What happened to the dolphins of the Humber

The cold waters of the River Humber don't sound like the natural habitat of the bottlenose dolphin - a creature with a penchant for warm seas. But research has revealed that the two most certainly have a history.

A resident bottlenose dolphin population swam the waters of the Humber as far back as Anglo-Saxon times, according to scientists at Durham University - much to the delight of a Saxon settlement at Flixborough, on the river's banks, which caught them for food. The research, published yesterday, drew on DNA from 7th and 10th century remains discovered at Flixborough. The population located only became extinct in the past 100 years, since there are recorded sightings from 1892.

The science raises more questions than it answers. "Bottlenose dolphins find local habitats and adapt to them and stay there," said Rus Hoezel, a professor of biological and biomedical sciences at Durham University, who has led the work. "If the Humber was a good place, why are they gone?"

The study examined whether pollution in the Humber and the amount of shipping in the area (84 million tonnes of cargo passed through its ports last year) might have contributed to the decline of the population. But since the bottlenose is found in other regions with high levels of boat traffic and pollution - such as New Orleans, at the mouth of the Mississippi, and Santa Monica Bay in Los Angeles - that has been discounted. Boat traffic and pollution would also have been less pronounced in the early years of the last century. In short, the scientists don't know what happened to the Humber bottlenoses and the only conclusions are that the creature's disappearance underlines the need to conserve those that are here now.

The discovery comes amid increasingly frequent sightings of the bottlenose in Britain. The two key British populations are in Scotland's Moray Firth (where there are about 130) and Cardigan Bay, west Wales (between 130 and 350), although another group was seen onthe Cornish coastline in 1991 after an absence of some years and that may prove to be another resident group.

But the creature - which can grow to 12ft, weigh 441lb and is found off European coasts from Spain to the Faroe Islands - faces numerous threats. In Devon and Cornwall last year, scores washed up dead on beaches - on one occasion 11 in a single day. All appear to have fallen victim to pair trawling, a practice illegal in British waters but still practised by some foreign trawlers, in which a large net is strung up between two craft to improve a catch of fish. Cornwall now braces itself for the environmental consequences every January when French trawlers lay nets and prepare to fish for lucrative sea bass.

In the Moray Firth, the Whale and Dolphin Conservation Society (WDCS) fears that fossil-fuel exploration and large ships are creating seismic noises that could be startling to dolphins and whales, which perceive their surroundings primarily by sound, and displacing them from their breeding grounds. "If you think of a herd of deer being chased by Land Rovers honking their horns, that gives you some idea of what it's like for them," said Mark Simmonds, the international scientific director of the WDCS.

A Scottish mathematical model, based mainly on data collected from the Firth, recently predicted an annual decline of almost 6 per cent in the dolphin population - which could mean extinction in less than 50 years.

Conservationists have lobbied to limit oil and gas exploration in Cardigan Bay for the same reasons. The bay is also home to a species of porpoise. In response to conservationists' fears, the Trade and Industry Secretary, Alistair Darling, has called a halt to drilling activities in both areas until further research had been done to assess their effects on the dolphins.

Warmer temperatures mean that Britain's marine life is becoming more diverse. About 20 giant ocean sunfish were recorded off the south-western tip of England last year. In January, a pod of killer whales were spotted swimming in the Firth of Forth by workmen repairing the Forth Rail crossing. The sightings were the first there in more than a decade. It is believed that there are at least four adults and two calves patrolling the waters and feasting on seals. That has increased calls for a rethink on plans to allow ship-to-ship transfers of Russian oil in the estuary.

Professor Hoezel said species which form colonies here must not go the same way as the Humber dolphins. "Our research has implications for the broader UK bottlenose dolphin population, including the possibility of a decline," he said.

The call of the wild

* Last year, Sharon Tendler, "married" her dolphin companion Cindy in a mock ceremony. Tendler had met Cindy 15 years earlier while on holiday in Jerusalem. She returned several times before deciding to tie the knot with her flippered friend.

* In Canada's northernmost territory, Nunavut, aboriginal hunters are spotting dolphins for the first time. With no word in their language for the creatures, hunters have described them to scientists studying climate change in the region.

* One species of dolphin, the whitebeak, has fled Scottish waters due to a rise in ocean temperatures. In a report out this month, the Whale and Dolphin Conservation Society said many marine mammals could be facing extinction.

* For years, a dolphin called Funghi has been entertaining visitors to Dingle, in Ireland. It is one of only six wild dolphins in the world to make regular contact with humans.

* The first large aquatic mammal to become extinct due to human activity was the whitefin dolphin, or baiji. It swam the Yangtze for 20 million years until the onslaught of overfishing and a huge rise in shipping. An expedition last year failed to spot any of the long-beaked creatures.

* While swimming with dolphins in Mexico, Billie Finley was attacked by a female who was bleeding from injuries. The tourists were told she was in season and it was not unusual for dolphins to fight, but there was no risk to humans. Minutes later, Ms Finley was dragged across the pool by her feet and slammed against a wall. She almost drowned, but has since made a full recovery.

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