State of the art

Mussel farming

There is worldwide very limited practical experience with mussel farming aimed at producing maximum biomass for least costs and no reports on production of mussels for feedstuff.

There have only been two production experiments in Danish waters resulting in different conclusions. The best documented showed that mussels can be produced in large quantities at low costs. The other study indicated similar findings in terms of production potential, however predation and wreckage of farm units showed that improved production techniques and technical skills levels are required.

Marine mitigation

Although eutrophication is a worldwide problem, knowledge on marine mitigation measures is limited. 

Using mussel farming as a tool to mitigate effects of nutrient run-off from land has been demonstrated as concept, but has not yet been implemented anywhere. Mussel production is one of the most promising measures, but the potential of mussel production needs to be documented at sites representing the spatial variation in environmental conditions of Danish coastal waters.

Further, assessment of the value of ecosystem services provided by mussel farming is required in relation to specific estuaries. Coastal zone planning is not a new area, but with the coming implementation of the EU Maritime Spatial Planning Directive, new tools are needed to be able to increase mussel production.

Mussel processing

Known techniques to produce mussel meal are based on separating shell and meat by boiling, followed by mechanical separation, tumble drying and grinding of the meat into meal. This two-step technique is however not optimal for feedstuff production due to relatively high costs and loss of the protein rich byssus. Furthermore, no processing technique is available to bio-refine the mussel oil.

Thus new techniques are required in order to increase value by upgrading blue mussels to oil and organic feedstuff for pigs and poultry.

Mussels as feedstuff

Mussels can surely be used as feedstuff, but documentation of the nutritional value of mussels for pigs and poultry is limited to a few research projects, and no true commercial steps have been taken so far.

Mussel meal has recently been analysed to contain 60% crude protein and has a good protein digestibility of 83-87% in piglets and a better-than-control protein digestibility in egg layers. Based on fish silage experiments, we anticipate mussel silage to have a stimulating effect on food intake in piglets.

In a pilot scale study on egg layers, it was indicated that the egg yolk colour was affected by mussel meal, and that egg consumers found 4% mussel meal better than the control whereas 12% was a too high concentration.
23 MARCH 2023