The Likely Suspects Framework data model
and salmon management support tool

What is the Likely Suspects Framework?

Wild Atlantic salmon are iconic, keystone species but across the North Atlantic their populations have declined by around 70% in the last 50 years.

The reasons for this decline are varied from region to region, and across different stages of their complex lifecycle and migration as they travel from freshwater, through coastal zones, into the open Atlantic Ocean, and then back again to their natal rivers and streams to spawn. Over recent decades, the number of adult salmon which survive that complex migration has fallen lower and lower, driven both by factors affecting juveniles in freshwater, and through a significant decline in their marine survival and return rate. The salmon’s lifecycle itself has not changed – so other factors are at play meaning that wild Atlantic salmon are no longer thriving in the way they should.

The Likely Suspects Framework is an ambitious data and science project seeking to understand why wild salmon stocks are declining, by identifying the key pressures influencing their decline at each life stage and across their whole lifecycle.

It models complex data gathered through research projects and against baseline salmon population data series from long-term monitored ‘index’ rivers, collating this against information on the pressures known to be a factor in each salmon life stage. Currently, the model defines wild Atlantic salmon life stages as:

  • River rearing juveniles

  • River migration smolts

  • Estuary migration smolts

  • Coastal migration post-smolts

  • Ocean migration

  • Coastal migration adults

  • Estuary migration adults

  • River migration adults

Creating a digital salmon manager’s restoration support tool

It is currently transforming this knowledge into a practical salmon management digital support tool, whereby managers can model their salmon population’s future trajectory and restoration potential by helping them to identify which life stages can be targeted for improvement, and what the outcome of this may look like.

Watch this space for further details about results from the Likely Suspects Framework to date and next steps for the project.