The Conservation of Salmon (Scotland) Regulations 2016 were introduced to manage the killing of Atlantic salmon in inland waters based on an annual assessment of the conservation status of stocks. Conservation Status is determined using an adult based assessment method. However, there is increasing interest in developing a new juvenile assessment tool to complement the existing approach.
Electrofishing surveys are undertaken by fisheries managers, scientists and regulators to capture and count juvenile fish, primarily in rivers. Where electrofishing is performed according to carefully defined standard operating procedures (SOPs) and combined with appropriate statistical analysis, it is possible to estimate the number of fish in a particular section of a river, or by upscaling, the total production of fish in a river or region.
Electrofishing data are one of the most commonly collected sources of information on the status of freshwater fish populations. However, they are not currently used to assess the status of salmon stocks at a national level because (1) until 2018 there was no strategic, statistically designed national electrofishing programme, and (2) the analysis and interpretation of electrofishing data is associated with substantial technical challenges.
Marine Scotland has undertaken a programme of research to address these challenges, with the overall aim of developing a juvenile assessment method that can be used to determine the status of salmon populations at a range of spatial scales, from individual electrofishing sites to catchments and regions (Figure 1).
The National Electrofishing Programme for Scotland (NEPS) provides the data necessary to carry out an annual assessment of the status of Scotland’s salmon stocks using electrofishing data. The first national survey was carried out in 2018 and this will be repeated in 2019. The survey is designed, managed and analysed by scientists at Marine Scotland Science (MSS). Data is collected by local fisheries managers according to protocols developed by MSS in consultation with the Scottish Fisheries Coordination Centre (SFCC).
In 2018 data collection was funded by Marine Scotland, the Scottish Environment Protection Agency (SEPA) and Scottish Natural Heritage (SNH). In 2019, the survey is being funded by Marine Scotland and Crown Estate Scotland (CES). Data collation, analysis and interpretation are carried out by MSS. A report has been prepared using data collected from the first year of NEPS in 2018 that shows how these data can be used in combination with an assessment benchmark to assess the status of juvenile salmon populations. The NEPS data can be visualised at a range of spatial scales using the NEPS R Shiny Application.