In Costa Rica, 29 species of sharks and rays have been studied, of which 66% are in danger of extinction, according to a report by scientists from the University of Costa Rica (UCR). Sharks and rays are organisms that contribute to the health of the oceans. These large predators in the food chain help maintain balance and biodiversity in marine environments, which has economic benefits for fishing and tourism. Knowing the distribution, abundance and diversity of the populations of these species, as well as their threats, is crucial to implement effective conservation measures.
In the last four years, scientists from the UCR, with the collaboration of the National System of Conservation Areas (Sinac) of the Ministry of Environment and Energy, have monitored these species with underwater cameras. The methodology is used for the first time in the country in a wide-ranging study. The results of the research were published by the specialized journal Scientific Reports on the previous October 14.
Marine biologist Mario Espinoza Mendiola, professor and researcher at the Center for Research in Marine Sciences and Limnology (CIMAR) and the School of Biology, UCR, stated that a wide variety of coastal and offshore habitats were examined in areas up to 60 meters deep, to record the species of sharks and rays associated with rocky and coral reefs.
Remote underwater baited video cameras were first used in 2003 in some countries to detect aquatic predatory species. The use of this technology has been growing gradually, as it offers a number of advantages compared to traditional methods with limitations in scope, depth and time.
The study monitored protected areas, including Isla del Coco National Park, Isla del Caño and the Murcielago Islands, and unprotected areas exposed to fishing activities. Among the main findings, it was possible to detect 54% of the diversity of species of sharks and rays of the Costa Rican Pacific that inhabit shallow waters. The percentage is very representative, according to the researchers, because it reaffirms the effectiveness of the method used to have a broad view of the various species and to monitor them in the future. “It is necessary to have a baseline study of how our shark and ray species are, where they are distributed, what kind of environments they like and how they change over time, to monitor them, especially since many are threatened by overfishing, the degradation of habitats and climate change”, said Espinoza.
The research also made it possible to determine that the greatest abundance of sharks and the largest species are found in marine protected areas. This is attributed to the management, availability of resources and surveillance in these environments, which are subject to constant pressure from illegal fishing.
“The positive fact is that we found a relationship between the marine protected areas system with the presence of large sharks, such as the tiger, the bull and the hammerhead. These are fundamental species and true top predators that control the abundance of other sharks and rays”, assured the researcher.
On the contrary, in the sites open to fishing, fewer sharks were observed, but there was an abundance of rays. This is explained by the fact that many sharks feed on rays and since there are no sharks in those places open to fishing, the number of rays increases. For researchers, this is an indication that something is not right in the coastal environments of Costa Rica.
In the study, they point out that illegal fishing continues to be the main threat to sharks and rays and emphasize the need to protect their habitats. Some species, such as the hammerhead shark, require areas such as mangroves, estuaries, and river mouths for breeding and rearing activities.
The Executive Director and Chief Scientist of “Beneath the Waves”, an NGO involved in shark conservation projects in the Caribbean, Dr. Austin Gallagher, stated that this study “unequivocally demonstrates the positive benefits of marine protected areas on many threatened shark species, and this publication sets an important standard for future monitoring of sharks and rays in the tropics.”
The park ranger of the Isla del Coco National Park, Isaac Chinchilla, co-author of this study, played a very important role in the field work and capacity building of his colleagues. His participation allowed him “to consolidate the value of perseverance and the ability to solve problems to adapt to the unknown and complex that results in investigating species from the bottom of the sea.”
The researchers who participated in the study, entitled “Monitoring of Elasmobranchs” (sharks and rays in a country in the eastern tropical Pacific with little data, by means of remote underwater video cameras with bait, are Mario Espinoza, Tatiana Araya Arce, Isaac Chaves Zamora; Isaac Chinchilla and Marta Cambra.
In Costa Rica there are 93 species of sharks, of which 43 (53%) are in danger of extinction, including the two that are fished the most in the country, according to data from the International Union for Conservation of Nature (IUCN). These species are: -Silky shark (Carcharhinus falciformis) -Hammer shark (Sphyrna lewini). Both species are part of Appendix II of the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES, for its acronym in English), where the lists of species protected against excessive exploitation are included.