ISRA FACTSHEETS
ISRA FACTSHEETS
NEW ZEALAND & PACIFIC ISLANDS REGION
Uchelbeluu Reef
Summary
Uchelbeluu Reef is located in Koror, Palau. The area is characterised by a habitat encompasses a shallow reef covered with large coral heads, a steep slope with crevices and canyons, and a vertical wall that goes down to 40 meters. Within this area there are: threatened species and undefined aggregations (Grey Reef Shark Carcharhinus amblyrhynchos).
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Uchelbeluu Reef
DESCRIPTION OF HABITAT
Uchelbeluu Reef is located in Koror, Palau. A dive site, known locally as ‘Short Drop Off’, is located in the southern corner of the area (Harel-Bornovski & Bornovski 2015). The habitat encompasses a shallow reef (3–8 m) covered with large coral heads, a steep slope with crevices and canyons (8–30 m), and a vertical wall that descends to 40 m depth (Harel-Bornovski & Bornovski 2015). The current usually sweeps along the reef flowing from north to south during the outgoing tide (Colin 2009, Harel-Bornovski & Bornovski 2015).
This Important Shark and Ray Area is benthic and pelagic and is delineated from surface waters (0 m) to 40 m based on the bathymetry of the area.
CRITERION A
VULNERABILITY
One Qualifying Species considered threatened with extinction according to the IUCN Red List of Threatened Species regularly occurs in the area. This is the Endangered Grey Reef Shark (Simpfendorfer et al. 2020).
CRITERION C
SUB-CRITERION C5 – UNDEFINED AGGREGATIONS
Uchelbeluu Reef is an important area for undefined aggregations of one shark species.
Grey Reef Sharks are regularly and predictably observed in the area. Recreational divers visit Uchelbeluu Reef year-round (~once a week), and aggregations of between 10–50 Grey Reef Sharks are observed on 80% of dives (T Harel-Bornowski pers. obs. 2009-2024). Most aggregations are observed at depths between 15–40 m. Shark counts were conducted by dive guides at 52 dive sites (n = 2,360 dives) in Palau from October 2007 to November 2012. The number of Grey Reef Sharks in Uchelbeluu Reef ranged from 3–150 (average = 11) and included all size classes (T Harel-Bornowski unpubl. data 2012). Records of Grey Reef Shark aggregations at the ‘Short Drop Off’ dive site within the area are also available on social media channels. The current usually sweeps along the reef in this area (Colin 2009), and the current strength in Palau has been positively correlated with the abundance of Grey Reef Sharks (Vianna et al. 2013). Between September and November, young-of-the-year (YOY) Grey Reef Sharks comprise most of the aggregations within this area. Visual estimates of their total length (TL) ranged between 60–80 cm TL (T Harel-Bornovski pers. obs. 2009–2024). The size-at-birth of this species is 45–60 cm TL (Ebert et al. 2021), indicating that most would classify as YOY. However, further information is required to understand the nature and function of this aggregation.
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