Europe’s summer drought threatens fish in rivers, lakes and farms

Small boats sit idle on parched ground in a dwindling side channel of the Danube River in northern Serbia, where the water has dwindled into mere puddles due to an extreme drought and scorching heat. Fish swim in the shallow pools. One fisherman, Dusan Jovanovic, says these fish are in grave danger due to insufficient water and temperatures soaring above 86 degrees Fahrenheit. "If they start to die, they will all die at once," he warns.

Extreme drought and intense heat have devastated ecosystems and businesses throughout the region, including in Slovenia, Serbia, Bosnia, the Czech Republic, Romania, and Hungary. The fish industry is particularly hard hit, with damage estimated in the millions of euros. This exacerbates the already severe impacts of energy and water supply issues, ruined crops, disrupted river traffic, and trade losses.

Countries and businesses are now grappling with how to mitigate the effects of future extreme weather events, which scientists attribute to human-induced climate change. In Hungary, nearly 99% of the country is under severe or extreme drought conditions, threatening around 27,000 hectares of fish ponds. Hungary's Agriculture and Food Economy Ministry reported that 1,588 hectares of these ponds have dried up, causing the deaths of nearly 280 metric tons of fish at 20 farms, resulting in a revenue loss of 1.3 billion forints ($4.2 million). Replacing lost fish could take years.

Romanian fish farmers, especially those cultivating carp, have been severely affected by this year's heatwave and persistent droughts in 2023 and 2024. Carp production has a three to four year cycle, so the losses from last year have had a cumulative impact. Water-use policies that prioritized irrigation for agriculture during previous droughts left little water for fish, according to Catalin Platon, president of ROMFISH National Association of Fish Producers.

Fish farmers in the Czech Republic have taken various emergency measures, including reducing or suspending feeding, aerating the ponds, or draining them when necessary. Long-term solutions to retain more water in the landscape are needed, officials say.

In Bosnia, trout breeders are struggling to survive the summer. Veljko Budjen, a trout farmer near Trebinje, notes that trout require cold water with high oxygen levels. During hot and dry summers, producers must reduce production and feeding to conserve resources. Adding liquid oxygen to the water during summer months is one option, while hoping for rain is another. In Slovenia, emergency teams are pumping water into Lake Pristava to prevent mass fish deaths due to lack of oxygen and water.