Mowi Farm visit
Fish Farmer observes Thermolicer in action on a busy day at Loch Alsh
AT Mowi’s Loch Alsh salmon farm on a drizzly day in January, manager Kendal Hunter has her hands full. Approaching the site, which is about a ten-minute boat ride from the shore base, housed in Kyle of Lochalsh railway station, the level of activity becomes clear.
One of Mowi’s three wellboats, the 63m Ronja Supporter, recently acquired from the Scottish Salmon Company, is positioned to the north of the pens (there to move fish around, said Hunter).
At another pen, a four-man dive team from Ross-Shire Diving Services are carrying out net inspections.
And at the furthest pen, a Thermolicer machine is in full swing aboard the Voe Earl, a 26m multicat tugboat built by Dutch yard Damen and operated by Delta Marine.
To support all these operations, two separate workboats are on site, mainly involved in tasks such as lifting up nets- with the heavy duty cranes fixed to their decks – in order to crowd fish.
As if this wasn’t enough for Hunter to oversee, the Fish Farmer team has descended to report on a day in the life of a farm and photograph the farm workers in action.
Hunter’s job is to ensure the smooth running of all the above, which she seems to do effortlessly, as well as nimbly manoeuvring a boat between the pens and the various procedures in progress.
The Loch Alsh site has 10 circular pens of 120m circumference, stocked with Q1 fish which currently weigh around 2.5-3kg, and are fed from a SeaCap cylindrical feed barge.
Hunter has managed the farm for a year and a half, since graduating in the first cohort of Mowi’s fast track training programme for
salmon farm managers in October 2018.
At just 25, she heads up a team of five full-time staff, although there were many more lending a hand on the day of our visit.
Hunter grew up on a (terrestrial) farm in Northern Ireland and had never heard of fish farming. Now she says her job is ‘just the same – instead of driving about in tractors, we drive about in boats’.
It was a love of the sea and diving that led her to a marine biology degree at SAMS (the Scottish Association for Marine Science) in Oban, before she joined Mowi’s 75-week intensive training scheme.
This introduced her to every aspect of the business, and she experienced farming from egg to harvest, in sites across the Highlands and islands, and also completed managerial and leadership courses.
She began working in seawater at two Mowi farms on Uist, before being appointed farm manager at Loch Alsh, a job she said she loves even though ‘it’s a lot of responsibility.’
Top of those responsibilities on the day of our visit is the sea lice treatment, which we are allowed to observe close up, from the walkway on the pen.
The Thermolicer, made by Steinsvik (now Scale AQ), is part of Mowi’s fleet of mechanical de-licers which include a second Thermolicer, on board the Orcadia 2, a twin-cat workboat operated by Scot Marine, as well as one Hydrolicer, which uses water pressure to remove lice.
Hunter said sea lice thresholds vary from site to site depending on the size of the fish.
‘For fish this size it would be 0.5 adult females and gravids per fish and once we reach that we go on to the treatment plan.
‘This changes a lot but we decide in what order sites should be treated, depending on how urgent they are.’
The Voe Earl can be deployed at any of Mowi’s seawater farms across the west coast, so does she have to join a queue for the Thermolicer treatment?
‘Not necessarily join a queue, it’s whatever is the best strategy for the company as a whole,’ said Hunter.
‘At some sites the lice levels will only very slowly rise depending on different factors, including health and cleaner fish efficiency. ‘
The Thermolicer was due to remain at the farm for five days, treating the whole site, with a two-man crew operating the Voe Earl, and Mowi staff managing the de-licing process.
Thermolicer technology is a non-medicinal treatment that removes sea lice from salmon
by bathing them in water slightly warmer than their ambient environment.
Treatments are carried out cage-side by crowding the fish in the pen and then vacuum pumping them into the device.
The salmon must be separated from the seawater before passing through a circuit of lukewarm seawater, heated at 22-24 deg C above the seawater, up to a maximum of 34 deg C. Sea lice are dislodged because of their intolerance to the increase in water temperature.
Hunter said the fish are in the system for about 20 to 30 seconds, and the salmon are then separated from the treatment water
“I try to spend as much time with the fish as possible, learning their behaviour”
and lice and returned to their cage. Lice are removed from the system continuously by filtration, captured and later disposed of on land.
The throughput rate used is also dependent on fish size, with heavier fish able to pass through the system faster because there are fewer individual fish per unit weight. The system has the capacity to treat up to 80 tonnes an hour.
In every batch, a few fish are checked for sea lice after treatment and then returned to the pen with the others.
Hunter said the rate at which they go back to feeding following treatment – a welfare indicator- can vary greatly, depending on the time of year and how well they’ve been feeding previously.
‘You can learn to look out for different health challenges,’ she said. ‘I try to spend as much time with the fish as possible, learning their behaviour.’
For all treatments and any wellboat activity, as well as for lice counts – which are carried out once a week- she tends to be on the site.
How many times in a cycle would she typically get the Thermolicer out for a treatment?
‘It completely varies, some sites maybe would be never but other sites could be up to once a month,’ she said.
The Thermolicer system can remove up to 95 per cent of mobile lice and it has become an indispensable tool in sea lice control for farmers like Mowi.
They can also Salmosan the fish in a bath treatment but Hunter said: ‘Our Salmosan consent is very small so we tend to only use it at the start of the cycle.’
The farm also hydrolices the fish with Mowi’s Hydrolicer, and uses wrasse and lumpfish as biological controls.
Mowi publishes all its farms’ weekly lice levels on its website, a practice to be adopted by the rest of the industry in Scotland this year, following the introduction of new legislation last year.
The company also conducts regular tours of its sites and Loch Alsh has become the focus of visits, on a tour that includes the Inchmore hatchery and the feed mill at Kyleakin, on nearby Skye.
Hunter is now accustomed to hosting visitors all year round, sometimes as often as twice a month, and believes ‘we definitely change the perception of fish farming as a result of these visits’.
As she delivered us back to the shore base I asked her what was the best thing about her job.
‘Probably every day is different,’ she said.
And the worst thing?
‘Low tide…we don’t have a floating jetty so it’s carrying things up and down lots of ladders. Once we hit low tide, it’s a lot higher up to walk… you’ll see when we come in.’
And we did, although Hunter took the climb – like the farm- completely in her stride..