It was a frustrating morning for John Turk, a grizzled boat builder dressed in a dazzling crimson blazer that bespeaks his rank as Master of the Queen's Game of Swans, or swan master for short.
''Frustrating,'' repeated Captain Turk as he stood on a dock in this idyllic Thames River town. ''When you get things not quite right, it's frustrating. We had a swan and cygnet down there get away. They all escaped and we had to try all over again, and we missed the interview.''
With that, he forlornly eyed the towering antenna of a television news van parked by the dock. Captain Turk and his crew of river men do love the publicity that is part of ''swan upping,'' their annual five-day cruise devoted to counting swans and their offspring, or cygnets, as well as long, beery lunches in carefully chosen riverside pubs.
But since the swan uppers rowed their six long boats into town a few minutes late, it was left to Dr. Christopher M. Perrins to give out the figures from the annual census of mute swans along 50 miles of river upstream from the outskirts of London. Only 54 Cygnets Survive in Area
In all that stretch, where thousands of swans once glided, only 54 cygnets have survived since the spring hatch.
Heavy boat traffic and shoreline development are part of the reason so few of the offspring grow to maturity, Dr. Perrins explained later while the boat crews enjoyed what he tactfully called an ''extended lunch hour'' at the Little White Hart Hotel.
But the big killer of swans on the Thames and some other heavily used rivers seems to be lead poisoning, according to the Oxford University biologist, who has performed autopsies on more than 300 swans.
''Although the anglers have tried to suggest it is lead from the petrol fuel used by powerboats, it's pretty clear,'' he said. ''The dead birds usually have bits of lead from fishing weights in their gizzards.''
Since 1964, the number of swans on this stretch of the Thames has declined from 1,300 to about 200, rebounding from a low of 120 in 1980. Nationally, the population of about 18,000 swans is holding steady despite high mortality in areas like the Thames valley. Fishermen Yield on Lead
Dr. Perrins's conclusion about fishing weights enraged many of the nation's three million fishermen. But after several years of name-calling between bird lovers and fishermen, the angling clubs and the National Federation of Anglers were eventually won over. Lead weights of a size swans can ingest were outlawed.
But the swan upping rubs the old raw feelings and points up the increasing pressures on Britain's waters, rural lands and wildlife. It also tells something about Britons' fondness for charming but outmoded ceremonies and their somewhat inconsistent attitude toward swans.
The history and reputation of the mute swan in Britain have been shaped by its beauty, its tasty flesh and its possession of one of the the most malevolent temperaments in the bird world.
A 12th century historian, Giraldus Cambrensis, reported the arrival in England of a giant ''cob,'' or male swan, that killed every other swan around Lincoln save for one ''pen,'' or female, spared for the ''comfort of her society.'' Ever since, it has been regarded as more decorative than companionable. A Bird of 'Formidable' Vices
In 1975, Lord Kingsale wrote The Times of London to accuse swans of ''formidable'' vices, including the drowning of grebes and mallards. He added that he had ''frequently intervened forcibly.''
The Daily Express has reported the near drowning of a fisherman who panicked and capsized his boat when it was rammed by a ''crazed swan.''
The royal management of mute swans, the dominant species in Britain, is linked to the royal appetite for swans. In 1251, for example, Henry III required 125 swans for his Christmas banquet. Swan was for centuries the most expensive bird in England. ''Swannage'' - a crime that amounted to unauthorized eating of swans by poor people - became a problem and measures were taken.
The first swan master was appointed in 1361 and the Act of Swans in 1482 decreed that only landholders could own swans. Eventually, 900 people were granted ''swan marks'' - a carving on the swan bill that designated the ownership of semidomesticated birds allowed to range freely. Swan upping - an annual sorting out of these bill-marked birds - started about 400 years ago. The term swan upping derived from ''driving up.'' #3 Swan Markings Still in Use But swanupsmanship is not what it used to be. Today, only three bill marks remain in use on the Thames. Birds with one notch in the bill belong to the Worshipful Company of Dyers, descended from a medieval guild.
Those with two marks belong to a similar group, the Worshipful Company of Vintners.
A bird with an unmarked bill belongs to Queen Elizabeth II.
Ownership is a meaningless distinction now that eating swans is out of fashion and, since 1983, illegal in most cases. But the dyers in their navy coats and sweaters, the vintners in green and white and the Queen's crew in crimson make a splendid sight as they row in boats of polished dark wood.
Upon sighting a brood, the six boats surround the cygnets and their hissing parents. After much flailing and dodging by the swans, the crews usually succeed in catching them by the necks with long hooks and dragging them into the boats. Depending on the marks carried by the parents, the cygnets either have their bills nicked with a knife or escape unnotched as a queen's swan. The affair is said to be painless, but the swans react to it with the enthusiasm that calves display at branding time.
Most of the swan uppers are boat builders or rivermen by trade, and they savor their busmen's holiday. Seats are passed from father to son. One man has been ''upping'' every July for 38 years. They can be a clannish lot - chiding pub owners who want to close after lunch at the traditional hour of 2:30 P.M. and growling at boaters who get between them and swans.
But their special ire is reserved for fishermen. Out of Sight, Boats Are Towed
Swan uppers, too, have their detractors - and their own little secrets. Once past a town like Henley, for instance, they hook their row boats to a yacht that tows them from one nesting area to the next.
Then there is the delicate question of swan eating by swan uppers. Until 10 years ago, this was a standard practice at the dryers' and vintners' annual ''swan feasts.'' Nowadays, Mr. Colley said, no swans are killed for banquets. But, he said, ''If there happens to be a swan that gets killed accidentally, it gets eaten.''
The swan uppers do not make a lot of noise about this. Eating the birds seems a practice linked to rowdier days. After all, not many years back, some river towns dreaded the arrival of the flotilla because of raucous hangers-on who delighted in dousing one another in the Thames.
Photo of A crewman plucking a cygnet from the river at Henley-on-Thames in the annual five-day ''swan upping.'' (NYT/Jonathan Player); Photo of Zoologists from Oxford University weighing a captured mute swan and taking a blood sample to check for lead. (NYT)