Coho salmon released by recreational anglers are far more likely to survive when handled without a landing net, according to new research. In salmon fisheries where anglers may be required to release salmon that are undersized, wild or not the target species, post-release survival is critical to conservation efforts.
Researchers in UBC’s Pacific Salmon Ecology and Conservation Laboratory, led by Dr. Scott Hinch, found that damage to a fish’s scales and fins was the strongest predictor of whether a released coho survived. Most of that damage occurred when the fish were landed using typical “fish-friendly” mesh nets, while fish landed using smooth, vinyl-coated materials suffered far less fin and scale damage.
“The main takeaway for anglers is that if they are releasing a coho, they need to do so in the water next to the boat, without using a net,” said lead author Quin Johnston, a master’s student in Dr. Hinch’s lab.
The team captured 235 adult coho off the west coast of Vancouver Island and held them in seawater tanks for up to two weeks. Ninety-six per cent of fish with little or no dermal injury survived, while only 62 per cent survived if their fins or scales were heavily damaged.
Not all injuries were caused by landing gear. Researchers found that some fish rolled during the fight, causing the fishing line to wrap around their bodies, stripping away scales or damaging fins. The study also found that tandem hooks caused more severe injuries and made fish harder to release than single hooks.
Recommended release practices
When a coho is likely to be released, the authors recommend anglers:
- Keep the fish in the water whenever possible.
- Avoid using landing nets—release fish at the waterline using pliers or a release gaff.
- Do not use tandem or treble hooks as they cause further injury and make it difficult to release fish at the waterline.
Because even careful handling creates some risk, the researchers also encourage anglers to keep their legal coho and stop fishing once they have reached their retention limit.
Catch-and-release impact underestimated
Researchers kept the fish in holding tanks at a lab long enough to detect delayed deaths that shorter observation periods would miss. Most deaths occurred three to eight days after capture, suggesting that studies focusing on 24-hour survival may underestimate the effects of catch-and-release.
“A fish can appear perfectly healthy when it swims away from the boat, only to die days later from injuries sustained during capture and release. Those delayed deaths are largely invisible to anglers,” said senior author Dr. Scott Hinch.
The study is the first experimental test of coho handling recommendations the lab published in 2024, which the researchers said have informed a number of changes to B.C. fisheries regulations governing hook types.
“With hundreds of thousands of coho reported released each year across B.C.’s south coast alone, the findings could help anglers improve coho survival and help fisheries managers predict how many salmon may ultimately return to spawn,” said Dr. Hinch.
The authors note that the study identifies the handling practices that give released fish the best chance of survival. It is not a direct estimate of post-release survival because tanks remove factors such as predation.
The project is the result of a partnership between the UBC lab, the Sport Fishing Institute of BC, the Pacific Salmon Foundation and the Bamfield Marine Sciences Centre. The research was funded by the B.C. Salmon Restoration and Innovation Fund and the Natural Sciences and Engineering Research Council of Canada and was conducted in the traditional territory of the Huu-ay-aht First Nation.
Interview language(s): English (Hinch, Johnston)
Article originally posted on UBC News.
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