The size of anchovies from the Bay of Biscay has decreased in the last three decades. This is the conclusion of a study carried out by the AZTI technology center, specialized in marine and food research, which has just been published in the journal Global Change Biology.
The research covers three decades of scientific data (from 1990 to 2021), evidence that demonstrates a decrease in the size and average weight of adult individuals of the European anchovy (Engraulis encrasicolus L.). “The specimens are not only smaller, but they are also adopting a more slender shape,” the researchers point out.
Fernando Taboada, one of the main authors of the work, has pointed out that “the decrease in weight is more pronounced than in total length, with reduction rates that in the last 20 years have accelerated up to 25% per decade.”
A complex interaction of environmental factors, including ocean warming, are associated with the physiological changes experienced by anchovies. But the study rules out that fishing pressure has a significant influence.
“As there is more abundance of anchovy, the specimens are smaller, but this relationship with population density is less clear in more advanced stages, where temperature has been revealed as the main cause of the decrease in size,” he adds. his part Guillem Chust, another of the authors of the work.
Another conclusion of the experts is that the growth of young fish that live in warm waters is faster than that of specimens that live in colder environments. However, these conditions affect later development, and the animals reach a smaller adult body size.
Observations made by the center reveal that, in general, individuals from different European anchovy populations tend to be larger in colder seas. But, the authors warn, “it is crucial to be cautious, because the study is based on observations and has its limitations.”
“Additional evidence points, however, to the fact that the decrease in the size of the anchovy could be an indicator of the response to changes in climate and the functioning of the ecosystem of the Bay of Bizkaia,” they conclude.
