Creek whaler

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Creek whaler
Carcharhinus fitzroyensis csiro-nfc.jpg
Scientific classification OOjs UI icon edit-ltr.svg
Kingdom: Animalia
Phylum: Chordata
Class: Chondrichthyes
Order: Carcharhiniformes
Family: Carcharhinidae
Genus: Carcharhinus
Species:
C. fitzroyensis
Binomial name
Carcharhinus fitzroyensis
(Whitley, 1943)
Carcharhinus fitzroyensis distmap.png
Range of the creek whaler [2]
Synonyms

Galeolamna fitzroyensisWhitley, 1943

The creek whaler (Carcharhinus fitzroyensis) 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.

Contents

The diet of the creek whaler consists mainly of small teleost fishes and crustaceans. It is viviparous, with the unborn young being sustained through a placental connection. The defined mating season lasts from May to July. Females give birth to one to seven pups annually, following a gestation period of seven to 9 months. A small number of creek whalers are caught incidentally in inshore gillnets and used for food, but the effect of fishing on its population seems to be inconsequential. As a result, the IUCN has listed this species under Least Concern.

Taxonomy and phylogeny

The creek whaler was described by Australian ichthyologist Gilbert Percy Whitley in a 1943 volume of Proceedings of the Linnean Society of New South Wales. He assigned the new species to the subgenus Uranganops of the genus Galeolamna, and gave it the specific epithet fitzroyensis because the type specimen, a 1.2-m-long female, was collected from Connor's Creek in the Fitzroy River estuary. [3] Subsequent authors have synonymized Galeolamna with Carcharhinus . [4]

The evolutionary relationships of the creek whaler have yet to be fully resolved. In comparative morphological studies published by Jack Garrick in 1982 and Leonard Compagno in 1988, it was tentatively placed in a grouping defined by the whitecheek shark (C. dussumieri) and the blackspot shark (C. sealei). [5] [6] Shane Lavery, in a 1992 study based on allozymes, reported that this species was close to the nervous shark (C. cautus) and the blacktip reef shark (C. melanopterus). [7] Ximena Vélez-Zuazoa and Ingi Agnarsson, in a 2011 study based on nuclear and mitochondrial genes, found it to be the basal member of a clade also containing the graceful shark (C. amblyrhynchoides), the blacktip shark (C. limbatus), and the Australian blacktip shark (C. tilstoni). [8]

Description

The body of the creek whaler is spindle-shaped and rather stocky. The long snout has a narrowly parabolic shape and large nostrils preceded by small, nipple-shaped flaps of skin. The eyes are circular and of medium size, and are equipped with nictitating membranes. The arched mouth has very short furrows at the corners. There are 30 upper and 28–30 lower tooth rows. The upper teeth are long and triangular with strongly serrated edges, and become increasing angled towards the sides of the jaw. The lower teeth are slender and upright with finely serrated edges. The five pairs of gill slits are short. [2] [4] [9]

The pectoral fins are distinctively large and triangular, with rounded to pointed tips. The large first dorsal fin originates over the rear of the pectoral fin bases. The second dorsal fin is relatively tall and long, and originates over or slightly behind the anal fin origin. There is no ridge between the dorsal fins. The anal fin is larger than the second dorsal fin. There is a crescent-shaped notch on the caudal peduncle just before the origin of the upper caudal fin lobe. The asymmetrical caudal fin has a well-developed lower lobe and a longer upper lobe with a ventral notch near the tip. The skin is densely covered by overlapping dermal denticles, each bearing three to five horizontal ridges leading to marginal teeth. This species is bronze to brownish gray above and pale below, and lacks an obvious lighter band on the flanks. Rarely, individuals may be light bluish gray above. It may reach 1.5 m (4.9 ft) in length, though 1.0–1.3 m (3.3–4.3 ft) is typical. [2] [4] [9]

Distribution and habitat

The range of the creek whaler is restricted to northern Australia, between Gladstone in central Queensland and Cape Cuvier in Western Australia. It is a common species that inhabits estuaries and inshore waters from the intertidal zone to a depth of at least 40 m (130 ft). [2]

Biology and ecology

Threadfin breams are among the prey taken by the creek whaler. Scolopsis bilineata.JPG
Threadfin breams are among the prey taken by the creek whaler.

The creek whaler feeds predominantly on small teleost fishes (including threadfin breams and lizardfishes) and crustaceans (including penaeid prawns and mantis shrimps); cephalopods are also infrequently consumed. [10] [11] Known parasites of this species include the tapeworm Callitetrarhynchus gracilis, [12] and a nematode in the genus Pulchrascaris. [13]

Like other members of its family, the creek whaler is viviparous, with the developing embryos receiving nourishment from the mother through a placental connection formed from the depleted yolk sac. Females produce litters of one to seven young every year. Mating occurs between May and July, with the females storing the sperm until ovulation takes place between July and September. After a gestation period of seven to 9 months, birthing occurs between February and May of the following year. [11] The newborns measure 35–50 cm (14–20 in) long and spend their first few months of life in shallow, inshore nursery areas such as Cleveland Bay in north Queensland. [9] [10] Males and females attain sexual maturity at lengths of around 83–88 cm (33–35 in) and 90–100 cm (35–39 in), respectively. [11]

Human interactions

The creek whaler is a minor bycatch of inshore gillnet fisheries operating in northern Australia; the meat is sold for human consumption. Given its relatively high reproductive rate, its population appears capable of withstanding present levels of fishing. Therefore, the IUCN has listed this species under Least Concern. [1]

Related Research Articles

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Requiem sharks are sharks of the family Carcharhinidae in the order Carcharhiniformes. They are migratory, live-bearing sharks of warm seas and include such species as the tiger shark, bull shark, lemon shark, spinner shark, blacknose shark, blacktip shark, grey reef shark, blacktip reef shark, silky shark, dusky shark, blue shark, copper shark, oceanic whitetip shark, and whitetip reef shark.

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

The blacktip reef shark is a species of requiem shark, in the family Carcharhinidae, which can be easily identified by the prominent black tips on its fins. Among the most abundant sharks inhabiting the tropical coral reefs of the Indian and Pacific Oceans, this species prefers shallow, inshore waters. Its exposed first dorsal fin is a common sight in the region. The blacktip reef shark is usually found over reef ledges and sandy flats, though it has also been known to enter brackish and freshwater environments. It typically attains a length of 1.6 m (5.2 ft). Like other sharks, the females are larger than the males.

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

The copper shark, bronze whaler, or narrowtooth shark, is a species of requiem shark, family Carcharhinidae, found mostly at temperate latitudes. It is distributed in a number of separate populations in the northeastern and southwestern Atlantic, off southern Africa, in the northwestern and eastern Pacific, and around Australia and New Zealand, with scattered reports from equatorial regions. This species can be found from brackish rivers and estuaries, to shallow bays and harbors, to offshore waters 100 m (330 ft) deep or more. Females are found apart from males for most of the year, and conduct seasonal migrations. A large species reaching 3.3 m (11 ft) long, the copper shark is difficult to distinguish from other large requiem sharks. It is characterized by its narrow, hook-shaped upper teeth, lack of a prominent ridge between the dorsal fins, and plain bronze coloration.

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

The blacktip shark is a species of requiem shark, and part of the family Carcharhinidae. It is common to coastal tropical and subtropical waters around the world, including brackish habitats. Genetic analyses have revealed substantial variation within this species, with populations from the western Atlantic Ocean isolated and distinct from those in the rest of its range. The blacktip shark has a stout, fusiform body with a pointed snout, long gill slits, and no ridge between the dorsal fins. Most individuals have black tips or edges on the pectoral, dorsal, pelvic, and caudal fins. It usually attains a length of 1.5 m (4.9 ft).

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

The blacknose shark is a species of requiem shark, belonging to the family Carcharhinidae, common in the tropical and subtropical waters of the western Atlantic Ocean. This species generally inhabits coastal seagrass, sand, or rubble habitats, with adults preferring deeper water than juveniles. A small shark typically measuring 1.3 m (4.3 ft) long, the blacknose has a typical streamlined "requiem shark" shape with a long, rounded snout, large eyes, and a small first dorsal fin. Its common name comes from a characteristic black blotch on the tip of its snout, though this may be indistinct in older individuals.

<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

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

The pigeye shark or Java shark is an uncommon species of requiem shark, in the family Carcharhinidae, found in the warm coastal waters of the eastern Atlantic and western Indo-Pacific. It prefers shallow, murky environments with soft bottoms, and tends to roam within a fairly localised area. With its bulky grey body, small eyes, and short, blunt snout, the pigeye shark looks almost identical to the better-known bull shark. The two species differ in vertebral count, the relative sizes of the dorsal fins, and other subtle traits. This shark typically reaches lengths of 1.9–2.5 m (6.2–8.2 ft).

<span class="mw-page-title-main">Borneo shark</span> Rare species of requiem shark

The Borneo shark is a species of requiem shark, and part of the family Carcharhinidae. Extremely rare, it is known only from inshore waters around Mukah in northwestern Borneo, though it may once have been more widely distributed. A small, gray shark reaching 65 cm (26 in) in length, this species is the only member of its genus with a row of enlarged pores above the corners of its mouth. It has a slender body with a long, pointed snout and a low second dorsal fin placed posterior to the anal fin origin.

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

The spinner shark is a type of requiem shark, in the family Carcharhinidae, named for the spinning leaps it makes as a part of its feeding strategy. This species occurs in tropical and warm temperate waters worldwide, except for in the eastern Pacific Ocean. It is found from coastal to offshore habitats to a depth of 100 m (330 ft), though it prefers shallow water. The spinner shark resembles a larger version of the blacktip shark, with a slender body, long snout, and black-marked fins. This species can be distinguished from the blacktip shark by the first dorsal fin, which has a different shape and is placed further back, and by the black tip on the anal fin. It attains a maximum length of 3 m (9.8 ft).

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

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<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">Smalltail shark</span> Species of shark

The smalltail shark is a species of requiem shark, and part of the family Carcharhinidae. It is found in the western Atlantic Ocean, from the northern Gulf of Mexico to southern Brazil. It inhabits shallow waters close to shore, particularly over muddy bottoms around estuaries. It tends to swim low in the water column and forms large aggregations segregated by sex. A slim species generally not exceeding 1.1 m (3.6 ft) in length, the smalltail shark has a rather long, pointed snout, a broad, triangular first dorsal fin, and a second dorsal fin that originates over the midpoint of the anal fin base. It is plain gray in color, without prominent markings on its fins.

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

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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 Harry, A.V.; Bennett, M.B.; Kyne, P.M. (2019). "Carcharhinus fitzroyensis". IUCN Red List of Threatened Species . 2019: e.T41735A68612902. doi: 10.2305/IUCN.UK.2019-1.RLTS.T41735A68612902.en . Retrieved 19 November 2021.
  2. 1 2 3 4 Last, P.R.; Stevens, J.D. (2009). Sharks and Rays of Australia (second ed.). Harvard University Press. pp. 260–261. ISBN   978-0-674-03411-2.
  3. Whitley, G.P. (September 15, 1943). "Ichthyological descriptions and notes". Proceedings of the Linnean Society of New South Wales. 68 (3–4): 114–144.
  4. 1 2 3 Compagno, L.J.V. (1984). Sharks of the World: An Annotated and Illustrated Catalogue of Shark Species Known to Date. Food and Agricultural Organization of the United Nations. pp. 472–473. ISBN   92-5-101384-5.
  5. Garrick, J.A.F. (1982). Sharks of the genus Carcharhinus. NOAA Technical Report, NMFS CIRC 445.
  6. Compagno, L.J.V. (1988). Sharks of the Order Carcharhiniformes. Princeton University Press. pp. 319–320. ISBN   0-691-08453-X.
  7. Lavery, S. (1992). "Electrophoretic analysis of phylogenetic relationships among Australian carcharhinid sharks". Australian Journal of Marine and Freshwater Research. 43 (1): 97–108. doi:10.1071/MF9920097.
  8. Vélez-Zuazoa, X.; Agnarsson, I. (February 2011). "Shark tales: A molecular species-level phylogeny of sharks (Selachimorpha, Chondrichthyes)". Molecular Phylogenetics and Evolution. 58 (2): 207–217. doi:10.1016/j.ympev.2010.11.018. PMID   21129490.
  9. 1 2 3 Voigt, M.; Weber, D. (2011). Field Guide for Sharks of the Genus Carcharhinus. Verlag Dr. Friedrich Pfeil. pp. 62–63. ISBN   978-3-89937-132-1.
  10. 1 2 Simpfendorfer, C.A.; Milward, N.E. (August 1, 1993). "Utilisation of a tropical bay as a nursery area by sharks of the families Carcharhinidae and Sphyrnidae". Environmental Biology of Fishes. 37 (4): 337–345. doi:10.1007/BF00005200. S2CID   22998036.
  11. 1 2 3 Lyle, J.M. (1987). "Observations on the biology of Carcharhinus cautus (Whitley), C. melanopterus (Quoy & Gaimard) and C. fitzroyensis (Whitley) from Northern Australia". Australian Journal of Marine and Freshwater Research. 38 (6): 701–710. doi:10.1071/mf9870701.
  12. Beveridge, I.; Campbell, R.A. (1996). "New records and description of trypanorhynch cestodes from Australian fishes". Records of the South Australian Museum. 29 (1): 1–22.
  13. Bruce, N.L.; Cannon, L.R.G. (1990). "Ascaridoid nematodes from sharks from Australia and the Solomon Islands, Southwestern Pacific Ocean". Invertebrate Taxonomy. 4 (4): 763–783. doi:10.1071/it9900763.