Carp up to two metres long
More than 30 years have passed since then and the animals, which are now up to two metres long, weigh a considerable amount. On average they weigh around ten kilos, says Krause, who has caught marbled carp himself by chance.
The animals don’t really let themselves be fished. “They don’t have teeth, but rather filter the water and absorb plankton and algae. That’s why they’re not interested in fishing hooks with prey on them.”
The district administration for the Saale-Orla district assumes that around a third of the carp that were introduced at the time are still in the Hohenwarte reservoir. With an original population of 70,000 animals, that would be around 24,000, with a corresponding total weight of 240 tons of fish.
They don’t have teeth, but instead filter the water and absorb plankton and algae. That’s why they’re not interested in fishing hooks with prey on them.
Joachim Krause
Experts speak of a ticking time bomb, as the lifespan is between 25 and 30 years. That has now passed, and residents and tourism professionals fear a mass death like at the Heyda dam. Thousands of fish died there of old age in spring 2013. Rescue workers had to laboriously remove the stinking carcasses.
Carp difficult to get out of the water
Such a scenario would be a catastrophe for tourism at the Hohenwarte reservoir. That is why they have long been calling for the carp to be removed before it is too late. But that is difficult. “We have different water depths here, so you have to find the fish first,” says Joachim Krause. “And with the trawl net you also remove a lot of commercial fish, which messes up the whole system.”
In addition to the giant carp, the reservoir is also home to many perch, pike and zander. They would probably be crushed in the trawl nets of the giant carp.
And the trawl net also removes a lot of commercial fish, which disrupts the whole system.
Joachim Krause
Experts now assume that the life expectancy of carp could be up to 70 years. That is why the district administration is also staying relaxed and does not want to start a major removal campaign for the time being. “Together with the district of Saalfeld-Rudolstadt, we have a water protection plan for the dams,” says the district administrator of the Saale-Orla district, Christian Herrgott (CDU). “The situation of a sudden mass death of fish is also regulated there.”
Are the carp in the Hohenwarte having offspring?
Experts are still arguing about whether the carp in the Hohenwarte reservoir are already producing offspring. Warmer waters are actually needed for this. But with climate change, the temperatures in the reservoir are also rising. And Martin Görner from the species protection center in Ranis is convinced that there is already a younger generation of silver and marbled carp in the reservoir. “We have a prepared carp from the Saale here in the center,” he says. “It was estimated to be around eight years old.”
Fish expert Joachim Krause does not believe that the carp will die in large numbers in the near future. Unlike in Heyda, there is enough water in the Hohenwarte reservoir in which the animals can move freely, even in winter. “So far I have only seen a few individual dead fish,” says Krause. “But that is normal.”
He is convinced that the carp are healthy and have enough food. In any case, he could not detect any signs of age in the few specimens he caught.
