Swedish authorities pleaded with the European Union earlier this month to help them close their borders — not to humans, but to lobsters arriving on their shores from America.
The Swedish Environment Ministry said more than 30 American lobsters, or those that are typically found off the coast of Maine, have been found in Sweden's coastal waters.
The ministry said the foreign lobsters "can carry diseases and parasites that could spread to the European lobster and result in extremely high mortality," according the Associated Press. It asked the European Union to list American lobsters as a foreign species that would ban it from being imported.
How Maine lobsters arrived in Sweden has perplexed scientists.
"I've heard rumors about this," said Winsor Watson, a lobster specialist and director of education at the University of New Hampshire's School of Marine Science and Ocean Engineering.
Lobsters can walk about two miles a day, Watson said. Migrations are seasonal and are typically driven by water temperatures. Migration patterns have shifted north "a bit" as Atlantic Ocean temperatures have warmed, he said.
"Lobsters are capable of long-distance migrations, although this is a little extreme," Watson said.
James Manning of the National Oceanic and Atmospheric Administration's Marine Fisheries Service noted that it would take over a year for lobsters to travel to Sweden if they were being carried along by ocean currents, and said he wasn't sure whether it was realistic to think that lobsters could make their way to Sweden in the warmth of the Gulf Stream.
Gro van der Meeren of the Norwegian Institute of Marine Research, however, said the reason why lobsters are moving abroad has more to do with humans, particularly Swedish ones who have imported American lobsters, than the behavior of the lobsters themselves. Some of the lobsters may have escaped from crates while in transit, she said.
"Natural dispersal across the Atlantic is the least possible theory for how they came to Europe," van der Meeren said, noting that the water currents were likely too slow to allow for transport.
Maine Congresswoman Chellie Pingree agreed and called Sweden's request to the EU a "complete overreaction."
"The idea that somehow lobsters are going to jump out of their tanks and crawl into the sea and survive just doesn't make sense," Pingree said in a statement. "Some reports have suggested that it's actually consumers who have bought lobsters and thrown them in the ocean. Whatever the cause, EU officials should figure out what's really happening before jumping to any conclusions."
Several of the lobsters were caught with rubber bands on their claws, van der Meeren pointed out, while others were found near airports. The first American lobsters were detected in Norway in 1999. Since then, others were found in waters off of Denmark, Sweden, and the United Kingdom, she said.
Epizootic shell disease, which causes black lesions and sometimes death in American lobsters, has been found in female American lobsters inhabiting European waters, van der Meeren said.
One female American lobster was pregnant with embryos of "viable hybrids," meaning mating between Maine and European creatures has occurred, she said.
The EU Invasive Alien Species regulation was enacted in January 2015 and aims "to protect native biodiversity and ecosystem services, as well as to minimize and mitigate the human health or economic impacts that [invasive] species can have."
Rep. Pingree said that before the European Union takes action, the problem should be given due diligence.
"We have safely exported live lobster to dozens of countries for decades," she said, "and even if it's true that a few Maine lobsters have been found in foreign waters, regulators need to look at the problem more carefully and not just jump to conclusions."
Follow Colleen Curry on Twitter: @currycolleen