Linking local changes to global ecosystems

Research lives: Dr Elvira De Eyto, zoologist, Marine Institute’s Newport research facility

What do you work on with the Marine Institute?

For nearly 20 years I have been involved in long-term monitoring of the Burrishoole catchment ecosystem in Co Mayo, where we monitor the freshwater and marine environments in the Burrishoole system, including the fish stocks in these waters.

A lot of my job is making sure that the data we collect here ends up in global scientific analyses, so we can contribute to the bigger picture.

What kinds of fish stocks do you measure and why?


We monitor fish populations of salmon, trout and eel. Essentially, we count fish coming through our catchment traps at Furnace every day. These are diadromous fish, they move between rivers and the ocean, and this means they are subject to multiple pressures.

The research station at Newport was established by the Salmon Research Trust in 1955, so we now have more than 60 years of data collected.

What are you seeing in the data?

We see that salmon populations have decreased substantially. It’s a worrying trend. Numbers have been fairly stable, but low, over the last couple of years, but over the longer, 50-year timeframe, the number of salmon returning from the sea to freshwater has been decreasing. The really big problem appears to be increasing marine mortality, the salmon are dying in the ocean.

Why are more salmon dying at sea now?

Historically, overfishing of Atlantic salmon at sea has definitely been an issue, and that is now tightly controlled through international agreements. The other main theory is that the feeding opportunities at sea for salmon have diminished. There is likely a tight link to climate change there.

What can be done to help the salmon survive?

Once salmon come back from the sea, we can do quite a lot in freshwater to make sure the rivers are in good condition, illegal fishing is minimised and the fish have ample spawning habitat.

But understanding what is happening at sea and improving marine survival is a much bigger challenge. At the Marine Institute we have been involved in fish-tagging research that is giving us a clearer picture of where Atlantic salmon migrate to feed in the ocean, which allows more targeted actions.

Ultimately, though, the solution will need the successful implementation of the Paris agreement on climate change, and a similar global ambition to address biodiversity loss.

Apart from the decline in salmon, what other local changes have struck you?

When I started measuring carbon dioxide – one of the main greenhouse gases responsible for climate change – at the surface of Lough Feeagh a few years ago, I would get atmospheric values in the high 300s in ppm (parts per million).

This year it’s around 415. I haven’t seen values in the 300s for three years and probably won’t ever again. Carbon dioxide levels are increasing globally, and I can see it happening here, right in front of us.

What drives you to keep going in research?

I love the underwater environment. I used to do lots of scuba diving and the waters in and around Ireland are spectacular. Also, I really want to help people join the dots between what is happening locally and how our planet is changing.

Everything we do in our lives is connected to the climate and how the world is functioning. It’s going to have a massive impact on our children’s generation and I would like to help people wake up to that reality. That is my mission.

Claire O'Connell

Claire O'Connell

Claire O'Connell is a contributor to The Irish Times who writes about health, science and innovation