Raising them takes a long time and requires a lot of patience: this summer, the North Sea Aquarium on Borkum released a total of 36 lesser-spotted catsharks into the wild. With a length of up to 1.20 meters, the slim, nocturnal hunters are among the smallest sharks found in the North Sea.
The animals can live up to 40 years, but they do not reach sexual maturity until they are about ten years old. “And that’s also the problem,” says Maria Oetjen from the North Sea Aquarium. For their protégés, which are only a few centimeters tall and were between three and five years old when they were released, it will only be a few years from now.
Harmless to humans
The exact stock of dogfish in the North Sea is not known. However, experts assume that there will be fewer sharks. According to the Schleswig-Holstein National Park Center Multimar Wattforum in Tönning, there are three species of sharks in the coastal waters of the German North Sea, so-called ground sharks, which are not dangerous to humans: the small-spotted dogfish, the large-spotted dogfish and the smooth shark.
Cat sharks are also bred there. “We want to offer them the most natural living conditions, and that includes reproduction,” says director Claus von Hoerschelmann. However, the sharks are not released into the wild there. Like other animals, they are exchanged with other aquariums – such as those in Kiel or Stralsund.