The Influence of Climate and Land Cover Change on Historical Brook Trout (Salvelinus Fontinalis) Populations in the Humber River, Rouge River, and Duffins Creek Watersheds

Long-term records of the abundance of organisms are neededto detect more progressive changes in their populations as a result of external stressors. Long-term changes in historical Brook Trout (Salvelinus fontinalis) population abundance were identified in the Humber River, Rouge River and  Duffins  Creek  watershedsin  Ontariothrough  statistical  analysis  of  twenty-six  years  of sampling records. Corresponding historical changes in air and stream water temperature,  and in land cover were also examined. Changes detected in climate parameters, and in land cover were then related  to  Brook  Trout  population  changes.  Results  revealed  that  Brook  Trout  abundance had decreased significantly. These changes were driven by populations in the Humber and Rouge River  watersheds.  Populations  in  the  Duffins  Creek  watershed  did  not  change  significantly. Climate parameters didchangebut notsignificantly over timein the region. However, land cover changes wereobserved. In the short term, Brook Trout population changes were more likely due to changes in land cover than climate.