The Swedish lobster season begins on 22 September. Still, fishers are being urged to stay alert for an unwanted visitor: the American lobster. Authorities warn that this species could spread disease and threaten the native European lobster.
A dangerous guest
The American lobster (Homarus americanus) originates from the east coast of North America. It is often shipped alive to Europe, including Sweden.
Since 2008, 36 have been caught in Swedish waters, though the species has not yet established itself. Experts say this is a critical time to prevent it from spreading.
Risk of disease and hybrids
The problem is not only competition for food and habitat. The American lobster can carry deadly diseases and parasites. One is Gaffkemia, a bacterial infection that is 100 per cent fatal for European lobster. Others include shell disease, which damages the shell, and parasites that eat lobster eggs.
“The health of our native lobster is essential for a sustainable fishery,” said Lina Tomasson, national coordinator for invasive species at the Swedish Agency for Marine and Water Management.
There is also a risk of hybridisation. In Skagerrak, American and European lobsters have already produced offspring. Scientists do not yet know how these hybrids might affect local ecosystems.
What to do if you catch one
Anyone who believes they have caught an American lobster should contact the SLU Marine Laboratory in Lysekil immediately.
The hotline number is 010-478 40 48. Fishers are advised to place the lobster in a plastic bag, keep it cool, and deliver it to the lab.
How to tell the difference
It can be tricky to distinguish between the species. The American lobster is usually 20–60 cm long, weighing 700–900 grams.
Its shell is dark blue-green or brown-green with reddish tones. Unlike the European lobster, it lacks white spots on the shell and has extra-small spines under the central rostral spine. The tail plates are not entirely black, while those of the European lobster are.
Authorities stress that vigilance is key. Preventing the spread of the American lobster now could save the native population — and the fishery that depends on it.