They're the whales that behave like dolphins, leaping right out of the water in one of the most spectacular animal displays on earth. They've enchanted millions. And they're the ones the Japanese are now off to kill. Not content with harpooning minke whales, fin whales, sei whales, Bryde's whales and sperm whales – all unnecessarily, all in the face of hostile world opinion and all in the laughable guise of "scientific research" – the Japanese whaling fleet set off yesterday to hunt the best-loved whale of all, the humpback.

It has been protected for more than 40 years, since long before the current international moratorium on commercial whaling came into force in 1986. It had been hunted so hard in preceding decades that its estimated numbers dropped to little more than a thousand in 1963 – even the whalers agreed to leave it in peace. Since then it has recovered to some extent, and gone on to become the icon of the whale-watching industry in numerous parts of the world. To many people it is the most fascinating and appealing of all the great whale species.

Encounter close-up a fin whale, a sei, a minke or a grey whale and you'll no doubt be thrilled, but what you will see is a glimpse of dorsal fin, a spout perhaps, and a view of the tail flukes as the animal makes its dive. Encounter a humpback and you're in for a different experience altogether. These are whales that, when the mood takes them, go in for "breaching" – hurling themselves entirely clear of the water, dolphin-style – despite the fact that they can be 50ft long and weigh 40 tonnes. It is an awesome sight, and to witness it is the single top whale-watching experience.

But the excitement and pleasure of watching humpbacks is running smack into the Japanese desire to kill them, and the ensuing row is certain to echo around the globe. It may well lead to direct clashes at sea between whalers and Greenpeace activists of the sort that electrified the world in the 1970s and 1980s, and eventually led to the 1986 moratorium. Japan ignores the moratorium, and has killed whales for years under the guise of "scientific research", a risible fiction believed by no one outside Japan, as the meat from the kills is sold on the open market.

This year, for the first time, it has awarded itself a "quota" of up to 50 humpbacks to be killed in the summer hunt in the Antarctic and Southern Oceans, which is starting now, to accompany the killing of as many as 935 minke whales and up to 50 fin whales, in what Japan's Fisheries Agency says is its largest-ever "scientific" whale hunt.

It is a growing industry, despite enduring global protests. This season's target of up to 1,035 whales is more than double the number the country hunted a decade ago, and Japan continues to work actively within the International Whaling Commission to undermine the moratorium.

Yesterday, after a farewell ceremony in the southern port of Shimonoseki, four ships led by the 8,000-tonne Nisshin Maru left for Antarctica to begin the hunt. Families waved little flags emblazoned with smiling whales and the crew raised a toast with cans of beer, while a brass band played "Popeye the Sailor Man". Officials told the crowd that Japan should not give into anti-whaling activists. "They're violent environmental terrorists," the mission leader, Hajime Ishikawa, told the crowd. "Their violence is unforgivable ... we must fight against their hypocrisy and lies."

Greenpeace, long the most directly active of the anti-whaling environmental groups, said its ship Esperanza was moored just outside Japan's territorial waters and would chase the fleet to the Southern Ocean. The Esperanza expedition leader, Karli Thomas, said she expected to spot the whaling fleet perhaps as early as last night.

"We are going to do everything in our power to reduce their catch," she said. "Japan's research programme is a sham. We demand [they] cancel it. This whaling programme is stealing money from Japanese taxpayers, and robbing other countries of much-needed tourist income. The threatened humpbacks targeted by the whalers are part of thriving whale-watching industries. The whaling fleet must be recalled now. If it is not, we will take direct, non-violent action to stop the hunt."

Other environmental groups issued strong protests. "Killing endangered whales for products that nobody needs is beneath the dignity of a great nation like Japan," said Robbie Marsland, director of the UK branch of the International Fund For Animal Welfare. "It is inherently cruel – there is simply no humane way to kill a whale." The American Cetacean Society estimates that the humpback whale population has recovered to about 30,000 to 40,000, about a third of the number that existed before modern whaling began. The species is listed as "vulnerable" by the World Conservation Union.

But Japanese fisheries officials insist that the population has returned to a sustainable level and that taking 50 of them will have no impact. The head of Japan's Fisheries Agency, Shuji Yamada, said at the Shimonoseki port ceremony yesterday: "The scientific research we carry out will pave the way to overturning the moratorium on commercial whaling, which will better help us to utilise whale resources," he said.

Greenpeace is collaborating with Pacific-based scientists through the Great Whale Trail project to demonstrate that whale research is possible without killing. The Great Whale Trail has been monitoring the location of tagged humpback whales as they migrate to the Southern Ocean from the Pacific. Its website will also track the Japanese whaling fleet.

(By Michael McCarthy, The Independet, 19/11/2007)