Science Advisory Report 2009/062

Assessment of habitat use and habitat quality for SARA-listed populations of white sturgeon in British Columbia

Summary

• New information to support critical habitat identification of SARA-listed populations of white sturgeon (Upper Fraser, Nechako, Columbia, Kootenay) has become available since a 2007 recovery potential assessment was completed. This information was the subject of science peer-review by the Pacific Scientific Advice Review Committee (PSARC) in June 2009.
• Natural populations in the Nechako, Kootenay, and Columbia rivers are declining as a result of recruitment failure or unsustainable recruitment declines related to extensive changes in habitat, many of which are believed to be associated with several factors including dams and river flow regulation.
• Participants at the June 2009 PSARC meeting agreed that recovery efforts should focus primarily on improving natural recruitment in each of the dam-affected populations.
• Identifying critical habitat requires judgments about the extent to which habitat contributes to a species' survival or recovery. Habitat was also classified as “important” in cases where existing knowledge was insufficient to meet a reasonable burden of proof in delineating boundaries for critical habitat, but where a subset of the habitat might yet qualify as critical habitat given further study. The purpose of identifying important habitat is, first, to emphasize that the full recovery of white sturgeon will require management of a larger set of geographic locations than can be designated as critical habitat at this time, and second, to highlight the specific geographic locations that are most likely to require additional protection in the future.
• Areas of present high use were recommended de facto as a partial specification of critical habitat. To meet recovery targets, additional critical habitat will likely have to be identified in the future as research and recovery efforts proceed. Measures may be necessary for some populations on both sides of the Canada-US border to recover trasboundary components of Canadian populations.
• Where detailed studies were lacking or inconclusive, expert opinion was used to identify important and critical habitats.
• Most participants at the June 2009 PSARC meeting agreed with the geographic locations identified as critical and important habitats. Details, source information, risk evaluation and maps with boundaries demarking potential critical habitats are documented by Hatfield et al. (2009).

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