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 Lobster hybrid about 1,5 cm long. The juvenile, who resembles a mini lobster, has setteled on the bottom at this stage.   
Photo: Eva Farestveit
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Unique lobster hybrid

Since the American lobster first appeared in Norwegian waters, scientists have been wondering whether it will interbreed with our local species of lobster: the European lobster. Now the answer to that question is scuttling around in tanks at The Institute of Marine Research in the shape of lots of hybrid lobsters with American mothers and European fathers.

By Marie Hauge

Artificial insemination has been used to cross the two species before, but the chances of a female American lobster and a local male European lobster mating in the wild are incredibly small, according to scientist Ann-Lisbeth Agnalt at The Institute of Marine Research. Firstly because only a few American lobsters have been found in Norwegian waters. Secondly, because there are various biological factors that make it more likely for a European female and an American male to interbreed.

Egg size raised suspicions

Highly unlikely, but not impossible, clearly. The proof is in the 140 one-and-a-half to two centimetre long lobster siblings that appear to be growing and thriving; blissfully unaware of the fact that they are so-called hybrids.

The mother is one of three live lobsters that were handed in for analysis at The Institute of Marine Research in autumn 2009. It was suspected that the three lobsters were suffering from a shell disease. DNA tests demonstrated that all three were American lobsters, a species that is not native to Norwegian waters. The hen was carrying eggs, and their size made Ann-Lisbeth Agnalt curious.

“American lobsters generally have relatively small eggs, whereas these ones were quite large. That indicated that perhaps the father was not American,” she explains.
The eggs were DNA-tested at the Institute in Bergen, and the results revealed that the father must indeed have been a European lobster. This was confirmed by an independent test carried out at Queens University in Belfast.

The importance of the precautionary principle

American and European lobsters are relatively similar in appearance, and they can only be distinguished with complete certainty through DNA testing.
The possibility of the two species interbreeding has been a key concern since the first American lobster was found in Norwegian waters at the end of the 1990s. Imported American lobsters are sold in Norway, and a few small-scale attempts have been made at farming them. The specimens in the wild that were caught and sent for testing probably escaped from holding pens, were dumped because they were thought to be dead/dying or may have been put out deliberately.
As of today, 22 American lobsters have been identified in the wild in Norway. That figure has not worried scientists unduly, explains Ann-Lisbeth Agnalt.
“We estimated that they were unlikely to interbreed. And it was an incredible coincidence that this fertilised female happened to be handed in to The Institute of Marine Research. It shows how important it is to take a precautionary approach to managing introduced species.”

Competition between species

Introduced species can have negative, and sometimes catastrophic, impacts on local ecosystems. American lobsters can carry the disease “Gaffkemia”, which is fatal to European lobsters. Shell disease is another risk that has been introduced with the American lobster. Norwegian lobster populations have been at historic lows for several decades, and these small populations are probably more vulnerable to competition with an introduced species.

Being carefully monitored

The lobster hybrids, which have been hatched with great care at a laboratory at The Institute of Marine Research, have most in common with the father’s species, explains Ann-Lisbeth Agnalt. They have now metamorphosed (transformed) from free-swimming larvae into tiny lobsters, and from now on they will live on the bottom.

The juvenile lobsters will be monitored carefully, and are being provided with as good as possible an environment in which to develop. We hope that a representative selection will reach sexual maturity, probably in three or four years’ time. Our scientists are very interested to find out whether the American-European lobsters are sterile, as is often the case with hybrids.

Lobsters, which can live to 60, normally reach sexual maturity when they are 25 centimetres long, but there are sometimes big local variations.

Controlled experimental fishing

Controlled experimental fishing for lobster has now started in the Larvik area. Local fishermen are catching the lobsters. The specimens collected will be examined for shell disease and will be DNA-tested. We are also looking for hybrids living in the wild and lobsters with “hybrid roe”.

Lobsters that are identified as being American, hybrid or suffering from disease will be removed from the area. The remainder will be tagged and put back where they belong.