Study links recovery of rays in the Balearic Islands to lower fishing pressure

A team of researchers from the Spanish Institute of Oceanography (IEO-CSIC) has found that several ray species in the Balearic Islands have shown signs of recovery in recent years, associated with reduced fishing pressure.

According to a statement, the study, carried out in collaboration with the University of the Balearic Islands (UIB) and the Institute of Marine Research (IIM-CSIC), links this recovery to the sustained reduction of the fishing fleet over recent decades and to the decrease in the number of fishing days available for the trawling fleet.

For the study, researchers analysed more than 180 genetic sequences from seven species, assessing the diversity of the mitochondrial COI gene and comparing it with ray populations from the Mediterranean and the North Atlantic.

The results show that species such as the thornback ray and the longnosed skate present low levels of genetic diversity, indicating that in the past they experienced episodes of intense fishing exploitation that reduced their variability.

Even so, the assessment models reflect a more sustainable current scenario, driven by the decline in fishing effort over the past two decades and recently reinforced by the implementation of the multiannual plan for demersal fishing in the western Mediterranean.

As a result, these species have experienced a recovery in abundance in recent years and are now at sustainable exploitation levels, while the spotted ray, another Mediterranean species, remains stable.

Researcher Francesca Ferragut-Perelló, lead author of the study, said that in order to understand the real state of marine populations, it is “essential” to understand their capacity for adaptation as well as their level of exploitation. She argued that combining both perspectives is key to designing more effective management strategies.

The study was made possible thanks to the MEDITS surveys, carried out in coordination between the IEO and the Ministry of Agriculture, Fisheries and Food, which facilitate the use of oceanographic vessels for research.