true

ISRA FACTSHEETS

NEW ZEALAND & PACIFIC ISLANDS REGION

ISRA FACTSHEETS

NEW ZEALAND & PACIFIC ISLANDS REGION

Northern Chatham Rise ISRA

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Northern Chatham Rise ISRA

Northern Chatham Rise

Summary

Northern Chatham Rise is located in the northern part of a ridge on the eastern side of New Zealand. It is characterised by muddy substrates with high microbenthic and low meiofaunal biomass. The area is dominated by the Subtropical Front where subtropical waters and subantarctic waters mix. It overlaps with two Key Biodiversity Areas. Within this area there are: threatened species (e.g., Kitefin Shark Dalatias licha); range-restricted species (e.g., Brown Chimaera Chimaera carophila); and reproductive areas (e.g., Birdbeak Dogfish Deania calceus).

Northern Chatham Rise

Northern Chatham Rise

DESCRIPTION OF HABITAT

Northern Chatham Rise is located in the northern part of a ridge on the eastern side of New Zealand. The area is characterised by muddy substrates with high microbenthic and low meiofaunal biomass (Nodder et al. 2003). It has abyssal mountains and hills and submarine canyons. Phosphorite nodules are spread around the crest of the rise along with exposed basement rock substrates (Bowden et al. 2017; Leduc et al. 2024). These habitats sustain large densities of deep-water corals (Leduc et al. 2024).

The area has a stable and permanent oceanography dominated by the Subtropical Front where there is a mix of subtropical waters and subantarctic waters (Sutton 2001; Chiswell et al. 2015). North subtropical waters are warmer, more saline and nutrient poor compared to the cold and nutrient rich subantarctic waters from the south (McGregor et al. 2019). This front is divided by a frontal zone in the north and south (Sutton 2001). Sea surface temperatures are warmer during austral autumn with a shallow mixed layer in subtropical waters while in spring, temperatures are cooler and there is a deeper mixed layer (Sutton 2001).

The area overlaps with the Chatham (offshore) and East Coast South Island (offshore) Key Biodiversity Areas (KBA 2024a; 2024b).

This Important Shark and Ray Area is benthic and pelagic and is delineated from surface waters (0 m) to 1,200 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 Endangered Leafscale Gulper Shark (Finucci et al. 2024) and the Vulnerable Kitefin Shark (Finucci et al. 2018).

CRITERION B

RANGE RESTRICTED

This area holds the regular presence of the New Zealand Catshark, Garrick’s Catshark, Longnose Deepsea Skate, Smooth Deepsea Skate, Prickly Deepsea Skate, Smooth Skate, Brown Chimaera, Australasia Narrow-nosed Spookfish, Pale Ghostshark, and Black Ghostshark. These species were regularly encountered in independent research surveys using demersal trawls (200–1,300 m) conducted in January–February annually from 2009–20124 and bi-annually since 2014 (O’Driscoll et al. 2011; Stevens et al. 2012, 2013, 2014, 2015, 2017, 2018, 2021, 2023; B Finucci unpubl. data 2024). Due to the fishing gear selectivity, the abundance recorded for some of the species is underestimated and does not represent their true abundances in the area.

For New Zealand Catshark, 47 individuals were recorded between 2020–2024 while for Garrick’s Catshark, 12 individuals were reported in the same period. There were not specific catches prior to 2020 as both species were grouped with other ones in the ‘catsharks’ category. For both species, Northern Chatham Rise was the area with the largest number of individuals caught during research surveys around all of New Zealand. Both species are endemic to the New Zealand Shelf Large Marine Ecosystem (LME).

For Longnose Deepsea Skate, 62 individuals were recorded between 2009–2024 and the largest number of individuals caught during research surveys for this species in all New Zealand were recorded in Northern Chatham Rise. This species is endemic to the New Zealand Shelf LME.

For Smooth Deepsea Skate, 37 individuals were recorded in the area between 2009–2024 with Northern Chatham Rise having the largest number of individuals recorded during research surveys for this species in all New Zealand. This species is endemic to the New Zealand Shelf LME.

For Prickly Deepsea Skate, 36 individuals were recorded in the area between 2009–2024 with Northern Chatham Rise having the largest number of individuals recorded during research surveys for this species in all New Zealand. This species is endemic to the New Zealand Shelf LME.

For Smooth Skate, 115 individuals were recorded in the area between 2009–2024 with Northern Chatham Rise having the third largest number of individuals recorded during research surveys for this species in all New Zealand. This species is endemic to the New Zealand Shelf LME.

For Brown Chimaera, 104 individuals were recorded in the area between 2009–2024 with Northern Chatham Rise having the largest number of individuals recorded during research surveys for this species in all New Zealand. This species occurs in the New Zealand Shelf LME and in the Southeast Australian Shelf LME.

For Australasia Narrow-nosed Spookfish, 2,008 individuals were recorded in the area between 2009–2024 with Northern Chatham Rise having the largest number of individuals recorded during research surveys for this species in all New Zealand. This species is endemic to the New Zealand Shelf LME.

For Pale Ghostshark, 3,487 individuals were recorded in the area between 2009–2024 with Northern Chatham Rise having the largest number of individuals recorded during research surveys for this species in all New Zealand. This species is endemic to the New Zealand Shelf LME.

For Black Ghostshark, 17 individuals were recorded in the area between 2009–2024 with Northern Chatham Rise having the second largest number of individuals recorded during research surveys for this species in all New Zealand. This species occurs in the New Zealand Shelf LME and in the Southeast Australian Shelf LME.

CRITERION C

SUB-CRITERION C1 – REPRODUCTIVE AREAS

Northern Chatham Rise is an important reproductive area for four shark species.

Based on records from research demersal trawl surveys conducted yearly between January–February from 2009–2014 and bi-annually since 2014 (O’Driscoll et al. 2011; Stevens et al. 2012, 2013, 2014, 2015, 2017, 2018, 2021, 2023) young-of-the-year (YOY) individuals and late-stage pregnant females (with egg cases ready to be deposited or with near-term embryos) of Leafscale Gulper Shark, Longnose Velvet Dogfish, Kitefin Shark, and Birdbeak Dogfish are regularly found in the area (B Finucci unpubl. data 2024). Species maturity was assessed at sea using the National Institute of Water and Atmospheric Research’s standard shark macroscopic maturity staging key. YOY were determined either through physical assessment at sea or estimated from published growth curves based on their size (Parker & Francis 2012; Francis et al. 2016). Due to the fishing gear selectivity, the abundance of YOY recorded does not represent the true abundances of these life-stages in the area.

For Leafscale Gulper Shark, 450 individuals were caught. Of these, 154 YOY (34.3% of captures) and two late-stage pregnant females were caught at depths of 356–1,200 m. YOY were defined as individuals measuring <50 cm total length (TL; Parker & Francis 2012; Francis et al. 2016). Northern Chatham Rise was the area with the largest number of YOY sampled in all New Zealand.

For Longnose Velvet Dogfish, 4,537 individuals were caught. Of these, 1,242 YOY (27.3% of captures) and 35 late-stage pregnant females were caught at depths of 414–1,200 m. YOY were defined as individuals measuring <50 cm TL (Parker & Francis 2012; Francis et al. 2016). Northern Chatham Rise was the area with the largest number of YOY and late-stage pregnant females sampled in all New Zealand.

For Kitefin Shark, 618 individuals were caught. Of these, 585 YOY (94.6% of catches) were caught in the northern part of the rise at 369–1,020 m. YOY were defined as individuals measuring <50 cm TL (Parker & Francis 2012; Francis et al. 2016). Northern Chatham Rise was the area with the largest number of YOY sampled in all New Zealand.

For Birdbeak Dogfish, 6,213 individuals were caught. Of these, 1,336 YOY (21.5% of catches) and seven late-stage pregnant females were caught in the northern part of the rise at 482–969 m. YOY were defined as individuals measuring <50 cm TL (Parker & Francis 2012; Francis et al. 2016). Chatham Rise was the area with the largest number of YOY sampled in all New Zealand.

Northern Chatham Rise

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