Lake Constance is the largest German inland body of water and is around 250 meters to the bottom at its deepest point. An animal can hide there, one would think, and yet researchers who are averse to superlatives speak of an “incredible catch” that they succeeded in 2014 and has been a mystery to this day: At that time, scientists from the Langenargen Fisheries Research Center and the Water Research Institute of the Switzerland Discovered deep-sea char in their nets, a fish species that was actually thought to be extinct.
But experts weren’t sure. The mystery has now been solved, as the Munich State Zoological Collection announced on Wednesday: Salvelinus profundus actually still lives in Lake Constance, the DNA of the animals living in the lake today is almost identical to the DNA of historical specimens.
The catch was also unbelievable because, according to the state collection, Lake Constance is one of the best-studied bodies of water in the world. It is therefore known that whitefish populations are declining, causing problems for fishermen and which scientists attribute to climate change. It is also known that the quagga mussel was introduced and is now populating the lake, altering the habitat.
For 40 years, the scientists only overlooked the admittedly pale and only up to 25 centimeters large deep-sea char, which is why the theory quickly arose after their rediscovery that these were only descendants of the normal, never extinct, normal char, which were up to 40 centimeters in size. Researchers have therefore specifically fished the depths of Lake Constance and have repeatedly found deep-sea char which – as has now become clear – not only genetically clearly resemble the animals that populated Lake Constance as a matter of course decades ago. The specimens also have different spawning areas and spawning times than normal char. Apparently, calls for help from professional fishermen in the 1950s helped to reduce the over-fertilization of Lake Constance at the time, which allowed some deep-sea char to survive.
The scientists hope that the deep-sea char will replace today’s normal char in the future. These were used until the 1990s, so they come from a “mix of farmed fish” from all over the world. The supposedly extinct deep-sea char would thus become the normal char again, which it was in Lake Constance until decades ago.