Economy

Plight of the Mussels

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.

In this short clip Jim Andrews from the Menai Strait Fisheries Management Organisation shares how the industry has been affected.

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.

Agriculture

Most land around the Strait and the surrounding rivers is used for cattle and sheep farming. Agriculture affects water quality through the release of nutrients (as a result of soil management and fertilizer application) and other chemicals (e.g., pesticides) into the water environment, through biological contamination (e.g., from microbiological organisms in manure), and via soil being eroded and washed off.

The more intense rainfall we receive due to climate change, the higher sediment loss into the water course, causing habitat loss and a process called Eutrophication. Despite the tidal range in the Strait, Eutrophication can also become a critical problem and increase invasive blooms.

Use of fertiliser combined with sediment loss is increasing eutrophication in our waterways, resulting in dead zones in rivers and seas. Sediment loss is increasing with climate change and more intensive rain.

Livestock, land use and machinery are increasing the volume of compacted soils., which in turn exacerbate nutrient runoff.

Working with farmers

Improving water quality in the Menai Strait means working alongside the landowners and farmers whose land borders the rivers feeding into it. As part of our Mynydd i’r Menai project, we’re working with farmers and landowners along these rivers, helping them access funding and implement improvements, while holding government to account on the legislation needed to support this. This protects the waterways entering the Strait and the banks of the Menai itself, helps farmers meet their nitrate targets, and ultimately improves water quality.