Population distribution, aggregation sites and seasonal occurrence of Australia’s western population of the grey nurse shark Carcharias taurus

Western Australia (WA) is host to a genetically discrete population of grey nurse sharks Carcharias taurus , listed by the IUCN as Near Threatened based on mean annual catch rates prior protection within Australian waters in 1997. Only one small aggregation has been documented WA date with little data available dynamics, or spatial and temporal distribution along coastline. We analysed C. from 16 years (2006-2021) diver observations (2347 sightings) commercial fisheries bycatch records (574 sharks), finding evidence 4 new sites. Sightings at Shark Cave, popular dive site near Perth, were related water temperature time year (non-linear), sightings per unit effort generally higher during warmer months summer autumn (20-22°C). Evidence fishing injuries was found 17% all photo-tagged Cave. Strong philopatry apparent most sites, included male shark that returned for 12 consecutive Exmouth Navy Pier. This study confirms range Australia’s western South Australia/WA border, north Bay, extending further coast when sea temperatures are lower (May-December). The beneficial role citizen science large observation studies such this supported. However, while research greatly increases knowledge base WA, information deficit still exists. identification assessment sites recommended, underpinning future management measures iconic species.