Longsnout Dogfish

• Maximum length1.15 m (3.8 ft); females larger than males
• WeightNot published; a metre-long animal is only a few kilograms
• LifespanUnknown; no validated ageing study exists
• Depth range150–1,360 m (490–4,460 ft), commonest at 400–820 m
• DietSmall bony fishes, some squid
• IUCN statusVulnerable (assessed 2019)

How to recognise a longsnout dogfish

Lead with the head. In Deania quadrispinosa the snout is flattened, blade-thin and takes up well over half the length of the head, so the eyes sit about midway along a face that looks stretched. The eyes themselves are large and oval, and in a freshly landed animal they glow faintly green under a torch, the reflection of the tapetum behind the retina.

Behind the head, the fin formula settles it. There are two dorsal fins, each carrying a stout grooved spine along its leading edge, and there is no anal fin whatsoever, which places the shark in the dogfish order and rules out every catshark and houndshark it might otherwise resemble. The first dorsal is low, short-based and angular; the second is distinctly taller, and its spine is the largest on the animal. The tail stalk carries no keel and the caudal fin has only a weak notch.

Colour runs from dark brown through grey-brown to nearly black above, a little paler below, with a dusky smudge on the dorsal fins of juveniles. Run a finger backwards along the flank and the skin feels coarse: the denticles of this genus are pitchfork-shaped, each crown split into three or four long cusps on a narrow stalk, unlike the flat overlapping scales of most sharks. The upper teeth are small, pointed and hooked; the lower ones are broad, blade-like and interlock into a continuous cutting edge.

How big does a longsnout dogfish get?

This is a small shark. The largest specimen on record measured 115 cm (3.8 ft) in total length, and most adults that reach a trawl deck are between 100 and 114 cm. Females run larger than males, the usual pattern in the gulper shark family, and the biggest animals in any haul are almost always female.

Maturity comes late in that short range. Published figures put first maturity at around 110 cm, which means a longsnout dogfish spends most of its life growing and only a small part of it breeding. Size at birth has not been recorded, because no full-term litter has been described; by comparison, the closely related birdbeak dogfish gives birth at roughly 30 cm, and something similar is likely here.

Weight is a gap in the literature. No published series of weights exists for the species, and honest reporting means saying so rather than quoting a figure. A shark of this build and length, slim-bodied with a huge oil-filled liver, would weigh only a few kilograms, far less than a bony fish of the same length. The bar below sets the 1.15 m maximum against a 1.8 m diver, and the comparison is the point: the longsnout dogfish is a knee-high animal, not a monster of the deep.

Where longsnout dogfish live

The species has a southern, temperate-to-subtropical distribution split between three regions. In the south-east Atlantic it is trawled off Namibia and along the Agulhas Bank and Algoa Bay in South Africa, continuing east into the south-west Indian Ocean off KwaZulu-Natal and southern Mozambique. In the south-west Pacific it occurs right around southern Australia, from Western Australia through the Great Australian Bight to New South Wales and Tasmania, and across the Tasman Sea to New Zealand. Scattered slope records also come from island groups further north, including Vanuatu.

Everywhere it is a slope animal, living just above the bottom rather than in open water. The verified depth range runs from about 150 m down to 1,360 m, and commercial catches concentrate sharply between 400 and 820 m. Older popular accounts of this shark quote a range beginning at 1,500 m, which is simply a transposed figure: the shallow end is 150 m, and the animal has never been taken below about 1,400 m.

At those depths the water is dark, still and cold, somewhere between 4 and 10 °C, and the seabed is soft mud or fine sand cut by canyons. That band of the slope is exactly where deep-water trawl fisheries work, which is why a shark almost nobody has seen alive is nevertheless well represented in catch records. For the wider picture of how sharks are spread through the water column, see where sharks live.

What longsnout dogfish eat

Stomach contents are the only evidence available, and they are consistent: small bony fishes dominate, with cephalopods appearing regularly and invertebrates occasionally. The fishes involved are the standard tenants of the upper slope, grenadiers, lanternfishes, morid cods and other soft-bodied species that hang close to the bottom, none of them fast and none of them armoured.

The jaws match that menu. The upper teeth are small, narrow and hooked backwards, good for gripping; the lower teeth are wider, blade-shaped and set edge to edge so the whole lower jaw works as one saw. A shark with this arrangement grabs with the top jaw and slices with the bottom, taking bites out of prey too large to swallow whole and cutting small fish in half rather than crushing them. There are no crushing plates here, so hard-shelled animals are not on the menu in any quantity.

Nobody has watched a longsnout dogfish hunt. What can be said from its anatomy is that it is built for economy, not speed: a soft body, a large oily liver that removes the need to swim to stay up, and a long snout crowded with the electroreceptive pores known as the ampullae of Lorenzini. In water with no light at all, a snout like that is a search tool, swept across the mud for the faint electrical signature of a buried or resting fish.

Behaviour and deep-sea adaptations

Most of what gets written about the senses of this shark is generic, and generic statements are worth little. What the anatomy actually shows is a set of specific deep-sea solutions. The liver is enormous relative to body mass and loaded with squalene, a light hydrocarbon oil that gives the shark near-neutral buoyancy; unlike a bony fish it has no gas-filled swim bladder, so the liver does that job instead, and the same oil is the reason the family is fished at all.

The eye is adapted rather than enlarged beyond reason. A reflective tapetum lucidum behind the retina bounces light back through the photoreceptors, doubling the chance of catching one of the rare photons produced by bioluminescent animals at 600 m. Rod-dominated retinas of this kind trade colour vision for raw sensitivity, which at these depths is the right trade.

Behaviourally the species is a near-blank page. Trawl catches often come back skewed towards one sex or one size class, which hints at segregation by depth or ground, a pattern well documented in other gulper sharks, but no tagging study has followed an individual. There is no evidence of migration, schooling or seasonal movement. Metabolic rates in slope squaloids are low, and everything about this animal, from its soft musculature to its unhurried growth, points to a life run at minimum cost. That slow pace matters later on, in why so many sharks are in trouble.

Reproduction and lifespan

The longsnout dogfish is a live-bearer of the simplest kind. Eggs are retained inside the mother, the embryos develop on the contents of their own yolk sacs with no placental connection and no supplementary feeding, and the pups are born fully formed. Older texts call this ovoviviparity; the modern term is yolk-sac viviparity, or lecithotrophy, and it is the standard mode for the whole dogfish order.

The numbers are thinner than most sources admit. Litter sizes of five to seventeen are repeated in popular accounts of the species, but they are not backed by a published series of pregnant females, and the honest position is that litter size for Deania quadrispinosa is unknown. What is known from relatives is sobering: gulper sharks in the genus Centrophorus often carry only one or two pups, and the birdbeak dogfish carries around six to twelve. Gestation has never been measured in this species either, though multi-year pregnancies are normal in deep-water squaloids.

Age is the biggest blank. No validated ageing study exists for the longsnout dogfish, so any lifespan figure you see is a guess. Related slope sharks that have been aged properly live a very long time indeed, with leafscale gulper sharks estimated at around seventy years, and there is no reason to think this one is quick. A shark that matures at about 110 cm out of a 115 cm maximum, breeds rarely and lives for decades has almost no capacity to absorb fishing pressure; the general principle is set out under how long sharks live.

Is the longsnout dogfish dangerous to people?

No. The shallowest verified record for the species is about 150 m, and the bulk of the population sits between 400 and 820 m, several hundred metres below the deepest recreational dive. Swimmers, surfers and divers will never meet one, and the SharkSider database holds no incident attributed to this species anywhere in the world.

The only people who handle longsnout dogfish are trawl crews and fisheries observers, and their risk is mechanical rather than predatory. Both dorsal fins carry stout spines that will go straight through a glove, and the pitchfork denticles make the skin rough enough to graze a forearm. A dead 1.1 m dogfish is a small animal with a modest mouth and no interest in anyone; the sensible precaution is a thick glove and a grip behind the head, the same as for any spined squaloid. Worth adding is that the spines are defensive rather than venomous: the spurdogs of the genus Squalus carry a mild venom gland at the base of each spine, but no such gland has been described in the gulper shark family, so a puncture here is a clean mechanical wound. The risk, as with any deep-sea species landed on deck, runs almost entirely in the other direction.

The SharkSider database has no incident attributed to this species. The database draws on the International Shark Attack File, the Global Shark Attack File and verified local reports, and is updated weekly.

Conservation status

The IUCN Red List assesses Deania quadrispinosa as Vulnerable, following the assessment carried out in 2019, with a decreasing global population trend. The figures behind that listing are blunt: standardised catch rates on the south-eastern Australian slope indicate a decline of more than 80 per cent, and the modelled global reduction over three generations is close to 30 per cent. Because generation length in a slope squaloid is measured in decades, those declines represent a long time and will take a long time to reverse.

The cause is deep-water trawling. The species has no targeted fishery and little commercial value as meat, but it is taken as bycatch wherever nets work the 400 to 800 m band, and the liver oil of centrophorid sharks is valuable enough that landings are rarely wasted. No member of the family is listed on CITES or the Convention on Migratory Species, so protection depends entirely on national fisheries rules.

Australia has done the most. Deepwater shark closures and depth limits on parts of the south-eastern slope, introduced after the collapse of other gulper shark stocks, apply to this species as well, and upper-slope trawl effort has fallen since its peak. Nothing comparable exists in the south-west Indian Ocean. Recovery for a shark with this life history is a multi-decade proposition, which is why deep-sea squaloids feature so heavily in work on shark fisheries and conservation.

Similar species and close relatives

The nearest relatives are the other members of the genus Deania, all of them long-snouted slope dogfishes with pitchfork denticles and no anal fin. The birdbeak dogfish (D. calcea) is the one most often confused with this species: it is longer, to about 1.6 m, with an even more exaggerated snout and a much smaller second dorsal spine, and the two overlap across southern Australia and New Zealand. The arrowhead dogfish (D. profundorum) is smaller and carries a low keel on the tail stalk that this species lacks.

Step out to the rest of the family and the snout shortens. The gulper shark, leafscale gulper shark, little gulper shark and blackfin gulper shark all belong to Centrophorus, share the two spined dorsals and the oily liver, but have blunt heads and block-shaped denticles. Further out among the dogfishes, the Portuguese dogfish and kitefin shark go deeper still and have no fin spines at all, while the prickly dogfish of the same southern slope is unmistakable: a high-finned, triangular animal that looks nothing like this one. For where all these branches sit on the family tree, see the evolution of sharks.

• Birdbeak Dogfish Sharkspecies profile
• Arrowhead Dogfishspecies profile
• Gulper Sharkspecies profile
• Leafscale Gulper Sharkspecies profile
• Little Gulper Sharkspecies profile
• Blackfin Gulper Sharkspecies profile

Written and reviewed by

SharkSider Editorial Team

A small team focused on researching sharks and making marine biology easy to understand. Every page is reviewed against current species records and the SharkSider attack database, and updated when new incidents or research appear.

Published October 26, 2022 · Last updated September 22, 2026 · No incident attributed to this species in the SharkSider attack database, which is updated weekly.