Each year, these remarkable fish return from their life at sea to breed in freshwater. One of their chosen spawning grounds lies right here in the Afon Marteg (River Marteg), which flows through Gilfach, Radnorshire Wildlife Trust's flagship nature reserve.

Their journey is epic: migrating up the Bristol Channel (after travelling all the way from the North Atlantic), beneath the Severn Bridge, into the River Wye, through Herefordshire, and finally into Wales. Gradually, they make their way upstream to Mid Wales.

By Mid-October and into November, when the River Marteg swells with rain, the salmon use every ounce of their strength to leap up waterfalls and push onward to calmer waters. There, the females sweep out hollows called redds in the gravel with their tails and lay their eggs, continuing a cycle that has played out for thousands of years.

A keystone species 

Atlantic salmon are a keystone species, meaning their presence plays a critical role in maintaining healthy ecosystems. By moving between rivers and the ocean during their life cycle, they help sustain biodiversity, regulate food webs, and support natural ecological processes that benefit both wildlife and people.

They are an important fishery species and have long supported Welsh fishing industries and river communities. Salmon also hold deep cultural significance in storytelling and tradition; in Welsh folklore, the Salmon of Llyn Llyw is described as the oldest and wisest of all animals.

Because Atlantic salmon require cold, clean, well-oxygenated water, they are powerful indicators of environmental health. Their success or decline reflects the condition of rivers, estuaries, and marine environments. In this way, salmon help build a broader picture of the health of our freshwater habitats, coastal waters, and the wider ocean ecosystems they depend on.

A species under pressure

Sadly, as a species they have faced drastic declines and they now face a range of pressures. Because their lifecycle spans a variety of habitats, from open ocean to upland streams, they encounter many threats along the way. 

Migration is disrupted by man-made barriers such as dams, which block fish passage and threaten population survival. Climate change is a factor that can affect them at all life stages; during the low flows of summer, water temperatures can reach 20°C, a threshold at which conditions become life-threatening, and without the protective shade of water crowfoot and trees, these already vulnerable fish are left exposed. Bankside vegetation, including overhanging trees such as alder and willow, are important as they help keep the water cool and provide a range of microhabitats.

Siltation from soil runoff caused by unsustainable land management can also cause degradation to spawning habitats, reducing the oxygen supply to developing eggs and threatening their survival. Overfishing at sea is another issue as well as poaching in rivers. Taken together, these pressures paint a concerning picture, and these fish face the harsh realities of a rapidly changing world. 

In December 2023, Atlantic salmon were officially classified as endangered in the UK on the IUCN Red List, a stark warning that without urgent intervention, the Atlantic salmon could no longer be seen in our waters.

Our role at Gilfach

So, what part do we have to play? As a small wildlife charity in Mid Wales, we cannot control what happens on a global scale. We cannot directly influence the condition of the open ocean or manage every stretch of the river systems that Atlantic salmon must navigate during their remarkable journey. But what we can do, is continue to protect the stretch of river that flows through Gilfach. By protecting and restoring the Afon Marteg and keeping its waters clean and healthy, we can help ensure that salmon returning from the sea still have a safe place to spawn. Here at Gilfach, thanks to all our amazing staff, volunteers and supporters, the river remains a haven for wildlife and an important refuge for salmon completing their epic journey. 

How you can help Atlantic Salmon as an individual:

• Support vital conservation efforts through raising awareness, donating or volunteering
• Learn more about Atlantic salmon: join our upcoming World Fish Migration Day event at Gilfach
• Reduce water usage: Using less water at home leaves more in the river for wildlife.
• Be mindful of pollution: Only flush the three P’s (pee, poo, and paper) down the toilet to help reduce sewage spills.

DID YOU KNOW?

Most salmon will die after spawning. A few females (about 5%) will go back out to sea and some of these may do the journey again. 

Juvenile salmon are called fry and then parr as they get older.