New Fish in Sweden

It was only to be expected that it would become established in Swedish waters sooner or later. Roe and fry can be spread via ballast water. It’s logical that the first specimen was found in Karlskrona considering the intensive boat traffic between Karlskrona and Polish waters,” says Gustaf Almqvist, who defended his doctoral dissertation on the round goby at Stockholm University earlier this year.

In his dissertation he showed how the round goby has become one of the most colorful features of the southern Baltic in less than three decades. The fish primarily feeds on mussels. It can be 30 cm long and is a popular food fish in its original home region. The species has rapidly adapted to Baltic conditions and locally can dominate coastal fish populations. This has also meant that they compete with domestic bottom-dwelling fishes, and studies have shown that it can edge out the European flounder from certain areas. It has also become an important component in the diet of key predatory fishes such as cod and perch, and during some part of the year can constitute the most important prey for these fishes...