Collaborative methods identify a remote global diversity hotspot of threatened, large‐bodied rhino rays

Abstract

North‐western Australia is considered a refuge to several highly threatened elasmobranch species, but there has been little research effort targeting lesser known, large‐bodied rhino rays. This study identified 2,343 records of globally threatened rays of the order Rhinopristiformes from the Pilbara region of Western Australia, with a focus on the Ningaloo Coast World Heritage Area and adjacent Exmouth Gulf. Occurrence data were compiled from various sources including commercial fishing reports (35%), citizen science records (34%), targeted scientific surveys (30%) and published literature (1%). The region was inhabited by all of Australia's Pristidae (four sawfish species), all of Australia's Rhinidae (three wedgefish species) and the sole Australian representative of the Glaucostegidae (giant shovelnose ray). Of the 2,343 records, ~49% were sawfishes, while giant guitarfish and wedgefishes contributed to ~33% and 18% of records, respectively. The Exmouth Gulf appears to be a globally important refuge and pupping area for green sawfish (Pristis zijsron) which was the most commonly encountered pristid. Bottlenose wedgefish (Rhynchobatus australiae) were the most commonly identified rhinid, with less frequent encounters of shark rays (Rhina ancylostoma) and eyebrow wedgefish (Rhynchobatus palpebratus). The Ningaloo Coast World Heritage Area and adjacent Exmouth Gulf host all life stages of giant shovelnose ray (Glaucostegus typus). The combined use of several data sources has highlighted the study region as a ‘lifeboat’ for these globally threatened large‐bodied rays. These data are essential in creating effective conservation and management plans in this globally important refuge, and are highly relevant to global conservation initiatives.