In the fjords, quite a number of juvenile cod of the coastal ecotype were caught. However, only a few specimens over 40 centimeters long were found in the nets. Credit: Håkan Wennhage
The rumor that the coastal cod is extinct is not true. Through DNA analyses, researchers at the University of Gothenburg have identified that there are still juvenile coastal cod off the west coast of Sweden. However, it is still difficult to find any mature adult cod in the area.
By genetically analyzing cod collected by test fishing, researchers from the University of Gothenburg and the Swedish University of Agricultural Sciences (SLU) have found that there are two distinct types of cod living in the waters along Sweden’s west coast. These types of cod belong to the same species—the Atlantic cod (Gadus morhua)—but they are different “ecotypes,” genetically adapted to different environments or lifestyles. The two types of cod found off the west coast are known as “offshore cod” and “coastal cod,” because one has its origins far out to sea, while the other resides close to the coast throughout its life. These two types of cod rarely mate with each other.
Coastal cod remain in the fjords
Many people have long believed that the west coast’s coastal cod have been completely fished out. But this new study, published in the ICES Journal of Marine Science, shows that there is still a cod population that spends all its life off the west coast of Sweden.
“Our analyses show that a high proportion of juvenile cod in the fjords and near the west coast of Sweden are coastal cod. That shows that there is still something left to save. But in the test fishing, you get very, very few adult cod. In test fishing near the coast, only a handful of cod over 40 centimeters in length were found,” says Simon…
2023-02-09 08:59:03 The coastal cod population is not extinct in Sweden, say researchers
Post from phys.org
The coastal cod population in Sweden is unlikely to be facing extinction, according to recent research done in the country. This finding is a relief to conservationists and the scientific community, who had feared the species was nearing the brink of extinction.
Research done by the Swedish Agency for Marine and Water Management (SWAM) has concluded that the coastal cod population, found mainly in the Baltic Sea, is stable and not at risk of rapid decline. This was confirmed by tests on samples of cod specimens collected from the Baltic to assess the general health of the species.
The SWAM research focused on three very important elements when assessing the health of the species in Sweden. The first was genetic diversity, with researchers evaluating the diversity of the species in order to ensure there was enough variation within the population, allowing cod to adapt to changes in environment. Next, the researchers looked at the spawning success, measuring the number of eggs produced and whether or not those eggs were successful in hatching. Lastly, the amount of food cod had access to in their habitat was determined, making sure there was enough to sustain the population.
The results were positive, with the coastal cod population meeting all criteria for healthy populations. This suggests that the species is not facing extinction, though it is still vulnerable to overfishing and habitat degradation, which are both major threats to the species.
The results of the study by SWAM come as welcome news to conservationists, who have long feared that the coastal cod population in Sweden could be in trouble. It appears that there is currently enough genetic variation and reproductive potential to keep the species stable and healthy in the country. The findings should also serve as a reminder that all measures need to be taken to safeguard coastal cod populations, to ensure that this success is sustained.