Species distribution, occurrence, and abundance patterns are key information for two main factors. First, the scale of distribution ranges are an important factor for species conservation (endemic vs. widely distributed), patterns which are determined by both environmental and biological aspects. Second, these are crucial data to support species and ecosystem conservation efforts. Sharks, despite their generally wide distribution ranges, are currently one of the most endangered taxonomic groups in the world, mostly due to overfishing. However, almost half of all shark species are considered as Data Deficient (DD) by the International Union for the Conservation of Nature (IUCN), mostly due to the lack of basic biological information throughout their distribution ranges. Our goal was to investigate Carcharhinus porosus distribution range and habitat preferences to provide updated information for future conservation status evaluations. Data were obtained through the revision of both published literature and species records in global databases - records were considered valid only when specimens were deposited in fish collections.
Results/Conclusions
In the last IUCN evaluation in 2006, C. porosus was still considered to occur in both tropical to sub-tropical American coasts. However, its taxonomy was revised and the Pacific Ocean’s populations were designated as a different species, C. cerdale, thus considerably reducing its distribution range. Furthermore, most records from North and Central America come from between the 1970s and 1990s, thus new information from these areas are scarce. A total of 3458 records were found, from which 1503 (43%) were from the Northern Coast of South America (NCSA), which is considered this species’ global center of abundance. A single study from Mexico comprised 49% of all records (1695 specimens caught between 1993 and 1994). Further records are limited and span from the rest of Brazil’s coast (6.8%), to the United States (0.23%), and Nicaragua (0.02%). Overall, catches occurred in mangrove rich areas just like the NCSA. C. porosus is known to occur in highly turbid coastal waters with Avicennia mangrove forests, which comprise most of the NCSA coastal habitats as well. Thus, we argue that C. porosus has a much more restricted geographical range than previously thought, with a patchy distribution throughout the Atlantic ocean and larger populations in NCSA and Mexico’s coast, both subjected to intense fisheries bycatch. Due to habitat preferences, these could be reproductively isolated, but genetic structure studies are needed to investigate this in depth.