Sharks are widely spread throughout the Baltic, but are being squeezed by a lack of cooperation between governments of the countries that border the sea, especially on fishing regulations, a report from the conservation coalition Shark Alliance found.
"We are surprised ourselves how many types there are in the Baltic Sea. And we're surprised at how little research there is on them," Heike Zidowitz, a marine biologist and chair of the German Elasmobranch Society, told German press agency DPA.
Excluding data from fisheries, surprisingly little scientific attention has been paid to the largely small and unimposing species of sharks that populate the Baltic, Zidowitz said.
But while researchers look elsewhere and governments fail to unify fishing regulations, the Shark Alliance report said some species are now under threat. Northeastern Atlantic populations of the most common variety, the spiny dogfish shark, have dropped by 95 to 98 percent in the last 20 years.
Sharks recover slowly from overfishing in part because they reach reproductive maturity relatively late in life. The spiny dogfish isn't ready to produce until it is 10 to 14 years old, and has a 24 month pregnancy, as well as slow egg development.
The spiny dogfish shark is especially common in the western Baltic, near Germany's coast.
The report credited Germany with pushing proposals to restrict international trade in porbeagle and spurdog sharks. Germany imports 2,000 tonnes a year of spurdog - its smoked belly flaps are known as Schillerlocken - which makes it among the top five importers of shark meat in the European Union, the report said.
But Berlin has taken blame from shark conservation organizations for being one of the few EU countries to allow shark fin fishing - in which the shark's fins, a delicacy especially in China, are cut off and the rest of the dead creature's body is thrown back into the ocean.
Known as "finning," the practice is wasteful and one of the biggest threats to shark populations in the world, the Alliance said.