Any deal with Japan to allow whaling would have to be very attractive to get New Zealand support, Foreign Minister Murray McCully says.

Murray McCully says NZ will consider joining any legal action to force Japan to stop whaling in the Southern Ocean if diplomatic channels fail.

A diplomatic crisis is looming over an anti-whaling protestor who is reportedly being held in custody on a Japanese whaling vessel.

Japanese whalers have confirmed a New Zealand protester who boarded one of their ships has received medical attention for a knife-wound.

Two Sea Shepherd activist ships say they are in pursuit of the Japanese whaling fleet in the Southern Ocean, exchanging water cannon fire with the whalers.

Something is holding down the herring population of Alaska's Prince William Sound, and marine scientists are tailing some rather large suspects: humpback whales.

Japanese whalers and anti-whaling group Sea Shepherd are once again pointing the finger at each other after a collision at sea.

John Key says progress has been made on a deal which would end Japanese whaling in Antarctica.

The Sea Shepherd Conservation Society today filed with NZ police a complaint of attempted murder against the captain of a Japanese whaling ship.

Sea Shepherd national coordinator Bill Watson has called for Foreign Minister Murray McCully to step down from his portfolio.