Rainbow trout are alive and well in Toronto's Humber River.
Imagine my surprise on moving to Toronto to find that the city not only contains a giant ravine system—our equivalent to the canals of Venice— but that the rivers running through it also contain fish; quite a lot of them.
Each spring steelhead—otherwise known as rainbow trout—migrate up the Humber River to spawn, and can be seen jumping dams at various points through the city. Chinook and coho salmon make the run in the fall. Although all three species were introduced from the Pacific, they have established wild, self-sustaining populations in the Great Lakes.
London (England, not Ontario), where I lived until recently, is renowned for the polluted state of its waterways. Half a century ago the River Thames was declared "biologically dead", and although the river is making a comeback, the chances of seeing such a spectacle as trout jumping so close to the city centre are virtually nil.
Trout face many barriers to make it their spawning grounds.
So I found myself one sunny Saturday afternoon in April, camera in hand, crouched by the river at Étienne Brûlé Park (near Old Mill station), watching as trout after trout flung themselves up a 1.5 metre dam. In the short space of time I was there I saw perhaps 100 fish attempt the jump, with only a handful making it over and on to the next stretch of river.
Rather than attempt the dam in one leap the trout aim for around halfway up, using their muscular bodies to aquaplane the rest of the way. A crowd of walkers and families had gathered to watch and shout support, or voice their dismay at another near miss. Nearby, cormorants and gulls hovered, while downstream several anglers stood motionless as herons (the fishing season officially opens on the fourth Saturday in April).
The few trout that make it past the barriers in the Lower Humber will return to their original hatching grounds in the headwaters of the Niagara Escarpment and Oak Ridges Moraine, where they will spawn.
Success! One trout makes it over.
Despite the presence of barriers, the trout face a better chance of survival in the Humber than many urban rivers. A recent freshwater health assessment from WWF Canada gave the river a "fair" rating; its water quality and fish populations are good, and it is well monitored thanks to the efforts of the Toronto and Region Conservation Authority (TRCA) and other watershed groups.
The dams themselves, built after Hurricane Hazel in 1954 to control erosion and water flow, are gradually being modified with fish ladders and "notching" to enable more fish to make the journey upstream and spawn in the upper reaches of the watershed.
The Friends of the Greenbelt Foundation is working to raise awareness of the hidden values of Toronto's urban rivers, and build support for their inclusion in Ontario’s Greenbelt. This will offer permanent protection, allowing future generations to appreciate natural spectacles like the steelhead run, and hopefully lead to renewed efforts to restore them along their full lengths.
To learn more about the Humber and its fascinating history, come to our Jane's Walk on Saturday May 3. The walk departs from Lion's Park in Toronto at 5:30 PM. More information can be found here!
-- Program Officer