Assessing the interactions and effects of sea lice on wild salmon populations: final report of project FW0050

Introduction

In 2015, Marine Scotland (now the Marine Directorate, MD) initiated a 10-year project (FW0050) to provide a long-term structure for advancing the science on interactions between farmed and wild salmon (Figure 1). The goal of the project was to provide information that could be used to inform the development and improved management of aquaculture together with the conservation of wild salmon stocks. Aims were set at the beginning of the project with the understanding that new developments/findings by investigators in the field may influence and change approaches, and the workplan, in subsequent years. At initiation the aims of the project were to determine the:

1. Migration routes and distributions of emigrating salmon smolts.

2. Variation in salmon lice levels across a range of temporal and spatial scales.

3. Spatial and temporal variation in the efficacy of various anti-salmon lice treatments.

4. Infestation pressure experienced by salmon in relation to numbers of salmon lice in the environment.

5. Impact of salmon lice on individual salmon.

6. Effects of anti- salmon lice treatments on population losses of salmon released into the wild around the coast.

This report considers each of the aims, summarising the main outputs, and also additional work that emerged as the project progressed. Detailed accounts of the science are provided in published papers and book chapters listed at the end of the report.