Île de la Couvée (QC127)

Île de la Couvée (QC127)

Brossard, Québec

Site Description

Îles de la Couvée is located on the south shore of the St. Lawrence Seaway in the Canal de la Rive Sud, Québec. This site is adjacent to the cities of St. Lambert and Brossard and includes the islands and islets between the Champlain and Victoria bridges.

Four artificial elongate islands ranging in size from 0.36 to 0.94 km² make up this Important Bird Area. The islands are made of deposit from dredging of the canal. Apart from a few trees (poplars) and sparse herbaceous vegetation composed mainly of Black Mustard on one of the islands, the islands are unvegetated.

Birds

Huge numbers of Ring-billed Gulls nest on Île de la Couvée #2. This colony has grown in size from 4,000 pairs in 1974 to over 28,000 pairs between 1989 and 1994. The colony then decreased in size so that in 2000 10,751 pairs were present. Thus in recent decades the colony has been equivalent to between 1 and 3% of the global Ring-billed Gull population. Small numbers of Herring Gulls (1994: 8 pairs) also nest on the islands. Common Terns formerly nested at this site (1974: 9 pairs) but are now extirpated.

Conservation Issues

A family of red foxes was discovered on the island in 1997 and was still present in 2000. These animals may in large part explain the decrease in the size of the gull colony. Many dead chicks were found around the fox den in 2000.

This site may be vulnerable to disturbance from recreational boats such as sailboats, yachts, and personal watercrafts. Oil and toxic pollution are also potential threats.

Fish Habitat

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:
American eel
American shad
Bridle shiner
Brown trout
Channel darter
Common carp
Copper redhorse
Eastern sand darter
Lake sturgeon
Muskellunge
Northern pike
Rainbow trout
Salmon
Smallmouth bass
Walleye
Yellow perch

Plants

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 :
American bulrush
Broad-leafed arrowhead
Broad-leafed cattail
Eurasian water-milfoil – invasive species
Great bulrush
Narrow leaf cattail
Sessilefruit arrowhead
Wild celery

IBA Criteria Habitats Land Uses Potential or Ongoing Threats Conservation Status

• Ring-billed Gull60,192 (max.)