New inland records of the bull shark Carcharhinus leucas from Sumatra, Indonesia

Abstract

Six new records of the bull shark Carcharhinus leucas from five different river basins of Sumatra, Indonesia, were reported as a result of captures by artisanal and recreational fishers, including records from rivers of northern and western Sumatra for the first time. These findings may higlight the importance of Sumatran river basins for the reproduction of this threatened species in Indonesian waters. Inland records of C. leucas in Southeast Asia and in particular Indonesia are scarce but important for nature conservation purposes and sustainable future fishery management.

Photographic evidence from a recreational angler of the northernmost record of the bull shark Carcharhinus leucas (Elasmobranchii: Carcharhinidae) in the western Pacific Ocean

“…Citizen science can also be expected to contribute to the accumulation of biological information on endangered sharks, such as the whale shark ( Rhincodon typus ; Araujo et al ., 2020), as well as observations of human and marine wildlife interactions (Pirotta et al ., 2022), being an information source not readily available to researchers or administrations (Miyazaki et al ., 2014; Eitzel et al ., 2017). As is the case with this study, the information or materials gained by recreational anglers could provide scientists with valuable evidence for fishery management and the critical habitat of sharks (Gibson et al ., 2019; Gausmann and Hasan, 2022). Especially in recent years, the magnitude of the contribution of those anglers for this topic in data-poor regions with some barriers to research such as financial limits and logistical difficulties has been emphasized (Gausmann and Hasan, 2022).…”

“…As is the case with this study, the information or materials gained by recreational anglers could provide scientists with valuable evidence for fishery management and the critical habitat of sharks (Gibson et al ., 2019; Gausmann and Hasan, 2022). Especially in recent years, the magnitude of the contribution of those anglers for this topic in data-poor regions with some barriers to research such as financial limits and logistical difficulties has been emphasized (Gausmann and Hasan, 2022).…”

“…In fact, several citizen groups have been formed in some regions, with initiatives for shark conservation (Bargnesi et al ., 2020), there being a shift in perception from protecting humans from sharks to protecting sharks from humans (Simpfendorfer et al ., 2011). Although the number of cases of records deriving from citizen science by recreational anglers is increasing (Gibson et al ., 2019; Gausmann and Hasan, 2022), the amount of shark research involving citizen science remains still small, with most studies having been conducted by scuba divers (Bargnesi et al ., 2020). Here, we provide photographic evidence of an immature specimen of C. leucas that was caught by a recreational angler which represents the northernmost record of this species in the western Pacific Ocean.…”

Updates on putative bull shark (Carcharhinus leucas) occurrences in the upper Mississippi River Basin of North America

“…There is already evidence for these behavioral shifts in the global fossil record of bull sharks dating back at least as far as the Pleistocene (Lopes et al 2020) and opportunistic exploration by bull sharks into man-made waterways are well documented worldwide (Alive... 1896;Montoya and Thorson 1982;Werry et al 2012;Curtis et al 2013). There are increased reports of bull sharks in these environments globally (Gausmann 2021;Hasan et al 2021;Gausmann and Hasan 2022), though it could be due to increased effort to gather these records rather than a behavioral shift.…”

First record of the bull shark Carcharhinus leucas (Valenciennes, 1839) from the Maldivian archipelago, central Indian Ocean

“…Sightings of bull sharks have been recorded in various locations, including the Seychelles, the continental coast of the Indian subcontinent, Sri Lanka, and Reunion Island (Blaison et al, 2015;Fernando, 2014;Hoarau et al, 2021;Nevill et al, 2013). This remarkable distribution raises intriguing questions about their reproductive behavior, as they rely on low-salinity environments like estuaries, river mouths, and freshwater rivers (Gausmann & Hasan, 2022;Heupel et al, 2007;Snelson et al, 1984…”