In this month's "In Depth" section of the Newsletter we talk about sharks, their presence on beaches, why they are important for the proper functioning of marine ecosystems and how to protect them.
In recent weeks sharks have been observed on Catalan beaches, which has forced the closure of some of them and has put swimmers on alert. Today we talk to Anabel Colmenero, an expert on these animals. She works in the Department of Renewable Marine Resources from the Institut de Ciències del Mar (ICM-CSIC) and is co-founder of the association Catsharks, which has been monitoring the different species of sharks in the Mediterranean for years. She also works with public administrations to contribute to their protection. Anabel has just returned from Greece, where she travelled with the Shark Specialist Group of the International Union for Conservation of Nature (IUCN) with the aim of identifying areas of interest for the protection of sharks and rays in the Mediterranean and Black Sea. He explains it to us in this interview.
1. Are there more sharks on the beaches now than some years ago?
There is really no scientific evidence to suggest that there are more sharks on the beaches. Social networks have a lot to do with the perception of the number of sightings. Before, when a shark was sighted, the information was not published on any social network, but now everyone has access to cell phones with cameras, something that did not happen 10 or 15 years ago. That is why the same sighting can appear on the networks dozens of times creating a false perception. It is also important to understand that sharks are marine animals that live in seas and oceans around the world. Some individuals may move closer to shore, especially when searching for food or when certain environmental or ecological changes occur. Hence, the number of sharks sighted in coastal areas may vary over time and from one location to another, but this does not necessarily imply that there are more of them.
2. Do they pose a danger to bathers?
Most shark species are not dangerous to humans, and there are no known recent shark incidents off our coasts. In fact, interactions between sharks and humans are relatively rare and, in most cases, sharks avoid contact with people. However, we must not forget that they are wild animals and, although they are not aggressive towards humans, it is necessary to take all precautions and avoid approaching them.
3. How should we act if we encounter them?
If a person sees a shark while swimming, he/she should remain calm (do not shout and avoid sudden movements) and move away from the shark. Once out of the water, call the lifeguards or call 112. It is also very important to upload the observation to the citizen science platform Sea Watchers and, specifically, to the Sharks and Rays Project.
4. Which is the most common species along the Catalan coast?
The blue shark (Prionace glauca), also known as blue shark. This species has a blue coloration and is easily recognized by its long and slightly curved dorsal fins. It can measure up to 3.8 meters, although the size of the individuals usually seen on our coasts is around 1.5-2 meters. It is a viviparous species and usually has 25 to 35 offspring. Their diet includes fish, squid and other marine animals and they can travel long distances in search of food. To humans, the blue shark is considered a relatively harmless species.
5. Are Mediterranean sharks endangered?
Most species are threatened or endangered. Among the most endangered sharks in the Mediterranean are blue, hammerhead and mako sharks, the latter being critically endangered. Currently, a total of 16 species of sharks are included in the Spanish list of protected species, although none of them is part of the catalogue of endangered species. This means that efforts to protect them are limited to the prohibition of catches, leaving aside research or plans for the study and monitoring of the different species listed. In the specific case of Catalonia, we can find 27 species of sharks and more than half of them are threatened with extinction due to fishing, both commercial and recreational, the degradation of the habitats in which they live and the impact of climate change.
6. Are there differences between the western and eastern parts of the basin?
In general, shark diversity is higher in the western Mediterranean than in the eastern part of the basin. This distribution gradient could be related to the proximity of the western side of the basin to the Atlantic, which favors the influx of species from the ocean into the Mediterranean.
7. And on a global scale?
The global pattern of shark diversity is very different from that of terrestrial animals and other marine taxa. Shark diversity is higher on continental shelves and in mid-latitudes (30-40 degrees N and S). In addition, there are specific points with high richness and endemism such as Japan, Taiwan, the coasts of Australia, southeastern Africa, southeastern Brazil and the southeastern United States. These patterns have to do with the optimal temperatures in these latitudes, but also with the presence of highly productive areas that present the optimal requirements for many of these species.
8. How can we protect sharks?
Several measures can be taken. Among them is the regulation of commercial and recreational fishing. In this sense, regulations and controls on shark fishing can be implemented, including limiting catches, closed seasons and minimum sizes for sharks caught. Finally, fishing for endangered species can be prohibited. In the end, promoting sustainable fishing and responsible use of marine resources is key, since proper management is key to recovering their populations, but also those of other marine species.
9. And what role do marine protected areas play?
The creation of marine reserves or areas of interest for sharks and rays is another protection measure that can be adopted. It involves establishing protected areas, such as marine reserves and natural parks, where fishing and other human activities that may negatively affect sharks and other marine species are prohibited or restricted. In this regard, areas of interest for sharks and rays (known as ISRAs), which are portions of the ocean important to one or more shark species that are delineated and have the potential to be managed for conservation, can also be determined.
10. What role does research play in protecting these animals?
Promoting and funding scientific research to improve knowledge about endangered shark species, their ecological needs and the risk factors affecting them is key to their protection. However, education and public awareness, which involves informing the public about the importance of shark conservation and their role in marine ecosystems, are also very important. In this sense, it is very important to promote environmental education and awareness to reduce prejudices and unfounded fears towards sharks.
11. Do you know of any success stories based on these protection measures?
Here I would like to point out that sharks have only recently begun to be studied in depth. For this reason, most of the scientific results have not yet been applied in management policies. However, several success stories can be highlighted, such as the shark sanctuaries in Palau, in the Pacific Ocean, or the banning of shark finning by the European Union in 2003.
12. What is being done at the ICM-CSIC?
Apart from research on trophic ecology, abundance and distribution of shark species on the Catalan coast, in 2019 a team from the ICM-CSIC founded Catsharks, a non-profit association whose objective is the study and conservation of elasmobranchs and their ecosystems through research and education. A little later, in 2020, the Sharks and Rays Project of the citizen science platform Sea Watchers was created, which tracks all shark and ray species around Catalonia and Spain. Finally, in 2021 a pioneering collaboration was initiated at the ICM-CSIC to carry out trandisciplinary art and science research in order to reach out in a different way to the citizenry.
13. Is there any action you are particularly proud of?
Yes, in 2022 Catsharks submitted a Protected Species Action Plan on sharks and rays to the Generalitat that allowed the inclusion of several of these species in the Catalogue of threatened native wildlife and measures for the protection and conservation of threatened native fauna of the Govern. Likewise, this year 2023, 6 ISRAs have been proposed for the Spanish Mediterranean, four of which are already accepted as areas of interest for sharks and rays, and the rest are in the revision phase.