Mussel, mussels (Caught at sea)

Mytilus edulis

Method of production — Caught at sea
Capture method — Dredge
Capture area — North East Atlantic (FAO 27)
Stock area — UK
Stock detail — All Areas
Picture of Mussel, mussels (Caught at sea)

Sustainability rating rating under review info

Sustainability overview

Mussels are widely cultivated and stocks generally considered to be under-exploited. The main methods of harvesting for wild and farmed mussels are dredging and hand-gathering. Hand-gathering is a more selective and sustainable method of harvesting mussels in the wild, and causes less disturbance than mechanical methods. The hydraulic elevator mussel fishery in the Exe estuary was certified as an environmentally fishery in July 2012.

Biology

Common mussels are bivalve molluscs found on shores throughout the north Atlantic, Mediterranean, North and Baltic Seas. They normally live in large aggregations, attaching themselves to rocks and each other with sticky threads known as byssus. They can be found from the high intertidal zone to the shallow subtidal zone. Found on the rocky shores of open coasts attached to the rock surface and in crevices, and on rocks and piers in sheltered harbours and estuaries, often occurring as dense masses. The shell is inequilateral and roughly triangular in outline. Size and shape vary considerably with environmental conditions, the colour usually purple or blue but sometimes brown. Shell smooth with a sculpturing of concentric lines but no radiating ribs. The ligament is inconspicuous. Length varies, specimens usually ranging from 5 -10 cm although some populations never attain more than 2-3 cm, and the largest specimens may reach 15 -20 cm. Mussels mature when one year old and may live 10-15 years or more. The breeding season is between April and September, with larvae settling after 1-6 months. Distribution: Very common all around the coast of the British Isles, with large commercial beds in the Wash, Morecambe Bay, Conway Bay and the estuaries of south-west England, north Wales, and west Scotland. Typically feeds on bacteria, phytoplankton, detritus, and dissolved organic matter (DOM).

Stock information

Stock Area

UK

Stock information

No assessment of stocks by ICES in North East Atlantic. It is a non-pressure or unprotected species, i.e. not subject to quota restrictions. Wild mussel fisheries are found in tidal flats of the Wash, Morecambe Bay, Solway and Dornoch Firths in Scotland and river estuaries such as Conwy, North Wales and the Teign and Taw, Devon. The commercial development of natural beds is hampered by sporadic and unpredictable recruitment. There has been a move away from exploitation of wild stocks to cultivation in Britain. Cultivated beds are generally privately owned.

Management

Mussel beds are managed locally. Bylaws may limit the minimum landing size of mussels, e.g. in the Wash in England a local bylaw prohibits the landing of mussels below 5cm in length. Some regions have closed seasons to protect the breeding stock, for example, the River Dart fishery in Devon is closed from the 1st April to 30th September each year.

Capture Information

The main methods of harvesting for wild and farmed mussels are dredging and hand-gathering. Hand-gathering is a more selective and sustainable method of harvesting mussels in the wild, and causes less disturbance than mechanical methods. Dredging can remove mussels in large quantities, reducing their overall numbers and sizes. There can also be a large disturbance of sediment with infaunal organisms (animals living in the mud/sand) being removed, potentially disrupting the local foodweb and ecosystem. Dredging is prohibited in some areas, and where it is permitted there are strict rules regarding the size of the dredge and the amount of sediment that can be brought up with the catch.

References

www.marlin.ac.uk/speciesfullreview.php?speciesID=3848; www.iucnredlist.org/search; www.mcsuk.org/downloads/fisheries/Most%20sustainable%20fishing%20methods.pdf; www.mcsuk.org/downloads/fisheries/Fishing_Methods.pdf; www.fishonline.org/fishery-production-areas; www.msc.org/track-a-fishery/fisheries-search/@@search_results?species=mytilusspp&status=&fisheryName=; www.sealifebase.org/summary/Mytilus-edulis.html