Japan kills 177 whales during annual hunt in Pacific Ocean

Three ships caught 43 minke whales and 134 sei whales

A dead minke whale is unloaded in Kushiro on the Japanese island of Hokkaido. (AP)

Japan has completed its whaling season in the northwest Pacific Ocean having killed 177 whales.

Three ships, which left port in June, caught 43 minke whales and 134 sei whales.

Japan's fisheries agency said it would collect data on the whales' stomach contents and report its findings to the International Whaling Commission.

The annual hunt remains highly controversial.

While Japan is a signatory to the IWC's moratorium on whale hunting, Tokyo exploits a loophole each year by saying its hunt is conducted for scientific research.

Critics say the research is actually a cover for commercial whaling, as the meat from the harpooned mammals is later sold.

Animal rights charity Humane Society International has called for an end to Japanese whaling.

Kitty Block, the group's president, said: “My heart sinks each time the Japanese fleet returns to port with these magnificent animals rendered into blocks of meat pre-packed for the super-markets.

"Japan continues to wrap its whaling activities in the disguise of science and uses extraordinary sophistry to try to confuse the global public. But make no mistake, this is about killing whales for commercial purposes, something clearly prohibited by international law.

She added: “The International Whaling Commission has not asked for this research, and its Scientific Committee has criticised the North Pacific research program.

"Astonishingly, Japan now says it is researching sustainable catch, meaning that the entire point is to kill more of these magnificent, protected creatures.”

Japan's fisheries agency submitted a plan to the IWC to capture 304 whales per year in the northwestern Pacific between the 2017 and 2028 fiscal years.