Intensive fishing has changed the DNA of cod

Humans have been evolving and building their homes on planet Earth for centuries. It was during prehistoric times that the human species began hunting and gathering food, whether land-based or marine, and one of the most developed activities to date is fishing. A profession that has been practiced since the beginning of time and now remains one of the foundations of our diet, although increasingly widespread. So much so that a word has been coined to describe this excessive hunting: overfishing . And its consequences are already visible today.

This is precisely what worries experts, who have already disseminated their hypotheses through scientific journals and news agencies such as SINC. In this case, a recent study conducted by researchers at the GEOMAR Helmholtz Centre for Ocean Research in Kiel (Germany) has proven that cod DNA has been modified due to this intensive fishing.

Evolutionary changes What happened to cod DNA?

The results, published in the journal Science Advances , have shown that overfishing has been the main cause of the dramatic change in this fish, found in the Baltic Sea. To understand what has happened to cod, it is necessary to look at the definition of evolution.

According to experts, a species evolves to adapt to changes in its surrounding environment. This is what happened to humans and all the animals that make up the current ecosystem. It is normally thought that this is a very arduous process and largely unremarkable on a time scale, although not all evolutions take the same length of time, and some have occurred so rapidly that they can be recorded in recent history.

This is what has happened to cod, which has gone from measuring over a meter in length and weighing about 40 kilos to a much smaller fish. Not only that, but its population has also declined considerably.

“Cod is evolving in response to human exploitation,” said Kwi Young Han, the first author of this study. This refers not only to its very small size, but also to a drastic change in the genetics of the Baltic Sea species. Specifically, the scientific discovery shows that most of the genetic variants linked to rapid growth have disappeared.

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This means that individuals that grow more slowly and reach reproductive maturity earlier have been favored. To reach this conclusion, the research team analyzed structures located in the fish's ear that record their annual growth, concluding that fishing demand was the cause of this change.

Fishing for this species is currently prohibited due to its declining numbers, and although it has been in place since 2019, there have still been no signs of recovery for this ancient marine giant. "This is evolution in real time, driven by human activity," they explained.