Working with Leading Academics to Understand the Reason for the Decline of the Atlantic Salmon

The North Atlantic salmon population has declined dramatically over recent years. Catches of Atlantic salmon in 2019 from almost every country were the lowest in the entire last 40-year time series. In response to this, Six Rivers is pledging to work with leading academics to understand the reason for the decline of the Atlantic Salmon.

Although Iceland has so far largely escaped this decline, there is no room for complacency. Given the drastic demise of the species, urgent work is needed to stave off the threat to the species and help re-grow salmon populations.

We have therefore established a long-term holistic programme which combines fundamental research on how best to help salmon populations, practical interventions to make a difference now, and ongoing state-of-the-art monitoring and measuring to understand the impact of what we do. The research is being done by a joint team from the MFRI, with its unrivalled history of studying salmon in Iceland, and Imperial College London, with its world-class ecology and modelling expertise.

Our initial focus is on understanding how to improve young salmon populations in the river, then measuring how many survive their sea journey to return to spawn, and how successful the spawning is. Already we know that food sources for young salmon are scarce and that we need to improve them, for example, by enhancing vegetation around the river. We have also found that predation – loss of salmon to birds – may be higher than originally thought. And we know that sufficient food exists in areas where we have opened up rivers by the addition of ladders.

We have also tagged parr and smolts in a key river – the Vesturdalsa – with very small tags which uniquely identify the fish. We have equipped the Vesturdalsa with antenna up and down the river to enable us to chart their movements and so gather new data on how many parr survive to become smolts, and how many smolts leave the river then survive to return to the next year as adult fish ready to spawn. Alongside this, by starting to measure food sources and the demands of the fish for food, we have set about the task of estimating the carrying capacity of the river, something that’s never been done before.

In the later stages of the project, we hope to turn our attention to the question of the sea. Where do our East Icelandic salmon go, and how known changes at sea might be affecting the population? For example, changes to currents and temperature.

Understanding all of these factors and collecting the data we can and have to date provides us with a comprehensive understanding of the life cycle of north Atlantic Salmon, which we have detailed further in our brochure and this page.

This research, coupled with re-forestation, egg planting and opening of salmon ladders, will give us unique insights into how best to sustain and grow the populations of salmon. By working with the international salmon community, for example, at our Annual Salmon Symposium, we hope to make sure that learnings from the pristine rivers of Iceland are transferred elsewhere and help salmon populations across the region.

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