Site Details: Gorsten

Gorsten
Ardgour
Fort William, Inverness-shire
PH33 7AH
Operator: Mowi Scotland Ltd
Water type: Seawater

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Netflix's 'Seaspiracy' exposes mass mortalities at RSPCA Assured & ASC-certified Mowi from Don Staniford on Vimeo.

Average female lice per fish

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Salmon Scotland mortality

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Cumulative mortality over full production cycle

Gorsten Production cycle end date: Oct 2019
Total losses: 17.8 %

Gorsten Production cycle end date: Jul 2021
Total losses: 8.7 %

Gorsten Production cycle end date: Oct 2022
Total losses: 10.9 %

Gorsten Production cycle end date: Nov 2023
Total losses: 17.8 %

Gorsten Production cycle end date: Mar 2025
Total losses: 13.9 %

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Fish Health Inspectorate mortality

Date:
09/10/23-15/10/23
Mortality:
10,060
Mortality Rate:
1.04%
Reason given: Bacterial
Bacterial
Contacted health manager, bacterial infection is Piscirickettsia
Health manager contacted for details of bacterial infection,First report this input. FHI to monitor
Date:
16/10/23-22/10/23
Mortality:
14,747
Mortality Rate:
1.54%
Reason given: Bacterial
Bacterial
Contacted health manager, bacterial infection is Piscirickettsia
Health manager contacted for details of bacterial infection, 2nd report this input. FHI to monitor
Date:
23/10/23-29/10/23
Mortality:
14,741
Mortality Rate:
1.56%
Reason given: Bacterial
Bacterial
Continuation of ongoing mortalities due to Piscirickettsia. Numbers have stabilised, FHI to monitor
Date:
30/10/23-05/11/23
Mortality:
13,245
Mortality Rate:
1.58%
Reason given: Bacterial
Bacterial
FHI to monitor
Date:
18/11/24-24/11/24
Mortality:
15,639
Mortality Rate:
1.78%
Reason given: Gill Infections
Gill Infections
First report this cycle. FHI to monitor.
Date:
22/09/25-28/09/25
Mortality:
12,086
Mortality Rate:
2.18%
Reason given: Bacteria/HSMI
Bacteria/HSMI
update 3/10; SRS which is being treated with antibiotic
First report this cycle. Business contacted for info on bacterial disease.
Date:
06/10/25-12/10/25
Mortality:
8,287
Mortality Rate:
1.79%
Reason given: SRS
SRS
Business contacted for additional information: Antibiotic treatment concluded. In-feed treatment may take time for mortality to drop as some fish may not be feeding.
Second non-consecutive report this cycle. Business contacted for additional information. FHI to monitor.
Date:
13/10/25-19/10/25
Mortality:
6,617
Mortality Rate:
1.46%
Reason given: SRS/poor performers
SRS/poor performers
Business previously contacted for additional information: Antibiotic treatment concluded. In-feed treatment may take time for mortality to drop as some fish may not be feeding.
Second consecutive report. Site visited 09/10/25 (2025-0389), no moribund fish observed and no diagnostic sampled collected. Decrease from previous week, following antibiotic treatment. FHI to monitor.
Date:
20/10/25-26/10/25
Mortality:
5,191
Mortality Rate:
1.16%
Reason given: SRS/predator
SRS/predator
Third consecutive report. Site visited 09/10/25 (2025-0389), no moribund fish observed and no diagnostic sampled collected. Decrease from previous week, following antibiotic treatment. FHI to monitor.

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Inspection reports

Case Number: 2020-0489


Download Site is made up of 3 sets of four 36 meter steel pens. All pens were inspected fish looked clean and healthy, no health issues were observed on site.
Site had 5 movements of Ballan Wrasse from Ireland from 1 supplier. [Original PDF]

Case Number: 2021-0542


Download Remote Inspection completed on the 25/11/21 physical inspection on the 1/12/2021
Site to be used as a nursery site this cycle. One more input to site due on the 2/12/2021.
No issues on site, fish feeding well. [Original PDF]

Case Number: 2022-0063


Download Wrasse mixed farmed from Anglesey and wild from Northern Ireland.
Site inspection and VMD sampling done on 16/03/2022 by , observed by .
No new movements since last inspection on 01/12/2021. The main population of fish on site appeared healthy. Small percentage of fish with lesions in pens 5 - 8 but still fairly active, the fish swam away quickly upon approach. The fish sampled for the VMD looked healthy. [Original PDF]

Case Number: 2023-0124


Download 75% of salmon mortality this cycle have been due to seal predation.
Lumpfish mortality last 4 weeks: Wk 9 - 1.86% (1103 fish), Wk 10 - 1.62% (940 fish), Wk 11 - 1.40% (803 fish), Wk 12 - 2.58%
(1,456 fish)
Currently treating with Salmosan to deal with sea lice. First in cycle but have also used SLICE.
SLICE - 24/11/2022 and 12/12/2022.
Site will move fish to Rum and Muck later in the cycle due to these sites being unable to grow salmon from smolt size.
FMA - 1 yearclass on site.
Wrasse will be used on site (approx. in 6 weeks time)
Health Check - 9/11/2022 - No significant findings found. Check conducted the week after smolt transfer.
Area not fallowed synchronously due to Gorsten and Linnhe sending fish off after one year while Leven and Kingairloch grow fish to harvest size.
Sea Lice -
Adult females: 17/06/22 - 0.53, 22/06/22 - 0.58 (Treating with Hydrolicer/Thermolicer
Treatments last year - SLICE - Between 27th - 1st Aug
Flouricol - moritella antibiotic pens 1-8 on 28/03/2022, 30/03/22, 05/04/22. 06/04/22, 16/04/22,
Salmosan - Pens 10-12 between 7th-9th June 22
Hydrolicer - Pens 1-4 between 20-21st June 22, Pens 5-8 between 22-23rd June 22
Thermolicer - Pens 9-12 on 8th July 22, Pens 6-8 on 18th July, Pens 2,4 and 5 on 19th July, Pen 3 20th July, Pens 9-12 on
25th July, 4-8th August, Pen 10 18th Aug
Inspection and paperwork by supervised by [Original PDF]

Case Number: 2025-0040


Download Paperwork and inspection by , accompanied by for Inspector Competency Audit. Mortality records, sea lice records, treatment records inspected remotely on 19/02/25, all remaining paperwork conducted on site on 20/02/35 Visibility was mixed during inspection with reduced visibility in pens 9 to 12 and clearer visibility in pens 2 to 8. Site consists on 3 groups of 4 steel pens, fitted with environets. Site will be swapping to 120m pens in future. Site is to receive an input of smolts in May 25, which will be onsite until approx Dec 25, when the stock will be moved to Creag an T'Sagairt (Loch Hourn). The site will fallow and receive an input from Loch Etive in Feb 26 for ongrowing and this is the planned production cycle for site, receiving inputs from Loch Etive and ongrowing for less than a year. 3 to 4 fish observed per pen with lesions (winter sores), most were deeper in the water and still active. One fish observed hanging vertically, but unable to catch. One moribund removed and examined at shorebase. A mock diagnostic was conducted on this fish as part of inspector competency audit. The majority of stock was observed shoaling and feeding well. Harvesting operation ongoing at time of inspection, site is conducting both live and dead haul harvests. Site has only had 1 Slice treatment and 2 thermolicer treatments this cycle Fish sampled for VMD appeared in very good condition with no sea lice observed on fish. Cleaner fish mortality (last 4 weeks) LUM - WK 4 - 515 (13.43%), WK 5 - 940 (28.32%), WK 6 - 830 (34.81%) and WK 7 - 734 (47.39%) WRS - WK 4 - 667 (1.54%), WK 5 - 1,036 (2.43%), WK 6 - 911 (2.19%) and WK 7 - 605 (1.49%) [Original PDF]

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