Global Population Trends and Human Use Patterns of Manta and Mobula Rays

Despite being the world’s largest rays and providing significant revenue through dive tourism, little is known about the population status, exploitation, and trade volume of the Mobulidae (mobulids; Manta and Mobula spp.). There is anecdotal evidence, however, that mobulid populations are declining, largely due to the recent emergence of a widespread trade for their gill rakers. Researchers from Dalhousie University and eShark.org used expert divers’ observations from two citizen science programs, REEF's Volunteer Fish Survey Project and eShark.org, to describe global manta and devil ray abundance trends and human use patterns. The study highlights the relative rarity of aggregation sites on a global scale and reveals that many populations appear to be declining. The authors warn that newly emerging fisheries for the rays gill-­‐rakers likely exceed their ability to recover. The study also demonstrates the deficiency of official catch reports, as only four countries have ever reported landing manta or devil rays– Indonesia, Liberia, Spain and Ecuador. However, numerous diver reports compiled in the paper illustrate that many other countries are regularly landing and selling these rays without reporting.