Palgrave Fishway Study
DAMS PROVIDE MAJOR OBSTACLES to migratory fish and fishways are often the solution. We frequently hear about migratory salmon, walleye and steelhead using these facilities to move upstream to spawn. But what about resident fish like brook, brown and rainbow trout?
Completed in 2001, the Palgrave Fishway on the Humber River in the Greater Toronto Area was constructed as a series of pools to allow the passage of non-jumping fish, and to provide public viewing through an underwater window. The fishway is unique because the lower reach (below pool) and upper reach (above pool) were constructed at different grades.
A study of the Palgrave Fishway was undertaken by TUC in partnership with Toronto and Region Conservation Authority and the Ontario Ministry of Natural Resources to determine if resident fish in the Humber utilize the fishway and, if so, under what conditions do they do so successfully.
Four antennas are installed in the fishway: at the inflow and the outflow, and at two points in between. Multiple antennas allow us to determine how far up the fishway individual fish get, as well as the direction of fish movement. These antennas are connected to a computer which records the date, time, tag number and antenna number of a tagged fish as it passes through.
Backpack electroshocking was used to sample fish within the stream and the fishway. The length, weight and species of all sampled fish were recorded, and those of taggable size were kept. Passive Integrated Transponders (PITs) were surgically implanted into the body cavity of anesthetized, taggable fish. When released, PIT-tagged fish swimming past an antenna in the fishway have these tags charged by a magnetic field and emit a signal which is recorded by computer.
By tagging a variety of fish species of different sizes, we can see how these factors play a role in fish movement. The results will tell us what size of fish and what fish species use the fishway, when and how often. Combining this information with other data like water temperature and flow rates will allow us to clarify factors related to fish movement. The overall results will allow us to make recommendations for existing and future fishways to increase fish movement around dams.
For more information on this project, contact Silvia D'Amelio.