An image taken from a video of one of the fallowed salmon sites.

Seabed seen to regenerate quickly after salmon farms are fallowed


Environmental monitoring of fallowed salmon farm sites has produced encouraging evidence of the seabed’s ability to regenerate, according to Scottish Sea Farms (SSF).

The impact of fish faeces and uneaten feed falling to the sea floor beneath pens has been a limiting factor on the size of farms and a source of criticism of the industry.

SSF, Scotland’s second largest salmon farmer, has been monitoring fallowed sites over the last year to better understand how quickly the seabed returns to normal its former state.

At Lismore North in Loch Linnhe, Argyll, where the company has farmed for more than 30 years prior to fallowing the site in early 2019, recent sampling indicates that significant recovery has taken place with faunal diversity now on par with before farming took place, SSF reports in its staff newsletter, The Source.

More recently, following a nine-month fallow period at SSF’s Toyness site in Orkney, the range of animals and their abundance was found to have increased significantly.

Promising findings

SSF’s sustainability and development chief Anne Anderson told The Source: “The initial findings are promising, indicating, as we have long argued, the ability of the marine environment to regenerate.

“The more post-fallow analysis we can do, be it several months or many years after a farm has been harvested, the more insights we will glean, the aim being to increase wider understanding of just how regenerative salmon farming really is in relation to seabed restoration.”

Anderson said that although salmon farming has one of the lowest carbon footprints of all the animal protein producing sectors and produces more edible meat per tonne of animal feed used, there remains a degree of caution about the sector stemming from a lack of science and understanding.

“With this new environmental monitoring programme, we hope to chip away at that,” she added.

Informing Holyrood

The Source reported that discussions are now under way with fellow salmon producers regarding rolling out post-fallowing environmental monitoring sector-wide, with plans for the shared findings to be reviewed by a leading independent scientist.

The need for more evidence in this area has taken on heightened importance against a backdrop of Scottish Government proposals to designate at least 10% of Scotland’s seas as Highly Protected Marine Areas (HPMAs), which would see several key commercial activities banned, including fishing and aquaculture.

The HPMA proposals fail to take into account the regenerative nature of salmon farming, just as they fail to acknowledge that Scotland’s salmon farmers have been co-existing with Marine Protected Areas for many years already

SSF sustainability and development chief Anne Anderson

“The proposals fail to take into account the regenerative nature of salmon farming, just as they fail to acknowledge that Scotland’s salmon farmers have been co-existing with Marine Protected Areas (MPAs) for many years already,” said Anderson.

“As with wild Atlantic salmon, our farmed salmon require high quality water if they are to live and thrive, therefore it’s in our own best interests as a sector to protect our marine environment.

“It’s why we invest so much time, effort, and resource into minimising any impact from our activities, ensuring we’re able to successfully farm at locations year after year – in the case of our longest-established farm at Dunstaffnage, for as many as 36 years.

“The priority now is demonstrating it to regulators and other key decision-makers.”

Bute House Agreement

Around 37% of Scotland’s seas are already protected by MPAs, which impose different restrictions depending on need.

HPMAs are the result of the Bute House Agreement, in which the minority Scottish National Party government agreed to policies suggested by the Scottish Green Party in return for the Greens’ support in the Scottish Parliament.

Ministers have committed to designating at least 10% of Scotland’s seas as HPMAs, regardless of specific need.

Former SNP rural affairs minister Fergus Ewing has called the HPMA consultation document “a notice of execution” for coastal communities that rely on fishing and other sea-based activities.

For salmon farming specifically, the proposals would mean no new farms could be sited within HPMAs and any existing farms in the area (or close enough to interact) would be forced to cease production, impacting on jobs, supplier spend and onward spend in local communities.

A crab and starfish on the seabed beneath one of the fallowed SSF salmon farm sites.