Information in support of a Recovery Potential Assessment of Lake Whitefish (Coregonus clupeaformis), Lake Opeongo large-bodied and small-bodied Designatable Units

Abstract

The Lake Whitefish (Coregonus clupeaformis) is a coldwater benthivore with a broad distribution and highly variable ecological and morphological traits across Canada. A species pair of Lake Whitefish in Lake Opeongo, consisting of a large-bodied and small-bodied form, was first discovered in 1940. Both forms (now considered separate Designatable Units, DUs) were assessed as Threatened by the Committee on the Status of Endangered Wildlife in Canada (COSEWIC) in April 2018. The reason for this designation was that both DUs are known only from Lake Opeongo, Algonquin Provincial Park, Ontario, and the introduction of aquatic invasive species could disrupt the unique ecological processes that drove divergence and maintains the species pair (COSEWIC 2018). The Recovery Potential Assessment provides background information and scientific advice needed to fulfill various requirements of the federal Species at Risk Act. This research document provides the current state of knowledge of the species pair including its biology, distribution, population trends, habitat requirements, and threats, which will be used to inform recovery plans. Limited information exists to adequately assess the status of either DU, particularly the small-bodied form. A threat assessment identified the greatest threats to the large- and small-bodied DUs of Lake Whitefish in Lake Opeongo as aquatic invasive species, climate change, and human disturbances; however, the impacts of these threats are not well understood. Mitigation measures and alternative activities related to the identified threats are presented, as appropriate. Important knowledge gaps remain regarding population trends, as well as differences in niche occupancy and impacts of current and anticipated threats on the two DUs.