Research Document - 2003/099
Review of potential critical habitats for white sturgeon (Acipenser transmontanus) in the
Fraser River estuary
By Levings, C.D. and Nelson, W.A.
Abstract
In this paper we review metrics and methods to assess potential critical habitat for white sturgeon (Acipenser transmontanus), a species which was formerly abundant in the Fraser River estuary in British Columbia. White sturgeon are listed with COSEWIC as a species of Special Concern. We also review the sparse literature on the environmental requirements of white sturgeon, discuss past and present threats to the species' habitats, and provide suggestions for research. Several of the existing water quality criteria are based on water column characteristics (e.g. temperature, flow, substrate type, dissolved oxygen, and toxicants), often from laboratory measurements of tolerance. Preliminary results from an age-structured density-independent model for white sturgeon populations and habitats in the lower Fraser River and estuary are presented. The simulations suggested that access, water flow, and sediment exchange between slough and channel habitat are key ecological processes for this species. Metrics for mapping substrate and related biophysical features important for white sturgeon are not well developed. Relationships between habitats and white sturgeon population dynamics are poorly understood. Mapping at the macroscale (1:1 M) showed that about 70 % of estuarine habitat has been lost in the Fraser River estuary owing to urbanization. It is not clear if the remaining habitat in its degraded configuration is sufficient to maintain present or restored white sturgeon populations.
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