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The University of Southampton
Ocean and Earth Science, National Oceanography Centre Southampton

Research project: Discovering salmon feeding grounds using fish scales

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The big science question: It is important to establish oceanic feeding grounds of Atlantic salmon and other fish species, as it provides direct evidence for management of river populations, and monitoring and science-based regulation of high seas fisheries. Management of salmon and sea trout is economically important as recreational angling contributes significantly to the UK economy. In Scotland, recreational angling for salmon and sea trout contributes approximately £100 million annually to the economy in terms of expenditure and associated jobs. Salmon populations are falling, and conservation of stocks is vital to maintain this important revenue source.

Scale of atlantic salmon
Scale of atlantic salmon

Research details

Research in Southampton has developed a new geochemical technique to forensically 'fingerprint' the feeding ground pattern of Atlantic salmon, using archives of fish scales from around the country. The research identifying feeding location involved assessing the carbon isotope composition of archived scales of Atlantic salmon, producing time series of variation of isotopic signals. These were then correlated with equivalent time series of satellite derived sea surface temperature data. As temperature strongly influences the isotopic composition, the highest correlations between the time series indicate likely feeding areas. We can therefore produce maps of likely feeding area that are specific to river and biological cohort. This sub-population level resolution has never been achieved before. We analysed two distinct river stocks from the UK, and demonstrate segregation in marine feeding area. These feeding locations can now be monitored to aid conservation of endangered river stocks.

Specific impacts

  • We have identified, for the first time, oceanic feeding grounds of Atlantic salmon: different river populations travel to different areas
  • The technique pioneered in our laboratory is applicable to any marine species
  • We have pioneered a new method to distinguish farmed and wild salmon from scale trace element chemistry

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returning to the north east coast of the UK after two winters at sea
Predicted salmon feeding grounds
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