Meet the largest of all fish in the St. Lawrence, the basking shark.
Basking shark, elephant shark, bone shark, nurse fish, sunfish, sailfish, hoe-mother, squale pèlerin (Fr.), squale géant (Fr.), éléphant de mer (Fr.), poisson à voiles (Fr.)
The basking shark is the second largest shark and fish in the world, and the only member of the Cetorhinidae family. It is found near the coast in northern and temperate waters where it is often observed feeding at the surface. In Eastern Canada, it seasonally ranges from Newfoundland in the north, to the St. Lawrence Estuary in the west.
Despite its huge size, the basking shark poses no threat to humans since it subsists on plankton. It is a filter feeder, relying solely on forward movement and its wide mouth to capture plankton while swimming at a speed of approximately 2 knots (3.7 km/h; 2.3 mph). It is not known where Canadian specimens spend winter although individuals tagged in New England during summer are known to have swum as far south as Brazil¹. A number of historical sources claim that the basking shark hibernates on the sea floor during winter, including in the St. Lawrence. This idea was debunked in 2003 when scientists of the Marine Biological Association (UK) discovered that the basking shark actually feeds on plankton at depths up to 900 m during the cold season².
The North Atlantic population, including individual sharks that make it into the St. Lawrence, is far more numerous than basking shark numbers in the northeast Pacific. Among other explanations, the British Columbia population was nearly hunted to extinction during the mid-twentieth century as it was viewed as a competitor for lucrative fisheries³.