Lake sturgeon at risk of extinction, says COSEWIC
The legendary lake sturgeon, one of the largest of Canada's freshwater fish, is at risk of extinction, says the Committee on the Status of Endangered Wildlife in Canada (COSEWIC). This was one of eight species assessed by the group of government and non-government experts at its meeting late last month in Gatineau, Quebec.
The lake sturgeon, like all sturgeons, is a living fossil and retains the shark-like features of its ancestors of the Devonian Period. It is an enormous, long-lived fish, weighing up to 185 kg (over 400 lb) and having a documented lifespan of over 150 years.
This species was found to be most at risk in the western parts of its range (Alberta to northwestern Ontario) where it was assessed as Endangered, and is considered to be at some level of risk throughout the remainder of its range in Canada. The lake sturgeon faces a variety of threats, including over-harvesting and habitat loss from the construction and operation of dams. Dams have been a significant threat to many other fish species assessed as "at risk" by COSEWIC in the past, including American eel, white sturgeon, and the copper redhorse.
Among the other wildlife species assessed at COSEWIC's latest meeting and determined to be at risk were: native populations of the westslope cutthroat trout, a popular freshwater sport fish in Western Canada (assessed as being of special concern in British Columbia and as threatened in Alberta); the Misty Lake sticklebacks, an endemic species pair found only in one small lake on Vancouver Island (important for the study of evolutionary processes in nature and assessed as endangered); and the Sowerby's beaked whale, a rarely observed Atlantic deepwater whale (assessed as being of special concern).
Threats to the various species asssessed include hybridization and competition with other species introduced into their habitats, habitat loss and degradation (often in connection with roadbuilding, development or other industrial activities), and the release (accidental or deliberate) of exotic and/or invasive organisms.
COSEWIC also considered a number of aquatic species that were referred back to it through Governor in Council by Fisheries and Oceans Canada (DFO) for further consideration. After evaluating the information provided by DFO, COSEWIC reaffirmed its original assessments for the Arctic population of Atlantic cod, among others.
On a positive note, the Committee reclassified one plant and one fish species as being no longer at risk. They included the Scouler's corydalis, a large and showy perennial plant found only on Vancouver Island, and the greenside darter, a colourful, perch-like fish found in the Great Lakes area of southern Ontario
Altogether, 521 species of plants and wildlife in Canada are now considered "at risk" by COSEWIC. This includes 212 species classified as Endangered, 136 considered Threatened, 151 deemed to be of Special Concern, and 22 that are Extirpated (i.e. no longer found in the wild in Canada). Another 13 are Extinct and 41 are Data Deficient, meaning that the available information is insufficient to (a) determine a wildlife species' eligibility for assessment or (b) enable a species' risk of extinction to be assessed.
In conducting its assessments, COSEWIC draws upon scientific, Aboriginal traditional and local or community knowledge provided by many experts from governments, academia and other organizations. Assessment summaries may be viewed on the COSEWIC Web site, www.cosewic.gc.ca, and will be submitted to the federal Environmnet Minister in August 2007 for listing consideration under the Species at Risk Act (SARA). At that time, the full status reports will be publicly available on the Species at Risk Public Registry (www.sararegistry.gc.ca).
More information is also available from COSEWIC chair Dr Jeff Hutchings at Dalhousie University's biology department, 902/494-2687.