Dasyatis fluviorum
Encyclopedia
The estuary stingray also called the estuary stingaree or brown stingray, is a species
of stingray
in the family
Dasyatidae. Endemic to eastern Australia
, it typically inhabits shallow, mangrove
-lined tidal river
s, estuaries, and bay
s in southern Queensland
and New South Wales
. This yellow-brown to olive ray grows to at least 93 cm (36.6 in) across. It has a diamond-shaped pectoral fin disc and a mostly smooth, whip-like tail bearing both dorsal and ventral fin folds. It can additionally be identified by its long, narrow nostrils and the row of thorns along the midline of its back.
While the estuary stingray has gained infamy for consuming farmed shellfish such as oyster
s, it mainly feeds on crustacean
s and polychaete worms. It is aplacental viviparous, with the unborn young sustained to term by maternal histotroph ("uterine milk"). Once common, this species has apparently declined across much of its range, likely from a combination of habitat degradation, mortality
from commercial
and recreational fishing
, and persecution by shellfish farmers
. As a result, the International Union for Conservation of Nature (IUCN) has assessed it as Vulnerable
.
William Saville-Kent
of a "Trygon pastinaca
" feeding on oysters in a Queensland
estuary. This species was formally described by Australian ichthyologist James Douglas Ogilby
in a 1908 volume of Proceedings of the Royal Society of Queensland, based on a specimen collected from the Brisbane River
. The specific epithet fluviorum means "of the rivers" in Latin
.
s. Between the long and narrow nostrils, there is a short and broad "skirt" of skin with a weakly fringed posterior margin. The small, bow-shaped mouth is surrounded by deep furrows and contains a row of five papillae across the floor, with the outermost pair tiny and set apart from the others. The teeth are small and arranged into pavement-like surfaces. There are five pairs of gill slit
s beneath the disc. The pelvic fins are relatively large.
The tail measures twice as long as the disc, and is broad and flattened at the base. On its upper surface is at least one, often two serrated stinging spines. Past the spines, the tail quickly tapers to become whip-like and bears a well-developed keel above and a long, low fin fold beneath. There are wide patches of small dermal denticles with flattened crowns between the eyes and over the middle of the back, along with a midline row of enlarged thorns that become progressively longer until they reach the base of the sting. Aside from the thorns at the base, the tail is smooth. This species is yellowish to greenish brown above, lightening towards the disc margins and darkening past the tail spine, and white below. It grows to at least 93 cm (36.6 in) across, and possibly reaches a width of 1.2 m (3.9 ft). Its maximum recorded weight is 6.1 kg (13.4 lb).
's eastern coast, from Repulse Bay in Queensland
to the Hacking River
in New South Wales
. It is most common in southern Queensland, including in Hervey Bay and Moreton Bay
. This species was formerly suspected to have disappeared from Botany Bay
and Port Jackson
in the 1880s, but recent observations have shown this is not the case. Additional species records from the Cape York Peninsula
, Northern Territory
, New Guinea
, and the South China Sea
probably represent misidentifications of other stingrays, primarily the freshwater whipray
(Himantura dalyensis) and an undescribed species presently called the "Merauke stingray".
The habitat
requirements of the estuary stingray appear to be rather stringent, as significant numbers are only found at particular locations. It prefers tidal river
s and the intertidal flats of estuaries and bay
s, which are lined with mangrove
s and have sandy to muddy bottoms. This species is rarely found outside these sheltered areas, though it has been recorded to a depth of 28 m (91.9 ft) in offshore waters. It inhabits marine and brackish water
s, and may be able to tolerate fresh water
as well as it has been known to swim upriver beyond the limit of high tide
. Surface water temperatures within its range vary from 24–29 °C (75.2–84.2 F) in the north to 17–23 °C (62.6–73.4 F) in the south. This species seems to segregate by size and sex.
Despite its reputation for preying voraciously on oyster
s and other farmed shellfish
, the estuary stingray's diet in fact consists mainly of crustacean
s and polychaete worms. In Moreton Bay, an important prey species is the soldier crab
(Mictyris longicarpus). This ray has been observed entering mudflat
s with the rising tide to forage for food. Known parasites of the estuary stingray include the tapeworms Heterocotyle chin and Shirleyrhynchus aetobatidis, the nematode
Echinocephalus overstreeti, and the monogenea
ns Empruthotrema dasyatidis and Neoentobdella cribbi.
Like other stingrays, the estuary stingray exhibits aplacental viviparity, with the developing embryo
s sustained initially by yolk and later by histotroph ("uterine milk") produced by the mother. Females probably produce offspring every year. Courtship, in which the male follows the female and bites her disc, has been observed at night in water approximately 80 cm (31.5 in) deep in Hays Inlet
from July to October. The newborns measure around 11 cm (4.3 in) across and 35 cm (13.8 in) long. Young rays have been caught in the Nerang
and Macleay River
s and in Hays Inlet; such fresh or brackish environments may serve as nurseries. Males mature at around 41 cm (16.1 in) across and seven years of age, and females mature at around 63 cm (24.8 in) across and 13 years of age. This disparity in maturation size between the sexes is among the widest known for stingrays. The maximum lifespan is estimated to be 16 years for males and 23 years for females.
fisheries; bycatch
mortality is exacerbated by the practice of "spiking", in which the ray's cranium is pierced with a metal bar or sharpened stick so as to move it. It is also readily caught, and often killed, by recreational anglers
. Surveys in Moreton Bay have found fishing-related effects, such as embedded hooks and mutilated tails, in over 10% of the population. Habitat degradation is another major threat to the estuary stingray, especially given its habitat specificity. Its range encompasses some of the most urbanized
areas in Australia, where there is extensive land reclamation
, water pollution
, and construction of flood
mitigation barriers on rivers. Finally, this ray's reputation for damaging shellfish has led to persecution by commercial shellfish farmers.
The estuary stingray's diminished population and susceptibility to multiple threats have led the International Union for Conservation of Nature (IUCN) to assess it as Vulnerable
. Demographic modelling has shown that it is likely to become Endangered without intervention. Several Marine Protected Area
s (MPAs) are located within its range, but at present they lack adequate protection from fishing. As this ray remains locally abundant in Hervey Bay and parts of Moreton Bay, these areas may become important centers for preserving the species. The Queensland government has listed the estuary stingray on the Back on Track species prioritisation framework, to facilitate the development of conservation measures.
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
of stingray
Stingray
The stingrays are a group of rays, which are cartilaginous fishes related to sharks. They are classified in the suborder Myliobatoidei of the order Myliobatiformes, and consist of eight families: Hexatrygonidae , Plesiobatidae , Urolophidae , Urotrygonidae , Dasyatidae , Potamotrygonidae The...
in the family
Family (biology)
In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...
Dasyatidae. Endemic to eastern Australia
Australia
Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...
, it typically inhabits shallow, mangrove
Mangrove
Mangroves are various kinds of trees up to medium height and shrubs that grow in saline coastal sediment habitats in the tropics and subtropics – mainly between latitudes N and S...
-lined tidal river
Tidal river
A tidal river is a river, or more typically a stretch of a river, whose flow and level is influenced by tides. An example of a tidal river is the portion of the Connecticut River flowing from Windsor Locks, Connecticut, to the Atlantic Ocean. The Brisbane River, which flows into the Pacific Ocean...
s, estuaries, and bay
Bay
A bay is an area of water mostly surrounded by land. Bays generally have calmer waters than the surrounding sea, due to the surrounding land blocking some waves and often reducing winds. Bays also exist as an inlet in a lake or pond. A large bay may be called a gulf, a sea, a sound, or a bight...
s in southern Queensland
Queensland
Queensland is a state of Australia, occupying the north-eastern section of the mainland continent. It is bordered by the Northern Territory, South Australia and New South Wales to the west, south-west and south respectively. To the east, Queensland is bordered by the Coral Sea and Pacific Ocean...
and New South Wales
New South Wales
New South Wales is a state of :Australia, located in the east of the country. It is bordered by Queensland, Victoria and South Australia to the north, south and west respectively. To the east, the state is bordered by the Tasman Sea, which forms part of the Pacific Ocean. New South Wales...
. This yellow-brown to olive ray grows to at least 93 cm (36.6 in) across. It has a diamond-shaped pectoral fin disc and a mostly smooth, whip-like tail bearing both dorsal and ventral fin folds. It can additionally be identified by its long, narrow nostrils and the row of thorns along the midline of its back.
While the estuary stingray has gained infamy for consuming farmed shellfish such as oyster
Oyster
The word oyster is used as a common name for a number of distinct groups of bivalve molluscs which live in marine or brackish habitats. The valves are highly calcified....
s, it mainly feeds on crustacean
Crustacean
Crustaceans form a very large group of arthropods, usually treated as a subphylum, which includes such familiar animals as crabs, lobsters, crayfish, shrimp, krill and barnacles. The 50,000 described species range in size from Stygotantulus stocki at , to the Japanese spider crab with a leg span...
s and polychaete worms. It is aplacental viviparous, with the unborn young sustained to term by maternal histotroph ("uterine milk"). Once common, this species has apparently declined across much of its range, likely from a combination of habitat degradation, mortality
Death
Death is the permanent termination of the biological functions that sustain a living organism. Phenomena which commonly bring about death include old age, predation, malnutrition, disease, and accidents or trauma resulting in terminal injury....
from commercial
Commercial fishing
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 pursue fish far into the ocean under adverse conditions...
and recreational fishing
Recreational fishing
Recreational fishing, also called sport fishing, is fishing for pleasure or competition. It can be contrasted with commercial fishing, which is fishing for profit, or subsistence fishing, which is fishing for survival....
, and persecution by shellfish farmers
Aquaculture
Aquaculture, also known as aquafarming, is the farming of aquatic organisms such as fish, crustaceans, molluscs and aquatic plants. Aquaculture involves cultivating freshwater and saltwater populations under controlled conditions, and can be contrasted with commercial fishing, which is the...
. As a result, the International Union for Conservation of Nature (IUCN) has assessed it as Vulnerable
Vulnerable species
On 30 January 2010, the IUCN Red List of Threatened Species identified 9694 Vulnerable species, subspecies and varieties, stocks and sub-populations.-References:...
.
Taxonomy
The first reference to the estuary stingray in scientific literature was probably a record by 19th-century English naturalistNaturalist
Naturalist may refer to:* Practitioner of natural history* Conservationist* Advocate of naturalism * Naturalist , autobiography-See also:* The American Naturalist, periodical* Naturalism...
William Saville-Kent
William Saville-Kent
William Saville-Kent was an English marine biologist.Born in Sidmouth, Devon, his childhood was marred by the death of his mother, the murder of his half-brother and conviction of his sister Constance to twenty years in prison...
of a "Trygon pastinaca
Common stingray
The common stingray is a species of stingray in the family Dasyatidae, found in the northeastern Atlantic Ocean and the Mediterranean and Black Seas. It typically inhabits sandy or muddy habitats in coastal waters shallower than , often burying itself in sediment...
" feeding on oysters in a Queensland
Queensland
Queensland is a state of Australia, occupying the north-eastern section of the mainland continent. It is bordered by the Northern Territory, South Australia and New South Wales to the west, south-west and south respectively. To the east, Queensland is bordered by the Coral Sea and Pacific Ocean...
estuary. This species was formally described by Australian ichthyologist James Douglas Ogilby
James Douglas Ogilby
James Douglas Ogilby was an Australian ichthyologist.Ogilby was born in Belfast, Ireland, and was the son of zoologist William Ogilby. He received his education at Winchester College, England, and Trinity College, Dublin.Ogilby worked for the British Museum before joining the Australian Museum in...
in a 1908 volume of Proceedings of the Royal Society of Queensland, based on a specimen collected from the Brisbane River
Brisbane River
The Brisbane River is the longest river in south east Queensland, Australia, and flows through the city of Brisbane, before emptying into Moreton Bay. John Oxley was the first European to explore the river who named it after the Governor of New South Wales, Thomas Brisbane in 1823...
. The specific epithet fluviorum means "of the rivers" in Latin
Latin
Latin is an Italic language originally spoken in Latium and Ancient Rome. It, along with most European languages, is a descendant of the ancient Proto-Indo-European language. Although it is considered a dead language, a number of scholars and members of the Christian clergy speak it fluently, and...
.
Description
The estuary stingray has a diamond-shaped pectoral fin disc about as wide as long, with gently convex anterior margins and broadly rounded outer corners. The snout is wide and triangular, and tapers to a point. The small, widely spaced eyes are immediately followed by the spiracleSpiracle
Spiracles are openings on the surface of some animals that usually lead to respiratory systems.-Vertebrates:The spiracle is a small hole behind each eye that opens to the mouth in some fishes. In the primitive jawless fish the first gill opening immediately behind the mouth is essentially similar...
s. Between the long and narrow nostrils, there is a short and broad "skirt" of skin with a weakly fringed posterior margin. The small, bow-shaped mouth is surrounded by deep furrows and contains a row of five papillae across the floor, with the outermost pair tiny and set apart from the others. The teeth are small and arranged into pavement-like surfaces. There are five pairs of gill slit
Gill slit
Gill slits are individual openings to gills, i.e., multiple gill arches, which lack a single outer cover. Such gills are characteristic of Cartilaginous fish such as sharks, rays, sawfish, and guitarfish. Most of these have five pairs, but a few species have 6 or 7 pairs...
s beneath the disc. The pelvic fins are relatively large.
The tail measures twice as long as the disc, and is broad and flattened at the base. On its upper surface is at least one, often two serrated stinging spines. Past the spines, the tail quickly tapers to become whip-like and bears a well-developed keel above and a long, low fin fold beneath. There are wide patches of small dermal denticles with flattened crowns between the eyes and over the middle of the back, along with a midline row of enlarged thorns that become progressively longer until they reach the base of the sting. Aside from the thorns at the base, the tail is smooth. This species is yellowish to greenish brown above, lightening towards the disc margins and darkening past the tail spine, and white below. It grows to at least 93 cm (36.6 in) across, and possibly reaches a width of 1.2 m (3.9 ft). Its maximum recorded weight is 6.1 kg (13.4 lb).
Distribution and habitat
The range of the estuary stingray spans approximately 1700 km (1,056.3 mi) along AustraliaAustralia
Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...
's eastern coast, from Repulse Bay in Queensland
Queensland
Queensland is a state of Australia, occupying the north-eastern section of the mainland continent. It is bordered by the Northern Territory, South Australia and New South Wales to the west, south-west and south respectively. To the east, Queensland is bordered by the Coral Sea and Pacific Ocean...
to the Hacking River
Hacking River
The Hacking River is a stream in the state of New South Wales in Australia. It rises near the Princes Highway west of Stanwell Tops, and flows through the Royal National Park before emptying into Port Hacking...
in New South Wales
New South Wales
New South Wales is a state of :Australia, located in the east of the country. It is bordered by Queensland, Victoria and South Australia to the north, south and west respectively. To the east, the state is bordered by the Tasman Sea, which forms part of the Pacific Ocean. New South Wales...
. It is most common in southern Queensland, including in Hervey Bay and Moreton Bay
Moreton Bay
Moreton Bay is a bay on the eastern coast of Australia 45 km from Brisbane, Queensland. It is one of Queensland's most important coastal resources...
. This species was formerly suspected to have disappeared from Botany Bay
Botany Bay
Botany Bay is a bay in Sydney, New South Wales, a few kilometres south of the Sydney central business district. The Cooks River and the Georges River are the two major tributaries that flow into the bay...
and Port Jackson
Port Jackson
Port Jackson, containing Sydney Harbour, is the natural harbour of Sydney, Australia. It is known for its beauty, and in particular, as the location of the Sydney Opera House and Sydney Harbour Bridge...
in the 1880s, but recent observations have shown this is not the case. Additional species records from the Cape York Peninsula
Cape York Peninsula
Cape York Peninsula is a large remote peninsula located in Far North Queensland at the tip of the state of Queensland, Australia, the largest unspoilt wilderness in northern Australia and one of the last remaining wilderness areas on Earth...
, Northern Territory
Northern Territory
The Northern Territory is a federal territory of Australia, occupying much of the centre of the mainland continent, as well as the central northern regions...
, New Guinea
New Guinea
New Guinea is the world's second largest island, after Greenland, covering a land area of 786,000 km2. Located in the southwest Pacific Ocean, it lies geographically to the east of the Malay Archipelago, with which it is sometimes included as part of a greater Indo-Australian Archipelago...
, and the South China Sea
South China Sea
The South China Sea is a marginal sea that is part of the Pacific Ocean, encompassing an area from the Singapore and Malacca Straits to the Strait of Taiwan of around...
probably represent misidentifications of other stingrays, primarily the freshwater whipray
Freshwater whipray
The giant freshwater stingray is a species of stingray in the family Dasyatidae, native to large rivers and estuaries of Southeast Asia. It is one of the largest freshwater fishes in the world, with reports from the Chao Phraya and Mekong Rivers of individuals weighing 500–600 kg...
(Himantura dalyensis) and an undescribed species presently called the "Merauke stingray".
The habitat
Habitat
* Habitat , a place where a species lives and grows*Human habitat, a place where humans live, work or play** Space habitat, a space station intended as a permanent settlement...
requirements of the estuary stingray appear to be rather stringent, as significant numbers are only found at particular locations. It prefers tidal river
Tidal river
A tidal river is a river, or more typically a stretch of a river, whose flow and level is influenced by tides. An example of a tidal river is the portion of the Connecticut River flowing from Windsor Locks, Connecticut, to the Atlantic Ocean. The Brisbane River, which flows into the Pacific Ocean...
s and the intertidal flats of estuaries and bay
Bay
A bay is an area of water mostly surrounded by land. Bays generally have calmer waters than the surrounding sea, due to the surrounding land blocking some waves and often reducing winds. Bays also exist as an inlet in a lake or pond. A large bay may be called a gulf, a sea, a sound, or a bight...
s, which are lined with mangrove
Mangrove
Mangroves are various kinds of trees up to medium height and shrubs that grow in saline coastal sediment habitats in the tropics and subtropics – mainly between latitudes N and S...
s and have sandy to muddy bottoms. This species is rarely found outside these sheltered areas, though it has been recorded to a depth of 28 m (91.9 ft) in offshore waters. It inhabits marine and brackish water
Brackish water
Brackish water is water that has more salinity than fresh water, but not as much as seawater. It may result from mixing of seawater with fresh water, as in estuaries, or it may occur in brackish fossil aquifers. The word comes from the Middle Dutch root "brak," meaning "salty"...
s, and may be able to tolerate fresh water
Fresh Water
Fresh Water is the debut album by Australian rock and blues singer Alison McCallum, released in 1972. Rare for an Australian artist at the time, it came in a gatefold sleeve...
as well as it has been known to swim upriver beyond the limit of high tide
High Tide
High Tide was a band formed in 1969 by Tony Hill , Simon House , Peter Pavli and Roger Hadden .-History:...
. Surface water temperatures within its range vary from 24–29 °C (75.2–84.2 F) in the north to 17–23 °C (62.6–73.4 F) in the south. This species seems to segregate by size and sex.
Biology and ecology
Oyster
The word oyster is used as a common name for a number of distinct groups of bivalve molluscs which live in marine or brackish habitats. The valves are highly calcified....
s and other farmed shellfish
Oyster farming
Oyster farming is an aquaculture practice in which oysters are raised for human consumption. Oyster farming most likely developed in tandem with pearl farming, a similar practice in which oysters are farmed for the purpose of developing pearls...
, the estuary stingray's diet in fact consists mainly of crustacean
Crustacean
Crustaceans form a very large group of arthropods, usually treated as a subphylum, which includes such familiar animals as crabs, lobsters, crayfish, shrimp, krill and barnacles. The 50,000 described species range in size from Stygotantulus stocki at , to the Japanese spider crab with a leg span...
s and polychaete worms. In Moreton Bay, an important prey species is the soldier crab
Mictyris longicarpus
Mictyris longicarpus is a species of crab that lives on sandy beaches from the Bay of Bengal to Australia; with other members of the genus Mictyris, it is "one of the most loved crabs in Australia". Adults are across, white, with blue on their backs, and hold their claws vertically. They feed on...
(Mictyris longicarpus). This ray has been observed entering mudflat
Mudflat
Mudflats or mud flats, also known as tidal flats, are coastal wetlands that form when mud is deposited by tides or rivers. They are found in sheltered areas such as bays, bayous, lagoons, and estuaries. Mudflats may be viewed geologically as exposed layers of bay mud, resulting from deposition of...
s with the rising tide to forage for food. Known parasites of the estuary stingray include the tapeworms Heterocotyle chin and Shirleyrhynchus aetobatidis, the nematode
Nematode
The nematodes or roundworms are the most diverse phylum of pseudocoelomates, and one of the most diverse of all animals. Nematode species are very difficult to distinguish; over 28,000 have been described, of which over 16,000 are parasitic. It has been estimated that the total number of nematode...
Echinocephalus overstreeti, and the monogenea
Monogenea
Monogenea are a group of largely ectoparasitic members of the flatworm phylum Platyhelminthes, class Monogenea.-Characteristics:Monogenea are very small parasitic flatworms mainly found on skin or gills of fish....
ns Empruthotrema dasyatidis and Neoentobdella cribbi.
Like other stingrays, the estuary stingray exhibits aplacental viviparity, with the developing embryo
Embryo
An embryo is a multicellular diploid eukaryote in its earliest stage of development, from the time of first cell division until birth, hatching, or germination...
s sustained initially by yolk and later by histotroph ("uterine milk") produced by the mother. Females probably produce offspring every year. Courtship, in which the male follows the female and bites her disc, has been observed at night in water approximately 80 cm (31.5 in) deep in Hays Inlet
Hays Inlet
Hays Inlet is a saltwater inlet off Bramble Bay in Queensland, Australia. The Brisway map reference is 420 L19. A mangrove forest is found in the inlet.-Geography:...
from July to October. The newborns measure around 11 cm (4.3 in) across and 35 cm (13.8 in) long. Young rays have been caught in the Nerang
Nerang River
The Nerang River is a river that begins in the McPherson Range in the Gold Coast hinterland and runs through Gold Coast City in South East Queensland, Australia...
and Macleay River
Macleay River
The Macleay River is a major river on the Mid North Coast , Australia.The headwaters of the Macleay River rise as the Gara River on the eastern side of the Northern Tablelands near Armidale and Walcha, New South Wales. From here the Chandler River, Styx River and Apsley Rivers are important...
s and in Hays Inlet; such fresh or brackish environments may serve as nurseries. Males mature at around 41 cm (16.1 in) across and seven years of age, and females mature at around 63 cm (24.8 in) across and 13 years of age. This disparity in maturation size between the sexes is among the widest known for stingrays. The maximum lifespan is estimated to be 16 years for males and 23 years for females.
Human interactions
Historical and anecdotal evidence strongly suggest that the once-abundant estuary stingray has declined substantially across its range. Although it is not commercially utilized, it faces a number of other threats. This species is captured incidentally by commercial bottom trawl and gillnetGillnet
Gillnetting is a common fishing method used by commercial and artisanal fishermen of all the oceans and in some freshwater and estuary areas. The gillnet also is used by fisheries scientists to monitor fish populations. Because gillnets can be so effective their use is closely monitored and...
fisheries; bycatch
Bycatch
The term “bycatch” is usually used for fish caught unintentionally in a fishery while intending to catch other fish. It may however also indicate untargeted catch in other forms of animal harvesting or collecting...
mortality is exacerbated by the practice of "spiking", in which the ray's cranium is pierced with a metal bar or sharpened stick so as to move it. It is also readily caught, and often killed, by recreational anglers
Recreational fishing
Recreational fishing, also called sport fishing, is fishing for pleasure or competition. It can be contrasted with commercial fishing, which is fishing for profit, or subsistence fishing, which is fishing for survival....
. Surveys in Moreton Bay have found fishing-related effects, such as embedded hooks and mutilated tails, in over 10% of the population. Habitat degradation is another major threat to the estuary stingray, especially given its habitat specificity. Its range encompasses some of the most urbanized
Urbanized
Urbanized is a 2011 documentary film by Gary Hustwit released on 26 October 2011 and considered the third of a three-part series on design known as the Design Trilogy, the first being Helvetica about the typeface and the second being Objectified about industrial design.The documentary discusses...
areas in Australia, where there is extensive land reclamation
Land reclamation
Land reclamation, usually known as reclamation, is the process to create new land from sea or riverbeds. The land reclaimed is known as reclamation ground or landfill.- Habitation :...
, water pollution
Water pollution
Water pollution is the contamination of water bodies . Water pollution occurs when pollutants are discharged directly or indirectly into water bodies without adequate treatment to remove harmful compounds....
, and construction of flood
Flood
A flood is an overflow of an expanse of water that submerges land. The EU Floods directive defines a flood as a temporary covering by water of land not normally covered by water...
mitigation barriers on rivers. Finally, this ray's reputation for damaging shellfish has led to persecution by commercial shellfish farmers.
The estuary stingray's diminished population and susceptibility to multiple threats have led the International Union for Conservation of Nature (IUCN) to assess it as Vulnerable
Vulnerable species
On 30 January 2010, the IUCN Red List of Threatened Species identified 9694 Vulnerable species, subspecies and varieties, stocks and sub-populations.-References:...
. Demographic modelling has shown that it is likely to become Endangered without intervention. Several Marine Protected Area
Marine Protected Area
Marine Protected Areas, like any protected area, are regions in which human activity has been placed under some restrictions in the interest of conserving the natural environment, it's surrounding waters and the occupant ecosystems, and any cultural or historical resources that may require...
s (MPAs) are located within its range, but at present they lack adequate protection from fishing. As this ray remains locally abundant in Hervey Bay and parts of Moreton Bay, these areas may become important centers for preserving the species. The Queensland government has listed the estuary stingray on the Back on Track species prioritisation framework, to facilitate the development of conservation measures.