The 8,044-tonne Nisshin Maru mother ship is scheduled to dock in Tokyo on Tuesday morning, ending a five-month voyage, while the five other fleet vessels will dock at various ports in the capital and western Japan.

The total catch for the year came to 551 minke whales with no fin whales "as a series of offshore protests prevented the fleet from achieving its initial goal," said Shigeki Takaya, a fishery agency official.

Japan, which says whaling is part of its culture, had aimed to kill 850 minke whales and 50 fin whales on its annual hunt. It dropped an original plan to kill up to 50 humpbacks after coming under international pressure.

The Sea Shepherd Conservation Society -- whose militant protest ship was involved in a series of high-seas clashes with the Japanese fleet -- has said that its campaign saved 500 whales.

Sea Shepherd tried to physically stop Japan's whaling in the Antarctic, throwing what it described as stink bombs filled with rancid butter onto the decks of whalers. Japan says the bombs contained acid that stings the eyes.

In January, the group also sent two protesters to board a whaling factory ship, sparking a two-day standoff.

Japanese authorities plan to inspect the ships and question the crew following the incidents.

"On-site inspection is scheduled (for Tuesday) in connection with the protests," another fishery agency official said.

According to local media, Japanese coast guards and police will jointly inspect the ships on suspicion of forceful obstruction of business and call on authorities in other countries to provide cooperation through Interpol.

Greenpeace Japan said the environmental group has no plan to stage a rally to mark the fleet's return but will issue a statement of protest against Japan's whaling.

Japan kills whales using a loophole in a 1986 whaling moratorium that allows "lethal research" on the giant mammals despite protests led by Australia. Only Norway and Iceland defy the moratorium outright.

Australia has stepped up pressure on Japan since Prime Minister Kevin Rudd took office in December, sending a customs vessel to monitor the Antarctic hunt and gather evidence for a possible court case against whaling.

Canberra caused a stir when it released grisly footage caught by the customs vessel of whales being killed.