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ISRA FACTSHEETS

NEW ZEALAND & PACIFIC ISLANDS REGION

ISRA FACTSHEETS

NEW ZEALAND & PACIFIC ISLANDS REGION

Natavaki Reef ISRA

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Natavaki Reef ISRA

Natavaki Reef

Summary

Natavaki Reef is located in the Koro Sea off the southern coast of Vanua Levu Island in Fiji. The area is characterised by steep coral reef slopes and walls, rocky plateaus, and a large, deep channel. It is influenced by strong currents. Natavaki Reef overlaps with the Vatu-i-Ra/Lomaiviti Ecologically or Biologically Significant Marine Area. Within this area there are: threatened species (e.g., Scalloped Hammerhead Sphyrna lewini) and undefined aggregations (e.g., Grey Reef Shark Carcharhinus amblyrhynchos).

Natavaki Reef

Natavaki Reef

DESCRIPTION OF HABITAT

Natavaki Reef is located off the southern coast of Vanua Levu Island in Fiji. The area is part of a large horseshoe-shaped barrier reef that surrounds a deep lagoon and encompasses Namenalala Island. In its northern and northeastern parts, including in this area, the barrier reef is broken up into smaller sections with channels between them, while in its southern and southwestern parts the barrier reef is continuous. The area consists of barrier reef sections and channels. Several popular dive sites are located within the area, including ‘Grand Central Station’, ‘Schoolhouse’, ‘Kansas’, and ‘North Save-A-Tack Passage’ (B Chaves pers. obs. 2024). The habitat is characterised by deep drop-offs, steep walls, reef slopes, and a large, exposed channel with strong currents influenced by the tides (L Gordon pers. obs. 2024).

This area overlaps with the Vatu-i-Ra/Lomaiviti Ecologically or Biologically Significant Marine Area (EBSA; CBD 2024).

This Important Shark and Ray Area is benthic and pelagic and is delineated from surface waters (0 m) to 100 m based on the bathymetry of the area.

CRITERION A

VULNERABILITY

Two Qualifying Species considered threatened with extinction according to the IUCN Red List of Threatened Species regularly occur in the area. These are the Critically Endangered Scalloped Hammerhead (Rigby et al. 2019) and the Endangered Grey Reef Shark (Simpfendorfer et al. 2020).

CRITERION C

SUB-CRITERION C5 – UNDEFINED AGGREGATIONS

Natavaki Reef is an important area for undefined aggregations of two shark species.

Aggregations of Grey Reef Sharks are regularly reported from Natavaki Reef (G Koroi pers. comm. 2024). Dive operators visiting this area over the past 20 years (average 1–2 times per month) have observed aggregations on every dive, with aggregation size ranging from 5–7 individuals (G Koroi pers. comm. 2024). Another operator conducting ~100 dives per year between February–November in the area also reported aggregations of Grey Reef Sharks on every dive, with 10–15 individuals per aggregation (B Chaves pers. obs. 2024). Aggregations comprise mostly adults or large juveniles, with small individuals rarely seen. Aggregations are usually seen on the incoming tide, when most dives are conducted, compared to during the outgoing tide (B Chaves pers. obs. 2024). Additionally, baited remote underwater video station (BRUVS) surveys sampled the area in 2009 and 2016 and recorded the species in six of 11 deployments (55%) compared to 18% at other sites (n = 168) on the barrier reef outside the area (MacNeil et al. 2020). Further information is required to determine the nature and functions of these aggregations.

Aggregations of Scalloped Hammerheads are regularly reported from Natavaki Reef by dive operators (B Chaves pers. obs. 2024, G Koroi pers. comm. 2024). Aggregations comprising 3–50 individuals are observed on ~40% of dives, with 1–2 dives per month since 2014 (G Koroi pers. comm. 2024). Another operator conducting ~100 dives per year between February–November since 2013 recorded aggregations of up to 100 individuals (R Barrell et al. unpubl. data 2024). Larger schools of >10 Scalloped Hammerheads are seen 2–3 times each year (B Chaves pers. obs. 2024). Further information is required to determine the nature and functions of these aggregations.

Natavaki Reef

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