Pilot project - developing new risk assessment frameworks for Atlantic salmon migration

In the most recent IUCN Red List of Threatened Species (IUCN , 2023 IUCN Red List of Threatened Species) , the main UK population of Atlantic salmon (Salmo salar) are classified as endangered. It is clear that the major drivers of the declines in population abundances are driven largely from climate-change mediated deterioration of various components of their freshwater and marine ecosystems. However, the hierarchical scaling of the responses to these primary environmental drivers, regional variation and their interplay with anthropogenic activities provide considerable challenges to managers in devising suitable responses. Variation in the success of salmon migrations through estuary and near-coastal habitats have been hypothesised as being key drivers of changing population status, and mortalities occur in response to changing environmental conditions and increases in predator encounter rates.

There is a growing need for us to recognise how human activities in aquatic systems are influencing ecological functions like migration success, and how they are interacting with other pressures to impact on populations of species of high conservation concern. We can embrace new and emerging technologies to better identify migration pathways and conditions to predict risks , mitigate impacts and drive efficiencies for future integrated planning in riverine, estuarine and coastal habitats.

General Aim To identify the migration behaviour of an endangered anadromous fish species through a highly modified estuary, establish the key environmental controls and integrate the knowledge into development of real-time management decision support tools. Using this as a model will provide an exemplar of how new knowledge networks can be developed into regionally-specific environmental indicators in ways that can be used to predict future conditions in estuaries used by salmon, highlighting areas of vulnerability for both the target species and wider resource- focused management. Mapping outcomes in imaginative and interactive ways into predictive risk mapping can inform local planning future conservation policies that can be adapted and applied more widely.

Objectives : To identify the migration behaviours of an endangered anadromous fish species through a river and highly modified estuary, establish the key environmental controls and integrate the knowledge into development of real-time management decision support tools. To utilise a unique opportunity to couple a high resolution environmental monitoring network with telemetry to evaluate the migratory behaviour captive-reared adult salmon and inform on efficacy of conservation translocation schemes for Atlantic salmon.

We propose a pilot telemetry research programme for the River Teith in spring 2025 as a preparatory step in building and submitting a more ambitious proposal for UKRI funding consideration later in the year.

The 2025 pilot has the following five specific aims:
1.Trial smolt sampling methodology at one site on the River Teith during spring 2025 , to assess feasibility of sampling and the size structure of the smolt population . This will inform on the availability of suitably-sized smolts for acoustic tagging. 2.To trial the logistics of deploying a network of up to 12 static acoustic receivers within the River Teith and lower Forth to detect passing tagged smolts. 3.To acoustically tag a maximum of 40 salmon smolts (minimum length 135mm) and track their seaward progress downstream via a network of static acoustic receivers. 4.To analyse the smolt migration data received from the receiver network in association with environmental data retrieved from the existing ForthEra digital network to trial the process of data integration. 5.To develop a working coalition between the partner organisations., refining and agreeing roles and scope of larger research proposal.