Within the Rouge River watershed, Toronto and Region Conservation Authority (TRCA) is researching the overwintering habitat needs of the Redside Dace — an endangered fish provincially and nationally.
Using underwater cameras, PIT tags, and in-stream array detection systems, field technicians track where adult Redside Dace and other minnow species that share similar habitat conditions huddle up during the cold winter months (November to February) when food resources are scarce and energy reserves are low.
Winter habitat conditions used by these species are also noted, such as sediment, vegetation types, stream flow, and salinity.
The data help to identify the habitat conditions that Redside Dace require to overwinter
For the Redside Dace and many other regional fish species, little is known about their overwintering habitat needs. TRCA researchers are hoping to discover where this species travels during the shoulder seasons, in order to help better protect and restore these habitats.
Gathering information on this critical piece of the life cycle history will contribute to best management practices and recovery plans for this coolwater member of the minnow family.
The video above was filmed in November 2020 and shows a Redside Dace swimming amongst a school of other fish.
This exploration began during the fall of 2020, thanks to multi-year funding provided by the Habitat Stewardship Program for Species at Risk, which supports projects that improve or manage important habitat for aquatic species at risk.
TRCA research scientists survey for Redside Dace in study pools within the Rouge River watershed.
In southern Ontario, Redside Dace are at their northern range limit. This species has been observed in the Humber River, Don River, Rouge River, Duffins Creek, and Carruthers Creek watersheds.
The Duffins Creek, Don River, and Rouge River watersheds have populations that are in “poor” condition, meaning they are experiencing range contraction with low estimated population numbers.
By contrast, populations in the Humber River and Carruthers Creek are more likely in “fair” condition, meaning they have a limited range contraction with good estimated population numbers.
Select the image below to view the full-sized map.
In warmer seasons, we know that the Redside Dace are found in pools or low-flow areas of the stream with soft sediment, protected by overhanging vegetation. Because their habitat is restricted to cool water reaches that are subject to low levels of urbanization, they may be threatened by the impacts of degrading aquatic habitat conditions, changes in hydrology and water quality, and increasing water temperatures.
By collecting scientific data to support the protection of critical habitat for the Redside Dace, we can conserve and protect other coolwater fish species that occupy the same reaches.
Beyond this special research project, TRCA also collects long-term fisheries data to assess the health and condition of our streams and lakefront habitats. LEARN MORE.
Funding for this project was provided by the Government of Canada’s Habitat Stewardship Program for Species at Risk:
Monitoring matters! Scientific data collection and research informs decisions affecting the natural areas and watercourses within our region. Connect with us online.