Atlantic salmon 2021: Scottish Marine and Freshwater Science Vol 14 No 4

1. Introduction

Wild Atlantic salmon populations are in decline throughout most of their native range including Scotland. In the face of declining salmon numbers and poor marine survival, it is increasingly important to protect and where possible improve freshwater salmon habitats to maintain and improve juvenile production and smolt output. This objective is at the heart of the Scottish Wild Salmon Strategy. Targeted management action requires both an understanding of the status of salmon populations at sub-catchment scales and information on the spatial extent and severity of pressures impacting those populations. Despite a substantial body of scientific information on Atlantic salmon, accurate quantitative assessments of the magnitude of impacts for individual pressures are scarce and can be site specific. In common with other countries, this situation reflects the difficulty of making appropriate controlled investigations of the species rather than a lack of ambition to obtain the information. Management therefore proceeds pragmatically on the basis of best available information, with monitoring of actions where feasible. In the absence of detailed quantitative scientific evaluations, expert opinion has a role to play (Forseth et al., 2017), with the caveat that uncertainty in the veracity of assessments must be considered. This study combined expert opinion from local fisheries managers with a scientific assessment of local salmon stock status.

In 2018, the National Electrofishing Programme for Scotland (NEPS) was established as a collaboration between Marine Scotland and local fisheries managers to improve understanding of juvenile salmon stocks and develop new assessment methods.^[1] In 2019, local fisheries managers were asked to map the spatial extent and severity of pressures acting on Atlantic salmon in Scotland, supported by a grant from the European Maritime and Fisheries Fund and technical inputs from the Scottish Fisheries Coordination Centre and Marine Scotland Science. The pressure mapping work was updated, refined and refreshed in spring 2021 with financial support from the Scottish Government. This report presents summary findings of this work, which for the first time attempts to assess and map the impacts of different pressures acting on salmon in Scotland, with a view to informing management and policy at local and national scales.