UK's Fish Population Plummeted In June – Here's The Grim Reason Why

Everyone noticed that June was particularly hot this year – but did you notice how it affected the UK’s fish?

Experts say we just had the hottest June on record, with temperatures peaking at 32C in some parts of England leading to heat-health alerts and water shortages.

But, even if you embraced the weather change, it did have some sad consequences. It killed an unprecedented number of fish, and shook whole ecosystems in the process.

Why did so many fish die in June?

In yet another sign of how the climate crisis is hitting us, last month’s record temperatures reduced water levels in British rivers and encouraged algae growth, meaning the amount of oxygen in rivers fell, too.

That spelled danger for the fish in UK rivers.

Dried up pollutants from cars were then pushed into various waterways during various flash storms which popped up across June, and became yet another major threat to the fish population.

Mark Owen, from the Angling Trust, told BBC News: “The reports of the fish death incidents in rivers for this time of year has been unprecedented. I would normally expect rivers to be affected later in the summer when it’s hotter and drier.”

Hundreds of dead fish were found floating on the surface of the River Cam, near Cambridge, and hundreds more washed up dead in Salford Quays.

The Environment Agency also said it had far more reports of dead fish compared to those in June 2022.

Why was June so warm?

Sea surface temperatures in the North Atlantic and around the British Isles have reached record-highs recently, meaning warmer winds which blow in from the ocean brought hotter temperatures with them.

At the same time, June was hit by slow-moving high pressure systems, which is why we had such dry, settled weather.

Then, there was the impact of the summer solstice. June always brings some of the longest days of the year and with it, more sun exposure. That, along with less ran, helped keep the temperatures high.

This was a recipe for disaster for our river wildlife.

What does this mean for the UK as a whole?

With more forecasts for very high temperatures in July and August – possibly hot enough to rival last year’s heatwaves – this isn’t great news for both the general environment and the UK’s water supplies.

Nature is being “pounded by extreme weather without a chance to recover”, according to Ali Morse from the Wildlife Trusts. She told the BBC the UK is lurching from one record-breaking event to another. 

And it’s not just fish who end up being affected either. In June, flowering plants ended up wilting under the hot sun, so insects had less nectar and pollen to feed on, too.

This was especially devastating for species with short lifespans like butterflies, as they are only adults for a short time.

Meanwhile, Water UK said people used more water with demand soaring by 25% at peak times in some areas – while Devon, Cornwall and parts of the south-east are under a hosepipe ban.

While rivers and reservoirs are healthier than last year, dry weather will continue to deplete water supplies and raise worries about droughts.

“The recent heatwave has served as a reminder that we need to prepare for weather extremes and act now to ensure resilient water supplies,” Simon Hawkins, chair of the National Drought Group, said.

If you want to lend your local wildlife a hand, try putting a bowl of water in your garden to offer water for thirsty hedgehogs, bees and butterflies, and think about not cutting your grass so a few smaller creatures can find a little respite from the hot sun.