SCOTLAND’S biggest salmon farmer, Mowi, is involved in a new programme to help boost stocks of wild salmon.
The company, which has long supported restocking efforts near its farm sites, is working with Jon Gibb, fishery manager of the River Lochy and director of the Lochaber District Salmon Fishery Board.
Gibb, who operates the Drimsallie Hatchery, near Glenfinnan, told the April issue of Mowi’s newsletter, The Scoop, that he is excited about the ‘smolt to adult supplementation programme’.
‘The idea is that we trap migrating wild salmon smolts in the rivers (over 95 per cent of which would die anyway at sea) and transfer these wild fish to Mowi sea cages.
‘Mowi would then grow the wild salmon smolts to adult stage and then, once they reach maturity, we would release them directly back into spawning burns.
‘The introduced salmon would spawn naturally in the wild and this would guarantee the numbers of juvenile fish going to sea in future generations.
‘This is pioneering work and has never been tried in Scotland before,’ Gibb added.
He said he has a close working relationship with Mowi (formerly Marine Harvest) and holds regular meetings with farm managers and vets about sea lice levels.
Previous restocking projects on the Lochy, involving Drimsallie and Mowi, focused on taking brood fish from the river, creating juvenile fish in the hatchery and then reintroducing those juvenile fish into the river.
In the early days, this was very successful, said Gibb, but increasing marine mortality rates of wild salmon call for a new approach.
Gibb told The Scoop he believes declining populations of wild salmon are a result of a combination of different factors and he thinks that the aquaculture industry is often unfairly criticised.
‘I spend 365 days a year on the largest river on the west coast of Scotland, which also happens to be in the same area as the largest aquaculture region.
‘In the early days of fish farming, the industry was not as regulated as it is today. Back in the 1990s I would have agreed that the biggest factor affecting wild salmon was rising levels of sea lice and escapes from fish farms.
‘But in 2019, the industry is far better regulated and the local wild fish interests and the aquaculture companies work with one another and not against one another.
‘Wild fish are affected by changes in the freshwater and oceanic ecosystems, and the oceanic ecosystem in particular is currently facing a lot of challenges.
‘There is simply no denying that the sea temperature is rising. Not only does the rising temperature encourage sea lice but it also makes it more difficult for wild salmon to find their naturally occurring food.
‘Wild salmon feed off krill, shrimp and sand eels which prefer to live in colder water. A direct consequence of rising sea temperatures is that wild salmon are having to swim further north to find food, sometimes without success.
‘Wild salmon are having to adapt and dive deeper to find food on the seabed which can result in them being attacked by parasites. We are currently experiencing an infestation of nematode worms in fish which are often thin and under-nourished.
‘Other factors include scallop dredgers which destroy vital marine habitats but also other burgeoning wildlife, be that seals or birds that feed off fish.’
The first smolts in the new restocking project will be transferred to Mowi pens in September.
Picture: Jon Gibb at the River Lochy last year with MSPs from the Rural Economy and Connectivity committee, which investigated the impacts of salmon farming. Gibb is pioneering a new restocking project with Mowi