| New Zealand smooth skate | |
|---|---|
 | |
| Dipturus innominatus caught off the southern coast of the North Island | |
Scientific classification  | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Chondrichthyes |
| Superorder: | Batoidea |
| Order: | Rajiformes |
| Family: | Rajidae |
| Genus: | Dipturus |
| Species: | D. innominatus |
| Binomial name | |
| Dipturus innominatus | |
The New Zealand smooth skate (Dipturus innominatus) is a skate of the genus Dipturus , found around New Zealand at depths between 15 and 1,300 m.
D. innominatus males grow up to 93 cm in pelvic length (PL). [1] PL is a measure from the tip of the animals’ snout to the outer margin of the pelvic fins. [1] Contrasting the males, the female smooth skates grow to a larger size around 112 cm PL. The largest recorded female smooth skate measured 158 cm PL. [1]
Smooth skates are the largest known skates in the world and can weigh up to 70 kg at maturity. [2] Their length has been reported up to 2.4 m. [3] The smooth skate has a dark grey upper side with darker grey to black spots and an underside that is lighter grey to white in color. Some adults have small prickles or whiskers on their snouts or noses. [4] Smooth skates are commonly mistaken for rough skates, but are larger in size and lighter in color.
D. innominatus is endemic to New Zealand. [1] They are found in the coastal waters of New Zealand's North, South and Stewart Islands, and are also found in the Snares Islands shelf and Chatham Rise. [1] D. innominatus is found at shorelines to depths of roughly 1200 m below sea level, although it is rare to find them exceeding depths of 800 m. [1] This species inhabits soft seafloor areas on the continental shelf and its upper slope: they are most numerous on the mid-outer continental shelf. [1]
D innominatus lives in the dermal zone near the sea bed. [2] The feeding habits of smooth skates have been researched specifically and results have shown the effects of the commercial fishing industry on this species' feeding habits. Smooth skates are bottom-feeding predators (benthic) and scavenge for food eating dead fish and scraps from larger predators [2] No difference exists between the diet of the individuals regarding the depth of the water or the sex of the individual. [2]
Though no change in the diet is seen between sex and depth, a change in diet occurs with maturity of the fish. [2] When the fish are young, most of their diet is made up of small crustaceans, and as the individuals mature, they start to consume larger crustaceans and small fish. [2] When reaching maturity, they consume larger fish and the leftover fish from predators and commercial fishing. [2] Mature skates no longer eat crustaceans that once were the majority their diet when they were younger. [2] This change of diet is also seen in the skate species Sympterygia acuta, which follows a very similar diet pattern to New Zealand smooth skate. [5]
The diet of mature D. innominatus is largely made up of shrimp, prawns, and fish coming from 17 different families. [2] The most common of these species were found to be hoki, a deepwater cod species, and many different species of discarded fish from the commercial fishing industry. [2]
Little information is known on the predation, parasites, and diseases affecting D. innominatus. Marine mammals, especially seals, are known to feed on other species of skate, so the assumption that New Zealand marine mammals would do the same is not unrealistic. [6] Skates are part of seals' diets, though this may be underestimated in the data, as skates do not have bony parts that are easily identified when seal stomachs are surveyed. [7]
Predation on skate egg cases by gastropods has been recorded to affect some skate species. [8]
Fishing has an impact on New Zealand smooth skate populations, so humans act as predators. New Zealand smooth skate is often caught as bycatch in the commercial fishing industry targeting hoki. [2]
In June 2018 the New Zealand Department of Conservation classified the New Zealand smooth skate as "Not Threatened" with the qualifier "Conservation Dependent" under the New Zealand Threat Classification System. [9]
The Atlantic cod is a benthopelagic fish of the family Gadidae, widely consumed by humans. It is also commercially known as cod or codling. Dry cod may be prepared as unsalted stockfish, and as cured salt cod or clipfish.
The spiny dogfish, spurdog, mud shark, or piked dogfish is one of the best known species of the Squalidae (dogfish) family of sharks, which is part of the Squaliformes order.
Demersal fish, also known as groundfish, live and feed on or near the bottom of seas or lakes. They occupy the sea floors and lake beds, which usually consist of mud, sand, gravel or rocks. In coastal waters they are found on or near the continental shelf, and in deep waters they are found on or near the continental slope or along the continental rise. They are not generally found in the deepest waters, such as abyssal depths or on the abyssal plain, but they can be found around seamounts and islands. The word demersal comes from the Latin demergere, which means to sink.
The bramble shark is one of the two species of sharks in the family Echinorhinidae. Aside from the eastern Pacific Ocean, it is found in tropical and temperate waters worldwide. This rarely encountered shark swims close to the bottom of the seafloor, typically at depths of 400–900 m (1,300–3,000 ft), though it may enter much shallower water. The bramble shark has a stout body with two small dorsal fins positioned far back and no anal fin. It can be readily identified by the large, thorn-like dermal denticles scattered over its body, some of which may be fused together. It is purplish brown or black in color and grows up to 3.1 m (10 ft) long.
The smooth deep-sea skate is a skate in the family Arhynchobatidae. It is found off New Zealand, at depths of from 200 to 1,300 m on the continental shelf. Their length is from 30 to 50 cm.
The prickly deep-sea skate, or spinydeep-sea skate, is a deep sea skate in the family Arhynchobatidae. It lives off New Zealand, at depths of from 170 to 1,400 m on the continental shelf. Their length is from 60 to 80 cm.
The longtail skate is a skate and is the only member of the genus Arhynchobatis. This species was first described by Edgar Ravenswood Waite in 1909. It is found off New Zealand at depths of from 90 to 1,000 m on the continental shelf. Its length is from 30 to 75 cm.
The Port Jackson shark is a nocturnal, oviparous type of bullhead shark of the family Heterodontidae, found in the coastal region of southern Australia, including the waters off Port Jackson. It has a large, blunt head with prominent forehead ridges and dark brown harness-like markings on a lighter grey-brown body, and can grow up to 1.65 metres (5.5 ft) long. They are the largest in the genus Heterodontus.
The blackbelly lanternshark or lucifer shark, Etmopterus lucifer, is a shark of the family Etmopteridae, found around the world in tropical to temperate seas, at depths between 150 and 1,250 meters. Its length is up to 47 centimeters. This species consumes mesopelagic cephalopods, fishes, and crustaceans.
The slender smooth-hound or gollumshark is a species of ground shark in the family Pseudotriakidae. It is endemic to the waters around New Zealand, where it is usually found close to the bottom over the continental slope at depths of 300–600 m (980–1,970 ft). An extremely slim, plain brownish shark reaching 1.1 m (3.6 ft) in length, the slender smooth-hound can be identified by its broad, flattened head with a long, distinctively bell-shaped snout. Its mouth is angular with short furrows at the corners, and contains a very high number of tooth rows in both jaws. Its two dorsal fins are roughly equal in size.
The New Zealand lanternshark is a shark of the family Etmopteridae mainly found off the coast of New Zealand. It can also be found in the Southern areas of Australia and Africa, inhabiting water depths between 500-1500m. These sharks can be commonly known as Baxter’s Dogfish and Giant Lantern shark. According to the New Zealand Threat Classification System (NZTCS), this species conservation status is considered non-threatened.
The smooth lanternshark or slender lanternshark is a species of dogfish shark in the family Etmopteridae, found widely in the Atlantic and Pacific Oceans. It inhabits benthic environments at a depth of 274–1,000 m (899–3,281 ft), and pelagic environments at a depth of 0–708 m (0–2,323 ft). The smooth lanternshark forms a species group with the larger blurred lanternshark, both of which are distinguished from other members of their family by small, irregularly arranged dermal denticles with a truncated shape. This species has a slender, dark brown body with an indistinct black band on the sides over the pelvic fins, and reaches 50 cm (20 in) in length. This slow-growing, ovoviviparous shark feeds on smaller squid, fishes, and fish eggs. Smooth lanternsharks are often caught as bycatch in eastern Atlantic and Japanese commercial fisheries. The International Union for Conservation of Nature (IUCN) has evaluated this species as of Least Concern because of its wide distribution and limited threats.
The velvet belly lanternshark is a species of dogfish shark in the family Etmopteridae. One of the most common deepwater sharks in the northeastern Atlantic Ocean, the velvet belly is found from Iceland and Norway to Gabon and South Africa at a depth of 20–2,490 m (66–8,169 ft). A small shark generally no more than 45 cm (18 in) long, the velvet belly is so named because its black underside is abruptly distinct from the brown coloration on the rest of its body. The body of this species is fairly stout, with a moderately long snout and tail, and very small gill slits. Like other lanternsharks, the velvet belly is bioluminescent, with light-emitting photophores forming a species-specific pattern over its flanks and abdomen. The ventral photophores are thought to function in counter-illumination, which camouflages the shark against predators and prey. The bioluminescent flank markings may play a role in intraspecific communication.
The common skate, also known as the blue skate, is the largest skate in the world, attaining a length of up to 2.85 m. Historically, it was one of the most abundant skates in the northeast Atlantic Ocean and the Mediterranean Sea. Despite its name, today it appears to be absent from much of this range. Where previously abundant, fisheries directly targeted this skate and elsewhere it is caught incidentally as bycatch. The species was uplisted to critically endangered on the IUCN Red List in 2006 and it is protected within the EU.
The spotback skate is a species of fish in the family Arhynchobatidae. It is found off the Atlantic coasts of Argentina, Brazil, and Uruguay where its natural habitat is over the continental shelf in the open sea. It is a large fish, growing to over a metre in length. It feeds mainly on other fish according to availability, with shrimps, octopuses and other invertebrates also being eaten. Reproduction takes place throughout most of the year, with the eggs being laid in capsules that adhere to the seabed. The spotback skate is the subject of a fishery and is thought to be overfished, resulting in Greenpeace adding the fish to its red list of fish to be avoided, and the International Union for Conservation of Nature listing it as an "endangered species".
The smooth butterfly ray is a species of cartilaginous fish in the family Gymnuridae. It is a member of the order Myliobatiformes, which contains 10 total families. Its natural habitats are shallow seas, subtidal aquatic beds, estuarine waters, and coastal saline lagoons. Its common name is derived from its compressed body, pectoral fins that are wider than their length, and overall diamond shape.
The bluespotted trevally, also known as the wide-mouthed trevally, is a species of moderately large marine fish in the jack family Carangidae. The bluespotted trevally is distributed through the tropical east Indian and west Pacific Oceans, ranging from Taiwan in the north to Australia in the south. It is an inshore species, found in sandy, muddy and seagrass environments, often in large bays. The bluespotted trevally is distinguished by dark blue spots on its upper body, as well as a number of more detailed anatomical features. It is a benthopelagic predator, taking a variety of crustaceans including crabs and prawns as a juvenile, before shifting to a more fish-dominated diet as an adult. It is one of the most common predators in the Gulf of Carpentaria of northern Australia, and is considered the most important predator of commercially important prawn species. Sexual maturity is reached at 110 mm in length and one year of age, with spawning occurring year round with a peak in spring. Growth is estimated to be 82.2 mm per year for both sexes, reaching a maximum known length of 66 cm. Bluespotted trevally are commonly taken as bycatch in prawn fisheries, however are of little commercial value and often discarded. They are occasionally taken by anglers on lures and baits, but are considered mediocre table fare.
Cepola macrophthalma is a species of marine ray-finned fish belonging to the family Cepolidae, the bandfishes. It is found in the eastern Atlantic and Mediterranean from Senegal north to the British Isles. This species is known as the red bandfish, though this name is also given to other members of the genus Cepola.
The Tasmanian numbfish is a species of electric ray in the family Narcinidae. Endemic to southeastern Australia, this common ray inhabits shallow continental shelf waters in the southern portion of its range and deeper continental slope waters in the northern portion of its range. It prefers sand and mud habitats. This species can be identified by its spade-shaped pectoral fin disc with concave anterior margins, long tail with well-developed skin folds along either side, and plain dark brown dorsal colouration. Its maximum known length is 47 cm (19 in).
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