PINKTrack

Background and Objective

The pink salmon (Oncorhynchus gorbuscha) is originally native to river systems that flow into the North Pacific, the Arctic, and the Bering Sea between Siberia and Alaska. Similar to Atlantic salmon, it spawns from late summer to mid-autumn in freshwater streams, rivers, and intertidal areas but migrates to the sea in spring to spend its adult life in the open ocean. Pink salmon return to rivers to spawn after spending just one winter at sea and die after spawning. This means that populations typically have a two-year life cycle, returning to rivers every other year and appearing in odd-year or even-year populations.

In 2017, an unprecedented occurrence of pink salmon was recorded in countries of the European and North American Atlantic region, where they have since returned in every odd year (2019, 2021, and 2023). In Germany, few specimens of this species have also been detected in the river basin districts of the Rhine, Weser, Elbe, and Eider. However, it must be assumed that there is a significant number of unreported fish.

In anticipation of the possible re-occurrence of this non-native fish species in 2023, the Thünen Institute of Fisheries Ecology began efforts to monitor the presence of pink salmon in key catchments throughout Germany. Since 2024, the Thünen Institute of Fisheries Ecology has also been involved in PINKTrack, an EU-funded collaborative project supported by the North Atlantic Salmon Conservation Organization (NASCO).

The PinkTrack project aims to develop and implement a standardized protocol for environmental DNA (eDNA) sampling to monitor the spread of invasive pink salmon in EU member states. The methodology includes the establishment of an eDNA sampling program to detect pink salmon and track their spatiotemporal distribution, using early warning systems for national monitoring programs. The project is divided into several work packages, including the development of standardized sampling protocols, workshops for protocol dissemination, and project coordination. Key areas of focus are detection accuracy and the creation of a sample repository for future assessments.

Approach