Sea Shepherd says it is successfully blocking the Japanese whaling operation in the Southern OCean.
The Institute of Cetacean Research claims to have footage showing stun grenades being thrown by Sea Shepherd onto the Yushin Maru II.
But the Sea Shepherd Conservation Society says its crew threw only smoke and stink bombs.
Captain Paul Watson told Summer Report the group is succeeding in its campaign to shut down the Japanese whaling operation.
"They haven't killed a single whale and we're going to try to keep it that way. We've been here 12 days," he said.
He said the aim is to harrass and slow the Japanese fleet in every way possible without causing injury to the whalers or damaging any of their ships.
