Scottish fish farms now operate at a scale that would previously have been unimaginable due to improved techniques in lice treatment, water quality, feed development and waste management

Salmon farming relies on invention: this is an industry which also works tirelessly to innovate. Constant improvement is the key to growth and success.

The aim is always to make the sector ever greener and more efficient – and the fish healthier and happier.
Coming up with new solutions can be challenging, not least because of the often harsh landscapes and environments in which Scottish farms are situated, but science, enthusiasm and raw determination help to overcome obstacles.

Innovations in areas such as lice treatment, quality of water, nutritional development and management of waste have improved greatly over the years and have helped many Scottish farms continue to operate on a major scale.

Clara McGhee is a trainee manager working onsite for one of the largest producers, Mowi. “On the Isle of Rum, we have 12 pens that are 120 metres in diameter and have just under 900,000 fish”, she explains. 


Clara McGhee is a trainee manager for major fish producer Mowi

“That means we have a biomass of up to 2500 tonnes at any time. Our barge holds 400 tonnes of feed and at the moment we’re feeding out eight or nine tonnes of that a day. It’s a huge operation, and that’s just at one site.”

Operating at this scale means that every aspect of growth and production, from logistics to vet visits and harvesting, has to be carefully planned. The size and economic importance of the sector has helped to drive the rapid pace of innovation.

Steve Bracken is a veteran of the sector, having worked in the industry for more than 40 years. He recalls how counting the fish – an essential exercise – has developed over the years in highly imaginative ways.

“Back in 1977, we were doing this manually using clicker counters, but they would rust up or you would lose them. Now we have some fantastic companies producing world class equipment for this kind of job.”
Feeding is another area that has seen innovation.

“Every day, we know how much each individual pen is getting”, says Clara. “We then enter that amount into an online system. 

“Over time, the software tells you how your fish have grown. When they get to harvestable size, you can then take them out of the pen.”

The problem of lice has been a perennial one and here, too, innovation has improved over the years. Cleaner fish – wrasse and lumpfish – which take the parasites off the salmon are used. As the knowledge of the use of these has built up, so management techniques have become more sophisticated.

In tandem with this is the use of fish hides. “These are placed in the pens so that the wrasse have somewhere to rest”, says Lewis Bennett, an authority on the use of cleaner fish. 

“It means the cleaner fish don’t have to sit on the base of the net or constantly swim round the pen, which leads to energy exertion. This year we will be trialling about six different hide systems, with two or three of them designed for the winter to improve survival from November to April. 

"We want to see if these suit the wrasse as well as the lumpfish. This will also help us to work out where the hives should be and what their design should look like.”
Another area which has seen imaginative new solutions is the sourcing of fresh water. “We actually now have two boats in the company that can produce their own supply through reverse osmosis”, says Clara.

“Through some incredibly clever technology, they can create fresh water from seawater, so that’s another bonus for us. These things are always evolving.”
The composition of the salmon feed has also moved on dramatically in recent years. 

“It’s hugely sophisticated now”, says Steve Bracken. 
“The marine ingredient content of the feed has dropped dramatically since the 1970s and 1980s and the methods of feeding have also changed. It’s just chalk and cheese – there’s no comparison to how it 
was before. In those days, we were flying blind.

“With modern monitoring, the amount of feed used can be controlled precisely. The inclusion of plant materials means that there is a lower environmental impact and we are getting a better conversion ratio from feed to protein.”

Feeding is the biggest cost associated with salmon farming and research into innovative and efficient new products continues, with the use of specially bred insects now on the horizon. “There’s a huge drive to make this even more efficient than it already is”, Clara McGhee adds.

Another area where improvements are being made is in the removal of excrement from the bottom of the pens. The sector has been criticised for buildup of this waste but once again innovation is paying dividends.

A new method is to pump this into a sludge holding tank. Polymers are added and water extracted to bind the waste together. This can then be transported and used as a highly efficient and nutrient filled fertiliser for farmers on the east coast of Scotland

Further options are being explored, including reducing the water content further and creating heat from the burned waste to power a turbine to produce electricity.
“The industry really is constantly evolving”, Clara says. “We still face a lot of challenges and we don’t yet have all the answers. 

“I don’t think any fish farmer would profess it’s a perfect industry, but it’s a lot better than many people think. And we are always trying to improve.”
Over the 50 years that the industry has been in existence, the advances have been huge, she adds.

“It’s almost unrecognisable now from what it used to be and changes are ongoing. Everything is continually developing and we are constantly looking for better alternatives. 

“I’ve no doubt that we will continue to progress and that the industry will be different again and better in 
10 years’ time.”


From a drop in the ocean to making a splash in the global export market

THE speed at which the Scottish salmon farming industry has developed has been remarkable. In just half a century, it has grown from nothing to become the biggest food exporting sector in the UK, selling its quality output all over the world.

As a new sector, those involved in it at the start had to learn as they went along. Adapting to open sea farming was never going to be easy and sometimes that journey has been a challenge, as any pioneering venture always is.


The Scottish industry has changed dramatically since the early days of fish farming at Cairidh in 1978

However, every step has led to greater knowledge and success, not least because of the enthusiasm of the early adopters and the support they received from Scotland’s development bodies and local people.

Many veterans of the industry look back on those early days with both bemusement and affection. Among them is Steve Bracken, who worked for Marine Harvest for more than 40 years. He still has strong memories of the clothing the first employees were asked to wear.

“On day one, you were given a Guernsey sweater, a cap and a pair of wellies. In my case, one was a size 11 and another a size 9. I spent my time walking barefoot around the pens.

“However, it was a fun and exciting time. You were really making it up as you went along. We were fortunate enough at that time to be owned by Unilever and they had a fantastic team of scientists and researchers.

“They were based in the south of England and they would put their technology into different ideas that the farmers had. There was a huge amount of enthusiasm and passion among the team, which put in a lot of hard work to take things forward.”

Counting the fish, he recalls, was an early challenge. “We came up with the idea of having a small Mini Countryman car with an aluminium scaffold tower mounted out of the windows at the rear.

“Perched on the top was a video camera along with the batteries to power it. The Mini was then put onto a raft, pushed out to the farm and pushed up against the salmon pens.

“The idea was that you would crowd the fish to one side and film them as they passed over the centre. 

“However, doing this was weather dependent and it wasn’t the most stable platform to have the car on. And if you were sitting inside it and it was rocking about, you could feel nauseous.”

Another issue, he adds, was that for the technique to work, the team had to move the fish across the pen gently. “There were fewer of them then – perhaps 1000 to 2000 – and if too many came at once, you couldn’t count them and you couldn’t start again. It was very time consuming.”

Su Cox, Communications and Development Director for the Scottish Salmon Company, remembers how groundbreaking it was to come up with the idea of filleting the fish into finger portions.

“We realised people didn’t really like skin and bones and felt this would be more appealing. 

“So we put the portions into packs and put cling film over them. I got a meeting with Marks and Spencer in London and we took it from there.”

She also recalls winning a royal warrant to supply the Queen with fresh salmon. “Much to my surprise, I got an appointment with the chef at Buckingham Palace. I took down a little box of samples and that was the start of our supply, though we had to do that for several years before we got the award.”

Like many others in the sector, Su recognises how lucky she has been. “I’ve been so fortunate to work in such an interesting industry and to live in and travel to the most beautiful places. 

“Our farms are absolutely stunning and even better, everyone who buys our salmon lives in beautiful places as well. I’ve had a wonderful career.”

  • This article was brought to you in association with the Scottish Salmon Producers Organisation as part of The Herald's Climate For Change campaign