Research Document - 2010/083
Information Relevant to a Recovery Potential Assessment of Lake Sturgeon: Red-Assiniboine Rivers – Lake Winnipeg Populations (DU4)
By H. Cleator, K.A. Martin, T.C. Pratt, B. Bruederlin, M. Erickson, J. Hunt, D. Kroeker, D. Leroux, L. Skitt, and D. Watkinson
Abstract
The Lake Sturgeon (Acipenser fulvescens) was common in nearshore waters across much of Canada in the nineteenth century, but intensive fishing, habitat loss and degraded water quality caused severe reductions in population size or extirpation across their range. Today they remain extant from the North Saskatchewan River in Alberta, to Hudson Bay in the north, and eastward to the St. Lawrence River estuary. In November 2006, the Committee on the Status of Endangered Wildlife in Canada (COSEWIC) assessed Lake Sturgeon in Canada. Designatable Unit (DU) 4, the Red-Assiniboine rivers – Lake Winnipeg populations, includes Lake Sturgeon in the Red and Assiniboine rivers, Lake Winnipeg and all eastern tributary rivers to Lake Winnipeg excluding the Winnipeg River upstream of Pine Falls. COSEWIC assessed and designated DU4 as Endangered, as Lake Sturgeon in this DU declined severely over the past century and a significant portion of their habitat has been degraded or lost, especially in the southern portion of the DU. Historically, over-exploitation from commercial fisheries was probably the primary threat, whereas more recently habitat degradation and loss associated with agriculture, urban development, dam/impoundments and other barriers and industrial activities, and bycatch from the commercial fishery on Lake Winnipeg have become the most important threats.
DU4 Lake Sturgeon is being considered for legal listing under the Species at Risk Act (SARA). In advance of making a listing decision, Fisheries and Oceans Canada (DFO) has been asked to undertake a Recovery Potential Assessment (RPA). This RPA summarizes the current understanding of the distribution, abundance and population trends of Lake Sturgeon in DU4, along with recovery targets and times. The current state of knowledge about habitat requirements, threats to both habitat and Lake Sturgeon, and measures to mitigate these impacts for DU4 are also included. This information may be used to inform both scientific and socio-economic elements of the listing decision, development of a recovery strategy and action plan, and to support decision-making with regards to the issuance of permits, agreements and related conditions, as per sections 73, 74, 75, 77 and 78 of SARA.
Eight Lake Sturgeon Management Units (MUs) have been identified for DU4. Available data and expert opinion indicate that due to stocking the current status of the stocked fish in MUs 1-3 is critical and their population trajectories are increasing. The indigenous Lake Sturgeon from MUs 1-3 are either extirpated or functionally extirpated. The current status, trajectory and potential for recovery of MUs 4-7 are unknown except in the Ontario portion of Berens River (MU6) where recent information suggests they are cautious, increasing and high, respectively. The status and population trajectory of MU8 is critical and unknown respectively. Limited data indicates that low numbers of Lake Sturgeon are now present throughout much of DU4. The long-term recovery goal is to protect and maintain viable populations of Lake Sturgeon in all MUs.
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