Lobsters are famously cooked alive, dumped straight into a pan of boiling water. This means the global lobster trade involves live animals being shipped around the world, which adds a risk not present with canned tuna or frozen cod – what if they escape and form invasive lobster colonies?
This process is already underway thanks to Europe’s taste for cheap, industrially-fished American lobster. Superficially, there are few differences between the European (Homarus gammarus) and American (Homarus americanus) species – even expert crustacean biologists can have difficulty telling them apart.
However, Sweden recently pushed for American lobsters to be regarded by the EU as a pest species and potentially invasive. This would mean a ban on the import of live animals, a significant economic activity with US$200m worth of live lobster (around 13,000 metric tonnes) imported into the EU each year.
Not all of these lobsters make it onto a dinner plate. It is likely that some unwanted or sickly animals in quayside restaurants have been released into the sea, and there have been reports of guilt-ridden passengers on cruise ships throwing non-native lobsters overboard rather than eating them.
We may not know exactly how all these invasive lobsters are escaping restaurants and fish farms, but we do know that they’re making their way into the wild somehow.
Swedish researchers lay out the scale of the problem in a recent risk assessment. In 2014, they report, 26 American lobsters were captured in just one area, Gullmar Fjord near Gothenburg on the country’s west coast. Another 29 were captured in Norwegian waters between 1999 and 2015, and 26 in UK waters between 1988 and 2011. Given the difficulty of telling the two species apart, is it likely that the real numbers are significantly higher.
Most worryingly of all is the fact that four of the females caught in Swedish waters were bearing eggs and critically one of them was carrying eggs that had been fertilised by a European lobster. Previous research has demonstrated that hybrid eggs can be viable and the resulting adults can be fertile.
The risk assessment goes on to suggest that American lobsters carry diseases such as Gaffkemia (a lethal bacterial blood disease that can wipe out lobsters kept in holding facilities) and may carry unwanted parasites that could potentially have significant effects on European lobster or more generally European marine habitats.
In the UK, the American lobster is already subject to some controls. If imported live they must be kept at least one mile from the sea and they are not by law allowed to be released into the wild. Despite the latter, there have been releases of non-native crustaceans by well-meaning religious groups seeking to save the animals from a garlicky death. In June 2014, following an ancient tradition called fang sheng, Buddhists bought 200 lobsters and crabs from fishmongers in Brighton that had been imported from North America and released them.
A group of US political representatives, led by Senator Edward Markey, have written to the EU director general for environment on “behalf of the hardworking men and women of the Massachusetts lobster industry”. They cast aspersions on the science of some of Sweden’s top marine biologists and refer to the repeated detection of American lobsters in EU waters over the years as “sporadic”.
Markey and colleagues are correct that there is not yet definitive proof of American lobsters being established in EU waters, nor that their offspring might be viable competitors. However, it only needs a few animals to become successfully established, or one to transmit a novel disease to which non-natives are not resistant, for there to be a significant and irreversible impact.
There are strong, relevant precedents. The signal crayfish, a freshwater lobster from North America, was introduced to Scandinavia in the 1960s. It has since spread to the UK. Unfortunately, they were carriers of a devastating crayfish plague which the European species have no resistance to. In the other direction, the common and familiar shore crab of the UK has spread to North America, South Africa, Australia and South America and has been listed among the world’s 100 worst invasive species.
Where we have a chance to prevent the spread of invasive species we should tread very carefully – however tasty they may be.