Hot Weather, Low Water: Why Droughts Are Bad News for Fish
It’s certainly been a hot, dry spring so far and whilst many of us welcome a sunny spell, this prolonged dry period is starting to take a serious toll on our rivers.
There is no denying that the UK is experiencing more frequent and intense weather extremes. Climate change is already making droughts more common in the UK by increasing temperatures and altering rainfall patterns. Warmer weather also increases evaporation and dries out soil, while shifts in seasonal rainfall can reduce the amount of water available during key times of the year (such as this spring).
This creates a worrying scenario where drought conditions are not just becoming more likely, but also harder to predict and harder to manage.
Droughts and The threats to fish
Atlantic salmon and brown trout, two of the key species we monitor, begin to struggle when water temperatures reach around 20°c. If the water temperature hits 25°C, then we start to see the death of fish, and other river inhabitants. This can soon wipe out entire food chains, and whole stretches of water can become dead zones.
This is because fish breathe by passing water over their gills, where dissolved oxygen travels into the fish’s blood. However, higher water temperatures cause a decrease in the levels of dissolved oxygen in the water, meaning that the fish essentially start to suffocate.
On top of this, as temperatures rise, the solubility of toxins also rises, reducing the quality of the water and increasing the concentration of pollutants. With the addition of algal blooms, our rivers can quickly turn from wildlife havens into deadly spaces.
And it doesn’t stop there. Warm water speeds up a fish’s metabolism, meaning they need more food and oxygen at exactly the time when both are in short supply. In general, for every 10°c that water temperature increases, a fish’s metabolic rate doubles. Meaning fish not only need to feed more, but they also need more oxygen.
It’s not just fish at risk
While the impact on fish is severe, people are also affected by droughts. Drought depletes reservoirs, rivers and groundwater sources, threatening water supplies for drinking, which can cause shortages and reduce water quality. It also impacts agricultural production by reducing soil moisture and water availability, leading to lower crop yields and livestock productivity.
And when water levels in reservoirs drop too low, water companies may begin abstracting directly from rivers to ensure we have enough water in our homes, but also taking water that fish, wildlife, and ecosystems desperately need to survive.
What are we doing to help?
Whilst climate change means this could be the new normal, there are some things we can do to help! Our research shows that planting riverside trees provides enough shade to keep rivers cool and flowing, even in the scorching sun. Hence why one of our main activities is tree planting!
Plus, our fish passage work means that fish can move up and down rivers more freely, helping them to escape drought hit rivers and move to cooler stretches of water, in a process called refuge migration.
Finally, by engaging with landowners, local communities, and young people, we can raise awareness of river pollution, helping to reduce the extra stress that pollution places on our already stressed river systems.
How you can help: easy ways to save water at home
In dry conditions like these, every drop counts. Reducing your household water use can help ease pressure on local water sources and protect wildlife during times of stress. Here are some simple tips:
- Use aerators and cistern bags: These nifty gadgets cut water use without affecting performance, and many water companies give them away for free!
- Switch to a shower: A short shower uses far less water than a bath. Bonus points if you fit a low-flow showerhead!
- Be tap smart: Turn off the tap while brushing your teeth or washing veggies. A running tap uses about 6 litres a minute.
- Water-friendly gardening: Plants love rainwater, so install a water butt if you can. You can also reuse cooled cooking water to feed your garden.
- Load up your dishwasher: Run it only when full and skip the pre-rinse to save hundreds of litres each year.
- Keep cool smartly: Instead of running the tap for cold water, fill a jug and keep it in the fridge.
If you see a fish in distress
If you see a fish in distress, it’s really important that you report it! You can do this by ringing the Environment Agency’s 24 hour emergency hotline on 0800 80 70 60. Or, if you’re not able to make a phone call, you can report it online using the Ribble Fisheries Consultative Association’s online reporting form, which enables you to report drought-stressed and trapped fish. You can view the form here: form.jotform.com
Rivers are at the heart of our local landscapes. Whether you’re casting a line, exploring a riverside trail, or simply basking in the beauty of nature, you can help protect these special places now, and for generations to come.
By becoming a Ribble Rivers Trust supporter for just £3 a month, you’ll be funding real, on-the-ground action.
Ready to make a difference? Learn more here: ribbletrust.org.uk/become-a-supporter
