Fish Behaviour and Swimming in Turbulent Flows
We have installed and operated cameras that stream fish movement inside fishways, onto the internet since 2007. In 1997, 1998 and 1999, we used underwater videography to monitor fish behaviour in several Denil and vertical-slot fishways. Miniature digital CCD cameras were placed at fishway entrances, exits and near areas that were identified as potentially problematic within primary fishway flows.
We have learned much about the behavioural effects of turbulence on fish passage using these techniques. Since 1999 we have used underwater videography to monitor fish spawning behaviour, fish passage and debris deflection at several fishways in Ontario, as well as overwintering congregations of fish under the ice in rivers and lakes. Check out the following video clip that shows a smallmouth bass (approx. 300 mm TL) negotiating turbulent flows in a Denil fishway on the Grand River, Ontario, Canada. Notice how fish appear to surf in von Kármán vortex streets, rather than using constant prolonged swimming to maintain positions in turbulent flows.