Traditionally, monitoring invasive species has relied on either human observation or targeted sampling methods. For Pink salmon, we have established a reporting system for anglers, and in some rivers, nets can be used to remove the fish.

Given the high numbers of Pink salmon reported in 2021 and their two-year life cycle, we anticipated similarly high numbers in 2023. However, this expectation was not met across the U.K. and Ireland, with only a few sightings recorded. As part of a national study coordinated by Fisheries Management Scotland, Tweed Foundation/River Tweed Commission biologists tested a rapidly evolving method known as eDNA sampling, which involves genetically testing water samples from rivers to determine the presence or absence of Pink salmon. By using a database of genetic codes, this method can now identify aquatic organisms that shed enough genetic material into the water, offering a potentially more effective way to detect species presence.

The video attached includes the findings. Results for the Tweed Catchment can be found at 15 minutes and 25 seconds. 

Professor Colin Bean discusses the recent invasion of Pink salmon into U.K. freshwater systems since 2017, emphasizing the role of the Pink Salmon Task Force in monitoring this issue in Scotland. He explains how the FMS app is used to record sightings and catches of Pink salmon by anglers and fishery boards. To complement this data and reduce spatial bias, an eDNA sampling program was implemented across sites in Scotland to detect Pink salmon DNA in the water. The presentation underscores the importance of optimizing data collection, securing sufficient funding, and enhancing international cooperation and data sharing to effectively monitor and manage the Pink salmon invasion.

Professor Colin Bean has extensive experience with invasive Pacific and Atlantic salmonids, having served as a visiting professor at the Universidad de Austral in Chile during the 1990s. Over the past 25 years, he has worked as the Senior Science and Policy Adviser on freshwater fish for NatureScot. He is a founding member of the Scottish DNA Hub, a member of the UKDNA Working Group, and serves on both the SEPA-led Pink Salmon Task Force and the NASCO Pink Salmon Working Group as the UK Government Representative.