The geographic distribution of reef and oceanic manta rays in the south-east Indian and south-west Pacific Oceans

Abstract

The reef manta ray, Mobula alfredi, occurs in tropical and warm temperate coastal 15 waters, and around islands and reefs in the Pacific and Indian Oceans. Published records that relate 16 to the distribution of M. alfredi in the south-east Indian and south-west Pacific Oceans are largely 17 restricted to locations where there is a focus on manta ray ecotourism, with little information from 18 elsewhere. Even less is known about the circumglobally distributed oceanic manta ray, 19 Mobula birostris, for which there are few published sighting records. We collated n = 11,703 20 sighting records from Australian waters and offshore territories for M. alfredi sourced from 21 scientific image databases (n = 10,715), aerial surveys (n = 375) and online reports (n = 613). From 22 collated records, we confirm that the species shows an uninterrupted distribution within Australian 23 coastal waters north of 26°S on the west coast to 31°S on the east coast, with a southernmost record 24 at 34°S. Confirmed locations for M. birostris encompass a latitudinal range of 10-40°S. Records 25 from more southerly locations relate to warm-water events. Sightings of M. birostris were rare, 26 but were confirmed at several geographically separate locations, probably reflecting its preference 27 for offshore waters. The study clarifies the occurrence and range of each species within coastal 28 waters of the south-east Indian and south-west Pacific Oceans, and highlights regions in northern 29 Australia that are of specific interest for future research into possible movements of individuals 30 between international marine jurisdictions.31

Flapping about: trends and drivers of Australian cownose ray (Rhinoptera neglecta) coastal sightings at their southernmost distribution range

“…The distribution, movement, and behavior of elasmobranchs are often complex and difficult to elucidate due to the myriad of potential biotic and abiotic drivers of habitat use (2,3). Biotic influences encompass the need to forage and find suitable prey (4)(5)(6), predator avoidance (7), reproduction (8), and symbiotic relationships (9,10). In addition, a range of abiotic factors can also influence the occurrence and behavior of elasmobranchs, including sea temperature (11,12), tidal and lunar cycles (9,(13)(14)(15), salinity gradients (16,17), rainfall (18,19), barometric pressure (20,21), and dissolved oxygen (22).…”