ISRA FACTSHEETS
ISRA FACTSHEETS
NEW ZEALAND & PACIFIC ISLANDS REGION
Long Lake
Summary
Long Lake is located in the Koror State of Palau. The habitat in the area includes a small shallow bay characterised by sandy substrates with seagrass and small coral heads. A mangrove channel connects the bay and the lagoon, and is mostly dry during low tide. The lagoon is characterised by sandy substrate on the edges and silt in the middle deeper part. Within this area there are: threatened species and reproductive areas (Blacktip Reef Shark Carcharhinus melanopterus).
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Long Lake
DESCRIPTION OF HABITAT
Long Lake is located in the Koror State of Palau. The area is formed by a group of basins and feeding channels found in the valleys between long lines of elevated fossil reefs (Colin 2009). Long Lake sits in two connected valleys between ridges and includes a connection to the lagoon by a few tunnels and an exceptionally long sill that feeds the Long Lake complex by tidal currents (Colin 2009). The habitat includes a very small shallow bay with a sandy substrate, seagrass beds, and small coral heads. A mangrove channel connects the bay and the lagoon is mostly dry during low tide and ~1 m depth during high tide.
This Important Shark and Ray Area is delineated from 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
Long Lake is an important reproductive area for one shark species.
Between 1998–2024, up to 12 neonates and/or young-of-the-year (YOY) Blacktip Reef Sharks were observed per sighting during high tide in the area. These sightings occurred in approximately 80% of ~30 kayaking trips through the mangrove forest sill (T Harel-Bornovski pers. obs. 1998–2024). Usually, if there has been no prior disturbance by tourists, around eight neonates and/or YOY Blacktip Reef Sharks can be observed in the area. However, animals quickly disperse when approached. The area is only accessible during new and full moon high tide. Only neonate and YOY Blacktip Reef Sharks are observed within the area. They are observed year-round but in higher abundance between November–May (T Harel-Bornovski pers. obs. 1998–2024).
Between 2021–2024, six Baited Remote Underwater Video Station surveys were deployed in the bay at the mouth of the sill and neonates/YOY were recorded in three deployments (up to five sharks per 60 min record). Blacktip Reef Sharks observed and recorded were visually estimated at 30–50 cm total length (TL) (T Harel-Bornovski pers. obs. 2009–2024). Blacktip Reef Shark size-at-birth is 30–52 cm TL (Ebert et al. 2021), confirming that the individuals observed were neonates or YOY.
Blacktip Reef Sharks use this mangrove area for foraging and shelter (T Harel-Bornovski pers. obs. 1998–2024). This is consistent with the ecological preference of young Blacktip Reef Sharks which are known to prefer shallow, sheltered waters (George et al. 2019).
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