Fish Species at Risk
Fish Species at Risk
The following information focuses on fish species at risk in the Ausable River watersheds:
Since the summer of 2002, the Ausable River Recovery Team has spent considerable time documenting the species at risk in the Ausable River watershed.
Extensive fish surveys have been conducted resulting in the discovery of two new fish species in the Ausable River (Black Redhorse and Bigmouth Buffalo).
In all, the Ausable River is home to 20 species at risk, including six (6) fishes, six (6) mussels and eight (8) reptiles.
Six species of fish in the Ausable River are listed as species at risk and their decline can be linked to: siltation/turbidity, habitat destruction and poor water quality.
Reason for Designation: The pugnose shiner has a limited, fragmented Canadian distribution, being found only in Ontario where it is subject to declining habitat quality. The isolated nature of its preferred habitat may prevent connectivity of fragmented populations and may prevent gene flow between existing populations and inhibit re-colonization of other suitable habitats.
Status History: Designated Special Concern in April 1985. Status re-examined and designated Endangered in November 2002.
Reason for Designation: A freshwater fish with a very small, highly fragmented distribution and area of occupancy, as well as restricted spawning habitat preferences. Native populations are found in only 5 Ontario watersheds in areas heavily impacted by urbanization and agriculture. It is at risk of habitat loss and degradation as a result of increased siltation and turbidity. Dams may adversely affect flow regimes and have fragmented populations in the two major rivers where this species occurs.
Status History: Designated Threatened in April 1988. Status re-examined and confirmed in May 2005.
Photo: S. Staton, DFO
Reason for Designation: A species with a restricted geographic Canadian range with small extant populations having very specific and narrow habitat preferences, which are under continued stress. It is extremely susceptible to habitat change driven by urban, industrial and agricultural practices resulting in increased turbidity. Two populations have been lost, and of the 11 extant populations, 3 are in serious decline as a result of the continuing and increasing threats posed by agricultural, industrial and urban development that are expected to impact the remaining populations of Lakes Erie and St. Clair.
Status History: Designated Special Concern in April 1994. Status re-examined and designated Threatened in November 2001. Status re-examined and designated Endangered in November 2008.
Eastern Sand Darter
Picture: Joseph R. Tomelleri, NYSDC
Reason for Designation: This species prefers sand bottom areas of lakes and streams in which it burrows. There is continuing decline in the already small and fragmented populations; four (of 11) have probably been extirpated. The extent of occurrence of this species in Ontario is approximately half of what it was in the 1970s as a result of habitat loss and degradation from increasing urban and agricultural development, stream channelization and competition with invasive alien species.
Status History: The species was considered a single unit and designated Threatened in April 1994 and November 2000. When the species was split into separate units in November 2009, the "Ontario populations" unit was designated Threatened.
Picture: Joseph R. Tomelleri, NYSDC
Reason for Designation: This freshwater fish species occurs in Ontario and Quebec and although it has been collected at new locations in both provinces, sometimes in large numbers, this is thought to reflect the use of more effective sampling techniques such as boat electrofishing. It has likely disappeared historically from the Ausable, Chateauguay and Yamaska rivers, since the use of boat electrofishing has failed to collect it recently. Threats to the species include habitat degradation (pollution, siltation), stream regulation that affects water flow (dams) and habitat fragmentation (dams). The Canadian range is highly fragmented and rescue effect is improbable because of the precarious conservation status in adjoining US States.
Status History: Designated Special Concern in April 1983. Status re-examined and confirmed in April 1987 and in April 2006.
Photo: J. Barnucz, D
Reason for Designation: A subspecies known from 10 locations between Lake St.Louis, Quebec and Lake Huron, Ontario. Its usual habitat is shallow water with abundance of aquatic vegetation. An overall decline of approximately 22% in the area of occupancy has been observed. This decline appears to be related to degradation and loss of habitat due to channelization and dredging operations in wetland habitats where this species occurs.
Status History: Designated Special Concern in May 2005.
Greenside Darter (Etheostoma blennioides) The Greenside Darter is a small (up to 11cm), olive-green member of the perch family. This species is identifiable by the 5-8 green V- or W- shaped marks on its side. The Greenside Darter is a bottom dweller and is usually found in clear, fast-flowing, gravelly bottomed riffle areas of streams and rivers. In Canada, this species is limited to southwestern Ontario.
*NOT AT RISK* (Last examined by COSEWIC in 2006)
Reason for Designation: Recent surveys have shown that the species is widespread and abundant in the Ausable, Sydenham and Thames rivers as well as Lake St. Clair. The total Canadian population has also increased through the recent colonization of the Bayfield River, Big Otter Creek, Detroit River and Grand River. Rescue of greenside darter populations in Canada is possible from Michigan populations.
Status History: Designated Special Concern in April 1990. Status re-examined and designated Not at Risk in November 2006.
Reason for Designation: Populations in Ontario appear to be doing well and there are no immediate threats to its continued survival; the area of occupancy appears to have increased and it has been found at 8 new locations since last assessed in 1989.
Status History: The species was considered a single unit and designated Special Concern in April 1989. Split into two populations in April 2008 to allow a separate designation of the Bigmouth Buffalo (Great Lakes - Upper St. Lawrence populations). The Bigmouth Buffalo (Great Lakes - Upper St. Lawrence populations) was designated Not at Risk in April 2008.