Wild Atlantic salmon and brown trout are important to the rural economy, biodiversity and cultural heritage of Scotland, and valuable indicators of ecosystem health. However, their populations are in decline across much of their native range. Reliable methods are thus required to understand the status (health) of populations, identify issues requiring management (pressures), inform regulation and policy development, and meet legislative reporting requirements.
Electrofishing data are one of the most commonly collected sources of information on freshwater fish populations. However, these data are often obtained using ad-hoc sampling approaches that makes their interpretation challenging. The National Electrofishing Programme for Scotland (NEPS) was established in 2018 to assess status and trends in salmon populations and the effects of selected pressures. It consists of a statistical survey design, a set of carefully documented data collection procedures, data storage, and statistical modelling approaches to harmonise data and determine expected fish densities for healthy populations in particular habitats (the benchmark). Surveys were undertaken in 2018, 2019, 2021 and 2023 using a range of funding sources. The project is a collaboration between the Scottish Government Marine Directorate, Fisheries Management Scotland, and local fisheries managers.
This report presents results from NEPS 2023, which in addition to salmon includes assessment of trout populations for the first time. Comparisons are made to previous surveys through careful harmonisation of data to account for changing survey designs. At the national scale, the mean densities of salmon fry (fish in their first year after hatching) and parr (fish over 1 year old) were only 74% and 56% of the benchmark. Although there was substantial regional variability in performance, healthy salmon populations (both fry and parr) were only found from the Moray Firth northwards. National trout fry and parr densities in 2023 were 86% and 64% of expected densities respectively, again with substantial regional variability. There was a strong relationship between mean regional fish densities and occupancy (the proportion of the river length where fish are observed) that makes it challenging to obtain accurate assessments of status at low population levels. NEPS provides a strong basis for the assessment of freshwater fish populations and the pressures affecting them, and is able to meet a broad range of data and reporting requirements at a range of spatial scales depending on reporting requirements and availability of sampling resource.
Data and Resources
- Report: The status of juvenile Atlantic salmon and brown trout populations : The National Electrofishing Programme for Scotland (NEPS) 2023html
Access the report on the Scottish Government publications
Go to resource
| Field | Value |
|---|---|
| Publisher | |
| Modified | 2025-06-11 |
| Release Date | 2025-06-09 |
| Identifier | 8b42b0a7-0638-4444-ac89-484856dcf362 |
| Spatial / Geographical Coverage Area | POLYGON ((-0.65917432308197 56.287583695981, -4.877924323082 53.977089577532, -8.6865162849426 56.255047889345, -9.6826136112213 59.877451522166, -1.4208948612213 61.371725695994, 1.3330149650574 60.805189496446)) |
| Temporal Coverage | 2018-07-01 to 2023-10-31 |
| Language | English (United Kingdom) |
| License | UK Open Government Licence (OGL) |
| Data Dictionary | For further information on NEPS please see the following web pages and previous reports: https://www.gov.scot/publications/national-electrofishing-programme-for-... I A Malcolm, F L Jackson, K J Millidine, P J Bacon, A G McCartney and R J Fryer. 2023. The National Electrofishing Programme for Scotland (NEPS) 2021. Scottish Marine and Freshwater Science Reports Vol 14, No 2, pp. 63 DOI: 10.7489/12435-1 Malcolm I.A., Millidine K.J, Jackson F.L, Glover R.S Fryer R.J. 2020. The National Electrofishing Programme for Scotland (NEPS) 2019. Scottish Marine and Freshwater Science Vol 11 No 9, 56pp. DOI: 10.7489/12321-1 Malcolm, I.A. Millidine, K.J. Jackson, F.L. Glover, R.S. and Fryer, R.J. 2019 Assessing the status of Atlantic salmon (Salmo salar) from juvenile electrofishing data collected under the National Electrofishing Programme for Scotland (NEPS). Scottish Marine and Freshwater Science Vol. 10 No. 2. Collaborators NEPS 2018 was supported by funding from Marine Directorate (formerly Marine Scotland), SEPA and SNH. NEPS 2019 and NEPS 2021 was funded by Marine Directorate (formerly Marine Scotland) and Crown Estate Scotland (CES). NEPS 2023 was funded by Marine Directorate. The NEPS survey design, project management, data analysis and reporting were funded under Marine Scotland Science Service Level Agreement (SLA) FW02g. The following collaborating organisations are thanked for their valuable efforts in facilitating or delivering data collection for NEPS 2018: West Sutherland Fisheries Trust; Northern District Salmon Fishery Board; Caithness District Salmon Fishery Board; Helmsdale District Salmon Fishery Board; Brora District Salmon Fishery Board; Kyle of Sutherland Fisheries Trust; Cromarty Firth Fisheries Trust; Ness and Beauly Fisheries Trust; Findhorn, Nairn and Lossie Trust; Spey Foundation; The Deveron, Bogie & Isla Rivers Charitable Trust; Ugie District Salmon Fishery Board; Ythan District Fishery Board; River Dee Trust; The Esk Rivers & Fisheries Trust; Tay District Salmon Fisheries Board; Forth Fisheries Trust; Tweed Foundation; The River Annan Trust; Nith Catchment Fisheries Trust; Galloway Fisheries Trust; Ayrshire Rivers Trust; Clyde River Foundation; Loch Lomond Fisheries Trust; Argyll Fisheries Trust; Lochaber Fisheries Trust; Skye & Wester Ross Fisheries Trust; Outer Hebrides Fisheries Trust; Waterside Ecology Independent Ecological Consultants. The following collaborating organisations are thanked for their valuable efforts in facilitating or delivering data collection for NEPS 2019: West Sutherland Fisheries Trust; Northern District Salmon Fishery Board; Caithness District Salmon Fishery Board; Helmsdale District Salmon Fishery Board; Brora District Salmon Fishery Board; Kyle of Sutherland Fisheries Trust; Cromarty Firth District Salmon Fishery Board; Ness and Beauly Fisheries Trust; Findhorn, Nairn and Lossie Trust; Nairn District Salmon Fishery Board; Spey Foundation; The Deveron, Bogie & Isla Rivers Charitable Trust; Ugie District Salmon Fishery Board; Ythan District Fishery Board; River Dee Trust; The Esk Rivers & Fisheries Trust; Tay District Salmon Fisheries Board; Forth Rivers Trust; Tweed Foundation; The River Annan Trust; Nith Catchment Fisheries Trust; Galloway Fisheries Trust; Ayrshire Rivers Trust; Clyde River Foundation; Loch Lomond Fisheries Trust; Argyll Fisheries Trust; Lochaber Fisheries Trust; Skye & Wester Ross Fisheries Trust; Outer Hebrides Fisheries Trust; University of the Highlands and Islands – The Rivers and Lochs Institute. The following collaborating organisations are thanked for their valuable efforts in facilitating or delivering data collection for NEPS 2021: West Sutherland Fisheries Trust; Northern District Salmon Fishery Board; Caithness District Salmon Fishery Board; Helmsdale District Salmon Fishery Board; Brora District Salmon Fishery Board; Kyle of Sutherland Fisheries Trust; Cromarty Firth District Salmon Fisheries Board; Ness District Salmon Fishery Board; Beauly District Salmon Fishery Board; Findhorn, Nairn and Lossie Trust; Nairn District Salmon Fishery Board; Spey Foundation; The Deveron, Bogie & Isla Rivers Charitable Trust; Ugie District Salmon Fishery Board; Ythan District Fishery Board; River Dee Trust; The Esk Rivers & Fisheries Trust; Tay District Salmon Fisheries Board; Forth Rivers Trust; Tweed Foundation; Nith Catchment Fisheries Trust; Galloway Fisheries Trust; Ayrshire Rivers Trust; Clyde River Foundation; Loch Lomond Fisheries Trust; Argyll Fisheries Trust; Lochaber Fisheries Trust; Skye and Lochalsh Fisheries Trust; Wester Ross Fisheries Trust; Outer Hebrides Fisheries Trust The following collaborating organisations are thanked for their valuable efforts in facilitating or delivering data collection for NEPS 2023: West Sutherland Fisheries Trust; Northern District Salmon Fishery Board; Caithness District Salmon Fishery Board; Helmsdale District Salmon Fishery Board; Brora |
| Contact Name | Scottish Government, Marine Directorate |
| Contact Email | |
| Public Access Level | Public |