MOSCOW, Russia—Russia released 2 killer whales and 6 beluga whales back into the wild on Thursday, the first group of almost 100 whales whose capture in the Far East last year caused an international outcry.
The mammals, caught last summer in order to be sold to marine parks or aquariums in China, were released in their natural habitat in the Sea of Okhotsk, a Russian oceanography research institute said in a statement.
The plight of the captive whales, which were held in cramped conditions, captured the imagination of people around the world and prompted celebrities such as actor Leonardo DiCaprio to petition for their release.
When it came, however, Russia was criticized again by Greenpeace Russia and wildlife activists who said the operation had not been transparent, was rushed and put the animals at risk.
The Russian Research Institute for Fisheries and Oceanology said the whales had been closely monitored as they were transported 1,800 kilometers to be freed and that none of them had suffered.
"Vets conducted all the necessary tests before they were freed, and the results showed the animals are in good health," the institute said.
The 2 orcas, which were released separately from the beluga whales, were "nervous" about their return to the wild and swam near to the shoreline for hours before finally heading out into the open sea, it said.
Greenpeace, however, said in a statement the animals had been transported for a week in small containers and were released without being rehabilitated on location first, "seriously raising the risk of trauma or death for the animals."
It said "the whole process took place in secrecy" and should have involved international and independent scientists.
Jean-Michel Cousteau, son of celebrated French marine expert Jacques Cousteau, said on Wednesday he had heard concerns from the public about a "lack of transparency" in the operation.
The move to begin gradually releasing the whales in their natural habitat was announced last week during President Vladimir Putin's annual question-and-answer phone-in, which he uses to burnish his image among the Russian public.
The Kremlin had ordered local authorities in the Russian Far East to intervene months ago, but the problem of how to release them without causing them harm caused delays.
The released whales have been tagged with tracking devices so their movements and behavior can be monitored.