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Collaboration between Trent and Ministry of Natural Resources and Forestry Revitalizes Threatened Fish Species

August 9, 2019

Biologists perform ‘genetic rescue’ to counteract inbreeding of aurora trout and increase survival

Aurora trout captured by MNRF

In the 1920s, scientists identified aurora trout as a new species native only to northeastern Ontario. Their habitat stood squarely in the path of emissions from Sudbury’s giant mines, and aurora trout became an early victim of acid rain and populations went into steep decline by the 1950s.

To save the species, Government of Ontario biologists captured every adult fish they could find – three females and six males – and raised the next generation at a local hatchery. Every aurora trout alive today is descended from those fish.

“After local lakes were restored, there were several attempts to reintroduce them to the wild,” says Chris Wilson, a research scientist with Ontario’s Ministry of Natural Resources and Forestry (MNRF).

But many of the fish weren’t surviving to adulthood.

MNRF and Trent researchers work together to find solutions
Researchers from Trent and the MNRF helped figure out why.

Dr. Wilson, who is one of about 20 MNRF scientists who serve as adjunct professors in Trent’s Environmental & Life Sciences graduate program, teamed up with Trent professors Michael Fox and Gary Burness.

“It's a win-win to work together,” Dr. Wilson says. “As a government lab, the MNRF was pursuing applied questions about aurora trout recovery linked to policy and management information needs. Trent researchers were pursuing more fundamental research questions about the evolutionary fitness of an endangered species. By teaming up, we were able to address the wildlife management question of ‘how can we fix this?’ and understand the solution within a bigger picture of species recovery.”

Research by Trent graduate students showed that aurora trout had all of the classic symptoms of inbreeding: poor survival, slower growth, and delayed maturity.

Due to the original population collapse, there were so few survivors, meaning little genetic diversity to pass down to new generations. After 50 years of captive breeding, aurora trout were so inbred that it was affecting their development and survival.

However, the scientists found that these could be reversed by ‘genetic rescue’ through limited interbreeding with brook trout.

“We were able to show through genetic analysis that aurora trout are actually brook trout,” says Dr. Wilson. “Because they are so similar, we introduced some genes from regular brook trout to restore the fitness of aurora trout.”

In just three generations, the team introduced enough genetic diversity through intermating to the aurora trout to counteract the problems from inbreeding, while keeping the traits that made the fish unique.

Additional research by graduate student Jason Mouland showed that the rejuvenated aurora trout were more ecologically fit thanks to the ‘genetic rescue’. Thanks to the genetic and ecological research, they’re one of the few species that have been removed from Canada’s endangered species list.

“Through this collaboration, we got something more than if any of us had tried this on our own,” Dr. Wilson says. “By being at the university, we can work with professors and graduate students. You can find people with an interest in tackling challenging questions and developing particular skills. Besides the rewards of mentoring talented young people, working with graduate students also helps foster the next generation of scientists.”