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ISRA FACTSHEETS

NEW ZEALAND & PACIFIC ISLANDS REGION

ISRA FACTSHEETS

NEW ZEALAND & PACIFIC ISLANDS REGION

Betikel ISRA

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Betikel ISRA

Betikel

Summary

Betikel is located in Ulebsechel Island, Koror in Palau. The area is a shallow basin that allows nutrient exchange during tidal changes between the semi marine Risong Lake and the Ngel Channel. Betikel is characterised by a shallow shelf with a sandy substrate, a seagrass bed, and is surrounded by mangroves. Within this area there are: threatened species and reproductive areas (Blacktip Reef Shark Carcharhinus melanopterus).

Betikel

Betikel

DESCRIPTION OF HABITAT

Betikel is located in Ulebsechel Island, Koror in Palau. The area is a shallow basin with an entrance that allows nutrient exchange during tide changes between the semi-marine Risong Lake and the Ngel Channel (Colin 2009). Ngel Channel has strong currents and is one of two channels draining Malakal Harbour on its eastern side (Colin 2009). Betikel is characterised by a shallow shelf with a sandy substrate, a seagrass bed, and is surrounded by mangroves (T Harel-Bornovski pers. obs. 2024). The area is also connected by shallow sill areas to the more general lagoon area the open ocean by a narrow channel (Colin 2009). Depth in the area is driven by the tide entering ocean water in the area mainly through the channel on the flood tide and exiting mixed water from the lagoon on the ebb tide (Colin 2009).

This Important Shark and Ray Area is benthic and pelagic and is delineated from inshore and surface waters (0 m) to 10 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 Vulnerable Blacktip Reef Shark (Simpfendorfer et al 2020).

CRITERION C

SUB-CRITERION C1 – REPRODUCTIVE AREAS

Betikel is an important reproductive area for one shark species.

Observations of up to seven Blacktip Reef Sharks at a time have regularly and predictably been observed in the area (T Harel-Bornovski pers. obs. 2009–2024). The area has a narrow entrance fed by ocean water, and at low tide the Blacktip Reef Sharks use the mangroves to enter the area. Neonates are almost always seen during the incoming tide, especially during new moon and full moon in <1 m depth (T Harel-Bornovski pers. obs. 2024). The area is known locally as ‘Black Tip Lake’. The seasonality of these sightings has yet to be determined. However, Blacktip Reef Sharks within this area are the smallest size classes observed across Palau (visually estimated ~25 cm total length [TL]; T Harel-Bornovski pers. obs. 2024). Blacktip Reef Shark size-at-birth is 30–52 cm TL (Ebert et al. 2021), confirming that the individuals observed were neonates or young-of-the-year (YOY).

Between 2021–2024, ~12–15 Baited Remote Underwater Video Station surveys were deployed between 2–10 m depth (duration 30–60 minutes). Up to three neonates and YOY Blacktip Reef Sharks (visually estimated at 25–60 cm total length [TL]) were recorded on ~80% of recordings (T Harel-Bornovski unpubl. data 2024).

Local ecological knowledge confirms the importance of this area for reproduction over several decades. Gravid female Blacktip Reef Sharks are reported to venture into the area to give birth (Boundless Journeys 2021).

Betikel

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