Chondrichthyans, a class of aquatic vertebrates (sharks, rays, and chimaeras), are facing a global extinction crisis driven by overfishing, habitat degradation, climate change, and pollution. Of the approximately 1,250 species studied, more than one third (37%) are at risk of extinction according to the International Union for Conservation of Nature Red List, making this group the second most threatened among vertebrates. There is limited biological and ecological information available on chondrichthyans, which hinders the identification of critical habitats. As a response, the Important Shark and Ray Areas (ISRA) approach was developed a tool designed to map essential areas for the life cycle processes of these species.
The aim of this research was to assess differences in the scientific approach and outcomes related to chondrichthyans in the Pacific region of Central and South America, in order to identify priority areas for their conservation. Four main aspects were analyzed: the existing information available to delineate critical habitats, the spatial representativeness of ISRAs, the most common species and ecological traits involved in the process, and the potential of the ISRA approach to guide conservation actions and spatial management where chondrichthyans are found. This study was conducted in a highly diverse region, home to 96 species of sharks, 83 rays, and 11 chimaeras, representing 15% of the global diversity of chondrichthyans.
The methodology included dividing the region into six biogeographic subregions, ranging from the Gulf of California to southern Chile, covering both Exclusive Economic Zones and Areas Beyond National Jurisdiction. Of the 821 studies reviewed, 48.51% met the necessary criteria to scientifically support the process of identifying Important Shark and Ray Areas. Monitoring of young of the year (YOY) individuals was applied to identify nursery areas for the species, along with local ecological knowledge (LEK), environmental DNA (eDNA) to detect species through genetic traces in the water, and technological tools such as BRUVS (baited remote underwater video systems), ROVs (remotely operated vehicles), among others.
ISRAs were defined based on ecological criteria such as vulnerability, reproductive, feeding, and movement areas, as well as species diversity and restricted range. A total of 65 ISRAs were identified for 97 of the 190 reported chondrichthyan species in the region.
The results revealed a concentration of ISRAs along the Central American Pacific coast (52.30%), and a low representativeness in oceanic and southern zones, highlighting significant gaps in ecological knowledge. Most of the qualified threatened species, particularly sharks and rays, were included in at least one ISRA. However, deep water species, chimaeras, and those with restricted distributions remain poorly represented. These findings highlight the urgent need to strengthen research and monitoring efforts in these lesser studied regions, ensure the protection of critical habitats, and support effective conservation policies based on scientific evidence.
Read the article here: https://doi.org/10.1371/journal.pone.0322445
