The Canal de Beauharnois is a branch of the St. Lawrence River that flows on the south side of the Île-de-Salaberry just west of Montréal. The site stretches from the upper side of the Beauharnois dam, to the west of the canal mouth were it meets Lac St-François. Hungry Bay, immediately to the south of the canal mouth is also included. The whole IBA, excluding areas west of the mouth of the canal, is included in the Beauharnois-Salaberry regional park. There is a diversity of wetland habitats here including: open water, marsh, wet shrubby areas and sandy shorelines, although cattails and phragmites are the most common shoreline plants.
During migration, numerous waterfowl species are present in the Canal de Beauharnois. Snow Geese are the most common species with high counts of 20,000 individuals observed in the fall at the St-Louis-de-Gonzague pond, and 50,000 individuals in the spring at Hungry Bay. Between 10,000 and 15,000 Canada Geese use the area in summer. 7000 Canada Geese have been counted, on different occasions, in the Hungry Bay and canal sections of the IBA in spring. A wide diversity of ducks use the IBA during migration and some species also breed here. Up to 2000 American Black Ducks have been observed here in the spring, with other common migrants including Mallard (maximum count of 9980 individuals), American Wigeon (maximum count of 1200 individuals in the St-Louis-de-Gonzague section), Ring-necked Duck (maximum count of 1000 individuals in the St-Louis-de-Gonzague section), Lesser Scaup, Greater Scaup, Common Goldeneye, and Common Merganser. Up until 2010, there were two Common Tern colonies using the artificial islands supporting the Laroque and Saint-Louis-de-Gonzague bridges; approximately 250 pairs of terns were recorded in this area. The reason for their disappearance is unknown. Peregrine Falcons are now nesting on the bridges. Nesting boxes were installed and Services environnementaux Faucon Inc. is responsible for the monitoring.
The growth of aquatic vegetation is causing a significant reduction in open water areas, i.e. the pond of the Saint-Louis-de-Gonzague bridge is covered with fragrant water lilies. This may negatively impact water birds in need of open areas to feed. Furthermore, poaching is reported every year despite the fact that a portion of the IBA is within a No Hunting Zone extending from the dam to the city of Saint-Louis-de-Gonzague and including all of the shoreline wetlands.
A variety of freshwater and diadromous fish coexist in different habitats in the IBA. We found between 70 and 80 species (including historical records) in the area. Several species, such as the northern pike, the yellow perch and the common carp exploit the aquatic vegetation and the floodplains as a spawning ground, a nursery and a feeding ground. Others, such as walleye, freshwater specie with an important economic value in Canada prefer rather to spawn in fast flowing waters. A special feature of this area is the presence of salmonids introduced for sport fishing (brown trout, rainbow tout, and salmons). Salmons were introduced in the Great Lakes and some drift into the St. Lawrence River where they are sometimes caught by anglers. Brown trout and rainbow trout were also stocked in riffles (in the river) for sport fishing.
Several pressures threaten the availability of fish habitats: the creation of embankments, the artificialization of banks, the residential, commercial and industrial development as well as developing the road network, while agricultural, industrial and urban waste deteriorate the water quality. The Eastern sand darter, among others, is very vulnerable to pollution and it is now on the list of endangered species. Among the species listed at risk frequenting the site, we found the lake sturgeon, the channel darter, the bridle shiner, the American eel and some historical records mention the presence of copper redhorse, a fish endemic to Canada designated endangered. In addition, the presence of invasive species such as round goby, threatens the natural dynamics of ecosystems and the water level regulation of the Great Lakes creates risks for the availability of spawning habitats of certain species.
Major species present:
Eastern sand darter
The sector is characterized by clear, alkaline and slow flowing water. Theses conditions promote dense plant bed that can cover up to 50% of the water bodies. Submerged plant beds are dominated by wild celery and Eurasian water-milfoil, while emergent marshes are filled with bulrushes, arrowhead and cattails. Several duck species forage in these areas, including the scaup that is fond of wild celery.
Shoreline erosion, whether due to natural factors (wind, freezing and thawing cycles, absence of ice protecting the river banks in spring) or human actions (waves caused by ships), all threaten the riparian habitat. Water level fluctuations affect the ecology of plant and animal species that live there. A significant and prolonged decrease of bank immersion could affect flora by promoting more land species such as shrubs or even trees. In addition, the spread of invasive species exerts considerable pressures on the native flora of these habitats.
Major species present :
Eurasian water-milfoil – invasive species
Narrow leaf cattail