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ISRA FACTSHEETS

NEW ZEALAND & PACIFIC ISLANDS REGION

ISRA FACTSHEETS

NEW ZEALAND & PACIFIC ISLANDS REGION

Astrolabe Bay ISRA

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Astrolabe Bay ISRA

Astrolabe Bay

Summary

Astrolabe Bay is located on the north coast of Madang Province, Papua New Guinea. It encompasses the waters along the coast from Madang south to Songun within Astrolabe Bay. The area is characterised by nearshore canyons and inter-canyon platforms, mangroves, and estuaries. The area is influenced by river discharge into the bay, the New Guinea Under Current, and the northwestern monsoon. Within this area there are: range-restricted species (Sailback Houndshark Gogolia filewoodi).

Astrolabe Bay

DESCRIPTION OF HABITAT

Astrolabe Bay is located on the north coast of Madang Province, Papua New Guinea. It encompasses the waters along the coast from Madang south to Songun within Astrolabe Bay. The area is characterised by nearshore canyons and inter-canyon platforms, mangroves, and estuaries including the Gogal River mouth (Sagumai et al. 2025).

The area is influenced by river discharge into the bay, the New Guinea Under Current, the northwestern monsoon (December to March) which coincides with seasonal upwelling, and a rainy season extending from October to April (Shearman et al. 2001).

This Important Shark and Ray Area is benthic and pelagic, and is delineated from inshore and surface waters (0 m) to 300 m depth based on the bathymetry of the area.

CRITERION B

RANGE RESTRICTED

Astrolabe Bay holds the regular and predictable presence of Sailback Houndshark as a resident range-restricted species. The type specimen for the species was originally collected from this area in 1970 (Compagno 1973). Between 2020–2022, this species was reported from the area as incidental catch during handline fishing for croakers (Sciaenidae) by fishers. Animals were reported from near the Gogol River mouth within the area at depths of 80–200 m (Sagumai et al. 2025). Landing and market surveys indicate that Sailback Houndsharks are occasionally caught in this fishery, particularly between March–July and the dry season from August–November (Sagumai et al. 2025). A total of five females ranging in size 59–76 cm total length (TL) were captured on two consecutive days in March 2020, and an additional male was captured in September 2022 measuring 73 cm TL (Sagumai et al. 2025). This area appears to be the only known habitat for the species, suggesting possible micro-endemism (Sagumai et al. 2025). Such restricted distribution highlights the importance of the area for Sailback Houndsharks, as being the only place globally where it has been reported. Sailback Houndsharks are restricted to this small area in Papua New Guinea which is outside of any Large Marine Ecosystems.

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