The New Zealand Government is seeking information from Japan on whether it has suspended its annual scientific whaling programme.
The Japanese Fisheries Agency on Wednesday said the operation in the Southern Ocean has been suspended for safety reasons.
Anti-whaling group the Sea Shepherd Conservation Society has been frustrating the hunt all season and Japan says activists have blocked a loading ramp of its main ship the Nisshin Maru, preventing harpooned whales being loaded.
Sea Shepherd is continuing to track the factory ship, which has left the Southern Ocean and is now steering an erratic course.
Foreign Affairs Minister Murray McCully says at this stage, it is unclear whether the whaling programme has been suspended or stopped for the season.
The minister said the Government wants to achieve the same objective as the environmentalists, despite not supporting some of their tactics.
However, Mr McCully says it remains to be seen whether Sea Shepherd has won its battle in the Southern Ocean.
Japan kills hundreds of whales a year under a loophole in a 1986 moratorium on commercial whaling that allows "lethal research".
Whalers may be relocating - activists
Sea Shepherd believes the whaling fleet could be relocating and that the Nisshin Maru has moved through Drakes Passage towards the South Atlantic Ocean.
Sea Shepherd Captain Paul Watson told Radio New Zealand's Morning Report programme the vessel is now steering an erratic course and could be taking a circuitous route back to Japan or heading back to the whaling grounds.
Mr Watson says if the fleet is simply repositioning, activists will continue to pursue the Japanese vessels and meet them in a new location.
The Sea Shepherd ships will stay in the Southern Ocean as long as Japanese whalers are there, he says.