The studies on sharks initiated by the Departament d'Acció Climàtica, together with the Sotamar immersion center in Cadaqués, confirm the Cap de Creus canyon as a "stable" breeding area for blue sharks and one of the only places in the western Mediterranean where This endangered species reproduces.
Between late spring and mid-August, about 90 specimens have been observed, ten of them babies measuring between 35 and 45 centimeters.
Studies also confirm that births are concentrated between mid-June and July. And once they are born, sharks are already completely capable of taking care of themselves. Afterwards, most of the adult specimens leave.
The project began to take shape between 2018 and 2019 with the help of the person in charge of the Sotamar immersion center, Jordi Riera.
Riera is passionate about sharks - he has been diving all over the world for years - and around that time he began to make sporadic outings to see if there were also any in this area of Cap de Creus.
Between 2020 and 2021 he began to glimpse the first specimens, although in very testimonial outings and from 2022 he decided to carry out a well-conducted study with two biologists and regular outings.
Between the months of April and September, it made a total of 54 outings attracting specimens with fish viscera. In total, he observed more than sixty between the months of June and July. Many of them babies. This pointed to the possibility that it was a breeding point for that species.
The proposal aroused the interest of the scientific community and also of the Department of Climate Action. And this 2023 they have come together to work together. From late spring to mid-August, around fifty outings have been made and around ten hatchlings of this species out of a total of 90 specimens have been observed.
The head of invasive species and conservation projects of Acció Climàtica, Jordi Ruiz, says that these are "extraordinary" data.
"Sharks have a gestation period of 12 months. Therefore, when they come here, both things coincide: birth and reproduction. This means that at such an important time for them, we have them here," explains Ruiz.
And this happens in "very specific" places. "If we look at the data, small specimens never appear because they only breed in very specific places in the Mediterranean. That we have seen ten is a lot," adds Ruiz.
Now, the Department wants to expand knowledge about the movements they make and their behavior through surveillance from boats, with attractants and direct observation. This will allow the development of an interannual census and monitoring system and follow-up. And after observations and births, towards mid-July they lose track of them.
"Nine out of ten we didn't see them anymore," he explains. They do not know if they hide in deeper waters or look for other areas after the first weeks of birth. This is what they now want to investigate.
To this end, Acció Climàtica is beginning to collaborate with the few teams that currently work with sharks in Catalonia, such as the Institute of Marine Sciences, the University of Barcelona, the University of Girona, CatShark and the Barcelona Zoo Foundation.
The second phase of the study, which will be launched in 2024, will cost 50,000 euros. The intention is to continue with the surveys and also mark some specimens and try to take tissue samples.
"We want to see the movements that those that reproduce here make and try to see where they live because we are beginning to see that perhaps the greatest risks to their survival are outside Catalan waters," Ruiz remarks.
Currently, most of the information about sharks comes from fishing activity and has little to do with the animals observed in their environment. The species of sharks that live in Catalonia - such as the blue shark - live in deep waters.
A study carried out by European researchers from different countries that marked dozens of blue sharks with satellite transmitters shows that it is very rare for them to approach waters less than 100 meters deep. Therefore, most of the specimens that can be observed very occasionally on the beaches either arrive injured or are individuals that have arrived dead or sick on the coast.
In fact, observations in this place have always been made from the "ledge" of the canyon in an area whose depths range from 200 to 500 meters. "When we have done it near the coast, we have not seen it," adds Ruiz.
Researchers believe that the Gulf of Lion area is a favorite place for this species. In fact, it is known that they also have a presence in a canyon on the French side and there is evidence of the observation of a small blue shark in the Begur canyon.
"Now we know that the Cap de Creus canyon is an important place for blue sharks not only in Catalonia but throughout the western Mediterranean. We know that there is a very specific concentration over time and, therefore, we have a very great responsibility in the conservation of this site," he says. "This, he says, must be done with the complicity of the professional and recreational fishing sector to prevent accidental captures."
"It is an area with pronounced relief that gives them opportunities to find food and protect themselves from predators and also has a well-known increase in nutrients," he details. This makes the area a favorable point for their reproduction because once the babies are born and go out to look for food, they have a better chance of finding food.
The blue shark is one of the seventy species of sharks and pods that live in the Mediterranean. In the Catalan Sea there are 26 species of sharks, a significant part of which are in danger of extinction or in critical condition, as is the case of the blue shark, according to data collected by the Department through the evaluation commissioned in 2020 in the CatShark entity, to have more information about the state of shark populations and pods in Catalonia.
