Canadian Aquatic Resources Section of the American Fisheries Society

Tracking Walleye in Hamilton Habour

Written by Jill Brooks, 2016 MSc. Larkin co-Awardee, follow her on Twitter too, @jillbrooks85!

I am currently an MSc student, supervised by Dr. Steven Cooke in the Fish Ecology and Conservation Physiology Lab at Carleton University in Ottawa. My research focuses on the movement of fish in response to various habitat restoration efforts in Hamilton Harbour at the western end of Lake Ontario. The aquatic ecosystem in the Harbour has been degraded over the last 120 years as a result of industrialization and land use change. Sewage, fertilizers and industrial pollutants flowing into the relatively small system, combined with extensive physical habitat alteration has resulted in Hamilton Harbour deemed as an Area of Concern (AOC). The past 30 years has seen collaboration between government, NGOs, and members of the public in restoring the Harbour to the pre- 1920s conditions. These efforts have included stricter sewage treatment policies, the protection and creation of fish habitat, the planting of native marsh plants, the installation of the great Lake’s first two-way fish barrier, and the reintroduction of native fish species, including walleye (Sander vitreus). The final stages of the Harbour’s Remedial Action Plan (RAP) are to monitor the progress of these restoration efforts to facilitate refinements necessary to meet delisting criteria.

Environment Canada employees deploying harbour moorings on which acoustic receivers are attached to. The heavily industrialised Harbour's steel factories can be seen operating in the background.

Environment Canada employees deploying harbour moorings on which acoustic receivers are attached to. The heavily industrialised Harbour’s steel factories can be seen operating in the background.

My research objectives are to acoustically track various species of fish which will allow us to assess if these ‘remedies’ are working. The re-introduced walleye have reached sexual maturity this year so this is a critical time to follow their movements. Are the fish using these protected and rejuvenated fish habitats? Are there other habitats they are using over winter that could be restored? Will they spawn in the Harbour or will they leave through the canal into Lake Ontario? Due to the four sewage treatment plants and several combined sewage outflows, the Harbour experiences eutrophication issues, in particular throughout the summer, with the majority of the harbour hypoxic or even anoxic underneath the thermocline.  How are fish responding to these dynamic conditions? How much habitat is actually available to them? Depth tags will allow us to determine their use of these oxygen-poor areas.

Jill is surgically implanting a freshwater drum with an acoustic transmitter. The fish was anaesthetized with electro-handling gloves.

Jill is surgically implanting a freshwater drum with an acoustic transmitter. The fish was anesthetized with electro-handling gloves.

The answers to these questions could inform future management decisions in Hamilton Harbour and other areas exhibiting similar habitat degradation issues, and will provide information that can be used to define targets and contribute to the delisting of the Hamilton Harbour Area of Concern.