Anti-whaling activists hope to prevent Japanese whalers from making a kill for the next three weeks, as they exchange water cannon fire on the high seas. The Sea Shepherd Conservation Society's ship Steve Irwin joined its other vessel, the Bob Barker, in Antarctic waters about 7am (AEDT) on Monday in pursuit of the Japanese factory ship, Nisshin Maru. "As we moved towards them they we had a bit of a water cannon fight and demonstrated ours was a more powerful water cannon," Captain Paul Watson told AAP on Tuesday from the Steve Irwin.