Fishing Lake Constance could become too warm for whitefish

The water temperature in Lake Constance has an influence on the distribution of whitefish. This is shown by research conducted by the University of Konstanz and the Baden-Württemberg Fisheries Research Center.

For the research project, eggs and larvae of bluefish and whitefish were reared at three different water temperatures, according to a press release issued by the University of Konstanz on Monday. The aim was to clarify what influence the warmth of the lake water can have on the whitefish population.

The result: the higher the water temperature, the higher the mortality rate of whitefish in the larval stage. At higher temperatures, the larvae hatch much earlier. This could prove problematic because at this time - the end of January - there are usually not enough food organisms available.

The researchers also found a higher mortality rate of the eggs because they have to contend with a higher infestation of microorganisms in warmer water.

Help with adaptation

Fish can adapt to new environmental conditions within certain limits, according to the press release. However, the changes caused by the climate crisis are happening so quickly that the natural ability to adapt is often unable to keep pace.

Measures are therefore needed. These include the targeted rearing of larger "stocking larvae" so that they can skip the first critical weeks of life in a protected environment. If the whitefish population recovers thanks to such measures, this will be a significant step towards adapting Lake Constance to the climate.

The whitefish population in Lake Constance has steadily declined over the last 20 years. A three-year fishing ban is therefore currently in place for this popular edible fish.