A fleet of five boats left the northern Japanese port of Kushiro earlier on Monday and brought back two minke whales.

A crane slowly placed them on a truck to be taken to a portside factory for processing.

Workers in plastic overalls poured sake from paper cups onto the first whale to express thanks.

It was the first commercial hunt since 1988, when Japan switched to what it called research whaling after commercial whaling was banned by the International Whaling Commission.

Japan gave six months' notice it was withdrawing from the IWC, a move that took effect on Sunday.

The Fisheries Agency said the hunts will stay within the country's exclusive economic zone and the catch quota for this year will be 227 whales, compared to the 637 Japan hunted in the Antarctic and the northwestern Pacific in its research program in recent years.

The announcement of the quota, originally planned for late June, was delayed until Monday in an apparent move to avoid criticism during this past weekend's Group of 20 summit in Osaka.

As the boats left port, whalers, their families and officials in major whaling towns, Shimonoseki in southwestern Japan and Kushiro in the north, celebrated the fresh start, hoping for their safe return and a good catch.

"We hope commercial whaling will be on track as soon as possible, contribute to local prosperity and carry on Japan's rich whale culture to the next generation," Deputy Chief Cabinet Secretary Yasutoshi Nishimura said.

Officials said the catch of the two minke whales was a nice surprise because they were not thought to be in the area and whalers were expecting Monday's trip to be only ceremonial.

Fisheries Agency officials said the whale meat will be auctioned at a local fish market on Thursday and later hit stores, mainly in the region but possibly in Tokyo.

While the resumption of commercial whaling was condemned by many conservation groups, others see it as a face-saving way to let the government's embattled and expensive whaling program gradually succumb to changing times and tastes.

Despite massive attention, tax money and political support, whaling in Japan involved only a few hundred people and accounted for less than 0.1 per cent of the total meat consumption in 2017.

Australian Associated Press