The International Union for Conservation of Nature (IUCN) has recognized the coasts of Cádiz and Huelva as the last areas in Europe with a stable population of the giant guitarfish (Glaucostegus cemiculus). This species, belonging to the ray family—cartilaginous fish related to sharks—is classified as Critically Endangered and is included in Spain’s List of Wild Species under Special Protection.
The declaration of the Gulf of Cádiz as an Area of Importance for Sharks and Rays (ISRA, in English) is part of the IUCN’s efforts to identify areas of interest for the protection of these threatened species on a global scale. Chondrichthyans (sharks, rays, and chimaeras) are facing a worldwide extinction crisis, with more than one-third of species estimated to be at risk of disappearing.
Fishing, especially over the last century, along with habitat loss and climate change, has worsened the situation. Coastal habitats host 75% of the threatened species, making sharks and rays one of the most vulnerable marine groups on the planet.
This is the case of the giant guitarfish (Glaucostegus cemiculus), which in recent years has disappeared from much of the European coastline due to threats such as bycatch, habitat loss, and human pressure. To reverse this situation, the Glaucostegus Project was launched—the first initiative in Europe to study these animals in their natural habitat—led by Dr. Jaime Penadés.
“With the declaration of this ISRA, the IUCN recognizes the efforts we have made over the past six years to improve knowledge of the giant guitarfish’s biology, ecology, and threats within Spanish waters. It also clearly sets a roadmap to enhance its protection at both the national and global levels. “, explains Penadés.”
The value of citizen science
The participation of recreational fishers is a key part of the project. Since 2018, Ángel Benítez, a recreational fisher and founder of the Glaucostegus Project, has coordinated the collection of data on accidental catches and sightings through his collaborations. Today, these data include over 80 confirmed observations of a species for which there had been hardly any recent records since 2008, when—after its protection—professional fleets stopped reporting their catches.
Anyone can contribute by sending photographs or videos of the specimen, including details such as the date, time, location of the encounter or catch, and any observations about the animal’s behavior. Thanks to these contributions, the presence of neonates has been confirmed in Cádiz and Huelva, indicating possible reproduction of the species in our waters.
“Everyone can contribute to science and the conservation of our species through citizen science. Different administrations and institutions should take into account both citizen collaboration initiatives and the recommendations and measures necessary for the conservation of our natural heritage, such as those of the IUCN in this case,” comments Ángel Benítez.
Threats to the species: poaching and post-capture stress
The Glaucostegus Project has also recorded cases of poaching, one of the ongoing threats to the species. Most findings involve severed heads left on beaches, with only the meat taken to conceal the capture of a protected species and hinder identification during potential inspections. Greater monitoring and enforcement are needed to reduce mortality.
Additionally, the project promotes rapid-release protocols in the event of accidental capture, with simple guidelines to minimize stress and reduce handling time.
The Glaucostegus Project is coordinated by the Oceanogràfic Foundation, the Fundación Azul Marino, the Aquarium of Seville, and the Associació LAMNA, all of which hold the permits and support of MITECO, the Regional Government of Andalusia, and the Doñana Biological Station. The project also collaborates with IFAPA, the University of Cádiz, the Lisbon Oceanário, Zoomarine Algarve, Seashore Environment & Fauna, as well as the Asociación Los Corrales de Rota and numerous local recreational fishers.