At the end of June we conducted a 4-day fishing event in the two streams Kilaån and Svärtaån in Södermanland. Fish that are infested with mussel larvae were our targets. Martin Škerlep, Helena Herngren and I electro-fished over stream stretches with present mussel populations where we also set out fish traps overnight. The idea was to transport the fish captured to the UC4LIFE-lab facility in Skåne, where we can collect juvenile mussels that fall off their fish hosts after successful transformation from a mussel larvae to a juvenile. In this way, the host fish species used by Unio crassus can be identified properly. However, as different mussel species exist in the two streams Kilaån and Svärtaån, DNA analysis of the juvenile mussels collected need to be conducted to guarantee the host fish suitability for the right mussel species.
After successful fishing, a long fish transport by car, the transfer of the fish to aquaria tanks fit with nets were juvenile mussels can be collected, we discovered the first juveniles after only one day! Over the past week more juveniles have been dropping off the fish. To mention a few host fish candidates: Common bleak (Alburnus alburnus), Bullhead (Cottus gobio), Perch (Perca fluviatilis), and Ruffe (Gymnocephalus cernuus). The results of a DNA analysis of the juveniles will soon tell us which fish species Unio crassus uses as host in Södermanland. We are all curious!
Greetings from Skåne!