- Pacific salmon and five different species of trout are declining due to 40 years of change in their marine and freshwater environments
- The species affected are declining in numbers in the Keogh River near Port Hardy on Vancouver Island.
- A fluctuating climate, an increase in seals, competitive salmon, warmer water temperatures and increased watershed logging are playing a part.
- Steelhead and coastal cutthroat trout populations declined by 80% and 70% between 1976 and 2015
Pacific salmon and trout populations are declining rapidly not only because climate change is worsening, but also because of 40 years of change in their marine and freshwater environments, a new study has found.
Five different species of Pacific salmon (Steelhead, Coho Salmon, Pink Salmon, Dolly Varden and Coastal Cutthroat Trout) are all seeing significant declines in numbers in the Keogh River near Port Hardy on Vancouver Island.
Pacific salmon and five different species of trout are declining due to 40 years of change in their marine and freshwater environments
Five different species of Pacific salmon (steelhead, coho salmon, pink salmon, Dolly Varden and coastal cutthroat trout) are all seeing significant declines.
The decline in numbers is occurring in the Keogh River near Port Hardy on Vancouver Island.
Researchers at Simon Fraser University’s Salmon Watershed Lab found that stresses in the environment in which fish swim and live, such as fluctuating climates, are taking their toll on seals and an increase in other competing salmon species.
Warmer water temperatures and increased watershed logging are also playing a role in the decline in populations of five salmon species as well as steelhead and coastal cutthroat trout.
Researchers found that steelhead and coastal cutthroat trout populations declined by 80 percent and 70 percent between 1976 and 2015
The researchers found that steelhead and coastal cutthroat trout populations declined by 80 percent and 70 percent between 1976 and 2015.
Study lead author Kyle Wilson said in a statement, ‘It is not just the ocean that is causing the decline. Statement.
particularly related to the low survival rates of juvenile salmon, which are affected by watershed logging
‘The combination of marine and freshwater stresses effectively ‘squeezes out’ some salmon populations by reducing survival in both river and ocean.’
Particularly related to the low survival rates of juvenile salmon, which are affected by watershed logging.
Competition from seals and other salmon, coupled with a decrease in the survival rate of adult salmon – wild and free from hatcheries – and populations is rapidly declining.
Project associate and SFU biology professor Jonathan Moore said, ‘This study demonstrates the power and importance of careful monitoring of the adult and juvenile life-stages of salmon and steelheads to understand which parts of their life-cycles are involved in the overall development. driving population change. .
Salmon populations in the Pacific Northwest have been declining for some time (Alaska salmon are actually decreasing in size), but the environmental factors that are causing the decline are only being understood by experts.
“Some research attributes the decline to deteriorating ocean conditions, while others point to climate change or overfishing,” Wilson said.
‘For salmon and steelhead declines, there has been even greater uncertainty, which is more attributable, freshwater or marine processes.’
Wilson said the findings could help inform the US government’s recent Pacific Salmon Strategy Initiative (PSSI), which will allocate $647.1 million to help recover the salmon through conservation and scientific efforts.
The study is published today in the journal Global Change Biology.
In July, Pacific Northwest salmon were seen dying of red sores and white fungus from the extreme temperature spike experienced in summer in the western part of the US.
Separately that month, researchers said the heatwave – caused by a ‘heat dome’ that hangs over the western US and Canada and in some places caused temperatures to rise to 121 degrees Fahrenheit – caused more than 1 billion marine organisms. dies of.