Revolution in the water: Baltic Sea herrings are becoming voracious predatory fish!

Revolution in the water: Baltic Sea herrings are becoming voracious predatory fish!

A new study from Sweden shows that Baltic herring has developed remarkably in recent years. The research carried out at the Uppsala University was carried out, documented the discovery of conspicuously large herring northeast of Uppsala. These herrings show a previously unknown behavior: they actively feed on other fish.

The analysis of the gill traps and stomach contents has shown that a genetically different population of Baltic Sea herring has developed into predatory fish. Damaged gill traps suggest that these herrings specifically catch and eat smaller fish. The phenomenon is so far unique because it has only been observed in the Baltic Sea worldwide. The researchers attribute the unusual behavior to a lack of classic predatory fish such as mackerel and tuna, which created an evolutionary vacuum that was occupied by herring. Predatory herring are almost twice as large as their plankton-eating relatives and also have a higher fat content and lower dioxin levels, which make them particularly tasty and healthy.

Adaptation of herring to the Baltic Sea

The herrings have colonized the Baltic Sea for around 10,000 years. A significant mutation in the visual pigment rhodopsin is crucial to ensuring that the herring can find their way optimally in their habitat. This mutation changes the light sensitivity of the herring by about ten nanometers into the red range. This enables the young fish to recognize predators earlier.

The Baltic Sea differs significantly from the North Atlantic: it is shallower, warmer, richer in nutrients and has a salinity that is up to ten times lower. These special properties of brackish water change the lighting conditions and make the water appear redder. The genetic adaptation of herring occurred quickly, within 23 to 65 gene generations. According to the study results in the Proceedings of the National Academy of Sciences published, the mutation first appeared 42,000 years ago and failed to establish itself in the Atlantic. These genetic changes are a prime example of how the herring were able to adapt to their specific environment.

– Submitted by West-East media