Each fall, Ontario’s rivers surge with salmonids fighting upstream currents. But many of these fish—Chinook Salmon, Coho Salmon, Brown Trout, and Rainbow Trout—are not native to these waters. Their migrations are spectacular, yet they carry consequences for the ecosystems they now inhabit.
Chinook and Coho Salmon (Pacific origin) were introduced to create recreational fisheries. However, they also compete directly with native Brook Trout and the historically extirpated Atlantic Salmon for spawning habitat. There has been an Atlantic Salmon restoration program since 2008 but the return rates have been extremely low.
Each small dam is an obstacle, yet the salmonid adapts and advances toward its spawning habitat.
A salmonid pushes upstream, meeting strong currents and natural obstacles on its way to spawn.
Brown Trout (European origin) are aggressive competitors, often displacing native Brook Trout in cold water habitats. Unlike Pacific salmon, they survive after spawning, maintaining year‑round pressure on native species.
