The aquarium's head veterinarian, Dr. Martin Haulena, tranquilized the animal Wednesday afternoon near Fanny Bay, B.C. to perform the procedure.
After removing the rope at about 1 p.m. PT, the team planned to treat the animal with antibiotics and tag it if possible, before releasing it.
Within an hour, the team was working on disentangling a second sea lion in the same area. They will continue to look for others, a spokesperson told CBC News.
It's not clear whether either of the animals was the large male sea lion that was also spotted near Fanny Bay with a deep laceration on his neck last week.
The Vancouver Aquarium estimates there are hundreds of sea lions with some sort of injury from marine debris on the B.C. coast.
The curious animals get tangled in rope, wires, lost fishing gear and other garbage.