Bob Earll: Two articles below on the thinking for offshore mussel culture in the south coast of Devon and the changes on biodiversity. The issue is one of scale and there is a huge difference between a small scale operation and one the size of ‘Heathrow airport’. The scale of this development poses a number of major questions and so before running away with enthusiasm consider these:

1. How big does an offshore mussel farm have to be before it qualifies for an Environmental Impact Assessment?

Even a cursory understanding of large-scale bivalve cultivation (see Ventilla below) shows that large scale mono-cultures have profound affects, not least on the species under culture. Conversely this should also reflect on the fact that sea beds dominated by mussel species are common place in rockier areas of the Channel, North & Irish Sea.

2. What is the role of marine planning and licensing in this process? Who will compensate fishermen for the loss of mobile fisheries as is currently being discussed for MPAs or will the fact that these are fishing activities which benefits to edible crab fisheries. Will the fisheries benefit obviate the need for compensation.

3. Large-scale mono-cultures of bivalves     Ventilla in the early 1980’s demonstrated the issues with monocultures of scallops in Japan. Increased disease levels, intra-species competition for food leading to reduced growth rates, reduced diversity in the planktonic species in the vicinity of farms, and the creation of scallop ecosystems. The scallop industry in Japan 1982 That was roughly 35 years ago; I suspect we know a great deal more about large scale bivalve mono-cultures now.

Two articles:

A mega mussel farm the size of Heathrow could transform the economy in Brixham

DevonLive: Offshore Shellfish Ltd want to tap into the huge European appetite for mussels

Plans to create the ‘UK shellfish capital’ in South Devon have taken a major step forward

Offshore Shellfish Ltd, operating out of Oxen Cove in Brixham, wants to increase the size of its vast farm, six miles offshore in Lyme Bay, to use all of the lease space of 1,540 hectares – about the size of the entire site of Heathrow Airport. Offshore Shellfish Ltd, operating out of Oxen Cove in Brixham, wants to increase the size of its vast farm, six miles offshore in Lyme Bay, to use all of the lease space of 1,540 hectares – about the size of the entire site of Heathrow Airport. The plan is to tap into the European market – selling into main processors in Holland who supply 100,000 tonnes a year to France and Belgium. It will mean the family-run business, owned by John and Nicki Holmyard, would become one of the largest employers in Brixham, creating around 70 jobs and generating millions of pounds for the Bay economy. Now, the Torbay Development Agency is seeking funding to press ahead with plans to allow Oxen Cove to be used by the marine industry after the idea was agreed in principle by Torbay Council’s harbour committee.   The move will pave the way to create a ‘shellfish village’ with the hope of attracting similar businesses to the site. Click here to read more

Rob Fletcher: Offshore longline mussel farming can have a positive impact on biodiversity, according to a research project that is currently underway off the south coast of England

Led by Dr Emma Sheehan from Plymouth University, the project is investigating the impact that Europe’s biggest mussel farm is having on the surrounding ecosystem. Although the farm – which aims to produce 10,000 tonnes of the bivalves a year by 2020 – is not yet complete, the investigation has so far produced extremely encouraging results, particularly in relation to biodiversity. Danielle Bridger is a PhD student studying the ecological impact of the farm. “During the project we have set up four research stations in the farm, four control stations located 500m from the farm, and four more 4km from the farm,” she explains. “So far, stations within the farm have picked up much more evidence of life, and it’s particularly encouraging to find species such as brown crab, scallops and lobster are thriving at the site.”

The Offshore Shellfish site in Lyme Bay will cover an area of 15 square km and produce 10,000 tonnes of mussels a year when at full capacity.

When plans to establish the mussel farm – which is being run by Offshore Shellfish in Lyme Bay, off the south coast of Devon – were initially unveiled, many local fishermen voiced opposition to the idea; after all it was going to exclude them from 15 square kilometres of their traditional fishing grounds. However, Danielle’s findings to date, as well as anecdotal evidence of increased catches in the vicinity of the mussel lines, have encouraged hopes that fishermen will soon see the value of the farm.

Studies on the impact of the farm have now been going on since 2013, and Danielle has been involved in the project since the start – first as a research assistant, which then evolved into her PhD – the results of which are due next year. And, over time, the project has evolved considerably from its original remit.

“Natural England required Offshore Shellfish to monitor the benthic impact of the mussels before they would consider issuing a full licence for the project,” says Danielle, “but we’ve since decided to record animals living on the ropes, mid-water fishes and larger vertebrates above the surface, including birds and dolphins.” Click here to read more