Sharks are “top predators” in the food chain and, compared to other organisms (bony fish, crustaceans, mollusks), they have a lower reproductive and natural mortality rate. These characteristics make sharks particularly vulnerable to overfishing, because in the face of constant fishing pressure, they will take much longer to recover. Despite this, in the last two decades the shark fishery has intensified. A recent global assessment using data from the International Union for Conservation of Nature (IUCN) found that a quarter of all shark and ray species are at risk of extinction, making them the most endangered group of marine vertebrates today. .
Sharks of Cocos Island National Park
Cocos Island is known as the “shark island” as it is one of the few refuges in the world where it is still possible to observe a great abundance of various species of sharks, which is why it is visited by hundreds of tourists every year. . This World Heritage Site boasts the largest congregations of hammerhead sharks (Sphyrmalewini) in the world in the Pacific Ocean. Cocos Island is of great importance for the conservation of a set of pelagic species (e.g. sharks, manta rays, rays, tuna, dorado, swordfish), being one of the most important gene banks in the Eastern Tropical Pacific.
14 species of sharks have been reported in the PNIC. Some species are resident, such as the whitetip reef shark (Triaenodonobesus), while others are highly migratory, such as the hammerhead shark (S. lewini) and the whale shark (Rhincodontypus). The underwater mountains, islets, and bays of the PNIC represent essential habitats (feeding, resting, cleaning, copulation areas) for the different species of sharks.
Research
Cocos Island National Park (PNIC) is part of the Eastern Tropical Pacific Marine Corridor (CMAR). To implement transboundary conservation strategies for pelagic species such as sharks, rays and turtles, it is necessary to generate information about habitat use, residence patterns and migratory routes (Hearn et al. 2014). The information on the movement of species allows us to identify other sites of importance for the conservation of these species within the Eastern Tropical Pacific, where it will be necessary to implement management actions. Despite the efforts that have been made to mark several species of sharks, only in Sphyrnalewini (hammer shark) have migratory movements between the continental islands of the Eastern Tropical Pacific been clearly documented. However, the PNIC and AMMB are important sites for many other pelagic species.
In the case of the Marine Conservation Area (ACMC), an enormous effort is being made in terms of research and ecological monitoring about sharks, their populations and migration patterns. Some of these efforts are thanks to the support of allies such as FAICO, CIMAR-UCR and MisiónTiburón (eg. Zanella et al. 2015), ACMC seeks to generate information for the effective conservation of pelagic species.
