Lake Constance: Riddles about mysterious fishing solved – hidden deep down

Lake Constance: Riddles about mysterious fishing solved – hidden deep down

Deep sea char spotted
Riddles about mysterious fishing in Lake Constance solved – there was one well hidden

As long as a hand: someone is holding a deep-sea char from Lake Constance

A hand holds a deep-sea char on a fishing boat in Langenargen on Lake Constance in August 2016

© Fisheries Research Center Langenargen / Alexander Brinker / Picture Alliance / DPA

Since 2014, researchers have been puzzling over the rediscovered specimens of deep-sea char in Lake Constance. After all, the species was considered lost in the well-studied body of water for more than 40 years. Now the riddle is solved.

From an “incredible catch of fish in the Lake Constance” is the speech of the Zoological State Collection Munich. This is not about belief, but about science. But what was discovered in 2014 for the first time in Lake Constance, researchers could not explain for a long time. Until now. The mystery of the deep-sea char in Lake Constance has been solved.

In 2014, scientists from the Langenargen fisheries research center and the Swiss Aquatic Research Institute discovered some specimens of deep-sea char in their nets. The fish is about the size of a large hand, measures up to 25 centimeters and has a slightly silvery sheen.

The unusual thing about the catch: At this point in time, the species had been considered lost in Lake Constance for 40 years. And that in the well-studied Lake Constance.

Genetic studies solve the mystery of deep-sea char in Lake Constance

Had the deep-sea char simply been overlooked for decades? Or were the rediscovered specimens descendants of the normal, never-extinct char that were able to adapt to life at depth? These questions drove the scientists. So they went on a search in the depths of Lake Constance. In addition to the 40 centimeter normal char, the much smaller deep-sea char also caught in the net.

Now the breakthrough has come – thanks to genetic studies. These have shown that the DNA of today’s deep-sea char is almost identical to the DNA of the earlier deep forms that lived in Lake Constance more than 40 years ago, writes the Munich State Zoological Collection. The work also provides clear evidence that normal and deep-sea char still have completely different spawning areas and spawning times. researchers from Munich, Langenargen and Bergen in Norway have published their study in the journal Ecological Applications.

Well hidden far down in Lake Constance

“Today’s deep-sea char are descended directly from original specimens. So some animals must have managed to survive undiscovered in the depths of the lake,” Jan Baer is quoted as saying by the fisheries research center in Langenargen. The fish were well hidden. In Lake Constance it sometimes goes far down, at the deepest point it is around 250 meters deep.

Apparently calls for help from commercial fishermen had an effect in the 1950s, says Baer. And apparently measures taken early on against over-fertilization would have had the effect of preserving the habitat of the deep-sea char.

Ulrich Schliewen, fish expert at the Zoological State Collection Munichadds: “But at the same time, our data also shows what stocking measures in Lake Constance with char from all over the world had until the 1990s: the original normal form of char from Lake Constance was almost completely displaced and largely replaced by a mix of farmed fish. ”

No longer “lost”, but “endangered”

As the SWR reports, the deep-sea char is now listed as “endangered” instead of “missing” on the red list of endangered species.

Those responsible for the project hope that deep-sea and normal char will continue to spread in Lake Constance. She is optimistic that no other char have been used in Lake Constance for several years. This example clearly shows the influence that humans can have, Baer told SWR: He can make species disappear, but also species like the deep-sea char can be preserved.

Source: Bavarian State Natural History Collections, SWR

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