Certifier : 
Lloyds Register (Acoura)
Certified status : 
Certified since : 
26 Jun 2012
Certificate expires : 
25 Dec 2022


Rope grown mussels from farms in the Shetland Islands and around the Scottish mainland within the Scottish Shellfish Marketing Group became the first enhanced fisheries in Scotland to be MSC-certified in June 2012. 

Mussel spat (seed) settlement in the area occurs generally in April-May, although earlier and later spawning also may take place. Each farm collects its own stock from wild spat-fall. The settled spat is then grown on ropes suspended from 200 to 400m longlines supported by plastic floats. 

The rope droppers, on which the mussels are grown, are usually 12mm in diameter and between 6 to 10m in length. Plastic pegs or discs may provide additional support for the mussels. Droppers are coiled so that they remain in the top 2 to 3m of the water column, and they are placed on the line in time to collect the natural spat. Each dropper may yield between 5 to 7kg of marketable mussels.

When they are ready for harvest, each dropper is raised from the water and the mussels removed either by hand or by machine. They may then be transferred to a shore-based facility or the next stages may take place on board the harvesting vessel. The mussels are separated, washed and graded, again by hand or automated line. Small mussels may be re-tubed and returned to the sea for further growth.

"The environment has always been key to our whole operation, so we remain focused on sustaining it." 

- Ruth Henderson, chief executive, Seafood Shetland

Blue Mussel (Mytilus edulis) image © Scandinavian Fishing Year Book