Forms of cultivation

Why aquaculture


Which specie

Problems associated with aquacuture

Cultivating molluscs

Cultivating blue mussels

Cultivation methods

Problems associated with mussel cultivation


Poisonous mussels?



The problems with poisonous mussels have increased globally the last 20 years and because of this an extensive control organ has evolved. The first poisonous mussels in Sweden were observed during the autumn of 1983. The poisonous mussels were said to suffer from DSP, PSP or ASP (Diarrhetic, Paralytic or Amnesic Shellfish Poisoning, that is diarré developing, paralyzing or causing loss of memory). The most common is DSP and the poison in question is known as DST (Diarrehetic Shellfish Toxin). The poisons are stored in the mussels hepatopancreas, which is an organ that functions in the same way as the pancreas and liver in humans. The toxins have no apparant effect on the mussel, but consumers of such mussels became sick.
    In Europe, both chemical and Biological tests (mice and rats) are applied as part of a toxin analysis consisting of several parts. Regular water tests form the first stage, while the analysis of mussels constitutes the second stage. In Sweden since 1985, mussels from diiferent blue mussel cultivators are randomly tested. In Sweden, chemical analysis is most common, but many countries that import Swedish mussels also require a Biological analysis. Many countries have a system for reporting daily and weekly test results to the public. On the Swedish west coast information about any toxins in blue mussels is posted via Miss Blue mussel (Fröken blåmussla, only in Swedish) on telephone: +46-31-60 52 90.
Is there any form of information near you? Try and find out!   

If it is shown that the mussels contain any toxins, the area is closed for harvesting until the tests give a negative result. In the Netherlands, the mussels are sometimes moved to toxic free Marine areas. Experiments have been done to try and detoxify mussels, but none as yet, have had positive results.
    The most important factor that effects the amount and spread of poison producing algae along the Swedish west coast is the season. Toxine concentrations appear to reach a peak during the autumn and winter and can vary in different areas. Along the Swedish west coast, more toxine producing algae have been found in the outlaying archipelagoes and even in higher concentrations further north. This is believed to be a result of water circulation in the North Sea, where the Jutland current transports dinoflagellates to the Swedish coast. Notably low concentrations of the above algae have been obeserved in the fjord systems.


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Bo Johannesson | Martin Larsvik | Lars-Ove Loo | Helena Samuelsson