Looking to Legislation, Policies and Guidelines to Protect Brook Trout Habitat in Toronto and Region
November 29, 2017
Brook Trout are the only remaining native Salmonid fish species naturally occurring in Toronto and region tributaries. Monitoring data from Toronto and Region Conservation’s (TRCA’s) long-term Regional Watershed Monitoring Program show that the occurrence of Brook Trout in Toronto and Region has decreased over the last sixteen years (2001-2017).
Regional Trend in Brook Trout Occurrence
This change in Brook Trout catch frequency across the TRCA watersheds is supported by similar data findings across both southern and northern Ontario.
Brook Trout are a sensitive coldwater fish species which rely on good water quality habitats with plenty of groundwater upwellings in order to support their spawning, feeding and overall habitat needs.
Brook Trout are known to prefer coldwater streams (less than 24 degrees Celsius) that have a year-round supply of clear, well-oxygenated waters protected by overhanging branches, logs and rocks (Freshwater Fishes of Canada, 1988). For these reasons, Brook Trout are often used as indicators of coldwater habitat and good water quality conditions.
Climate change, invasive or stocked species, habitat fragmentation, and land use changes all pose a threat to Brook Trout habitat. For example, increases in impervious surfaces (e.g. roads) in urbanizing areas means there is less opportunity for groundwater recharge resulting in reduced baseflows and warmer stream temperatures. Regionally, Brook Trout are found in the Duffins Creek, Humber River and Rouge River watersheds, predominantly where these watersheds overlap with the Oak Ridges Moraine or Greenbelt lands.
Effect of Road Density on Regional Fish Communities
The Regional Watershed Monitoring Program data from 2001-2012 shows that Brook Trout are not found in regional streams where surrounding road density thresholds are above 6 km/km2, and that only four fish species typically persist when road densities are higher than 11 km/km2. The assumption here is that the higher the density of roads in a given catchment, the greater the level of urbanization.
What is TRCA doing to help?
At the November 2017 Latornell Conservation Symposium, TRCA’s Environmental Monitoring staff highlighted how different departments in TRCA work together to help prevent or minimize the threats facing Brook Trout and their regional habitat.
The presentation underscored the important regulatory and guidance roles that TRCA has in helping to prevent and/or mitigate the above listed threats and the negative effects they have on Brook Trout. The presentation also highlighted TRCA’s ecosystem approach in restoring and/or creating habitat that benefit many species, including sensitive species like Brook Trout and the federally endangered Redside Dace. Through their monitoring activities, TRCA also gauges ecosystem health, identifies areas of concern, and identifies the success of conservation management efforts.
Learn More: Monitoring Sensitive Fish Species on Seaton Development Lands
Despite these efforts, however, the reality is that the threats facing Brook Trout extend beyond the physical boundaries of Toronto and surrounding region. For that reason, TRCA is actively working with its municipal partners and other government agencies to foster sustainable development. A collaborative, multi-agency approach will help to ensure that Brook Trout will continue to persist in our regional streams for future generations to come.
Through scientific data collection, TRCA’s Environmental Monitoring and Data Management team tell the stories about the changes affecting the natural areas and watercourses within our regions. For more information, please visit our webpage, follow us on Twitter, subscribe to our Monitoring Matters e-newsletter, or check out our YouTube playlist.