· Effect of overfishing could be greater still, say experts · Porbeagle, spiny dogfish and common skate at risk

More than a quarter of sharks and rays in the north-east Atlantic face extinction through the effects of overfishing, with 7% classed as critically endangered, conservationists have warned.

The Red List published by the International Union for Conservation of Nature states that 26% of these species are at risk of being wiped out and a fifth are now regarded as "near threatened".

The true number of fish under threat may be considerably larger, the report by the IUCN's shark specialist group cautions, because scientists have too little information on 27% of them to determine the health of their populations.

Many of the animals at risk are slow-breeding fish that have few young and reach sexual maturity late in life, a fact that makes them especially vulnerable to the fisheries' activities.

The spiny dogfish (rock salmon) and porbeagle shark, both caught for their meat, are critically endangered. They are among a handful of species under EU fishing restrictions, though these quotas are well above the zero-catch levels proposed by scientists at the International Council for Exploration of the Sea (Ices).

Angel sharks and common skates are also critically endangered in the north-east Atlantic, according to the report. The realisation is prompting Ices scientists to call for greater restrictions on fisheries which either deliberately catch the fish or land them as bycatch.

The basking shark, the world's second largest fish, is listed as vulnerable.

The report was released ahead of European commission recommendations for tighter controls on fishing, including zero-catches for porbeagle sharks and spiny dogfish. The advice is also for a ban on fishing vessels keeping aboard common skates, undulate rays, white skates and angel sharks, which should be returned safely to the water wherever possible.

Fisheries ministers are due to discuss the new restrictions at a meeting next month. If the quotas are cut in line with the proposals, fisheries would lose permission to catch 600 tonnes of porbeagles and 2,600 tonnes of spiny dogfish.

Sonja Fordham, policy director at the Shark Alliance and co-author of the report, said: "The north Atlantic is one of the most overfished regions in the world and yet only four species of sharks and rays are protected. This is a clear consequence of overfishing, whether these species are targeted or taken as bycatch."

Another species listed as critically endangered is the deepwater gulper shark, sought for its rich liver oil, which is used by the cosmetics industry. In 2005 Ices urged the EU to ban deepwater shark fishing, but current quotas will allow more than 800 tonnes to be taken next year.

The IUCN finds that the percentage of sharks and rays in the north-east Atlantic region classified as threatened is higher than the figure for the species globally - which is given to be 18%. It says the decline in numbers is due to the activities of fishing nations such as Spain, Portugal, France and Britain.

Two species of guitarfish, whose fins are among the most highly sought after for use in shark fin soup in Asian markets, are classified as endangered in the north-east Atlantic. There are no limits on catches of them in European waters.

Scientists working for the IUCN said that it could already be too late to save two types of sawfish, both of which were critically endangered.

Claudine Gibson, former programme officer for the IUCN shark specialist group and lead author of the report, said: "North-east Atlantic populations of these vulnerable species are in serious trouble, more so than in many other parts of the world.

"Most sharks and rays are exceptionally vulnerable to overfishing because of their tendency to grow slowly, mature late, and produce few young. Those at greatest risk of extinction in the north-east Atlantic include heavily-fished large sharks and rays ... as well as commercially valuable deepwater sharks and spiny dogfish."

The EU is also looking to protect a string of other species, including cod and haddock, in proposals that reduce quotas by up to a quarter next year.

"We have made real progress in fisheries management over the last six years and we are starting to see positive results, such as the recovery in certain stocks under long-term management plans," said the EU fisheries commissioner, Joe Borg. "But this good news remains the exception, not the rule. There has been so much overfishing over many years that the balance of the marine ecosystems on which our fisheries depend is seriously disturbed."

Marine conservationists urged tighter curbs. "Such action is immediately possible and absolutely necessary to change the course toward extinction of these remarkable ocean animals," said Fordham.