It doesn't feel like we're in the vicinity of an economic powerhouse and the habitat of a consumer delicacy enjoyed in restaurants across the globe.

Our boat travels across the water of a dreich and windswept voe in Shetland, heading for a rope-mussel farm.

We reach blackened barrels, seaweed-covered ropes and flocking seagulls, and the treasure is still well hidden below.

But when we pull up the ropes to check on the progress of the maturing molluscs, it becomes clear why this farm is part of a burgeoning industry that generated £5 million for Shetland's economy last year and supplied more than two-thirds of all the mussels farmed in Scotland.

Mussel farming was introduced to Shetland in 1974 and, despite uncertain beginnings, it has blossomed into a prosperous and growing industry that employs about 132 people full-time.

About 4340 tonnes of rope-mussels were produced in Shetland's 24 farms in 2012, representing 69% of the mussels farmed in Scotland that year.

That figure is now predicted to increase, with Seafood Shetland estimating about 4759 tonnes of mussels will be produced in 2013, 5272 tonnes in 2014 and 5411 tonnes in 2015.

Shetland's shellfish and fish are exported to the UK mainland, Europe, the Middle East, China, Russia and America.

However, it is not just Shetland's economy that's benefiting from rope-mussel farming: it's also the community.

The industry has become an integral part of island life and Michael Laurenson, 44, owner of Blueshell Mussels in Brae, Shetland, believes the impact of his business reaches much further than his 50 employees.

Mr Laurenson, who has five ports and currently manages 45 farm sites, said: "Our business is very important for the community and employment.

"We have got 50 people employed directly here and each one has a family, so they are involved too. We also have a number of seasonal staff and fishermen, which would add another 50 on top of that.

"We are using local people and resources and it's important we keep doing what we are doing.

"Part of the reason we exist is to provide employment for our local community. It is important that we are profitable but that is not the main reason we exist: the local community is more important."

Mr Laurenson, a first-generation fisherman, set up his company in 1997, harvesting his first crop in 2000.

The firm harvests all year round and gives its mussels three years to mature before collecting them for export and sale.

Mr Laurenson has progressively built his business, which also works with scallops and brown and velvet crabs.

His award-winning firm is now the UK's largest shellfish company, producing 3000 tonnes of mussels in 2012 and enjoying a turnover of £5.5m.

Following the growth of Shetland's rope-mussel farming industry, Blueshell and other companies have formed close ties with groups such as Scottish Natural Heritage, public bodies and the local community to ensure they can maintain the clean waters and environmental conditions needed to allow their product to thrive.

Mr Laurenson said: "It's important that we look after the environment and that our sites are sheltered with plenty of clean sea water. Mussels need a pristine environment if they are to be healthy and in top condition."

The industry has also received support from the Marine Stewardship Council, which promotes sustainable fishing practices.

All mussels grown on Shetland have now achieved MSC certification and Mr Laurenson believes this support has been crucial in ensuring the continued growth of his business and the rope-mussel farming industry as a whole.

He said: "MSC certification has been very important for us and for the industry. Farmers have recognised the sustainability of the product for some time now but it's important that consumers have assurance in it: it's crucial to show sustainability."

This is a view echoed by Seafood Shetland, which has helped and encouraged businesses to get involved in the MSC programme.

A spokesperson said: "The benefits of MSC certification are that it shows good practice and that the mussels are sustainable. Achieving full MSC accreditation underpins Shetland's shellfish growers' commitment to sustainability, which they can, in turn, demonstrate to their customers."

Seafood and the fishing industry is an integral part of Shetland. Shetlanders' have a strong historic connection to this industry: it's in their blood, and this experience – along with the island's clean waters and strong communities – has helped rope-mussel farming thrive.

Ruth Henderson, chief executive of Seafood Shetland, said: "What you have to remember about Shetland is that seafood is part of it.

"It's part of the whole culture of Shetland, it's tied up in it and has been for hundreds of years.

"Shetland is unique: you can never be further away from the sea than three miles here. Shetlanders have always been fishing and working with fish and seafood. People have written songs about it, made clothes to go fishing – it's part of the psyche here.

"Shetlanders have lived both by and from the sea for centuries.

"A long tradition of fishing – and now aquaculture – has resulted in an industry that benefits from past experience and a growing expertise in making the most from the natural resource.

"As a result, Shetland's shellfish and mussel farming is not only at the forefront of industry development, it is managing its precious environment for the future."

In terms of the industry's future, Seafood Shetland believes it is looking very bright.

A spokesperson said: "Fishing, fish processing and aquaculture are vital to Shetland.

"With a great reputation for quality in the marketplace, strong nutritional credentials, and MSC accreditation, we believe that the demand for mussels will only increase, ensuring a very positive future for the industry."


Factfile Shetland mussel farming

1974: Shetland was first considered an ideal location to develop an aquaculture industry.

1975: Public bodies encouraged  the development and several experimental mussel rafts were deployed at sites around Shetland. The Marine Laboratory confirmed the product was marketable.

1977-78: Rafts were designed, built and deployed in Wester Quarff, Bridge End, Skeld and Wadbister.

1980-82: A grant scheme was developed that offered 50% towards the construction of rafts.

1984-85: A growers’ association  was established. The association organised refrigeration and transportation to Aberdeen. A buyer collected from Aberdeen to distribute to high-end restaurants in the Glasgow area. The industry then saw a decline as farmers focused on the developing, and more lucrative, salmon farming industry.

1990s: Interested resumed, with those who had been involved in early experimental mussel farming realising the business potential.

Details provided by Seafood Shetland