Pink salmon invasions in the UK: origins and impacts


Non-native species invasion into new geographic areas is a major threat to biodiversity. Invasion is becoming more common, caused by anthropogenic activities and climate change. Time-series informed molecular techniques are a powerful high resolution approach to identify the true origins of invasive species and the colonisation processes by which they are entering new habitats.

A very recent invasive species to the northern areas of the UK is the pink salmon (Oncorhynchus gorbusha). This is an anadromous Pacific species that has successfully and widely established outside its natural range. Having been found in UK rivers only sporadically since the 1960s, in 2017 there was a dramatic increase in encounters and the first recorded spawning. Other areas in northern Europe also had an explosion of pink salmon in 2017 and 2019. Yet the origins of these pink salmon populations, the impacts of this sharp rise in abundance on its diversity, and its effects on rivers are not known. This studentship project will identify the evolutionary and geographic origins of pink salmon invasion to the UK.

Currently it is not known where the pink salmon that arrive in the UK are from, whether they are self-sustaining, and if and how they might affect local species. Pink salmon were deliberately transplanted from Russia’s Pacific to the White Sea Basin, and it is believed but not yet demonstrated that this is the origin of the populations that are now rapidly expanding into Europe and the UK. Such processes generate novel strong selection pressures and genetic bottlenecks for rapid evolutionary changes; life history traits, morphology, fecundity, immune system, and population genetics were affected. The overall risk of pink salmon to the biodiversity of Scotland and England is current rated by governments as being “highâ€ but “data-poorâ€. This project will aim to address that knowledge gap using advanced ecological and genomic analyses.

Clearly there is pressing need to gain fundamental knowledge about the habitats that are being preferentially invaded, immediate population origins of invasive pink salmon, and consistency across years. Different geographic origins will bring different locally adapted genes and behaviours. Identifying local adaptation and response to selection in the genome will indicate the most relevant evolutionary material of pink salmon invasion and future establishment. This will impact future policy and implementation by SNH in relation to potential biodiversity loss and the control of invasive non-native species, as well as the need to protect high value fisheries for Atlantic salmon and other fish species. This project will advance the field internationally and address this data gap using high resolution genomic approaches and environmental context.

This project will:
1. infer the source populations of UK invasive pink salmon, their demographic histories and patterns of contemporary expansion;
2. determine the characteristics of waterways with most propensity to invasion;
3. infer functional genomic regions associated with local adaptation to UK waterways and genetic associations with colonisation success.

Click on an image to expand

Image Captions

1. Image of salmon retrieved from invasive population in Norway, Photo: Eilif Andreas Aslaksen/NRK with permission
2. Pink salmon encounters 2017, distribution map of Scotland. Used with permission. C. Bean SNH
3. Pink salmon from the River Ness. Used with permission. C. Bean SNH
4. Viable eggs and young from pink salmon collected in Scotland. Used with permission. C. Bean SNH


Biological material for the project will be drawn from our national and international networks. Samples are committed (global, UK, Scotland) for historical to present, for Russia, Scandinavia, UK, Europe, and North America. The student may participate in additional fieldwork.

Genomic analyses will be conducted using genome-wide next-generation sequencing approaches and bioinformatic pipelines for non-model organisms. This is made possible by the existing resources and expertise established in the PI’s group. These will lead to high resolution inferences of population genetic structure and diversity. Coalescent analyses to reconstruct divergence timing, migration rates and demography of all populations will be inferred. Genomic regions responding sharply to selection will be inferred using established outlier approaches. Candidate loci for association with invasive phenotypes and environmental variables will be inferred from partial redundancy analysis.

Environmental correlates of rivers that are and are not experiencing invasion by pink salmon will be examined and patterns linked to the biological data.

Project Timeline

Year 1

Molecular lab work, library preparation and sequencing; research visits to collaborating institutions; field collections.

Year 2

Analysis of genomic and environmental data; research visits and training courses.

Year 3

Analysis of genomic data, analysis of environmental data, coordination with partners, manuscript preparations, training in transferrable skills

Year 3.5

Data analysis; dissemination of results by high impact publications and presentation at conferences and seminars.

& Skills

The student will train with internationally esteemed researchers to acquire a breadth of skills necessary to pursue a career in quantitative biology: skills in molecular biology for high throughput sequencing, fieldwork and sampling for fisheries, and learn cutting edge genomic approaches for understanding relationships between phenotypic, environmental, and genotypic variation.

PI Elmer is expert in adaptation and ecological ‘omics of natural populations, including salmonid fishes. Co-I Bean is expert in biodiversity and fish research and leads research directed policy at SNH. SNH will provide valuable supports and networks for sample collection and outcomes that can have policy impacts. Co-I Lucas is expert in fish ecology, conservation, and migration.

We have drawn together a strong international cooperation of partners focused on inputs and outcomes. The project has clear evidence of collaborative working between agencies from the UK and internationally. The studentship will leverage expertise from Scotland and internationally (Ireland, Russia, Norway, Canada, Scandinavia), and build new expertise around a hub of biodiversity research with an explicit aim to inform management policy.

References & further reading

Armstrong JD, Bean CW, Wells A (2018) The Scottish invasion of pink salmon in 2017. Journal of Fish Biology, 93, 8-11.

Gordeeva NV, Salmenkova EA (2011) Experimental microevolution: transplantation of pink salmon into the European North. Evolutionary Ecology, 25, 657-679.

Jacobs, A., M. Carruthers, R. Eckmann, E. Yohannes, C. E. Adams, J. Behrmann-Godel, and K. R. Elmer (2019) Rapid niche expansion by selection on functional genomic variation after ecosystem recovery. Nature Ecology and Evolution 3: 77-86.

Korsu K, Huusko A, Muotka T (2007) Niche characteristics explain the reciprocal invasion success of stream salmonids in different continents. Proc Natl Acad Sci U S A, 104, 9725-9729.

Recknagel H, Hooker O, Adams CE, Elmer KR (2017) Ecosystem size predicts eco-morphological variability in a postglacial diversification. Ecology and Evolution, 7, 5560-5570.

Seeb LW, Waples RK, Limborg MT, Warheit KI, Pascal CE, Seeb JE (2014) Parallel signatures of selection in temporally isolated lineages of pink salmon. Molecular Ecology, 23, 2473-2485.

Further Information

Applications: to apply for this PhD please use the url:


For questions please contact Dr. Kathryn Elmer, or +44 141 330 6617

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