Research Document - 2010/080

Information Relevant to a Recovery Potential Assessment of Lake Sturgeon: Western Hudson Bay Populations (DU1)

By H. Cleator, K.A. Martin, T.C. Pratt, and D. Macdonald

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) 1, the Western Hudson Bay populations, includes Lake Sturgeon in the Churchill River system of northern Manitoba and Saskatchewan. COSEWIC assessed and designated DU1 as Endangered, as Lake Sturgeon in this DU declined severely over the past century. Historically, over-exploitation from commercial fisheries was the primary threat, whereas more recently habitat degradation or loss associated with dams/impoundments and other barriers, and domestic/subsistence fisheries, have become the most important threats.

DU1 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 DU1, 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 DU1 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.

Three Lake Sturgeon Management Units (MUs) have been identified for DU1. The current conservation status of MU1 is unknown, MU2 is likely critical and MU3 is cautious. Population trajectories of all three MUs are unknown. MU2 is thought to have moderate potential for recovery, while MU3 is thought to have low potential for recovery as a result of habitat limitations. The recovery potential of MU1 is unknown. There are estimated to be at least 1,300 adults in the lower Churchill River. The long-term recovery goal for DU1 is to protect and maintain healthy, viable populations of Lake Sturgeon in all MUs.

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