Oral Presentation Freshwater Sciences 2023

Does mitigation achieve conservation? Evaluating the effectiveness of freshwater mussel species at risk translocations in southern Ontario (#16)

Lauren Damphousse 1 , Catherine Febria 1
  1. University of Windsor, Maidstone, ON, Canada

Freshwater mussels (Unionidae) serve as critical structural and functional links for aquatic food webs and are bioindicators of ecosystem health. Unfortunately, many species are declining globally - including in Canada where many are listed as species-at-risk of extinction (SAR). Restricted in their ability to move readily throughout riverbed habitats, Unionidae are vulnerable to human activities such as infrastructure projects, namely bridge construction, culvert replacements, and earth moving which can take place in or adjacent to rivers. Translocation efforts are a common mitigation response to these activities and operate under the federal Fisheries and Species at Risk Act. Since publication of a standardized protocol for freshwater mussel translocations (Mackie et al. 2008), practitioners have been conducting translocations with little to no follow-up or evaluation of this practice. To address this, we accessed translocation reports spanning 15 years from which we have conducted a data synthesis. Additionally, multiple sites of previous translocations in the Grand and Thames River watersheds located in southern Ontario were surveyed during 2022 to expand upon the submitted reports. Together these data were combined to assess the effectiveness of SAR policy. Preliminary findings indicate that mussel communities do not fully recover following translocation, negatively affecting overall population density and biodiversity of freshwater communities. Moreover, it appears that a critical reason for this is that the habitats themselves do not fully recover, even 15 years post translocation. This research offers evidence to improve conservation of the species-at-risk policy and practice in support of coordinated actions including habitat restoration and benthic macroinvertebrate community indicators.