Stockholm -- The waters of the Baltic Sea are home to 31 species of sharks, rays and chimaeras but they are "under threat due to over-fishing," conservationists said Thursday.

Sharks are sought for their meat, fins and livers -- uses range from human food to pet food and liver oil that is used for cosmetics or lubricants, the Shark Alliance that groups some 50 non-governmental organizations said in a new report.

However, overall shark catches were in excess of reproduction, the group formed to lobby for sharks within the European Union said.

Sharks are vulnerable since they mature slowly and over-fishing puts them at risk due to their long gestation periods and they have only a few young, said Heike Zidowitz, Shark Alliance coordinator for Germany and lead author of the report, Sharks in the Baltic.

The highly-prized spurdog that is also known as the spiny or piked dogfish (Squalus acanthias) is one example of a species under threat, Zidowitz told DPA, noting that "the spurdog can live for 70 years but matures at 15 to 20 years."

More research as well as safeguards are necessary to ensure that sharks continue to remain part of the marine environment, the group said.

The International Union for Conservation of Nature (IUCN) estimated that four shark species -- the spurdog, porbeagle, common skate, and angel shark - were "critically endangered" in the Baltic Sea region.

"We need to regulate (shark) fishing," Zidowitz said, noting that researchers have called for zero quotas to protect stocks.

Other recommendations in the 17-page report, Sharks in the Baltic, included ensuring that "all sharks be landed with their fins attached."

"Finning is a very wasteful practice," Zidowitz said of the procedure where the shark's valuable fins are sliced off at sea and the carcass is thrown back into the sea.

The European Union has tried to ban the practice but here were "loopholes," allowing for finning to continue, Zidowitz and Shark Alliance policy director Sonja Fordham said.

On the eve of the publication, Fordham met with a Swedish fisheries official to discuss concerns and rally support for stronger action within the 27-nation EU bloc including avoiding "watering down" a plan to protect sharks being drafted by the European Commission.

Fordham said a public Swedish response was pending but was hopeful it would address some of the "inconsistencies" in Swedish shark policies and offer better protection for threatened species.

Meanwhile the Shark Alliance will continue efforts to highlight the pressures facing sharks by lobbying for support also from landlocked countries in Europe, Fordham said.

DPA