The Atlantic Salmon (Lake Ontario population) a Species at Risk in Ontario

This species has been identified as Extirpated by the Committee on the Status of Endangered Wildlife in Canada (COSEWIC). It is currently being considered for listing under the federal Species at Risk Act (SARA). Protection is afforded through the federal Fisheries Act. If listed under the SARA, it will be afforded additional protection. Under the SARA, a recovery strategy must be developed for this species.

General Description

Salmo salar

© J. R. Tomelleri

The Atlantic Salmon (Salmo salar) is a member of the family Salmonidae, which also includes trouts, charrs, graylings, whitefishes and Pacific salmons. Atlantic Salmon that spend their entire life in freshwater are also known as Lake Atlantic Salmon, Ouananiche, Sebago, and Freshwater Salmon. The Atlantic Salmon has the following characteristics:

• Streamlined body;
• Ontario population (freshwater) generally smaller and darker than those that go to sea;
• X-shaped and round, dark spots mostly above the lateral line; and
• Juveniles have pigmented vertical bands or parr marks with a single red spot between each band along the lateral line.

Distribution

Freshwater (non-migratory or non-anadromous) Atlantic Salmon occur in Europe, Scandinavia and North America. In Canada, populations are present in the Atlantic region in lakes in Newfoundland, Labrador and Quebec. About 40 tributaries of Lake Ontario were also known to support runs of Atlantic Salmon. This population was isolated from the other Great Lakes upstream by Niagara Falls. Unfortunately, the colonization of Upper Canada led to the extirpation (no longer exists in the wild) of the Lake Ontario population of Atlantic Salmon before 1900. Stocking efforts using non-native stocks have had limited success and self-sustaining populations have not yet been established. However, stocking in Trout Lake Ontario has resulted in a naturally reproducing population

Atlantic Salmon  Distribution - Ontario Population

Habitat and Life History

Habitat requirements of the Atlantic Salmon vary depending on the life history stage. Typically, salmon ascended their natal streams just prior to spawning in mid-November. An April/May spawning run was also known to occur in some areas. Streams were clear, cold and swift-flowing with rather steep gradients and gravel substrates. The female constructed a nest (redd) in which both eggs and sperm were deposited and buried. Due to the low flow and volume of most Lake Ontario tributaries, adults returned to the lake shortly after spawning. Emerged alevins remained at or near the spawning area until the egg sac was absorbed. Juveniles eventually left their tributaries for downstream lacustrine feeding areas where they matured for one to two years before returning to their natal streams to spawn.

Diet

Juvenile Atlantic Salmon are visual drift feeders that consume aquatic insect larvae such as chironomids, mayflies, blackflies and stoneflies that are supplied by stream currents. In lakes, they are opportunistic feeders consuming invertebrates, amphipods and fishes. Forage fishes comprise the diet of adults.

Threats

Human settlement was the most significant factor leading to the demise of the Lake Ontario population of Atlantic Salmon. Activities such as land clearing for timber and agriculture degraded and destroyed habitat by altering water levels and adversely impacting water quality through increased erosion and siltation. Further, the construction of mill and driving dams for the timber trade prohibited fish passage, and congregating fish at the base of the dams were overexploited by fishers. A short-lived commercial fishery also contributed to the loss of this population of Atlantic Salmon.

Similar Species

The Atlantic Salmon resembles the Brown Trout (Salmo trutta).

Text Sources: COSEWIC Status Report 2006.

For more information, visit the SARA Registry website at www.SARAregistry.gc.ca.