Sizzling temperatures leading to ‘catastrophe’ for fish in Swiss lakes and rivers

Water temperatures have already reached 25 Celsius, threatening the survival of certain fish species in Switzerland's watercourses, warned the head of the Swiss Fisheries Association.

Sizzling temperatures leading to 'catastrophe' for fish in Swiss lakes and rivers
Dead trout. Photo: crookid/Depositphotos

For grayling, trout and whitefish in Lake Constance and the Rhine river, the current temperatures already pose an existential threat.

The unusually warm summer – June was the hottest for a century in Switzerland – has set alarm bells ringing among conservationists and administrative bodies. The specter of 2003, when dead fish lined the banks of Lake Constance and the smell of rotting fish became a mainstay of lakes in Swiss villages, looms once again because of the unusually hot summer temperatures. 

“We are not far off experiencing the same catastrophe again,” Philipp Sicher, managing director of the Swiss Fisheries Association, told Swiss daily Blick. 

The water temperature in Lake Constance is currently 25 degrees Celsius and a mere two degree increase would mean that most fish species would no longer be able to survive. In some areas, fish can be relocated, but in others only heavy rainfall can determine their fate.

“Unlike in the midlands, where we have the opportunity in rivers and smaller rivers to fish out threatened species and relocate them to cooler waters, we lack this opportunity in the Rhine and Lake Constance,” added Sicher. 

While bream, roach and carp are at home in such tropical temperatures, most commercial fish specimen cannot survive above 27 Celsius. 

READ ALSO: Switzerland's driest summer for more than a decade threatening water supplies

The scorching summer is only the latest woe for Swiss fish. Thousands of fish die every year in Swiss lakes because of more than 1,000 obstacles created by the country's hydroelectric plants' turbines, reports local daily Solothurner Zeitung. 

The hydroelectric plants have been ordered to remodel their infrastructure by 2030 and nearly 1 billion Swiss francs, alongside taxes generated through electricity, have been set aside for the task. 

“I fear that the renovations will be postponed endlessly because the money is missing,” Sicher told Solothurner Zeitung, adding that the government is neglecting its conservation obligations towards fish species. 

A petition by Aqua Viva, the WWF and the Swiss Fisheries Association aims to pressure the government and has already collected 25,000 signatures. 

Migratory fish such as eel and trout are particularly affected. As a result of more than 1,000 artificial obstacles created by the hydrolelectric industry, “the fish are cut off from their seasonal spawning and feeding grounds,” states the fishing association's petition.

Approximately 70 species of fish live in Switzerland's water bodies, of which 54 are indigenous, according to 

“We are running out of time. At some point it will be too late for our already highly-endangered Swiss fish,” said Sicher. 

Only a dramatic increase in rainfall can remedy the situation, added Sicher. 

READ MORE: Summer in April: parts of Switzerland see record temperatures


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Heatwave: Why is it so hot in Switzerland right now?

Not so long ago we complained about the cold and rainy weather in Switzerland, wishing for sunnier and warmer days. Our wish has come true — but why exactly is it so hot and what can we expect for the coming weeks?

Heatwave: Why is it so hot in Switzerland right now?

The temps have reached high 20s across much of Switzerland in the past days, but the best (or the worst, depending on who you ask) is yet to come: meteorologists forecast the high of 32 degrees for Friday.

“The current heat wave is relatively extreme for a month of May”, meteorologist Joshua Gehring from official weather service MeteoSwiss said in an interview with Watson news platform.

Why is it so unseasonably hot right now?

One reason should come as no surprise to anyone: “What we are currently experiencing, that is to say a relatively early heat wave, is a direct consequence of climate change”, Gehring noted.

READ MORE: EXPLAINED: How the climate crisis is hitting Europe hard

Specifically, a phenomenon called “heat dome” is hovering over Europe. It is, according to Gehring, “a stagnant anticyclone that acts as a lid to accumulate and retain heat”.

This is pretty much what happens when you put a lid over a boiling pot — the heat therein is captured and can’t escape.

What can we expect for next week?

The forecast calls for the heat wave to end from the beginning of next week, with more seasonal, 20-degree-plus temperatures expected throughout the country.

This is what the forecast looks like for Tuesday:

MeteoSwiss screenshot

What can you do in the meantime to cool down?

Indoor air-conditioning is rare in Switzerland, but keeping cool is easier outdoors.

For instance, the abundance of lakes and rivers in Switzerland provides a welcome relief on hot days.

And if you like swimming pools, the good news is (at least during a heat wave) that some are turning off heating to boycott Russian gas, so you could have a nice, cool swim.

READ MORE: Swiss pools go cold in boycott of Russian gas

Also, most public fountains in Switzerland spout cold water you can drink and splash yourself with.

If all else falls, head for the glaciers (while they last).