See the shark release in the clip above and the significance of the acoustic transmitters



The audio signals from the transmitter-equipped sharks are picked up by about 20 receivers placed in Gullmarsfjorden.

Via the transmitters' signals, it is then possible to see and understand how the sharks move.

Small-spotted red shark is protected in Sweden and forbidden to catch.

Since the project was started in 2003, about 140 sharks have been released into the sea, of which 11 have been found.

Most are believed to have swum along the Bohus coast up to Norwegian waters.

Behind the annual shark releases are the World Wide Fund for Nature and the House of the Sea, but it also takes place in collaboration with researchers from the Swedish University of Agricultural Sciences, SLU, who for several years have used the method to study fish, including salmon and bluefin tuna.