The aquarium says the seals, named Petunia and Johnny Jump Up, were released Friday in Narragansett, Rhode Island.
Both were brought to Mystic in May.
Petunia, a female harp seal, is about 16 months old. She was rescued in Scarborough, Maine, with multiple wounds and pneumonia.
Johnny Jump Up is an approximately 6-month-old gray seal. He was rescued in Sandwich, Massachusetts, with a severe infection and entanglement wounds.
Mystic says Johnny Jump Up still has scars of his entanglement with marine debris. The aquarium’s Janelle Schuh says the seal’s injuries serve as a reminder for people to pick up litter at the beach and properly dispose of fishing line.