The last of the belugas and orcas held in an infamous "whale jail" in Russia have been released.

Ten orcas and 87 belugas had been housed in overcrowded enclosures at a holding facility in Srednyaya Bay in the town of Nakhodka, on Russia's Far East coast. They have since been released in batches, back into the wild.

"During transportation, the animals behaved calmly, their behavior was monitored by scientists, veterinarians and experienced trainers," says a news release from the Russian Federal Research Institute of Fisheries and Oceanography on the last day of the whales' release. "From 9 o'clock in the morning, work began on the release of 19 Beluga whales, which were successfully completed. 3 large individuals have satellite tags that will allow scientists to monitor the movement of animals in the wild."

While the initial news was met with celebration, conservation groups are concerned that Uspeniya Bay, where the whales were released, is not the best choice as the belugas are not native to that area and may be at risk of being recaptured.

The whales were illegally captured in the summer and fall of 2018 by four Russian companies that reportedly planned to sell them to marine parks in China, reported The Whale Sanctuary Project. Whales can sell for millions of dollars each, depending on the species, according to The New York Times.

The statement was signed by the governor of Russia's Primorsky region, Whale Sanctuary Project Executive Director Charles Vinick and oceanographer Jean-Michel Cousteau. Cousteau is the son of famed oceanographer Jacques Cousteau.

'It might take years'

Stories about the whales' situation first were reported in fall 2018, according to Smithsonian. Aerial images of their small pens were released, causing an outcry over the cramped quarters. There were reports of ice-encrusted enclosures, rotten food and animals sick with infections. Four of the original whales were no longer in the pen and were presumed to have died, according to the Whale Sanctuary Project.

The Times reports that there was some disagreement about the best way to handle the animals' rehabilitation. Because of their health or their young age, some might not be able to survive unassisted. Some were babies or very young, for example, when they were caught.

"Their ability to survive on their own if the gates were just opened is limited," Vinick said at one press conference.

The scientists wanted to return the whales to the area where they were caught so that there's a chance they can reunite with their family and better adjust to life in the wild but that isn't where all of the whales ended up. Monitoring of the whales will continue.

"It might take years; we don't know yet," Cousteau said. "It depends on each and every one of them."