Study will map risks to West shellfish stocks
Scientists from Swansea University are appealing to fishermen for information on crab and lobster "black spot" shell disease, and the locations of American Lobster – an invasive alien species that may quickly take over from the native European lobster.
University researchers plan to create a map of hot spots of the disease. The work is part of a collaborative project, SUSFISH, between Welsh and Irish universities investigating the impacts of climate change on commercial shellfish productivity within the Irish Sea – a region often fished by some of the bigger South West crabbing boats.
The black spot disease – caused by bacteria that degrade the shell and form the characteristic black spot – is still present in a small number of Westcountry areas. Of no damage to human consumption, spotting and tackling the disease remains a priority to all shellfishermen. Many believe that a well maintained fishery where black spot animals are removed keeps the infection at bay.
A recent report on TheFishSite.com claimed: "Black spot affects a variety of commercial crustacean species and in severe cases will cause mortality.
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"The disease is thought to occur in some areas and not others, suggesting that it may be affected by environmental factors.
"The economic cost of black spot has not been calculated but discards and mortality during storage in keep pots and vivier tanks could be a significant burden to fishermen."
Recent reports of American or Canadian lobsters being caught in European waters highlight potential problems caused by alien species and their associated diseases.
In the USA, the southern New England's lobster fishery has recently been decimated by a new shell disease, causing the lobsters shell to completely rot away. Infected lobsters are often unable to moult properly and may die in the process.
Also, diseased animals may have weakened immune systems allowing other infections to kill the lobster. Large females that produce the most offspring are considered most at risk.
Researchers in the US have reported infection rates as high as 30 per cent in Massachusetts and 43 per cent in Rhode Island. Alarmingly, an American lobster with this epizootic disease was caught in Norway waters in 2010 – and over previous years several have been caught off the Westcountry.
To carry out further research, a Fisheries Challenge Fund grant has been awarded by the Marine Management Organisation to the Swansea University team and Dr Michael Tlusty from the New England Aquarium, USA. The Shellfish Association of Great Britain (SAGB) is also the main stakeholder.