Speaking for both countries, Steven Wilson, a deputy director of the National Oceanic and Atmospheric Administration (NOAA), told a news conference that Swedes had “found some evidence that there are lobsters in their waters”.
“But those lobsters could not thrive and could not rise to a population that could either pass disease or overcome the native species,” he said.
Current evidence points only to lobsters escaping, not a full blown invasion, he added.
“There just isn’t enough scientific information that gives you the impression that this is something that could take hold, which is important in the invasive-species standard internationally,” he said.
Sweden has asked the European Union to block the import of live American lobsters, saying it fears contamination of its native species.
More than 30 American lobsters have been discovered off Sweden’s west coast in recent years, the Swedish government said.
The European lobster is relatively small and delicate compared to its larger American cousin.
The spread of disease and parasites as well as interbreeding of species threaten the European lobster’s survival, Sweden says.
Canadian and US exports of live lobster to the European Union totalled some $200 million last year, government figures show.