The 39,000-dwt Atlantic Erie (built 1985) got stuck on Sunday off Iles-de-la-Madeleine.
Three tugs are now on the scene.
Part of its 20,000-tonne cargo has been replaced by seawater to aid stability, Radio Canada cited CSL’s vice president of operations, Claude Dumais, as saying.
A refloating attempt will be made within 48 hours depending on weather conditions.