Toronto Harbour: updating the fish telemetry project

2013-2015 Funding: $697,500, including $142,000 provided by the Great Lakes Sustainability Fund

Other Project Contributors: Toronto and Region Conservation Authority, Fisheries and Oceans Canada, Carleton University, University of Toronto, Toronto Remedial Action Plan, Aquatic Habitat Toronto, and Ministry of Natural Resources and Forestry.

Habitat managers continue to gain a better understanding of how fish are responding to restored habitat in the Toronto Harbour, through an ongoing project supported by the Great Lakes Sustainability Fund.

Rehabilitating fish and wildlife habitat and restoring degraded fish populations are two key goals under the Toronto and Region Area of Concern’s Remedial Action Plan. Since 2010, the project has been tracking the seasonal and lifecycle movements of more than 300 fish, including Northern pike, Largemouth bass, Walleye and Common carp. The first three species are important native sportfish, while the non-native carp can damage habitat used by other species.

The project is using fish acoustic telemetry, in which the movements of individual fish are tracked through implanted fish tags. The tags transmit to receivers placed in the inner and outer harbours. Many of the receivers are located in restored habitat, such as restored coastal wetlands and sheltered bays that are used as feeding, nursery and spawning habitat.  

By assessing the response of a particular species to ongoing rehabilitation efforts in the Toronto Harbour, habitat managers can gauge the efficiency of specific measures to restore habitat and increase populations. The findings will be applied throughout the Great Lakes to help create habitats that favour native fish populations over non-native ones.

In 2013, habitat managers tagged more fish to ensure that there are sufficient numbers to be detected until the completion of the study in a few years. In addition, a number of younger Northern pike and Largemouth bass were tagged to allow for a comparison of movement and habitat use between juveniles and adults.

Preliminary analysis completed in 2014 showed that Largemouth bass, Walleye and Common carp - which all tend to prefer vegetated areas with moderate depths during the summer month - are frequently using the little bays of the Toronto Islands. The outer harbour marina area also was identified as an important area for Walleye. Northern pike, on the other hand, showed different habitat preferences, preferring deeper water - reflecting their role as cool water predators. More detailed analysis of the data is underway to better identify key areas within the harbour for individual species.

Results from the ongoing research have been presented at public information sessions, such as the Lake Ontario Evenings series, and at scientific conferences.

For more information on the Toronto and Region Area of Concern, please visit: Aquatic Habitat Toronto.