Two sea turtles that were rescued and put under the care of the S.E.A. Aquarium have been released into the wild after more than two years of rehabilitation.

The turtles were released into the waters around Singapore yesterday morning, in hopes they will breed and increase their population in the wild, the aquarium said. The release was made with support and assistance from the National Parks Board, the aquarium added.

Hawke, a hawksbill turtle, was released in the waters of Sisters' Islands Marine Park, while Louie, a green sea turtle, was returned to the waters off Pulau Semakau. Both turtles belong to highly endangered species.

Before their release, they were tagged and microchipped so they can be identified if they return to Singapore's shores in the future, the S.E.A. Aquarium said.

During their two years at the aquarium, the turtles were under the care of curatorial and animal health teams.

Aquarist Kenneth Kwang said it was an emotional moment for the team to see both turtles return to the ocean.

"Our team has spent more than two exciting years caring for them like our babies and it is an aquarist's dream to see our animals grow healthy after rehabilitation and return to the wild so they can contribute to the overall marine ecosystem," he said.

Upon release, both turtles started swimming immediately and disappeared from sight within seconds, the aquarium said.

"Louie was later spotted swimming near the same boat with its head out of the water, as though it was bidding farewell to its caretakers," it added.

Prior to their release, both turtles underwent a veterinary examination, including a blood test and weight and length measurement, to ensure they were healthy.

To prepare them for the wild, both turtles were moved gradually from back-of-house areas to larger habitats at the S.E.A. Aquarium, to encourage exploration and interaction with other marine life.

Louie was one week old and weighed 20g when he came under the care of the aquarium in 2015, after being found in a drain by a member of the public.

Hawke is believed to have been kept illegally as a pet, and weighed 800g when he first arrived at the aquarium. He now weighs 23kg and measures 59cm, said the aquarium. Hawke also has a shell deformity, probably due to poor nutrition and care when he was young, added the aquarium.

Both Louie and Hawke are native to Singapore, and were the first sea turtles to join the aquarium's marine life collection.