Fish have been found in several Norwegian lakes and ponds in recent years red-billed sun perch.
Lierpost writes that a young fisherman recently received five specimens of the species during a fishing trip to Stuvstjern in Lier. Also Drammens Tidende has discussed the matter.
The problem is that red-billed sun perch is an alien species, which actually originates from North America, and does not belong in Norwegian nature at all.
County secretary Anne-Mette Kirkemo of the Norwegian Hunters’ and Fishermen’s Association in Buskerud confirms to Dagbladet that they are familiar with the new findings in Lier, and says that she reckons that the fish has arrived there after someone released it into the water.
– One should never release species in the wild that do not belong there. This is a popular aquarium fish, which has not gotten into the water on its own, she says.
– What, among other things, can then be a problem is that it competes with what we experience as attractive food fish, Kirkemo continues.
You need to be aware of this
Parasites
Group leader Roar Sandodden, who works for the control group at the section for environment and infection measures at the Veterinary Institute, says that a larger survey has recently been made of the distribution of red-billed sun perch in Norway, and that it has also been found elsewhere in the country.
– It is found in a good number of ponds in Asker, and a locality has also been proven in Moss, he says to Dagbladet.
– And this is very unfortunate, he continues, and elaborates.
– The fish can be a carrier of parasites and diseases, and it can also compete for the food or nutrition of the other fish that naturally belong in the water.
– An introduced species can also change the aquatic environment where it ends up. In ponds and puddles, such a species can cause the entire system to be severely altered. The water quality can be poorer, and the bottom can be messed up, so that the water becomes cloudy and less attractive, he continues.
He says that the Veterinary Institute knows that red-billed sun perch are carriers of two specific parasites – among them a haptor field – and that the researchers are concerned about the extent to which this could have serious consequences.
– Another haptor field, the salmon parasite named Gyrodactylus salaris, has previously come to Norway via imports of fish from Sweden. This has been spent over a billion kroner on getting rid of, and we suspect that red gill sun perch are carriers of a similar type of parasite. We still do not know to what extent this parasite is dangerous in Norwegian waters, he says.
– But there is a great potential for damage there all the time, he adds.
Alarms: – It can be dangerous to swim
– Released
Sandodden says that it is not known for sure how the original North American fish ended up in the Norwegian ponds and lakes, but that it is assumed that someone who first had it as an aquarium fish “has released it”.
And according to him, the fish seem to be doing quite well in the Norwegian climate.
– We know that it manages to multiply, despite the fact that it is adapted to a warmer climate, he says.
