SFU researchers find logging impacts on salmon populations

Colin Bailey discusses connection between clear cutting forests and salmon decline

Salmon jumping over water
PHOTO: Brandon / Unsplash

By: Karissa Ketter, News Writer

SFU researchers have found changes in saltwater and freshwater ecosystems are decreasing the survival rates for North Pacific salmon species. PhD candidate Colin Bailey, a researcher on this project, spoke with The Peak about the group’s findings. 

Bailey explained there’s a relationship between logging and ecosystems. The team analyzed data of clear cut logging — when all trees are cut from a site and replaced — in watershed areas and the effects on salmon survival rates. Because the effects can take up to 15 years to show, long term data is crucial for this research. 

Watersheds are areas where smaller water bodies can drain into larger bodies of water, such as the “mouth of a bay” or a larger reservoir.

“When you have a lot of logging activity, you can free up a lot of sediment to move into the river systems,” Bailey explained. 

The sediment — sand, grit, and clay — that travels into the rivers should be held back by trees and foliage. Clear cutting forests in watershed areas means rainwater is forced to flood the rivers. This can make it difficult for salmon eggs to receive the oxygen they need to survive during incubation.

Bailey noted another major impact of logging is the way rainwater moves through the land. Clear cut forests prevent rainwater from being able to absorb into the ground. This leads to them running overtop of the land, causing flood activities. Excessive water movement can then pull large rocks and boulders into the river which disturbs and destroys the fish eggs incubating in the river beds. Untouched forests allow rain water to penetrate the ground and slowly seep into rivers. 

The current consensus among researchers in this field is that putting energy into improving the health conditions of freshwater ecosystems won’t have an impact on the salmon populations if marine ecosystems do not improve first, said Bailey. “And this paper really counters that narrative,” he added.

“We found that the impact of the freshwater environment and the marine environment were approximately equal on the number of adult female steelhead you had coming back and spawning.”

This tells Bailey putting effort into freshwater environments will have an impact on the number of fish returning to spawn and will increase the survival rate of their incubating eggs. 

Bailey clarified logging is not the singular cause for salmon decline. “But ultimately, that logging impact is still there, and it’s still placing a big weight for those fish to carry.”

When asked about using this research to inform policy decisions across the BC provincial government and Canadian federal government, Bailey noted he hopes to see more Indigenous involvement in land and marine management in Canada. 

“As First Nations gain the recognition of title over their land again, over unceded land, land management will move to those First Nations again. They’ve been taking care of land for millennia [ . . . ] So in the future there’s going to be probably more co-management of land resources between the provincial government and First Nations,” said Bailey. 

Additionally, he suggested wood harvesting policies that work to better manage the forestry industry of clear cutting and logging practices to reduce the impacts that they have on watersheds. Specifically the streams that feed fish-bearing rivers. 

This research was funded by the Habitat Conservation Trust Foundation, amongst many other sponsors. It was carried out on Kwakiutl First Nations territory in Port Hardy. 

The study was led by SFU’s Dr. Kyle Wilson and supervised by Dr. Jonathan Moore, a professor of biology and resource and environmental management.