The Introduced American Lobster, Homarus americanus in Scandinavian Waters

Abstract

Transport of live American lobsters to Scandinavia serves as a vector of introduction as specimens inevitably escape or are released into local waters. The presence of live American lobster in Norwegian waters has raised concerns about disease transfer, ecological interactions and hybridisation with the European lobster. Since 2000, 91 specimens were collected. These were morphologically examined, as well as analysed for genetic characteristics. Diagnostic DNA methods based on microsatellites were developed and have been in use since 2000 to resolve problems stemming from overlapping morphological characters. Based on DNA profiles, 24 of the 91 were identified as American lobsters, in Norway found from Oslofjord in the eastern part and along the southern and western coastline north to the More region. Recently American lobsters were also found in Danish and Swedish waters. The remaining specimens, though morphologically similar to the American lobster, had a typical DNA profile of the European species. Several American lobster specimens were egg-carrying, but so far, no evidence for hybridisation has been found. The local lobster fishery should be carefully monitored to detect specimens H. americanus, and signs of Gaffkemia and shell disease in the native population investigated. Tighter controls should be enforced on holding live imports to reduce the likelihood of escape and release.