcas and to sustain local fisheries." If funded, the study will be launched next spring, and Riddell is already anticipating the long-term outcome. "In another year we should have gathered considerable data that we can share with the fishing industry, government, biologists and other experts," he says. "If all this leads to eŽective Chinook recovery strategies, it could be of significant benefit to orcas and people." T he old adage "You are what you eat" is particularly applicable to research undertaken by Sandra M. O'Neill and other marine biologists on behalf of the Salish Sea Marine Survival Project. Her work could be of value to both orca and human health. O'Neill, who works for the Washington Department of Fish and Wildlife, is identifying contaminants in adult Chinook salmon and using them as a roadmap to determine where the Chinook are rearing. There are many causes of marine pollution, including sewage, toxic chemicals from industry, nuclear waste, and plastics. As such, marine environments along the West Coast diŽer in their contaminant level based on how the region was used historically and local water circulation. Says O'Neill: "Generally speaking, the Southern California marine food web has a lot of DDT contaminants. In contrast, the deep inland •ord- like waters of Puget Sound and parts of the Strait of Georgia have limited exchange with the Pacific Ocean and are PCB hotspots – and what gets into •ords stay in •ords." DDT was originally developed as an—insecticide, but later became commonly used as an agricultural and household pesticide. By 1972, it was banned for its environmental impacts and links to cancer. PCBs are used in industrial products and chemicals. "Even the relatively pristine waters of Haida Gwaii have contaminants," she adds. Chinook tend to linger along the coast compared to other salmon species. Repurposing tagging technology from previous juvenile salmon research could reveal the true importance of Chinook in the SRKW diet Studying contaminants consumed by Chinook and orcas offers a wealth of crucial data for salmon scientists Receivers will track tagged Chinook as they swim by. By measuring the quantities of these contaminants, the researchers can pinpoint where they're feeding. Such data will eventually help regulatory bodies better manage fisheries and even issue consumption advisories when necessary. O'Neill's focus also includes orca behaviour. Specifically, she is collaborating with scientists from the NOAA Northwest Fisheries Science Center on contaminant research in orcas. The two streams of data could ultimately lead to a comprehensive understanding of which Chinook stocks the orcas are eating; that, in turn, may help identify which stocks require conservation management. Although as of this writing O'Neill was still in the midst of compiling her findings and couldn't disclose numbers, she is excited by the prospect of being able to aid in Chinook recovery eŽorts. She concludes: "This work is an adjunct to what I do for the Department of Fish and Wildlife, and using chemical contaminants as tracers to where animals are feeding I think has enormous potential for further study." Sandra M. O'Neill

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