The northern river shark or New Guinea river shark (''Glyphis garricki'') is a

species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...

requiem shark Requiem sharks are sharks of the family Carcharhinidae in the order Carcharhiniformes. They are migratory, live-bearing sharks of warm seas (sometimes of brackish or fresh water) and include such species as the bull shark, lemon shark, blac ...

, in the

family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...

Carcharhinidae, found in scattered

tidal river A tidal river is a river whose flow and level are caused by tides. A section of a larger river affected by the tides is a tidal reach, but it may sometimes be considered a tidal river if it had been given a separate and another title name. Gene ...

s and associated coastal waters in northern

Australia Australia, officially the Commonwealth of Australia, is a country comprising mainland Australia, the mainland of the Australia (continent), Australian continent, the island of Tasmania and list of islands of Australia, numerous smaller isl ...

and in

Papua New Guinea Papua New Guinea, officially the Independent State of Papua New Guinea, is an island country in Oceania that comprises the eastern half of the island of New Guinea and offshore islands in Melanesia, a region of the southwestern Pacific Ocean n ...

. This species inhabits areas with poor visibility, soft bottoms, and large

tide Tides are the rise and fall of sea levels caused by the combined effects of the gravitational forces exerted by the Moon (and to a much lesser extent, the Sun) and are also caused by the Earth and Moon orbiting one another. Tide tables ...

s, with immature sharks ranging into

fresh Fresh may refer to: Arts, entertainment, and media Films and television * ''Fresh'' (1994 film), a crime film * ''Fresh'' (2009 film), a documentary film on sustainable agriculture * ''Fresh'' (2022 film), a thriller film *''Fresh with the Aust ...

and

brackish water Brackish water, sometimes termed brack water, is water occurring in a natural environment that has more salinity than freshwater, but not as much as seawater. It may result from mixing seawater (salt water) and fresh water together, as in estuary ...

. It is similar to other river sharks in having a stocky grey body with a high back, tiny eyes, and broad fins. It measures up to long. Northern river sharks are likely

piscivorous A piscivore () is a carnivorous animal that primarily eats fish. Fish were the diet of early tetrapod evolution (via water-bound amphibians during the Devonian period); insectivory came next; then in time, the more terrestrially adapted rept ...

. This species is

viviparous In animals, viviparity is development of the embryo inside the body of the mother, with the maternal circulation providing for the metabolic needs of the embryo's development, until the mother gives birth to a fully or partially developed juve ...

, with females bearing litters of 9 young possibly every other year before the

wet season The wet season (sometimes called the rainy season or monsoon season) is the time of year when most of a region's average annual rainfall occurs. Generally, the season lasts at least one month. The term ''green season'' is also sometimes used a ...

. Very rare and facing threats from

commercial Commercial may refer to: * (adjective for) commerce, a system of voluntary exchange of products and services ** (adjective for) trade, the trading of something of economic value such as goods, services, information or money * a dose of advertising ...

and

recreational fishing Recreational fishing, also called sport fishing or game fishing, is fishing for leisure, exercise or competition. It can be contrasted with commercial fishing, which is occupational fishing activities done for profit; or subsistence fishing, ...

, and perhaps also

habitat degradation Habitat destruction (also termed habitat loss or habitat reduction) occurs when a natural habitat is no longer able to support its native species. The organisms once living there have either moved elsewhere, or are dead, leading to a decrease ...

, this species has been assessed as Vulnerable by the

International Union for Conservation of Nature The International Union for Conservation of Nature (IUCN) is an international organization working in the field of nature conservation and sustainable use of natural resources. Founded in 1948, IUCN has become the global authority on the stat ...

Taxonomy

The first known specimens of the northern river shark, two newborn males from Papua New Guinea, were discovered by

New Zealand New Zealand () is an island country in the southwestern Pacific Ocean. It consists of two main landmasses—the North Island () and the South Island ()—and List of islands of New Zealand, over 600 smaller islands. It is the List of isla ...

ichthyologist Ichthyology is the branch of zoology devoted to the study of fish, including bony fish (Osteichthyes), cartilaginous fish (Chondrichthyes), and jawless fish (Agnatha). According to FishBase, 35,800 species of fish had been described as of March 2 ...

Jack Garrick John Andrew Frank Garrick (24 March 1928 – 30 August 2018) was a New Zealand ichthyologist. Career Garrick specialised in elasmobranchs and published many books and articles about shark and ray biology. In 1982, he published a thorough taxonom ...

, after whom the species was eventually named. This shark was referred to as "''Glyphis'' sp. C" until 2008, when it was formally described by

Leonard Compagno Leonard Joseph Victor Compagno (1943-2024) was an international authority on shark taxonomy and the author of many scientific papers and books on the subject, best known of which is his 1984 catalogue of shark species produced for the Food and Agri ...

, William White, and

Peter R. Last Peter Robert Last is an Australian ichthyologist, curator of the Australian National Fish Collection and a senior principal research scientist at CSIRO Marine and Atmospheric Research (CMAR) in Hobart, Tasmania. He is an elasmobranch expert and ...

in a

Commonwealth Scientific and Industrial Research Organisation The Commonwealth Scientific and Industrial Research Organisation (CSIRO) is an Australian Government agency that is responsible for scientific research and its commercial and industrial applications. CSIRO works with leading organisations arou ...

paper. The

type specimen In biology, a type is a particular wikt:en:specimen, specimen (or in some cases a group of specimens) of an organism to which the scientific name of that organism is formally associated. In other words, a type is an example that serves to ancho ...

is a female long, collected from the

East Alligator River Alligator Rivers is the name of an area in an Arnhem Land region of the Northern Territory of Australia, containing three rivers, the East, West, and South Alligator Rivers. It is regarded as one of the richest biological regions in Australia, ...

Kakadu National Park Kakadu National Park is a protected area in the Northern Territory of Australia, southeast of Darwin. It is a World Heritage Site. Kakadu is also gazetted as a locality, covering the same area as the national park, with 313 people recorded l ...

Northern Territory The Northern Territory (abbreviated as NT; known formally as the Northern Territory of Australia and informally as the Territory) is an states and territories of Australia, Australian internal territory in the central and central-northern regi ...

. (ISBN corrected) (invalid, listed in publication).

Distribution and habitat

The northern river shark has been reported from

King Sound King Sound is a large gulf in northern Western Australia. It expands from the mouth of the Fitzroy River (Western Australia), Fitzroy River, one of Australia's largest watercourses, and opens to the Indian Ocean. It is about long, and averag ...

, the

Ord River The Ord River is a river in the Kimberley (Western Australia), Kimberley region of Western Australia. The river's catchment covers . The lower Ord River and the confluence with Cambridge Gulf create the most northern estuarine environment in ...

, and Doctors Creek near

Derby, Western Australia Derby ( ) is a town in the Kimberley region of Western Australia. At the 2016 census, Derby had a population of 3,325 with 47.2% of Aboriginal and Torres Strait Islander descent. Along with Broome and Kununurra, it is one of only three town ...

, the

Adelaide Adelaide ( , ; ) is the list of Australian capital cities, capital and most populous city of South Australia, as well as the list of cities in Australia by population, fifth-most populous city in Australia. The name "Adelaide" may refer to ei ...

and

Alligator Rivers Alligator Rivers is the name of an area in an Arnhem Land region of the Northern Territory of Australia, containing three rivers, the East, West, and South Alligator Rivers. It is regarded as one of the richest biological regions in Australia, ...

in Australia's

, and the

Daru Daru is the capital of the Western Province of Papua New Guinea and a former Catholic bishopric. Daru town falls under the jurisdiction of Daru Urban LLG. The township is entirely located on an island that goes by the same name, which is lo ...

region and possibly the

Fly River The Fly River is the third longest river on the island of New Guinea, after the Sepik and Mamberamo, with a total length of . It is the largest by volume of discharge in Oceania, the largest in the world without a single dam in its catchment, an ...

in Papua New Guinea. It inhabits large

river A river is a natural stream of fresh water that flows on land or inside Subterranean river, caves towards another body of water at a lower elevation, such as an ocean, lake, or another river. A river may run dry before reaching the end of ...

estuaries An estuary is a partially enclosed coastal body of brackish water with one or more rivers or streams flowing into it, and with a free connection to the open sea. Estuaries form a transition zone between river environments and maritime environm ...

, and coastal

bay A bay is a recessed, coastal body of water that directly connects to a larger main body of water, such as an ocean, a lake, or another bay. A large bay is usually called a ''gulf'', ''sea'', ''sound'', or ''bight''. A ''cove'' is a small, ci ...

s, all of which are characterized by high

turbidity Turbidity is the cloudiness or haziness of a fluid caused by large numbers of individual particles that are generally invisible to the naked eye, similar to smoke in air. The measurement of turbidity is a key test of both water clarity and wa ...

, silty or muddy bottoms, and large tides. Young and juvenile sharks are found in fresh, brackish, and salt water (

salinity Salinity () is the saltiness or amount of salt (chemistry), salt dissolved in a body of water, called saline water (see also soil salinity). It is usually measured in g/L or g/kg (grams of salt per liter/kilogram of water; the latter is dimensio ...

ranging from 2 to 36 ppt), whereas adults have only been found in marine environments.

Description

Like other members of its genus, the northern river shark has a stocky body with a high back. The head is wide and flattened, with a broadly rounded snout and minute eyes equipped with

nictitating membrane The nictitating membrane (from Latin '' nictare'', to blink) is a transparent or translucent third eyelid present in some animals that can be drawn across the eye from the medial canthus to protect and moisten it while maintaining vision. Most ...

s. Each

nostril A nostril (or naris , : nares ) is either of the two orifices of the nose. They enable the entry and exit of air and other gasses through the nasal cavities. In birds and mammals, they contain branched bones or cartilages called turbinates ...

is divided into a very large incurrent opening and a small excurrent opening by a triangular skin flap. The sizable mouth is broadly arched, with short furrows at the corners. 31 to 34 tooth rows are in the upper jaw and 30–35 tooth rows are in the lower jaw; the upper teeth are upright and triangular with serrated edges, while the lower teeth are narrower and straight to slightly curved. In the largest individuals, the first few lower teeth from the jaw median are spear-shaped with serrations near the tip. The

pectoral fin Fins are moving appendages protruding from the body of fish that interact with water to generate thrust and help the fish aquatic locomotion, swim. Apart from the tail or caudal fin, fish fins have no direct connection with the vertebral column ...

s are large and broad, with gently backward-curving margins and pointed tips. The

pelvic fin Pelvic fins or ventral fins are paired fins located on the ventral (belly) surface of fish, and are the lower of the only two sets of paired fins (the other being the laterally positioned pectoral fins). The pelvic fins are homologous to the hi ...

s are triangular with nearly straight trailing margins. The first

dorsal fin A dorsal fin is a fin on the back of most marine and freshwater vertebrates. Dorsal fins have evolved independently several times through convergent evolution adapting to marine environments, so the fins are not all homologous. They are found ...

is long-based and triangular, with the apex almost forming a right angle; the second dorsal fin is some two-thirds as high as the first. The origin of the first dorsal fin lies over the pectoral fin insertions, while that of second dorsal fin lies over the pelvic fin rear tips. No ridge exists between the dorsal fins. The

anal fin Fins are moving appendages protruding from the body of fish that interact with water to generate thrust and help the fish swim. Apart from the tail or caudal fin, fish fins have no direct connection with the back bone and are supported o ...

is smaller than the second dorsal fin and has a strong notch in the rear margin. The

caudal fin Fins are moving appendages protruding from the body of fish that interact with water to generate thrust and help the fish swim. Apart from the tail or caudal fin, fish fins have no direct connection with the back bone and are supported only ...

has a strong lower lobe and a long, narrow upper lobe with a ventral notch near the tip. The

dermal denticle A fish scale is a small rigid plate that grows out of the skin of a fish. The skin of most jawed fishes is covered with these protective scale (zoology), scales, which can also provide effective Underwater camouflage, camouflage through the us ...

s are small, oval, and overlapping, bearing three horizontal ridges leading to marginal teeth. This shark is steel-gray above and white below; the colour transition is sharp, located well below the eye, and becomes jagged on the sides of the trunk. The anal and caudal fins become dusky or black towards the trailing margins and tips. The maximum known length is . This species differs from the

speartooth shark The speartooth shark (''Glyphis glyphis'') is a rare species of river shark, belonging to the family Carcharhinidae. It inhabits coastal marine waters and tidal reaches of large tropical rivers in northern Australia and New Guinea. Despite bei ...

(''G. glyphis'') in several morphological and

meristic Meristics is an area of zoology and botany which relates to counting quantitative features of animals and plants, such as the number of fins or scales in fish. A meristic (countable trait) can be used to describe a particular species, or used to i ...

characters, including having fewer

vertebra Each vertebra (: vertebrae) is an irregular bone with a complex structure composed of bone and some hyaline cartilage, that make up the vertebral column or spine, of vertebrates. The proportions of the vertebrae differ according to their spina ...

e (137–151 versus 213–222) and a lower, jagged gray-white colour boundary.

Reproduction

Biology and ecology

With its slender teeth, small eyes, and high density of

ampullae of Lorenzini Ampullae of Lorenzini (: ''ampulla'') are electroreceptors, sense organs able to detect electric fields. They form a network of mucus-filled pores in the skin of Chondrichthyes, cartilaginous fish (sharks, Ray (fish), rays, and chimaeras) and of ...

, the northern river shark seems to be

adapted In biology, adaptation has three related meanings. Firstly, it is the dynamic evolutionary process of natural selection that fits organisms to their environment, enhancing their evolutionary fitness. Secondly, it is a state reached by the p ...

for hunting

fish A fish (: fish or fishes) is an aquatic animal, aquatic, Anamniotes, anamniotic, gill-bearing vertebrate animal with swimming fish fin, fins and craniate, a hard skull, but lacking limb (anatomy), limbs with digit (anatomy), digits. Fish can ...

in conditions of poor visibility. In Doctors Creek, sharks may move to and from favored feeding areas with the tide.Thorburn, D.C., D.L. Morgan, A.J. Rowland and H.S. Gill. (February 2004)
The northern river shark (''Glyphis'' sp. C) in Western Australia
. Report to the National Heritage Trust, Murdoch University. Retrieved on 10 January 2010. Like other requiem sharks, this species is

, with the developing

embryo An embryo ( ) is the initial stage of development for a multicellular organism. In organisms that reproduce sexually, embryonic development is the part of the life cycle that begins just after fertilization of the female egg cell by the male sp ...

s forming a

placenta The placenta (: placentas or placentae) is a temporary embryonic and later fetal organ that begins developing from the blastocyst shortly after implantation. It plays critical roles in facilitating nutrient, gas, and waste exchange between ...

l connection to their mother after exhausting their supply of

yolk Among animals which produce eggs, the yolk (; also known as the vitellus) is the nutrient-bearing portion of the egg whose primary function is to supply food for the development of the embryo. Some types of egg contain no yolk, for example bec ...

. Females give birth around October, before the start of the

, on possibly a biennial cycle. One female examined contained nine

fetus A fetus or foetus (; : fetuses, foetuses, rarely feti or foeti) is the unborn offspring of a viviparous animal that develops from an embryo. Following the embryonic development, embryonic stage, the fetal stage of development takes place. Pren ...

es. The young are born at under long; males

mature Mature is the adjectival form of maturity, as immature is the adjectival form of immaturity, which have several meanings. Mature or immature may also refer to: * Mature, a character from ''The King of Fighters'' series *"Mature 17+", a rating in ...

between lengths of , while females mature between lengths of .

Human interactions

The northern river shark appears to be extremely rare, though more subpopulations may remain to be discovered in Australia and Papua New Guinea. Based on present information, no more than 250 mature individuals are estimated to exist in the wild, with no more than 50 in any particular subpopulation. This species is caught legally and illegally by

commercial fisheries Commercial fishing is the activity of catching fish and other seafood for commercial profit, mostly from wild fisheries. It provides a large quantity of food to many countries around the world, but those who practice it as an industry must often p ...

using longlines and

gillnet Gillnetting is a fishing method that uses gillnets: vertical panels of netting that hang from a line with regularly spaced floaters that hold the line on the surface of the water. The floats are sometimes called "corks" and the line with corks is ...

s, as well as by recreational fishers;

may pose a further threat to its survival. Because of its low natural abundance, limited distribution, stringent habitat requirements, and susceptibility to various human-caused threats, the

IUCN The International Union for Conservation of Nature (IUCN) is an international organization working in the field of nature conservation and sustainable use of natural resources. Founded in 1948, IUCN has become the global authority on the status ...

has assessed the northern river shark as Vulnerable. It has also been listed as endangered on the 1999 Commonwealth Environment Protection and Biodiversity Conservation Act, and on the 2000 Territory Parks and Wildlife Conservation Act. Kakadu National Park may be an important protected area for this species. No regulations restrict the capture of this species in Papua New Guinea.

References

{{Taxonbar, from=Q311339

northern river shark The northern river shark or New Guinea river shark (''Glyphis garricki'') is a species of requiem shark, in the family Carcharhinidae, found in scattered tidal rivers and associated coastal waters in northern Australia and in Papua New Guinea. ...

Freshwater fish of Papua New Guinea Freshwater fish of the Northern Territory Freshwater fish of Western Australia Brackish water organisms Critically endangered fish Critically endangered fauna of Oceania Critically endangered fauna of Australia Taxa named by Leonard Compagno Taxa named by Peter R. Last