The pike in the Baltic Sea are becoming fewer and fewer.
There is no determined cause.
But with the help of implanted transmitters, scientists are now close to getting the answer.
– We have marked roughly 500 pikes over five years to try to understand why they finally disappear, says Petter Tibblin, associate professor of ecology at Linnaeus University.
Pike 3044 is alert for being newly operated. After a short while in a net next to the researchers’ boat, the anesthesia has worn off and she can return to the other pike in the water outside Mönsterås.
But they are becoming fewer and fewer, the pike in the Baltic Sea.
Researchers at the Linnaeus University now hope to find out why with the help of implanted transmitters.
– We are carrying out a large marking project on pike in the Kalmar strait. Here, we have marked roughly 500 pikes over five years to try to understand where the fish are on the coast, what happens to them and perhaps why they finally disappear, says Petter Tibblin, associate professor of ecology at Linnaeus University.
Measures position and temperature
The pike are fished up, put to sleep and then the operation takes place in a couple of minutes. A small incision in the abdominal cavity, in with the transmitter and then the patient is sewn together.
The transmitters are not large but give the researchers important information about the pike. Partly where they are, and partly what body temperature they have.
– Fish are heat exchangers. They have approximately the same temperature as the surrounding water, which means that they are greatly affected by the temperature in the surroundings. And the fish has an optimal temperature for different types of physiological processes and with climate change the temperature that the fish experiences changes. It can affect, for example, the success of the game and we can study that with this type of technology, says Oscar Nordahl, researcher at Linnaeus University.
Eutrophication, predation and climate change
There are many theories as to why the pike population in the Baltic Sea is declining. Eutrophication in the water, predation from larger animals, and temperature changes in the water are some.
The project has now been going on for five years and soon it is hoped to have enough data to be able to understand the disappearance of the Baltic pike.
– We have already started to get a lot of important answers and we are probably quite close to more important answers about what is happening to the pike stocks. Then we will still want to continue because other things may be added over time. We have climate change and it is not something that can be fixed or stopped in three, four or five years. For that reason, we want to continue, but we will have important answers within three years, I would say, says Petter Tibblin.