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Recovery Strategy for the Aurora Trout in Canada [Proposed]

Executive summary

First discovered in 1923 by an angling party, aurora trout (Salvelinusfontinalistimagamiensis) were initially described in the literature as a new species (Salvelinustimagamiensis).  Today aurora trout are generally believed to be a form of brook trout (Salvelinusfontinalis) that are endemic to only two lakes – Whirligig Lake and Whitepine Lake.  Both lakes are located within the same watershed within Lady Evelyn Smoothwater Provincial Park, about 110 kilometers north of Sudbury, Ontario.  While many similarities to brook trout have been noted, significant differences have been reported for aurora trout with respect to colouration, skeletal features, and possibly spawning behaviour.  These differences have been, and continue to be, used to support arguments for aurora trout to receive a subspecies designation.  While genetic evaluation has not supported a subspecies designation to date, recent advancements in genetic assessment may assist in determining their taxonomic status. 

Although there remains an element of uncertainty as to whether aurora trout are distinct sub-specifically from brook trout, the Committee on the Status of Endangered Wildlife in Canada (COSEWIC) designated aurora trout as an endangered species in 1987.  In reconfirming this designation in 2000, COSEWIC referred to aurora trout asSalvelinusfontinalistimagamiensis, a subspecies of brook trout.  However, COSEWIC did note concern about their ability to list it as a designatable unit in light of its uncertain taxonomic status.   

Aurora trout populations were noted to be declining as early as the 1940s and were extirpated from the wild by 1967 due to lake acidification.  A captive breeding program, established by the Ontario Department of Lands and Forests in the late-1950s, prevented the aurora trout from going extinct.  Reductions in atmospheric pollutants, in concert with whole lake liming, enabled the re-establishment of self-sustaining populations of aurora trout in both native lakes by the mid-1990s. 

While short-term recovery efforts have been extremely successful in terms of re-establishing self-sustaining aurora trout populations into both native lakes, the success of long-term recovery efforts are unknown.  Past human intervention (whole lake liming treatments) has been relied upon to maintain adequate lake pH.  Although no further intervention has been necessary in over a decade, the principle threats to the long-term success of aurora trout recovery continue to be acidification as well as the potential for inbreeding depression.

The primary long-term goal of this recovery strategy is: To maintain secure self-sustaining aurora trout populations in both native lakes (Whirligig Lake and Whitepine Lake) at a minimum biomass target of 13 kg/ha for Whirligig Lake and 12 kg/ha for Whitepine Lake; a density of adult fish of 29 fish/ha for Whirligig Lake and 20 fish/ha for Whitepine Lake; and an age class structure that demonstrates no missing year classes.  These targets must be achieved in the absence of any further human intervention (e.g. liming).

In addition to the primary goal, three secondary recovery goals have been identified: (1) To establish a secure, self-sustaining aurora trout population in one or two non-native, well-buffered lakes to act as a wild brood stock refuge for the native populations in Whitepine Lake and Whirligig Lake; (2) to clarify the taxonomic status of the aurora trout, that is to determine if aurora trout are distinguishable from brook trout at the molecular genetic level; and (3) to maintain the captive breeding program.

To achieve these goals, a suite of short-term recovery objectives for the period 2005 – 2010 have been developed.  To facilitate the delivery of these recovery objectives, specific approaches and strategies were produced and are organized into four broad recovery categories – Legislation and Policy, Research, Habitat Management and Population Management.  Implementation will be delivered via a subsequent Recovery Action Plan (RAP) by the ATRT, other government and non-government agencies, experts and stakeholders.  A series of specific steps and anticipated effects has been prepared to guide recovery efforts.  The evaluation of the success of this strategy will employ a series of biological and social criteria.