The gray seal and its human champions have just won a notable triumph here over politicians, bureaucrats and business-minded farmers of the sea.

Faced with a national outburst of indignation, the minister for Scotland, Bruce Millan, has called off the Norwegian hunters he hired to help kill 5,800 of the sad-eyed beasts in the Orkneys.

A campaign by conservationists brought thousands of protesting letters to 10 Downing Street, thoughtful letters to The Times of London and a wave of sympathetic sentiment from most Britons, a nation of animal lovers. After the hunters were shadowed at sea for eight days by a trawler carrying conservationists, Millan conceded defeat late Monday night.

Tuesday, the Norwegian vessel Kvitungen and its marksmen with 10 high powered rifles were heading back to their home port of Bergen, probably delighted to see the last of the Orkneys, the seals and their defenders. The crew will get only a portion of the promised $40,000 fee and will lose the handsome sums they expected from the white and blue pelts of slaughtered newborn pups.

In contrast, the converted trawler Rainbow Warrior, the ship manned by conservationist volunteers, sailed into Kirkwall, the Orkneys' capital, with all its lights blazing in triumph.

The hunters' intended victims were the pups and cows among the gray seals who have been flourishing in the Orkneys off the north coast of Scotland ever since a 1914 law gave them protection. Nobody has firm figures on their numbers, but Millan's ministry has put the population at 60,000 to 70,000. A gray seal is larger than the common variety and has domed, not a rounded, head.

Scottish fishermen who, along with others, have helped deplete the stock of fish in British waters, complained that the seals were consuming anywhere from 50,000 to 200,000 tons of cod, haddock, salmon and whiting annually costing them from $24 million to $40 million.

Inshore fishermen, by contrast, argued that the seals also eat squid, which in turn eat costly lobster and other shell fish. But the deep sea fishermen outnumber the inshore fishermen, and last year Millan quietly launched a six-year program to wipe out 25,000 seals.

Officials got away with it last year. But this time, a constellation of conservationists mounted a counterattack. Funds came from the World Wildlife Fund and the Royal Society for the Prevention of Cruelty to Animals. Greenpeace, an international ecology organization, supplied the man-power and planned the tactics.

Among the contributors were the four former Beatles, Brigitte Bardot and Twiggy, the model-turned-actress.

Greenpeace carefully avoided an extreme position. Its leaders said they did not oppose the traditional cull or kill - limited to 2,000 seals - by 16 local hunters armed with .22 rifles. But the conservationists insisted that Millan postpone his hunt until he had the scientific evidence to justify his claim of overpopulation.

A Dutch biologist aboard the Rainbow Warrior charged that Millan's cull was "an attempt to shift the blame for declining fish stocks from human overfishing to the seals." The human catch in British waters, he said, has jumped from 271,000 tons in 1960 to 442,000 in 1976. Another estimate put the human catch at 20 times the consumption of seals, yet no one knows for certain.

Millan ignored the protests and, on Oct. 8, the Kvitungen went to sea. Its hunters looked forward to collecting $60 for the white pelt from each three-day-old baby and $20 for the blue skin from three-week-old pups. Adults can be ground up as pet food!

But everywhere the Kvitungen went, the Rainbow Warrior was sure to follow, and the marksmen never got on shore. In addition, Greenpeace posted volunteers on the lonely islands where the colonies of gray seals live - places with exotic names like Muckle Greenholm, Holmes of Spurness and Little Rona.

The Norwegian captain, Per Boe - "killer captain" in the blockbuster headline of one British tabloid - made plain he would not risk firing at a human. His crew even befriended the conservationists when they warned the Kvitungen that a radical band was threatening to sabotage the hunter ship.

Day after day, Millan insisted that the cull would take place. Night after night, a wind-blown Sue Lloyd-Roberts, a reporter for commercial television, told an enthralled nation of the Rainbow Warrior's saga. Viewers saw cuddly pups moanig and shrieking for their barking mothers.

Novelist Brigid Brophy wrote The Times suggesting that a chemical contraceptive in the seals' food would be a more humane way to deal with any problem. A Sussex University biologist scornfully wondered if there was a problem at all since there had been virtually no analysis of the contents of the Orkney seals' stomachs. At least 14,000 letters poured in to Prime Minister James Callaghan.

Monday night, Millan threw in the towel, "conscious," he said, "of the widespread public concern." He promised to hold open hearings on the issue, taking evidence from any group that wanted to come forward.

A spokesman for Scottish fisherman complained that sentiment had triumphed over sense, but the conservationists were ecstatic.

Peter Wilkinson, the London director of Greenpeace, called it "a total victory".

A spokesman for the Royal Sociey for the Prevention of Cruelty to Animals declared that "humanity has prevailed. In these times of commercially oriented actions, it is gratifying to know that non-violent, reasonable protest and public reaction can still cause government departments to reconsider their decisions."