Sharks, Skates, and Rays (Phylum Chordata, Class Chondrichthyes)
Malcolm P. Francis, Franz Smith, Clinton Duffy, and Taoho Patuawa
General Description
Fishes of the class Chondrichthyes have skeletons made of cartilage rather than bone, and are known as cartilaginous fishes. They have strong jaws with tooth plates or serially replaced teeth. Most of these fishes can be identified by the five pairs of gill slits, but a few sharks have six or seven pairs, and chimaerids (ghost sharks) have only a single pair of gill slits. Sharks, skates and rays have low fecundity, producing small numbers of eggs or live young, and many mature at a relatively late age compared with other fishes.
Most species are important predators of other fishes and invertebrates.
Several species of shark are considered anatomically primitive, and are largely restricted to deep water. The frill shark, Chlamydoselachus anguineus, is the only species in the family Chlamydoselachidae. It is eel-like, reaches 1-2 m in length, and is distinguished by frilled gill slits, the first of which almost encircles the head. The sixgill shark, Hexanchus griseus (family Hexanchidae), is a powerful, heavily built, round-snouted shark with a single dorsal fin and six pairs of gills; it is commonly 2-3 m in length, but can reach 5 m. The broadnose sevengill shark, Notorynchus cepedianus (also in the family Hexanchidae) is similar to the sixgill shark, but has seven pairs of gills, and reaches 2-3 m in length. Little is known about the ecology of these species, although they are probably key predators of deepwater areas.
Oceanic and pelagic sharks come from about six families. The mackerel sharks (family Lamnidae) include the shortfin mako, Isurus oxyrinchus, porbeagle Lamna nasus, and great white, Carcharodon carcharias, sharks. These species are warm blooded, being able to maintain their body temperature several degrees above that of the surrounding water. The whaler sharks (family Carcharhinidae) include the tiger, Galeocerdo cuvier, blue, Prionace glauca, and bronze whaler, Carcharhinus brachyurus, sharks. These species are all key predators in coastal and offshore waters of New Zealand; they feed mainly on schooling fishes and squids, although the great white eats mainly marine mammals (especially seals and dolphins) when they are longer than about 3 m.
The basking shark, Cetorhinus maximus, is the only species in the family Cetorhinidae, and is a large plankton-eating filter-feeder that averages about 5-8 m in length, but can exceed 10 m. It often feeds in surface waters in spring-summer and can be seen in aggregations from Hawke Bay south to the Auckland Islands. In winter, basking sharks have been found in deep trenches off Westland. The largest fish in the world, the whale shark (Rhincodon typus, family Rhincodontidae), may reach lengths greater than 20 m. They occur in northeast New Zealand waters in summer-autumn, but retreat to the tropics as the water temperature drops. Like basking sharks, whale sharks filter-feed, but they consume small fishes as well as plankton. The pelagic stingray (Pteroplatytrygon violacea, family Dasyatidae) is unique among stingrays in having a pelagic lifestyle in open waters.
Other pelagic sharks, such as the thresher, Alopias vulpinus (family Alopiidae), and hammerhead, Sphyrna zygaena (family Sphyrnidae), are wide ranging in tropical and subtropical waters, and are occasionally seen around the North Island. The thresher can extend to the South Island. These sharks are chiefly predators of pelagic fishes.
The cat sharks (family Scyliorhinidae) include about a dozen species, many of them recently discovered and undescribed. The carpet shark, Cephaloscyllium isabellum, is the only species found in shallow coastal waters, with the remainder usually occurring deeper than 200 m. Dawson's catshark, Halaelurus dawsoni, and several species of Apristurus are endemic to New Zealand. Dawson's catshark is the smallest shark commonly found in New Zealand, reaching a maximum length of 42 cm. The even smaller, tropical, pygmy shark, Euprotomicrus bispinatus, grows to only 27 cm long, but it is rarely seen in New Zealand waters.
Several families of small- to medium-sized sharks comprise predominately bottom-dwelling inshore species. In the family Triakidae, the school shark, Galeorhinus galeus, and rig, Mustelus lenticulatus, are common around coastal New Zealand, and are fished commercially. Rig is endemic to New Zealand.
The greatest shark diversity in New Zealand waters occurs among the dogfish. Previously lumped into one large family, this heterogeneous group is now split into six families (Squalidae, Centrophoridae, Etmopteridae, Somniosidae, Oyynotidae, and Dalatiidae). These sharks are distinguished from others by their lack of an anal fin. Many, but not all, dogfish also have strong spines in front of each dorsal fin. Comprising over 25 species, dogfish occur mainly in depths greater than 300 m, though the spiny dogfish, Squalus acanthias, is abundant in shallow water around the South Island. Dogfish are generally small, with few growing longer than 1.5 m, but the southern sleeper shark, Somniosus antarcticus, is very large, reaching 6 m or longer.
New Zealand has about 16 species of skates (families Arhynchobatidae and Rajidae), most of which are endemic. Skates can be distinguished by their flattened, angular shape. Two species are common in coastal waters-the rough skate, Dipturus nasutus, and the smooth skate, Dipturus innominatus; both are endemic to New Zealand. Electric rays include representatives from two families, Torpedo fairchildi (family Torpedinidae), and the endemic Typhlonarke aysoni and T. tarakea (family Narkidae). Stingrays can be distinguished by their ovoid to angular shape with one or more tail spines. Several families are represented in New Zealand waters, including the true stingrays (family Dasyatidae, three species), eagle rays (family Myliobatidae, one species), and manta rays (family Mobulidae, two species). The manta ray is a seasonal visitor to New Zealand waters and is occasionally recorded from northeastern New Zealand. Apart from the pelagic stingray, the other rays are abundant in shallow coastal waters around northern New Zealand.
Chimaeras are relatives of sharks, but are distinguished by their smooth skins and a single slit on either side of the head. There are representatives of three families in New Zealand waters, including the elephantfish (Callorhinchus milii, family Callorhinchidae), the ghost sharks (family Chimaeridae), and the long-nosed chimaeras or spookfish (family Rhinochimaeridae). The elephantfish is restricted to southern New Zealand and southern Australia, and lives mainly in shallow coastal waters, where it lays pairs of egg cases on the seabed. The other species of chimaera are common below the shelf edge, usually in depths greater than 300 m.
About 107 chondrichthyans are known from New Zealand waters, though new discoveries are still being made. This total includes 70 species of sharks, 25 skates and rays and 12 chimaeras. About 30 species are endemic, but the exact number cannot be determined until further work is done on the taxonomy and distribution of species around New Zealand and elsewhere.
Status
One hundred species of chondrichthyans found in New Zealand have been classified according to their threat status. Most are regarded as Not Threatened (53%) or Data Deficient (26%). A few are transient Migrants (5%) or Vagrants (1%) whose natural range is mostly outside New Zealand. Thirteen species (13%) are classified as Sparse, because of their naturally low population densities and presumed low total population numbers. Two species (2%) (great white shark, Carcharodon carcharias, and basking shark, Cetorhinus maximus, are classified as Gradual Decline, indicating that they are at risk of extinction, but that their population decline rates are slow and long-term. These two species have low productivity because of their very low reproductive rates (probably fewer than five young per year per female) and presumed high ages at maturity. These features, in combination with their naturally low population sizes, mean that population recovery following increased mortality is likely to be very slow.
Key Locations
Few key locations are known. Some species (eg, elephantfish, rig, school shark, stingrays, eagle ray) are dependent on estuaries or shallow coastal waters for their nursery grounds and/or adult feeding grounds. But many species are large and mobile, and are not restricted to small areas. The Chatham Rise and Puysegur area west of Stewart Island support a high diversity of species, particularly dogfishes.
Summary of Threats
The greatest threat to cartilaginous fishes in New Zealand waters comes from commercial fishing activities. Some species are targeted by certain fishing methods (eg, rig, school shark, elephantfish), but most are caught as bycatch in fisheries for other species. Blue, porbeagle and mako sharks are caught in large numbers in the tuna longline fishery, and deepwater dogfishes and chimaeras are taken by midwater and bottom-trawl fisheries, especially those for hoki, orange roughy, and oreos.
Species that require access to estuaries and shallow coastal waters for breeding, nursery grounds, or feeding may be affected by sedimentation and pollution, leading to loss of habitat or food resources.
Typical Habitats
Chondrichthyans occur in most parts of New Zealand's exclusive economic zone. Some species (eg, elephantfish, rig, school shark, stingrays, eagle ray) spend a considerable amount of their lives in shallow estuaries or coastal waters. At the other extreme, some dogfishes and chimaeras penetrate to depths of several thousand metres, and rarely occur shallower than 800 m. A number of oceanic pelagic species wander the oceans of the world, and individuals found in the New Zealand exclusive economic zone comprise only a small portion of the overall population. Most species, however, occur on the outer continental shelf and upper- to mid-continental shelf. They are typically demersal (living near the seabed).
State of Information
The biology and habitat requirements are well understood for a small number of species that are targeted by commercial fisheries, and information is growing for some species that are important bycatch in fisheries. Some New Zealand species occur elsewhere in the world, so inferences can be made from overseas studies (though caution is required because population parameters vary geographically). Information is poor or non-existent for most of New Zealand's cartilaginous fishes. No quantitative stock assessments exist for any New Zealand cartilaginous species, despite 11 species now being managed under the Quota Management System. Enough studies have been done here and overseas to determine that cartilaginous fishes are among the least productive fishes in the ocean, because of their very low reproductive rates, and usually slow growth rates, late age at maturity, and high longevity.
Significance for Maori
Sharks were generally referred to as mango, and there are many names for various species of sharks. Some of the more significant include the mango makomako (mako shark), mango taniwha (great white shark), kapeta (rig, Northern tribes), and the koinga (northern spiny dogfish). Stingrays and skates were collectively known as manumanu, and eagle rays were referred to as whai repo.
Sharks were, and to a lesser extent still are, an important source of food and oil for Maori. Coastal hapu (extended family units) would gather during the summer months and fish for sharks using nets, a line and baited hook, or sometimes a noose to save damage to the prized teeth caused by the hooks. Some of the meat would be eaten fresh, while a large portion of the catch would be hung up to dry on large, multi-tiered wooden frames for up to a month or more. This supply of dried meat was often stored in pataka (communal storage houses) and eaten during the winter months. Shark livers were placed in leaf funnels and compressed with heated stones to extract oil, which was used to anoint human bones, and make paint and cosmetics. Evidence from middens suggests that, when available, eagle rays and stingrays were also eaten.
Key References
Anderson, O F, Bagley, N W, Hurst, R J, Francis, M P, Clark, M R and P J McMillan. 1998. Atlas of New Zealand fish and squid distributions from research bottom trawls. NIWA technical report 42. 303pp.
Cavanagh, R D, Kyne, P M, Fowler, S L, Musick, J A and M B Bennett (eds). (2003). The conservation status of Australasian chondrichthyans. Brisbane, Australia, The University of Queensland. 170pp.
Cox, G and Francis, M. 1997. Sharks and rays of New Zealand. Canterbury University Press, Christchurch. 68pp.
Francis, M P. 1998. New Zealand shark fisheries: development, size and management. Marine and freshwater research 49: 579-591.
Francis, M P, Griggs, L H and S J Baird. 2001. Pelagic shark bycatch in the New Zealand tuna longline fishery. Marine and freshwater research 52: 165-178.
Francis, M P, Hurst, R J, McArdle, B H, Bagley, N W and O F Anderson. 2002. New Zealand demersal fish assemblages. Environmental biology of fishes 65: 215-234.
Hitchmough, R. 2002. New Zealand threat classification system lists. Threatened species occasional publication 23. 210pp.
Paul, L. 2000. New Zealand Fishes: Identification, natural history and fisheries. Reed Publishing, Auckland, New Zealand. 253pp.
Sullivan, K J, Mace, P M, Smith, N W M, Griffiths, M H, Todd, P R, Livingston, M E, Harley, S, Key, J M and A M Connell (eds). (2005). Report from the Fishery Assessment Plenary, May 2005: stock assessments and yield estimates. Wellington, Ministry of Fisheries. 792pp.
Strickland, R R. 1990. Nga tini a Tangaroa: A Maori-English, English-Maori dictionary of fish names. MAF Fisheries. 65pp.
Table 13: Cartilaginous fishes (chondrichthyans) in New Zealand
Compiled by Malcolm Francis1, Andrew Stewart2, Clinton Duffy3 and Peter McMillan1 National Institute of Water and Atmospheric Research, Wellington 2 Museum of New Zealand, Wellington 3 Department of Conservation, Auckland
| Family | Species | Common name | Breeding Species | Endemic Species |
|---|---|---|---|---|
| Callorhinchidae | Callorhinchus milii | Elephantfish | 1 | |
| Rhinochimaeridae | Harriotta haeckeli | Smallspine spookfish | 1 | |
| Harriotta raleighana | Longnose spookfish | 1 | ||
| Rhinochimaera pacifica | Pacific spookfish | 1 | ||
| Chimaeridae | Chimaera lignaria | Purple/giant chimaera | 1 | |
| Chimaera panthera | Leopard chimaera | 1 | ||
| Chimaera sp. ?C | Brown/longspine chimaera | 1 | ||
| Hydrolagus bemisi | Pale ghost shark | 1 | ||
| Hydrolagus novaezealandiae | Dark ghost shark | 1 | 1 | |
| Hydrolagus trolli | Pointynose blue ghost shark | 1 | ||
| Hydrolagus sp. A | Black ghost shark | 1 | ||
| Hydrolagus sp. D | Giant black ghost shark | 1 | 1 | |
| Chlamydoselachidae | Chlamydoselachus anguineus | Frill shark | 1 | |
| Heptranchias perlo | Sharpnose sevengill shark | 1 | ||
| Hexanchus griseus | Sixgill shark | 1 | ||
| Notorynchus cepedianus | Broadnose sevengill shark | 1 | ||
| Echinorhinidae | Echinorhinus brucus | Bramble shark | 1 | |
| Echinorhinus cookei | Prickly shark | 1 | ||
| Squalidae | Cirrhigaleus barbifer | Mandarin dogfish | 1 | |
| Squalus acanthias | Spiny dogfish | 1 | ||
| Squalus sp. cf mitsukurii | Northern spiny dogfish | 1 | 1? | |
| Centrophoridae | Centrophorus sp. | 1 | ||
| Centrophorus squamosus | Leafscale gulper shark | 1 | ||
| Deania calcea | Shovelnose dogfish | 1 | ||
| Deania quadrispinosum | Longsnout dogfish | 1 | ||
| Etmopteridae | Centroscyllium sp. | Fragile dogfish | 1 | 1? |
| Etmopterus baxteri | Baxter's dogfish | 1 | ||
| Etmopterus lucifer | Lucifer dogfish | 1 | ||
| Etmopterus molleri | Moller's lantern shark | 1 | ||
| Etmopterus pusillus | Smooth lantern shark | 1 | ||
| Etmopterus sp. B | Bristled lantern shark | 1 | ||
| Somniosidae | Centroscymnus coelolepis | Portuguese dogfish | 1 | |
| Centroscymnus owstoni | Owston's dogfish | 1 | ||
| Centroselachus crepidater | Longnose velvet dogfish | 1 | ||
| Proscymnodon plunketi | Plunket's shark | 1 | ||
| Scymnodalatias albicauda | Whitetail dogfish | 1 | ||
| Scymnodalatias sherwoodi | Sherwood's dogfish | 1 | 1 | |
| Scymnodon cf. ringens | Knifetooth dogfish | 1 | 1? | |
| Somniosus antarcticus | Southern sleeper shark | 1 | ||
| Somniosus longus | Little sleeper shark | 1 | ||
| Zameus squamulosus | Velvet dogfish | 1 | ||
| Oxynotidae | Oxynotus bruniensis | Prickly dogfish | 1 | |
| Dalatiidae | Dalatias licha | Seal shark, black shark | 1 | |
| Euprotomicrus bispinatus | Pygmy shark | 1 | ||
| Isistius brasiliensis | Cookie cutter shark | 1 | ||
| Narkidae | Typhlonarke aysoni | Blind electric ray | 1 | 1 |
| Typhlonarke tarakea | Oval electric ray | 1 | 1 | |
| Torpedinidae | Torpedo fairchildi | Electric ray | 1 | 1 |
| Arhynchobatidae | Arhynchobatis asperrimus | Longtail skate | 1 | 1 |
| Bathyraja richardsoni | Richardson's skate | 1 | ||
| Bathyraja shuntovi | Longnose deepsea skate | 1 | 1 | |
| Bathyraja sp. | Blonde skate | 1 | 1? | |
| Brochiraja albilabiata | 1 | 1 | ||
| Brochiraja asperula | Smooth deepsea skate | 1 | 1 | |
| Brochiraja leviveneta | 1 | 1 | ||
| Brochiraja microspinifera | 1 | 1 | ||
| Brochiraja spinifera | Prickly deepsea skate | 1 | 1 | |
| Notoraja [subgenus C] sp. A | 1 | 1 | ||
| Notoraja [subgenus C] sp. B | 1 | 1 | ||
| Notoraja [subgenus C] sp. C | 1 | 1 | ||
| Notoraja [subgenus D] sp. A | 1 | 1 | ||
| Rajidae | Amblyraja ?hyperborea | Arctic skate | 1 | |
| Dipturus innominatus | Smooth skate | 1 | 1 | |
| Dipturus nasutus | Rough skate | 1 | 1 | |
| Dasyatidae | Dasyatis brevicaudata | Shorttail stingray | 1 | |
| Dasyatis thetidis | Longtail stingray | 1 | ||
| Pteroplatytrygon violacea | Pelagic stingray | 1 | ||
| Myliobatidae | Myliobatis tenuicaudatus | Eagle ray | 1 | |
| Mobulidae | Manta birostris | Manta ray | ||
| Mobula japanica | Spinetail devil ray | 1 | ||
| Heterodontidae | Heterodontus portusjacksoni | Port Jackson shark | 1 | |
| Rhincodontidae | Rhincodon typus | Whale shark | ||
| Odontaspidae | Odontaspis ferox | Smalltooth sand tiger shark | 1 | |
| Pseudocarchariidae | Pseudocarcharias kamoharai | Crocodile shark | 1 | |
| Mitsukurinidae | Mitsukurina owstoni | Goblin shark | 1 | |
| Alopiidae | Alopias superciliosus | Bigeye thresher | ||
| Alopias vulpinus | Thresher shark | 1 | ||
| Cetorhinidae | Cetorhinus maximus | Basking shark | 1 | |
| Lamnidae | Carcharodon carcharias | Great white shark | 1 | |
| Isurus oxyrinchus | Mako, shortfin mako | 1 | ||
| Lamna nasus | Porbeagle | 1 | ||
| Scyliorhinidae | Apristurus exsanguis | Pale cat shark | 1 | 1 |
| Apristurus ?sp. A | Freckled cat shark | 1 | ||
| Apristurus sp. C | Fleshynose cat shark | 1 | ||
| Apristurus sp. D | Roughskin cat shark | 1 | ||
| Apristurus sp. G | Pinocchio cat shark | 1 | ||
| Apristurus sp. | Cat shark | 1 | 1? | |
| Apristurus sp. | Cat shark | 1 | 1? | |
| Bythaelurus dawsoni | Dawson's cat shark | 1 | 1 | |
| Cephaloscyllium isabellum | Carpet shark | 1 | 1 | |
| Cephaloscyllium sp. | 1 | 1? | ||
| Parmaturus macmillani | McMillan's cat shark | 1 | ||
| Parmaturus sp. | 1 | 1? | ||
| Pseudotriakidae | Gollum attenuatus | Slender smooth hound | 1 | |
| Pseudotriakis microdon | False cat shark | 1 | ||
| Triakidae | Galeorhinus galeus | School shark, tope | 1 | |
| Mustelus lenticulatus | Rig | 1 | 1 | |
| Mustelus sp. | 1 | |||
| Carcharhinidae | Carcharhinus amblyrhynchos | Grey reef shark | 1 | |
| Carcharhinus brachyurus | Bronze whaler | 1 | ||
| Carcharhinus falciformis | Silky shark | |||
| Carcharhinus galapagensis | Galapagos shark | 1 | ||
| Carcharhinus longimanus | Oceanic whitetip shark | |||
| Carcharhinus obscurus | Dusky shark | 1 | ||
| Galeocerdo cuvier | Tiger shark | |||
| Prionace glauca | Blue shark | 1 | ||
| Sphyrnidae | Sphyrna zygaena | Smooth hammerhead shark | 1 | |
| Total endemic | 31? | |||
| Total species | 109 |
Figure 33: Elephant fish Callorhinchus milii annual distribution.
Figure 34: Rig Mustelus lenticulatus annual distribution.
Figure 35: Basking shark Cetorhinus maximus annual distribution.
Figure 36: Rough skate Dipturus nasutus annual distribution.
Figure 37: Smooth skate Dipturus innominatus annual distribution.