- The Oceanogràfic Foundation, the Azul Marino Foundation, the Seville Aquarium, and the LAMNA Association are coordinating, along with other entities, the Glaucostegus Project, an initiative to save the last European population of the guitarfish, a species listed as Critically Endangered.
- Since 2018, recreational fishermen have provided images and data that have confirmed the reproduction of the guitarrón and detected cases of poaching along the Andalusian coast.
Cádiz, June 18, 2025.– The coasts of Cádiz and Huelva are the last places in Europe where a stable population of the giant guitarfish or guitarrón (Glaucostegus cemiculus) can be found, a species of cartilaginous ray related to sharks and listed as Critically Endangered by the International Union for Conservation of Nature (IUCN).
In recent years, the species has disappeared from much of the European coastline due to multiple threats such as bycatch, habitat loss, and human pressure. To reverse this situation, the Glaucostegus Project was created, the first initiative to study these animals in their natural habitat in Europe.
The research, led by Dr. Jaime Penadés, aims to generate scientific knowledge about the biology, ecology, and threats to the guitarrón in its habitat. “With this study, we will be able to obtain information on the status of this species on the Andalusian coast, its reproduction, habitat use, and threats—vital information for improving its protection nationally and globally,” explains Penadés.
The value of citizen science
The Glaucostegus Project is an initiative coordinated by the Oceanogràfic Foundation, the Azul Marino Foundation, the Seville Aquarium, and the LAMNA Association, with permission and support from MITECO, the Andalusian Regional Government, and the Doñana Biological Station. Other collaborators are IFAPA, the University of Cádiz, the Lisbon Oceanarium, Zoomarine Algarve, Seashore Environment & Fauna, the Los Corrales de Rota Association, and numerous recreational fishermen in the area.
The participation of these recreational fishermen is a fundamental part of the project. Since 2018, Ángel Benítez, founder of the Glaucostegus Project, began collecting incidental catch data thanks to their collaborations. Today, this data exceeds 80 confirmed sightings of a species for which there were hardly any recent records.
Fishermen collaborate by sending a photo or video showing the specimen, as well as providing information such as the date, time, location of capture, and type of bait. This citizen participation has been essential to confirm reproduction in the area—with sightings of newborns—and to detect cases of poaching, one of the latent threats to the species.
Scientific sampling campaigns
In parallel with the collection of citizen data, the first scientific sampling campaign of 2025 was carried out at the end of May. More than 40 researchers traveled to Valdelagrana Beach, in the Bay of Cádiz. During this campaign, 33 specimens of the guitarrón were handled, both juveniles and adults.
These scientific surveys are conducted under MITECO permits and follow a species-specific protocol that reduces handling times. These efforts provide information about the species in the area, such as specimen size, sex, DNA samples, blood samples, and other biological variables that allow for assessing their health status.
A hope for the species
The knowledge generated by the Glaucostegus Project opens the door to new conservation strategies. Among them is the comparative genetic study of specimens kept in the zoological collections of four of the main aquariums on the Iberian Peninsula.
This approach will allow for the assessment of the viability of an ex situ reproduction plan for the species, with a view to possible future reintroduction in areas considered safe.
“In the context of the UN-declared Ocean Decade and the challenge of restoring nature in Europe, the guitarrón is a symbol of everything we still have to do, an opportunity to act before it’s too late for this and many other species. By working collaboratively, we can significantly increase our impact on marine conservation,” concludes Jaime Penadés.