The deepwater nurse shark is a deepwater relative of the grey nurse shark and is often mistaken for that species. This poorly known shark is protected under the Wildlife Act (1953), so it is illegal to hunt, kill or harm deepwater nurse sharks within New Zealand’s Territorial Sea and Exclusive Economic Zone.
Other common names for the deepwater nurse shark include Herbst’s nurse, smalltooth sandtiger shark and sand shark.
Deepwater nurse shark, Canary Islands, Spain
Image: Francis Perez
Deepwater nurse sharks are a naturally rare species and little is known about them.
The deepwater nurse shark (Odontaspis ferox) has a bulky body with a relatively long, bulbous, slightly flattened snout.
The dorsal fins are large. The first dorsal fin is distinctly larger than the second and originates over or just behind the inner corner of the pectoral fin.
The grey nurse shark (Carcharias Taurus) for which deepwater nurse sharks are sometime mistaken are similar in size but the origin of the first dorsal is located well behind the pectoral fin.
The teeth of deepwater nurse sharks have a long, slender central cusp, with two small, curved cusplets either side of the base.
They are usually grey-brown above and lighter below, with dusky margins to the dorsal fins and upper margin of the tail.
In New Zealand and Australia adults often have a scattering of small dark blotches on the body. These blotches vary in size and density between individuals and possibly between sharks from different populations.
Very occasionally ‘piebald’ individuals are encountered. These spectacularly coloured individuals are covered in large, irregular patches of white, black, grey and brown.
Deepwater nurse shark, Canary Islands, Spain
Very little is known about the biology and behaviour of deepwater nurse sharks including their diet. Prey items identified to date consist of small to moderate sized bottom-dwelling sharks and rays, bony fishes and prawns.
While they may appear large and daunting their behaviour during encounters with divers indicates they are harmless to humans unless provoked.
The deepwater nurse shark is patchily distributed throughout most warm temperate and tropical regions of the World.
Deepwater nurse shark with divers, Canary Islands, Spain
They are found on steep rocky terrain as well as open sandy and muddy bottoms along the margins of the continental shelf and the upper continental slope.
They also occur around sea mounts, on oceanic ridges and sometimes in open water.
Their reported depth range is from 10 metres to at least 880 metres. All juveniles less than 150 cm length have been taken below 200 m depth. Adults and larger juveniles have been reported across their entire depth range.
Deepwater nurse sharks usually swim near the sea bottom and appear to aggregate on or near reefs. Photographs of distinctively marked individuals suggest that like the grey nurse shark this species returns annually to favoured sites.
New Zealand sightings
All records of this species from New Zealand waters have come from the upper North Island and Kermadec Ridge.
Deepwater nurse sharks have been observed by divers at L’Esperance Rock in the Kermadec Islands, around White Island in Bay of Plenty, and at Monowai Rock north of Gisborne.
Kelly Tarlton’s Underwater World (Auckland) has made several unsuccessful attempts to exhibit specimens collected from deep reefs off Volkner Rocks, Bay of Plenty, and several specimens have been caught off Mahia Peninsula and Lachlan Banks, Hawke Bay.
Outside the Exclusive Economic Zone they are also known to occur on the Norfolk and Louisville Ridges.
Deepwater nurse sharks are a naturally rare species and little is known of their population size or structure in New Zealand waters.
The species is classified as Vulnerable (population trend: decreasing) by the IUCN Red List of Threatened Species.
Size at birth is uncertain but appears to be between 100 - 105 cm total length (TL). Size at maturity is unknown.
The available data indicate males mature between 2 - 2.5 metres total length, and females between 3 - 3.5 metres total length.
Maximum size is at least 4.25 metres total length, with a weight of more than 600 kg.
Deepwater nurse shark
Deepwater nurse sharks are naturally rare and have low resilience to fishing.
They are vulnerable to longlines, set nets and trawling.
Long-term monitoring of trawl fisheries in New South Wales indicates a marked decline in abundance off eastern Australia due to bycatch in fisheries.
Historically there have been few reported commercial landings of deepwater nurse sharks in New Zealand. However, anecdotal information from commercial fishers indicates they were regularly taken in deepwater gill net fisheries in the outer Bay of Plenty.
They are occasionally reported by scientific observers as bycatch in midwater and bottom trawls for deepwater species such as orange roughy.
Kelly Tarlton’s Underwater World has netted 17 individuals at Volkner Rocks. Of the nine retained for display none have been successfully acclimated to life in the aquarium.
IUCN Red List of Threatened Species status: Vulnerable (population trend: decreasing).
DOC monitors the bycatch of deepwater nurse sharks and other protected species in commercial fisheries through its Conservation Services Programme.
Wildlife Act 1953
Deepwater nurse sharks (Odontaspis ferox) are protected under the Wildlife Act 1953.
This means it is illegal to hunt, kill or harm deepwater nurse sharks within New Zealand’s Territorial Sea and Exclusive Economic Zone (200 nm limit around New Zealand).
Trade in teeth, jaws and fins is illegal.
Fishers and bycatch
It is not illegal to accidentally catch a deepwater nurse shark but the shark must be returned to the sea alive and unharmed. Report the catch to the Department of Conservation and/or Ministry of Fisheries as soon as possible. DOC may request that dead sharks be landed for scientific research.
You can help
When fishing, carefully release any unwanted sharks and rays.
Do not discard plastics, nylon fishing line and other types of rubbish at sea. Like whales, large filter-feeding sharks and rays can accidentally ingest these, and all species suffer from entanglement in marine debris.
As very little is known of the biology of deepwater nurse sharks dead specimens are of considerable scientific value. Should you inadvertently kill a deepwater nurse shark please notify the Department of Conservation immediately.
You may be requested to return the specimen to shore if this is practical. Useful information to provide with the specimen includes the location and depth that the fish was taken in.
Report details of sightings or captures to (email@example.com) or to 0800 DOC HOT (0800 362 468).