Filtering, cleaning, protecting, restoring
mussels are vital for the ecosystem and for the local economy
The eastern Menai Strait between Beaumaris and Menai Bridge has been an important shellfish farming area for decades. Since the 1960s, the shellfish farmers based in Porth Penrhyn built the Strait into the most productive aquaculture site in the entire UK, exporting thousands of tonnes of mussels to the EU prior to Brexit. Although EU exports are now reduced, the Strait still produces hundreds of tonnes of mussels per year.
Jim Andrews from the Menai Strait Fishery Order Management Association explains the issues affecting the shellfish industry.
Water Quality
Water quality is vital to shellfish farming in the Strait. Mussels feed by filtering microscopic plants (plankton) from seawater. If the water also contains bacteria from sewage, the mussels can be contaminated. Local authority environmental health officers regularly sample shellfish from the Strait to ensure that they are safe to eat. The very best shellfish are given a “Class A” classification. These mussels can be eaten straight out of the sea and can be exported to the EU. Any mussels that are “Class B” have to be treated before they are eaten and cannot be exported directly to the EU.
The central part of the Strait has the very best “Class A” designation, and other areas are a high “Class B”, which means that shellfish farmers have been able to maintain production for the UK market as well as exports to the EU. The future of shellfish farmers in the Strait depends now, more than ever before, on maintaining and improving water and shellfish quality. Any decline could spell the end of the industry, and the loss of jobs and livelihoods that are critical to the coastal economy.
The Menai Strait Fishery Order Management Association (MSFOMA) is responsible for ensuring the future success of shellfish farming. The Association has joined forces with North Wales Rivers Trust to work together to protect and enhance water quality in the Menai Strait. The Association and the Trust recognise that forging links with regulators, industry, and other users is the best way to improve environmental quality and to protect the future – not just for shellfish farmers but also for water sports enthusiasts, wildlife and coastal communities.
Mussels are ecosystem engineers
As well as being healthy, nutritious food with a really low carbon footprint, mussels, oysters and other bivalve shellfish are incredible for ecosystems. Wherever they grow they are busy filtering water to feed, making it cleaner and removing harmful nutrients. A single mussel can filter up to 25 litres of water per day. Mussel farms are being used in places such as the Baltic Sea to reduce the risk of eutrophication from agriculture.
The list of these “ecosystem services” provided by mussels and other bivalves is a very long one. It includes locking up atmospheric CO2 in their shells, protecting coastal areas from flooding and erosion, and providing vital living reef habitats that benefit other marine species. Scientists from the University of Bangor’s School of Ocean Sciences at Menai Bridge have studied mussels in the Strait for decades. They have published a comprehensive review of the ecosystem services that mussels and other bivalves provide. You can read all about it here.