Responses of vulnerable fishes to environmental stressors in the Canadian Great Lakes basin1

Abstract

Quantifying the responses of rare and vulnerable species to environmental stressors poses special challenges. This study examined the responses of vulnerable fish species listed under the Species at Risk Act to environmental stressors in lakes, streams, and wetlands of the Canadian Great Lakes basin. We used a joint species distribution model (JSDM) to improve the estimates of responses of vulnerable species to environmental stressors, and the effects of functional traits on those responses, by “borrowing information” from abundant species for which we have more information. We measured abundance, functional traits, and taxonomic relationships for 115 freshwater fish species (including 12 vulnerable species), and environmental features, at 1972 sites. The JSDM yielded more precise estimates of responses than single-species models fitted to each vulnerable species. Habitat associations inferred from the JSDM showed substantial overlap with those provided in COSEWIC status reports. Model-derived responses to environmental stressors can provide a management-friendly basis for species classification in terms of species’ tolerances to various forms of environmental change, and supplement the qualitative criteria for habitat requirements currently used in assessments of species vulnerability.