After months of international outcry, the so-called "Russian whale jail" is set to close.
On Sunday, authorities signed an agreement with a group of international scientists to free nearly 100 whales that have been held for months in cramped pens in the country's Far East.
The move coincides with a highly publicised visit by a team of scientists led by Jean-Michel Cousteau, son of French marine expert Jacques Cousteau.
Images of the 10 orcas and 87 beluga whales first appeared after they were caught last summer by firms which planned to sell them to marine parks or aquariums in China.
Their plight angered animal rights groups and spurred a petition to release the whales, shared by actor Leonardo DiCaprio on social media, which gathered almost 1.5 million signatures online. Actress Pamela Anderson also posted an open letter to Russian President Putin on her website.
The Kremlin intervened and ordered local authorities to act, prompting Russia's FSB security service to bring charges against four companies for breaking fishing laws.
But although the Kremlin agreed that the whales were held in cruel conditions, it said it was difficult to release them into the wild without harming them.
Their release is likely to be phased. "A decision in principle has been taken to release all the animals into the wild," Oleg Kozhemyako, the governor of Primorsky Region, told reporters after the signing ceremony.
"Scientists, including both Russian and international scientists from the Cousteau Team, will continue to evaluate the animals to determine when and how to release them," according to a joint statement by Russian authorities and scientific organisations.
"We also expect that a rehabilitation centre will be created for those animals that are injured in wild nature and that need to be rehabilitated," the statement said.
Cousteau told reporters it was a very emotional moment for him and the scientists would do all they could to save the animals.
"I know it's a lot of work, but I have no doubt that we are going to succeed," said Cousteau.
The scientists promised they would devise a plan to release the whales, some of which were captured as long ago as July, by next month.