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Recovery Strategy for the Atlantic Whitefish (Coregonus huntsmani) in Canada (Final)


Introduction

Atlantic whitefish are found only in Nova Scotia, Canada and occur in the wild as a single population distributed among three small, connected, semi-natural lakes. They are presently at critically low levels, assessed as “endangered” by the Committee on the Status of Endangered Wildlife in Canada (COSEWIC) and protected under the federal Species at Risk Act (SARA).

The Atlantic whitefish is a member of the salmon and trout family Salmonidae. This fish was historically referred to as Acadian whitefish, Sault whitefish, round whitefish, and common whitefish (Edge and Gilhen 2001). It appears dark green or blue on its back with silvery sides and a silvery to white underbelly. They possess a deeply forked tail and an adipose fin (Figure 4). The fish has been used by humans for food and have been angled for recreational purposes (Scott and Scott 1988).

Atlantic whitefish can be distinguished from other whitefish species by their genetic structure (Bernatchez et al. 1991; Murray 2005) and physical characteristics (Edge et al. 1991; Hasselman 2003). Thought to represent the sole living representative of the early form of whitefishes (Smith and Todd 1992), the species represents a unique component of the local, national and global biodiversity.

First described by Huntsman (1922), the Atlantic whitefish is a Canadian endemic species known historically to occur in the Tusket River and Petite Rivière in southwestern Nova Scotia (Scott 1987; Edge and Gilhen 2001) (Figure 1). An anadromous (sea-going) population was reported from the Tusket River (Figure 2) (Edge and Gilhen 2001); however, there is no documented record of a fall run in the Petite Rivière (Bradford et al. 2004a). Since the construction of the dams on the Petite Rivière Atlantic whitefish have been documented downstream in both the freshwater and marine portions of the watershed (Figure 3) (Edge and Gilhen 2001). It is presumed that these fish somehow passed downstream over the Hebbville dam, and were able to tolerate marine conditions.

Declining numbers in both the Tusket River and Petite Rivière watersheds in recent decades (Edge 1984b) and a global distribution restricted to two river drainages, resulted in the Atlantic whitefish being assessed as “endangered” by COSEWIC in 1984, the first fish species in Canada to be so designated. Re-assessment of the species status by COSEWIC in 2000 concluded that a remnant anadromous population may exist in the Tusket, that the land-locked Petite Rivière population continues to persist, and that there is uncertainty concerning the status of any anadromous run to the Petite Rivière. A continued decline in abundance, an absence of mitigation of threats identified in the previous assessment, and new threats (Edge and Gilhen 2001) were cited in support of the designation of the species status as “endangered”.

Information acquired since the 2000 COSEWIC assessment confirmed the existence of the land-locked population in the Petite Rivière, casts uncertainty on the existence of an anadromous run to that river (Bradford et al. 2004a) and indicates that the species has been extirpated from the Tusket River (the last confirmed specimen was captured in 1982 (Edge 1984a)). The species range is currently restricted within the 16km2 aggregate area of three small semi-natural lakes (Hebb, Milipsigate and Minamkeak) within the Petite Rivière (Figure 3) (Bradford et al. 2004a; DFO 2004a).

Canadians recognize that our natural heritage is an integral part of our national identity and history, as well as part of the world's heritage. We further recognize that wildlife (including fish) has value in and of itself as well as being valued for aesthetic, cultural, spiritual, recreational, educational, historical, economic, medical, ecological and scientific reasons. Therefore, when a species becomes at risk, as is clearly the case with Atlantic whitefish, both Canada and Nova Scotia have responsibilities through their respective conservation mandates to protect, conserve, and recover the species. These jurisdictions have determined that preparation of a recovery strategy for Atlantic whitefish is the appropriate first formal step to meeting these responsibilities.

In summary, the Atlantic whitefish is found only in Nova Scotia, recognized to be of considerable evolutionary significance, at risk of extinction from several threats, and in need of immediate recovery actions. Intended to provide a common direction to be followed by participating parties, the purpose of this document is to lay out a strategy for the recovery of the Atlantic whitefish by setting a goal and objectives to arrest or reverse the decline of the species and identifying the main areas of activities to be undertaken.