Cumulative effects of forest harvest on Pacific salmon productivity in coastal British Columbia

BCSRIF Project Summary

Species Group: Pacific Salmon
Location: Broughton Archipelago.
Partners: None listed
Organization: University of Victoria
Session(s): Freshwater Stressors
Presentation Date(s): December 02, 2025
Speakers: Maria Kuruvilla
Abstract:
Industrial forest harvesting has altered the functioning of watersheds and aquatic habitats that support wild Pacific salmon for over a century, yet the population-level effects of forestry on salmon and the timescale for recovery remain uncertain. We reconstructed an annual time series of forest disturbance history for 1,746 watersheds with salmon population monitoring data in coastal British Columbia (BC) dating back to 1883, when forestry accelerated in the region, with cumulative disturbance to many watersheds today now exceeding 80%. A strong negative effect of forestry on chum salmon recruits per spawner was observed with productivity declines of 19-52% which exceed that predicted by changes to marine conditions for many populations. Forestry can cause shifts in watershed functioning that can last for decades leading to salmon population declines and long timescales for recovery.

Bio:
Maria Kuruvilla is a postdoctoral fellow in the Lewis Research Group, University of Victoria. She uses Bayesian statistical models to estimate the impact of forest harvesting on salmon population in coastal BC. Her work occasionally takes her to Salmon Coast Field Station, in the Broughton Archipelago. Maria completed her PhD in Quantitative Ecology and Resource Management at the University of Washington, Seattle. Her dissertation explored the effects of hatchery releases on salmon migration timing, providing evidence that juvenile salmon use social information to decide when to migrate. Additionally, she investigated various environmental factors influencing the migration timing of juvenile salmon.

Collaborators:
Salmon Coast Field Station, Musgamagw Dzawada’enuxw Fisheries Group Society, DFO, University of Toronto, Ecofish Research, University of Alberta, BC Ministry of Water, and Pacific Salmon Foundation

Authors:
Hocking, M.D., M. Kuruvilla, J. Braga, E.M. Atkinson, D. Greenberg, L. Krichel, O. Cornies, A. Buren, J. Speier, M. Nicolson, P. Tschaplinski, B. Connors, M. Lewis, A. Bateman, F.J.A. Lewis, R.M. Hechler, and M. Krkosek