The study, published in Bird Conservation International, found that 28% of species are considered to be in the highest categories of risk.

Conservationists are particularly concerned by the albatross family.

Threats to the birds include commercial fishing and damage to breeding colonies caused by rats and other invasive species.



Seabirds make up just a small proportion (3.5%) of the world's bird species. But researchers say they are an important indicator of the health of the oceans.

The review, carried out by BirdLife International, found that of 346 species, 47% are known or suspected to be in decline.

It says that seabirds are now more threatened than any other group of birds.

Prof John Croxall, Chair of BirdLife's Global Seabird Programme, told the BBC: "They are top predators in their marine systems. The fact that almost a third are globally threatened should really be telling us something about how we need to look after where they occur to breed on land and where they go to feed in the ocean."

BirdLife assesses the threat status of seabirds on behalf of International Union for Conservation of Nature (IUCN), which compiles the internationally-recognised Red List. On that list, 5% of seabirds are in the highest category of Critically Endangered.

One of those is the Balearic shearwater, which can be found in UK waters in the summer.

The review also found that 17 out of 22 species of the albatross family are threatened with extinction.

Conservationists say commercial fishing is one of the key threats to seabirds with large numbers killed as a bycatch in nets and on lines.

Another is the impact that invasive species such as rats and feral cats have on breeding colonies, either damaging habitats or eating chicks and eggs.

Some of the most important breeding colonies are on remote islands in UK overseas territories. Last year an Royal Society for the Protection of Birds (RSPB) project, part-funded by the UK Government, carried out a programme to eradicate rats on Henderson Island in the South Pacific.

Helicopters guided by GPS dropped rat poison pellets on the island, which is the only known breeding site of the endangered Henderson petrel.

Grahame Madge of the RSPB said: "Without projects like this, these seabirds would have a finite life. On Henderson Island the rats were bringing birds towards extinction."

A pilot study is being carried out to look at the feasibility of removing mice from another important breeding site, Gough Island in the South Atlantic.

The whaling ships headed home from the Antarctic Ocean this week with 266 minke whales and one fin whale, said the agency on Friday.

This is far short of the quota of about 900 set when they began the hunt in December 2011.

Japan's fleet sails south to the Antarctic in the autumn each year, returning the following spring.

There has been a ban on commercial whaling for 25 years, but Japan catches about 1,000 whales each year in what it says is a scientific research programme.



Critics say it is commercial whaling in another guise.

Anti-whaling group Sea Shepherd which follows the Japanese fleet south every year in a bid to disrupt its hunt announced on its website on Thursday that the whalers had left the Southern Ocean.

There have been several clashes between the activists and whalers in the past months.

In January, three activists said they suffered cuts and bruises after clashing with a Japanese ship, the Yushin Maru No 2, about 300 miles north of Mawson Peninsula off the coast of Antarctica.

The Institute of Cetacean Research (ICR), which sponsors Japan's whaling activities, said the activists were trying to ''sabotage'' the Yushin Maru, throwing ropes with hooks attached and also hurling glass bottles of paint.

The vessel was one of the security ships escorting the whaling fleet.

The week before the incident, Japan handed three anti-whaling activists who had boarded a whaling support ship back to Australian authorities.

"The catch was smaller than planned due to factors including weather conditions and sabotage acts by activists," AFP news agency quoted an agency official said. "There were definitely sabotage campaigns behind the figure."

The agency said the fleet had departed "as scheduled".

The dispute has never seemed fully settled, however, and shifting geology in the region could also add confusion.

Nepal is now seeking international help to support a new, official measurement.

With outside funding, expertise and equipment, it hopes to complete the job and finally, quantitatively settle the matter within the next couple of years.

"Since we lack the capacity to do the job on our own, we are preparing a project plan with the request for donors and we will soon be sending them out," Krishna Raj BC, director general of Nepal's Survey Department, told BBC News.

He said the three-year project was finally getting underway, with much remaining to be done.

"Funding and technology have been the main constraints. We don't have, for instance, the equipment that works in a place with -45C temperature," he said.

"We basically need data from gravity instruments, levelling points and the global positioning system (GPS) to get a complete picture.

"For all these technologies to work, first there has to be infrastructure in places like the Everest base camp, and then we need to mobilise Sherpas up and down the mountain with someone who can handle all those technologies.

"And then finally, the data will have to be processed in such a way that it will be acceptable to the international scientific community."

The need for a fresh measurement has arisen mainly as a result of the dispute with China, which rules Tibet, on whose borders the mountain range also sits.

China had argued the world's highest mountain was nearly 4m shorter than Nepal's official figure, contending it should be measured to its rock height.

Nepal has said that the snow height should also be included, as with other peaks in the world.

The disagreement surfaced in past meetings on the two countries' Himalayan borders, and recently scheduled talks on the matter were postponed.

Nepali officials say even if the issue of Everest comes up during border talks, they will stick to what Nepal maintains is the official height of the mountain.

But they also say a fresh measurement has become necessary to "set the record straight once and for all."

Geologists say the Himalayan peaks are young and still growing as the Indian subcontinent slides under the Eurasian plate, causing the mountains to rise further.

Officials said a Danish university and an Italian NGO were already trying to help the Survey Department to make formal measurements.

But they added that these foreign organisations have limited funds and capacity to offer, and therefore more support from international community is required.

They said it was yet to be decided how much funding would be sought, and some critics have said the project may become too donor-dependent.

"The project to measure the height of the Everest is being developed in such a way that Nepalese officials and experts will have quite less say," said Buddhi Narayan Shrestha, a border expert and former director general of the Survey Department.

"This project will be basically about foreigners doing the job for us even when we have technology, software, and expertise to do so much on our own."

The height of Everest has been disputed ever since the first measurement was made in 1856, with the broadly accepted height of 8,848m first recorded by an Indian survey in 1955.

In 1999, an American team used GPS technology and recorded a height of 8,850 metres - a figure now used by the US National Geographic Society - but again, Nepal did not accept that and continued to use its own official figure.