Two’s company: first record of two free-swimming megamouth sharks, Megachasma pelagios (Lamniformes: Megachasmidae), off the California coast

Abstract

On September 11, 2022, two megamouth sharks (Megachasma pelagios), estimated at 3.7–4.6 m TL, were observed swimming together near the surface about 39 km off the coast of San Diego, CA, USA. Megamouth sharks are rarely observed pelagic sharks, and the film from this encounter provided new insight into the social behavior of this species. We attempt to put the behavior of these two individuals into the context of past sightings, known megamouth shark biology, and with analogous behavior observed in other shark and pelagic fish species.

First record of the megamouth shark Megachasma pelagios (Lamniformes: Megachasmidae), from the United Republic of Tanzania

“…The specimen still had all fins intact (Figure 2C) and the meat was likely sold for local consumption. This record of M. pelagios is the first ever from the United Republic of Tanzania or anywhere along the East African coastline and represents the 274 th published record globally after the two most recent sightings in September 2022 off California (Skelton et al 2023). Furthermore, this specimen is only the 8 th record from the Indian Ocean, the 6 th record from Africa, the second record of this species from FAO Major Fishing Area 51-Western Indian Ocean (FAO 2023), and the first ever record from the Western Indian Ocean Marine Province as defined by Spalding et al (2007).…”

“…From 1976 to 2010 M. pelagios was considered rare, with only 50 individuals recorded globally during that time (Nakaya 2010). In recent years it is apparent that it is more common and widespread than previously thought, with 273 confirmed records to date across 16 countries in the Atlantic, Indian and Pacific Oceans (Yu et al 2021;Diez et al 2022;Skelton et al 2023). This species is classified as Least Concern on the IUCN Red List of Threatened Species, as it is globally distributed and does not appear to be heavily impacted by fisheries (Kyne et al 2019).…”