Whale and Dolphin Conservation (WDC) says this appears to be an effort to stock some overseas marine parks.
Researcher Erich Hoyt, with WDC and the author of Orca: The Whale Called Killer, says the animals are now being held near Vladivostok in SE Russia, along with a young female killer whale named Narnia which was captured last year. He says they were captured under permits obtained by a Russian company called White Sphere, which designs, builds and operates dolphinariums and other marine-life attractions. Rumours indicate two of the orca are going to a Chinese aquarium and two are going to Moscow.
These eight orca were taken from the same sea as 18 beluga whales that a consortium of US aquarium owners (incl.Seaworld) had been trying to import. A spokesman for SeaWorld, which 'owns' approx. half of the world's captive orca, says it has not provided any support for the Russian captures nor was it even aware of the activity beyond rumours.
Killer-whale captures are extremely rare, both because captures are very expensive and logistically difficult, and because they can trigger an international uproar. Before Narnia was captured in 2012, the last capture (as opposed to rescue) was 15yrs ago in the marine bloodbath town of Taiji, Japan.
At this stage, no-one knows the final destination of the orca, or indeed the fate of the 18 beluga whales either...WDC has organised a global petition to return them to the wild.