Swimming the ladder to survival

Improving the fishway at Saint-Ours Canal National Historic SiteFootnote *

What’s the issue?

A little girl looking through the fishway window.
Through a window installed in the fishway visitors can observe fish going up the Richelieu River.

Dams can keep some fish from thriving – especially endangered species like the copper redhorse. When the historic Saint-Ours dam was rebuilt there was an urgency to make it fish friendly. Thus, the Vianney- Legendre fishway project was born. The fishway was constructed like a ladder, or series of pools built like steps. Fish inhabiting the Richelieu River climb the steps to reach the other side of the dam and their preferred breeding grounds at the Chambly rapids. However, since 2001, research has shown that whirlpools in the ladder can disorient some fish, causing them to expend energy, which jeopardizes their migration. For endangered fish, migration is essential to their survival. Improved design of the Vianney- Legendre fishway may be required to allow the copper redhorse to swim its way to recovery.

What’s our approach?

  • Use simulations to determine what is causing disorienting whirlpools in the fishway.
  • Find strategies to reduce water current flow and eliminate vortices, allowing fish to rest and save energy during migration through the fishway.
  • Implement practical solutions and monitor their effectiveness for the copper redhorse.
  • Share results with visitors and the conservation community.

What’s been accomplished?

  • Conducted hydraulic simulations to evaluate ways to break up vortices in fishpond bays; based on simulations, made recommendations to improve the fishway.
  • Hired engineering consultant to design deflectors and prepare plans and specifications for improving the fishway; deflectors to be installed in 2018 with further research planned to assess their impact and usefulness.

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