RESEARCHERS at the Norwegian Institute of Marine Research have examined two lobsters caught in Viksfjord in Larvik that appear to be infected with epizootic shell disease.

This disease has not been observed in Europe before, but it is a serious problem in some parts of the United States – in 2005 thirty percent of lobsters in coastal areas of southern New England and Long Island Sound were said to be affected.

In addition, two other American lobsters that have developed the same symptoms have been examined. Both of these developed similar skin damage while they were on exhibition in Drøbak and Risør aquaria. These lobsters were caught in the Oslo Fjord in the period 1999-2001, and were not visibly injured when they were captured.

To determine whether the lobsters have the disease, bacteriological samples have been taken.

If the four lobsters now being examined in Norway have the disease, it will be very worrying for lobster fishers all over Europe as it will be the first time that it has been found on this side of the Atlantic.

According to a Rhode Island Sea Grant Fact Sheet on Lobster Shell Disease, “it is caused by bacteria that invade from the outside of the lobster through pores in its cuticle-or the outermost layer of the shell-that cannot be seen by the naked eye. There is a range in the severity of the disease from shallow pits that eat away at the cuticle and cause unsightly black spots or ulcerations, causing the shell and the membranes underneath it to fuse together. This can stop the lobster from releasing its shell and can cause it to become stuck during the moulting process and die."

The disease does not taint the lobsters' meat, but makes shells so unattractive that they are too unappetising to serve whole. Larger female lobsters are the most severely affected because they retain their shell for a longer period of time while carrying eggs.

“Studies suggest the lobsters may be contracting the disease from alkylphenols, chemicals that are byproducts from industrial sources. These compounds may be interfering with the lobster's normal hormonal system and stimulating the animal to begin moulting too early. It's still unclear what's causing it to spread. Shell disease is not contagious from lobster to lobster, and biologists suspect that environmental factors such as water temperature or polluted run-off may be weakening the lobster's immune system and allowing the bacteria to grow faster than the lobster can fight it.”