Northern river shark

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Northern river shark
Glyphis garricki csiro-nfc.jpg
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Chondrichthyes
Subclass: Elasmobranchii
Subdivision: Selachimorpha
Order: Carcharhiniformes
Family: Carcharhinidae
Genus: Glyphis
Species:
G. garricki
Binomial name
Glyphis garricki
Glyphis garricki rangemap.png
Range of the 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. This species inhabits areas with poor visibility, soft bottoms, and large tides, with immature sharks ranging into fresh and brackish water. 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 2.5 m (8.2 ft) long.

Contents

Northern river sharks are likely piscivorous. This species is viviparous, with females bearing litters of 9 young possibly every other year before the wet season. Very rare and facing threats from commercial and recreational fishing, and perhaps also habitat degradation, this species has been assessed as Vulnerable by the International Union for Conservation of Nature.

Taxonomy

The first known specimens of the northern river shark, two newborn males from Papua New Guinea, were discovered by New Zealand ichthyologist Jack Garrick, 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, William White, and Peter R. Last in a Commonwealth Scientific and Industrial Research Organisation paper. The type specimen is a female 67 cm (26 in) long, collected from the East Alligator River, Kakadu National Park, Northern Territory. [2]

Distribution and habitat

The northern river shark has been reported from King Sound, the Ord River, and Doctors Creek near Derby, Western Australia, the Adelaide and Alligator Rivers in Australia's Northern Territory, and the Daru region and possibly the Fly River in Papua New Guinea. It inhabits large rivers, estuaries, and coastal bays, all of which are characterized by high turbidity, silty or muddy bottoms, and large tides. Young and juvenile sharks are found in fresh, brackish, and salt water (salinity ranging from 2 to 36 ppt), whereas adults have only been found in marine environments. [2] [3] [4]

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 membranes. Each nostril 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 3035 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. [2]

The pectoral fins are large and broad, with gently backward-curving margins and pointed tips. The pelvic fins are triangular with nearly straight trailing margins. The first dorsal fin 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 is smaller than the second dorsal fin and has a strong notch in the rear margin. The caudal fin has a strong lower lobe and a long, narrow upper lobe with a ventral notch near the tip. The dermal denticles 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 2.5 m (8.2 ft). This species differs from the speartooth shark (G. glyphis) in several morphological and meristic characters, including having fewer vertebrae (137151 versus 213222) and a lower, jagged gray-white colour boundary. [2]

Biology and ecology

With its slender teeth, small eyes, and high density of ampullae of Lorenzini, the northern river shark seems to be adapted for hunting fish in conditions of poor visibility. In Doctors Creek, sharks may move to and from favored feeding areas with the tide. [1] [5] Like other requiem sharks, this species is viviparous, with the developing embryos forming a placental connection to their mother after exhausting their supply of yolk. Females give birth around October, before the start of the wet season, on possibly a biennial cycle. One female examined contained nine fetuses. [3] The young are born at under 67 cm (26 in) long; males mature between lengths of 1.2 and 1.4 m (3.9 and 4.6 ft), while females mature between lengths of 1.4 and 1.7 m (4.6 and 5.6 ft). [2]

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. [1] This species is caught legally and illegally by commercial fisheries using longlines and gillnets, as well as by recreational fishers; habitat degradation 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 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. [1] No regulations restrict the capture of this species in Papua New Guinea. [4]

Related Research Articles

<span class="mw-page-title-main">River shark</span> Genus of sharks

Glyphis is a genus in the family Carcharhinidae, commonly known as the river sharks. They live in rivers or coastal regions in and around south-east Asia and parts of Australia.

<span class="mw-page-title-main">Ganges shark</span> Species of shark

The Ganges shark is a critically endangered species of requiem shark found in the Ganges River and the Brahmaputra River of India and Bangladesh. It is often confused with the more common bull shark, which also inhabits the Ganges River and is sometimes incorrectly referred to as the Ganges shark. The genus is currently considered to contain three recent species; genetic evidence has shown that both the Borneo river shark and Irrawaddy river shark should be regarded as synonyms of the Ganges shark, expanding the range of the species to Pakistan, Myanmar, Borneo, and Java. While the other members of the genus Glyphis occur in coastal marine waters as well as rivers, the Ganges shark is found only in fresh water, making it the world's only exclusively freshwater shark. The species remains poorly known and very rare.

John Andrew Frank Garrick was a New Zealand ichthyologist.

<span class="mw-page-title-main">Speartooth shark</span> Species of shark

The speartooth shark 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 being a member of the river shark genus, it is also found in near-shore marine waters, favoring highly turbid environments over a wide range of salinities. This robustly built, gray-colored shark is characterized by a short and broad snout, tiny eyes, a relatively large second dorsal fin, and a black blotch beneath each pectoral fin near the tip. Another identifying trait is its teeth, which are large, triangular, and serrated in the upper jaw and narrow, spear-like, and serrated only near the tips in the lower jaw. Adults grow to about 2.6 m (8.5 ft) long.

<span class="mw-page-title-main">Graceful shark</span> Species of shark

The graceful shark or Queensland shark is a species of requiem shark, in the family Carcharhinidae, found in the tropical Indo-Pacific, from the Gulf of Aden to northern Australia. It is a midwater species that has been recorded to a depth of 50 m (160 ft). A stoutly built shark growing up to 1.7 m (5.6 ft) long, the graceful shark has a short, wedge-shaped snout, large, sickle-shaped pectoral fins and first dorsal fin, and black tips on most fins.

<span class="mw-page-title-main">Hardnose shark</span> Species of shark

The hardnose shark is a species of requiem shark, in the family Carcharhinidae, so named because of the heavily calcified cartilages in its snout. A small bronze-coloured shark reaching a length of 1.1 m (3.6 ft), it has a slender body and a long, pointed snout. Its two modestly sized dorsal fins have distinctively elongated rear tips. The hardnose shark is widely distributed in the western Indo-Pacific, from Kenya to southern China and northern Australia. It inhabits warm, shallow waters close to shore.

<span class="mw-page-title-main">Creek whaler</span> Species of shark

The creek whaler is a common species of requiem shark, and part of the family Carcharhinidae, endemic to northern Australia. It frequents shallow waters close to shore, including estuaries. This small, stocky shark usually grows to 1.0–1.3 m (3.3–4.3 ft) long and is brownish in color without conspicuous fin markings. It can be identified by its long snout, large, triangular pectoral fins, and large, anteriorly positioned first dorsal fin.

<span class="mw-page-title-main">Nervous shark</span> Species of shark

The nervous shark is a species of requiem shark, and part of the family Carcharhinidae, so named because of its timid behavior in regard to humans. It is common in shallow, coastal waters off northern Australia, Papua New Guinea, and the Solomon Islands. A small brownish or grayish shark typically measuring 1.0–1.3 m (3.3–4.3 ft) long, this species has a short, blunt snout, oval eyes, and a relatively large second dorsal fin. The leading margins of most fins are finely edged with black, and the lower caudal fin lobe is black-tipped.

<span class="mw-page-title-main">Pondicherry shark</span> Species of shark

The Pondicherry shark is an extremely rare species of requiem shark, in the family Carcharhinidae. A small and stocky gray shark, it grows not much longer than 1 m (3.3 ft) and has a fairly long, pointed snout. This species can be identified by the shape of its upper teeth, which are strongly serrated near the base and smooth-edged near the tip, and by its first dorsal fin, which is large with a long free rear tip. Furthermore, this shark has prominent black tips on its pectoral fins, second dorsal fin, and caudal fin lower lobe.

<span class="mw-page-title-main">Smoothtooth blacktip shark</span> Species of shark

The smoothtooth blacktip shark is a species of requiem shark in the family Carcharhinidae. It is known only from the type specimen caught from the Gulf of Aden, off eastern Yemen, and a handful of additional specimens caught from the Persian Gulf, off Kuwait. Reaching 1.3 m (4.3 ft) in length, this species has a stocky greenish-colored body, a short snout, and black-tipped fins. It can be distinguished from similar species by its teeth, which are narrow, erect, and smooth-edged.

<span class="mw-page-title-main">Australian weasel shark</span> Species of shark

The Australian weasel shark is an uncommon species of ground shark in the family Hemigaleidae. It inhabits shallow waters off northern Australia to a depth of 170 m (560 ft); smaller sharks frequent sand and seagrass habitat and shift to coral reefs as they grow older. A slim, drab species reaching a length of 1.1 m (3.6 ft), it has sickle-shaped fins with dark tips on the second dorsal fin and caudal fin upper lobe. Its upper teeth are broad with strong serrations only on the trailing edge. The lateral line along each side is prominent and exhibits a downward curve below the second dorsal fin.

<span class="mw-page-title-main">Australian sawtail catshark</span> Species of shark

The Australian sawtail catshark is a common species of catshark, and part of the family Scyliorhinidae, endemic to southern Australian waters. It is found on or near the bottom of the outer continental shelf and upper continental slope, at depths of 85 to 823 m. This slim-bodied species is characterized by crests of enlarged dermal denticles along both the dorsal and ventral edges of its caudal fin and caudal peduncle, along with a color pattern of broad, dark saddles outlined in white. It can grow to 61 cm (24 in) in length. The Australian sawtail catshark feeds mainly on fishes, crustaceans, and cephalopods. Females are oviparous and lay eggs enclosed by capsules. This species is often caught incidentally by commercial bottom trawl fisheries, but is not significantly threatened by fishing activity. Thus, it has been assessed as of Least Concern by the International Union for Conservation of Nature (IUCN).

The saddled swellshark is a rare species of catshark, and part of the family Scyliorhinidae, endemic to Eastern Australia. This bottom-dwelling species is found on the outer continental shelf and upper continental slope at a depth of 115–605 m (377–1,985 ft). It is a robustly built shark with a short, broad, flattened head and a capacious mouth. Adults are patterned with saddles on a brownish or grayish background, which varies between tropical and temperate sharks; juveniles are light-colored with many spots. This shark reaches 74 cm (29 in) in length. Like other swellsharks, it can inflate itself as a defensive measure. Reproduction is oviparous.

The narrowbar swellshark is a rare species of catshark, and part of the family Scyliorhinidae, known only from two specimens collected near Flinders Reef off northeastern Australia. This species reaches at least 44.5 cm (17.5 in) in length, and has a stocky body with a short, broad head. It can be readily identified by its zebra-like dorsal color pattern of transverse brown bars on a yellowish background. Like other swellsharks, it can inflate its body as a defensive measure.

The speckled swellshark is a little-known species of catshark, and part of the family Scyliorhinidae, endemic to the waters off northwestern Australia. It occurs on the outer continental shelf and upper continental slope, at a depth of 150–455 m (492–1,493 ft). This species grows to 69 cm (27 in) long and has a stocky body and a short, broad, flattened head. As its common name suggests, its color pattern consists of many dark spots and white-spotted dark saddles and blotches on a light gray background. The juveniles are yellow with dark spots and lines, and a distinctive eyespot-like mark behind each eye. Like other swellsharks, this species can inflate itself as a defensive measure.

<span class="mw-page-title-main">Striped stingaree</span> Species of cartilaginous fish

The striped stingaree is a common but little-known species of stingray in the family Urolophidae, endemic to shallow, inshore waters off southwestern Australia. Reaching 61 cm (24 in) long, this species is characterized by an oval, grayish to brownish disc with darker mask-like markings around the eyes and paired blotches at the center of the disc that are extended posteriorly into horizontal lines. Its nostrils have enlarged lobes on the outer margins and a skirt-shaped curtain of skin with a deeply fringed trailing margin in between. Its tail terminates in a relatively large leaf-shaped caudal fin, and bears a small dorsal fin just before the stinging spine. The rounded, flexible disc of the striped stingaree enable it to maneuver through the rocks, reefs, and seagrass that comprise its favored habitats. The International Union for Conservation of Nature (IUCN) has listed this species under Least Concern; it is seldom caught by fisheries due to its habitat preferences.

<span class="mw-page-title-main">Tropical sawshark</span> Species of shark

The tropical sawshark, Pristiophorus delicatus, is a recently described species of sawshark, family Pristiophoridae, formerly known in literature as Pristiophorus sp. B. It is endemic to northeastern Australia, found on the upper continental slope off Queensland from south of the Samaurez Reef, at a depth of 246–405 meters (807–1,329 ft). Its specific epithet delicatus is Latin for "delicate", referring to the fine teeth on its saw-like rostrum.

The flagtail swellshark is a little-known species of catshark, belonging to the family Scyliorhinidae, found at a depth of 480–700 m (1,570–2,300 ft) off northeastern Queensland, and possibly also nearby islands. This stout-bodied shark has a short, broad, and flattened head with a capacious mouth. Adults have a variegated brown coloration with 9–10 darker dorsal saddles and V-shaped blotch at the tip of the upper caudal fin lobe. Juveniles are yellow with narrow brown bars instead of saddles, and a distinctive marking between the spiracles shaped like two loops connected by a line. Like other swellsharks, this species can inflate its body when threatened.

<span class="mw-page-title-main">Australian blackspot shark</span> Species of shark

The Australian blackspot shark or Coates's shark is a species of requiem shark found off northern Australia and possibly also off the coast of New Guinea. It belongs to a species complex of Blackspot sharks in the family Carcharhinidae. These sharks are not widely studied due to their cryptic nature, but there was a recent reclassification distinguishing it from the Whitecheek shark and the Blackspot Shark in 2012. Much of the existing literature predates this reclassification and groups the Australian blackspot shark with the aforementioned closely related species.

<i>Carcharhinus tjutjot</i> Species of shark

The Indonesian whaler shark, is a species of requiem shark belonging to the family Carcharhinidae. Until recently, it was thought to be a junior synonym of the whitecheek shark. The Indonesian whaler shark, along with the family Carcharhinidae, is a key economic group in global fisheries including commercial and small-scale fisheries within the Indo-Pacific region. Common spawning and nursery areas overlap with commercial fishing grounds and it is often caught as bycatch which has caused it to be listed as a vulnerable species.

References

  1. 1 2 3 4 Kyne, P.M.; Rigby, C.L.; Cheok, J.; Darwall, W.R.T.; Grant, I.; Simpfendorfer, C. (2021). "Glyphis garricki". IUCN Red List of Threatened Species . 2021: e.T42712A68624151. doi: 10.2305/IUCN.UK.2021-2.RLTS.T42712A68624151.en . Retrieved 19 November 2021.
  2. 1 2 3 4 5 Compagno, L.J.V.; W.T. White & P.R. Last (2008). "Glyphis garricki sp. nov., a new species of river shark (Carcharhiniformes: Carcharhinidae) from northern Australia and Papua New Guinea, with a redescription of Glyphis glyphis (Müller & Henle, 1839)". In Last, P.R.; W.T. White & J.J. Pogonoski (eds.). Descriptions of new Australian Chondrichthyans. CSIRO Marine and Atmospheric Research. pp. 203–226. ISBN   978-0-1921424-1-2. (ISBN corrected) ISBN   1-921424-18-2 (invalid, listed in publication).
  3. 1 2 Pillans, R.D.; J.D. Stevens; P.M. Kyne & J. Salini (25 August 2009). "Observations on the distribution, biology, short-term movements and habitat requirements of river sharks Glyphis spp. in northern Australia" (PDF). Endangered Species Research. 10: 321–332. doi: 10.3354/esr00206 .
  4. 1 2 White, W.T.; S.A. Appleyard; B. Sabub; P.M. Kyne; M. Harris; R. Lis; L. Baje; T. Usu; J.J. Smart; S. Corrigan; L. Yang & G.J.P. Naylor (7 October 2015). "Rediscovery of the Threatened River Sharks, Glyphis garricki and G. glyphis, in Papua New Guinea". PLOS ONE. 10 (published online): e0140075. Bibcode:2015PLoSO..1040075W. doi: 10.1371/journal.pone.0140075 . PMC   4596488 . PMID   26445387.
  5. 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 Archived 8 November 2011 at the Wayback Machine . Report to the National Heritage Trust, Murdoch University. Retrieved on 10 January 2010.