Japanese media have highlighted the scars on Japan's whaling fleet left by clashes with protesters as the vessels returned to port this week, while the country's internet users are increasingly inflamed by what they say is racism behind the whaling debate.

The fleet spent three months in the Southern Ocean before returning on Monday with a catch of 506 minke whales and one fin whale - just half its expected haul.

New Zealand anti-whaling activist Peter Bethune climbed on board a ship after a series of high seas clashes and had already arrived in Tokyo. He has been charged by the district public prosecutor for trespass, possession of a weapon, injury to persons, damage to property and obstructing the passage of a vessel.

Two of Japan's top television stations, TBS and NTV, led their reports on the fleet's return with images of its main ship's hull splattered with red marks from protesters' paint bombs. They followed this with footage of nets torn by Bethune when he climbed on board.

They both described the marks as "raw" (namanamashii) evidence of violent clashes in the Southern Ocean.

The state broadcasting service, NHK, featured whaling fleet leader Shigetoshi Nishiwaki speaking at a press conference, where he said he was furious about repeated disruptions by protesters.

"The activists say they want to protect the ocean, but they don't care about leaking oil or leaving pieces of a broken ship behind," Mr Nishiwaki said, referring to Bethune's boat Ady Gil, which was disabled after colliding with a whaling ship.

On Japanese online discussion board 2channel - which gets more than two million posts every day - discussions about whaling repeatedly made reference to an assault in Tokoroa last year, where a Japanese-born boy was bullied for being a "whale muncher" and almost died in Waikato Hospital.

Many posters argued that anti-whaling protests were racially-motivated and ill-informed, complaining that western countries were targeting Japan more than Norway and Iceland.

Discussions about Bethune focused on his eating habits while captive on a Japanese ship: news reports in Japan had quoted crew saying Bethune happily ate fish up to three times a day and likely had a better diet in captivity than while with the vegan Sea Shepherd protest group.

Also published in the Japanese media this week was a report on a "whale festival" in South Korea, said to feature whale burgers and whale pizzas. It will be held in Ulsan from July 1 to 4.

On Japanese social networking site Mixi, more than 1000 people have joined a community group called "Disapproval for Sea Shepherd terrorism", with the slogan: "Whaling is Japanese cultural tradition. It is different from the Western massacre of whales for oil."

Meanwhile, on Facebook, a group called Stop Sea Shepherd Violence!, with more than 1000 members, many of whom are Japanese, asks: "How many people know that Minke whales are abundant now and they are not a global endangered animal at all?

"World has been filled with the wrong information by the people who are taking advantage of good will animal lovers to raise their funds."

One Japanese blog from yesterday, reposted on dozens of blogs, said what was so uncomfortable about the debate was that both anti- and pro-whalers had grandiose official arguments, but one could see what seemed like a truth they did not want to admit just underneath.

It seemed anti-whalers really had a "whales are cute", elitist attitude, while Japanese pro-whalers had a victimised, anti-foreigner attitude, it said.