Île Shag is located about 1 km east of the southern part of the Île du Havre aux Maisons' South Dune in the Magdalen Islands archipelago. It is a small island with a flat top, and cliffs that rise from the water's edge. Vegetation is restricted to short grasses and other herbaceous plants. The cliffs, which are comprised of red sandstone, are irregularly shaped as a result of wind and tidal erosion. The mean annual temperature is 4.4°C, and the wind speed during summer averages about 27 km/h. The maximum tide level is about 1 metre. Access to Île Shag is possible with a small motor boat, but landing is difficult.
Île Shag supports one of the largest colonies of Great Cormorants in Québec. A total of 247 nests was recorded during the last survey, which was completed in 1990. This represents almost 4% of the estimated North American Great Cormorant population. The colony on Île Shag has been in existence for quite some time, with an estimate of at least 200 pairs in 1976, and 40 pairs in 1972. In addition to Great Cormorants, 148 pairs of Black-legged Kittiwakes were also recorded during the surveys completed in 1990. Small numbers of Black Guillemots and Great Black-backed Gulls also nest around the shores of the island.
Wind and tidal erosion are a major threat to the long-term existence of this site. Unfortunately, however, there is little that can be done to reduce the erosion of the island. Oil pollution (spills) in the general vicinity is also a threat since the Magdalen Islands are close to the main shipping route that leads to the St. Lawrence seaway. It has been suggested that conservation of Île Shag should be promoted through acquisition of the island; the cost of its purchase would likely be relatively low, and could be ecologically rewarding. The Bureau de la publicité et des droits des îles-de-la-Madeleine has no information about Île Shag. It seems that it has never been described in the local land register.
The area is a paradise for many marine animals, both vertebrates and invertebrates. The deep-water of Gulf harbor a variety of crustaceans, mollusks and benthic fish, including the yellowtail flounder, the winter flounder and the Atlantic halibut, a species highly prized by commercial fishermen. The American lobster is a important economic resource in the region. Many species also inhabit the offshore waters. For example, the mackerel is important for both the fishing industry and for its role in the food chain. The sandy beaches are populated by Atlantic surf clam and by soft-shell clam, two species targeted by the local population for recreational fishing. The Atlantic surf clam is also fished commercially with hand tools and hydraulic dredges. Spartina marshes and numerous brooks are found in the area and they are used as feeding and resting areas for a variety of fish, such the rainbow smelt and American eel. Brooks are also used for the reproduction of some species, such as rainbow smelt.
The main pressures on fish habitat are related to port operations, navigation, dredging and increased coastal erosion (increased suspended sediment, increased noise, riprap, etc.).
Major species present:
Atlantic surf clam