Greenback stingaree
Encyclopedia
The greenback stingaree (Urolophus viridis) is a little-known species
of stingray
in the family
Urolophidae, endemic to the outer continental shelf
and upper continental slope off southeastern Australia
. Growing to a length of 51 cm (20.1 in), this species has a diamond-shaped pectoral fin disc wider than long and uniformly light green in color above. Between its nostrils is a skirt-shaped curtain of skin. Its tail bears skin folds on either side and a deep, lanceolate caudal fin, but lacks a dorsal fin
.
Usually found over soft substrate
s at a depth of 80–180 m (262.5–590.6 ft), the greenback stingaree is a predator of polychaete worms and crustacean
s. It is aplacental viviparous, with developing embryo
s are sustained by maternally produced histotroph ("uterine milk"). Females bear litters of 1–3 pups annually after a 10–12 month gestation period
. Substantial numbers of greenback stingarees are caught incidentally
in trawls; captured rays rarely survive and also tend to abort their young. Stingaree populations on the New South Wales
upper slope, presumably including this species, have declined precipitously as a result of commercial fishing
. Consequently, the International Union for Conservation of Nature (IUCN) has listed the greenback stingaree as Vulnerable
.
in an 1916 volume of the scientific journal
Biological Results Endeavour, who gave it the specific epithet viridis from the Latin
word for "green". The type specimen was collected from a depth of 90 m (295.3 ft) off Green Cape
in New South Wales
, by the research vessel FIS Endeavour. An undescribed stingaree possibly belonging to this species has also been found in deep water off southwestern Australia; it is very similar to the greenback stingaree but has more pectoral fin rays (106–107 versus under 100).
waters from Portland
in Victoria
to Stradbroke Island
off Queensland
, including all of Tasmania
. Deeper-living than most other stingarees in the region, this benthic species is mainly found over fine sediment
at a depth of 80–180 m (262.5–590.6 ft) on the outer continental shelf
and upper continental slope. However, it has been reported from as shallow as 20 m (65.6 ft) and as deep as 300 m (984.3 ft).
s with rounded posterior margins. There is a skirt-shaped curtain of skin between the nostrils, with a finely fringed posterior margin; the posterior corners of the nasal curtain are extended into small lobes. The medium-sized mouth contains 4–7 variably shaped papillae (nipple-like structures) on the floor; additional papillae are found in a narrow strip on the lower jaw. The teeth are small with roughly oval bases, and the five pairs of gill slit
s are short. The pelvic fins are small and rounded on their trailing margins.
The tail is flattened at the base and measures 75–91% as long as the disc; a prominent skin fold runs along each side, and a deep, lance-shaped caudal fin is found at the end. The upper surface of the tail bears a serrated stinging spine about halfway along its length; there is no dorsal fin
. The skin entirely lacks dermal denticles. This species is a plain light green above, becoming lighter towards the edge of the disc, and off-white below, becoming purplish or pinkish towards the lateral margins of the disc; the ventral, lateral disc margins may also have a dark brown edge or blotches. The caudal fin is colored dark brown in juveniles and olive in adults. Some individuals are dark beneath the tail and/or on the tip of the snout. The maximum recorded length is 51 cm (20.1 in).
s. It is known to be parasitized by a species of monogenea
n in the genus Calicotyle. Like other stingrays, it is aplacental viviparous with the developing embryo
s sustained via histotroph ("uterine milk") produced by the mother. Females produce 1–3 pups per year, following a gestation period
lasting 10–12 months. Males and females attain sexual maturity
at approximately 28 cm (11 in) and 26–31 cm (10.2–12.2 in) long respectively; rays found around Lakes Entrance, Victoria apparently have a smaller maturation size than those elsewhere.
of the Southern and Eastern Scalefish and Shark Fishery (SESSF), operating on the upper continental slope off New South Wales
. The New South Wales Oceanic Prawn Trawl Fishery and the Queensland
East Coast Trawl Fishery also operate within the geographical and depth range of this species. Because of its deepwater habits, the greenback stingaree is unlikely to survive capture, and the process also often causes it to abort any gestating young. Though specific data is lacking, between 1976–77 and 1996–97, stingaree numbers on New South Wales upper slope fell by some two-thirds. Given these declines and the continuing intensity of fishing activities within its range, the International Union for Conservation of Nature (IUCN) has assessed this ray as Vulnerable
. It would potentially benefit from the implementation of the 2004 Australian National Plan of Action for the Conservation and Management of Sharks.
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
Myliobatiformes
Myliobatiformes is one of the four orders of batoids, cartilaginous fishes related to sharks. They were formerly included in the order Rajiformes, but more recent phylogenetic studies have shown that the myliobatiforms are a monophyletic group, and that its more derived members evolved their...
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...
Urolophidae, endemic to the outer continental shelf
Continental shelf
The continental shelf is the extended perimeter of each continent and associated coastal plain. Much of the shelf was exposed during glacial periods, but is now submerged under relatively shallow seas and gulfs, and was similarly submerged during other interglacial periods. The continental margin,...
and upper continental slope off southeastern 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...
. Growing to a length of 51 cm (20.1 in), this species has a diamond-shaped pectoral fin disc wider than long and uniformly light green in color above. Between its nostrils is a skirt-shaped curtain of skin. Its tail bears skin folds on either side and a deep, lanceolate caudal fin, but lacks a dorsal fin
Dorsal fin
A dorsal fin is a fin located on the backs of various unrelated marine and freshwater vertebrates, including most fishes, marine mammals , and the ichthyosaurs...
.
Usually found over soft substrate
Substrate (marine biology)
Stream substrate is the material that rests at the bottom of a stream. There are several classification guides. One is:*Mud – silt and clay.*Sand – Particles between 0.06 and 2 mm in diameter.*Granule – Between 2 and 4 mm in diameter....
s at a depth of 80–180 m (262.5–590.6 ft), the greenback stingaree is a predator of polychaete worms and 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. It is aplacental viviparous, with 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 are sustained by maternally produced histotroph ("uterine milk"). Females bear litters of 1–3 pups annually after a 10–12 month gestation period
Gestation period
For mammals the gestation period is the time in which a fetus develops, beginning with fertilization and ending at birth. The duration of this period varies between species.-Duration:...
. Substantial numbers of greenback stingarees are caught incidentally
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...
in trawls; captured rays rarely survive and also tend to abort their young. Stingaree populations on the 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...
upper slope, presumably including this species, have declined precipitously as a result of commercial fishing
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...
. Consequently, the International Union for Conservation of Nature (IUCN) has listed the greenback stingaree 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 greenback stingaree was described by Australian ichthyologist Alan Riverstone McCullochAlan Riverstone McCulloch
Alan Riverstone McCulloch was a prominent Australian ichthyologist.McCulloch was born in Sydney, and began his scientific career at the age of 13 as an unpaid assistant to Edgar Ravenswood Waite in the Australian Museum there; Waite encouraged McCulloch to study zoology...
in an 1916 volume of the scientific journal
Scientific journal
In academic publishing, a scientific journal is a periodical publication intended to further the progress of science, usually by reporting new research. There are thousands of scientific journals in publication, and many more have been published at various points in the past...
Biological Results Endeavour, who gave it the specific epithet viridis from the 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...
word for "green". The type specimen was collected from a depth of 90 m (295.3 ft) off Green Cape
Green Cape
Green Cape is a headland or cape on the far south coast of New South Wales. It is located at 37° 15' S 150° 03' E, within Ben Boyd National Park, south of Eden, New South Wales...
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...
, by the research vessel FIS Endeavour. An undescribed stingaree possibly belonging to this species has also been found in deep water off southwestern Australia; it is very similar to the greenback stingaree but has more pectoral fin rays (106–107 versus under 100).
Distribution and habitat
Once common, the greenback stingaree occurs in warm-temperateTemperate
In geography, temperate or tepid latitudes of the globe lie between the tropics and the polar circles. The changes in these regions between summer and winter are generally relatively moderate, rather than extreme hot or cold...
waters from Portland
Portland, Victoria
The city of Portland is the oldest European settlement in what is now the state of Victoria, Australia. It is the main urban centre of the Shire of Glenelg. It is located on Portland Bay.-History:...
in Victoria
Victoria (Australia)
Victoria is the second most populous state in Australia. Geographically the smallest mainland state, Victoria is bordered by New South Wales, South Australia, and Tasmania on Boundary Islet to the north, west and south respectively....
to Stradbroke Island
Stradbroke Island
Stradbroke Island, also known as Minjerribah, was a large sand island that formed much of the eastern side of Moreton Bay near Brisbane, Queensland until the late 19th century...
off 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...
, including all of Tasmania
Tasmania
Tasmania is an Australian island and state. It is south of the continent, separated by Bass Strait. The state includes the island of Tasmania—the 26th largest island in the world—and the surrounding islands. The state has a population of 507,626 , of whom almost half reside in the greater Hobart...
. Deeper-living than most other stingarees in the region, this benthic species is mainly found over fine sediment
Sediment
Sediment is naturally occurring material that is broken down by processes of weathering and erosion, and is subsequently transported by the action of fluids such as wind, water, or ice, and/or by the force of gravity acting on the particle itself....
at a depth of 80–180 m (262.5–590.6 ft) on the outer continental shelf
Continental shelf
The continental shelf is the extended perimeter of each continent and associated coastal plain. Much of the shelf was exposed during glacial periods, but is now submerged under relatively shallow seas and gulfs, and was similarly submerged during other interglacial periods. The continental margin,...
and upper continental slope. However, it has been reported from as shallow as 20 m (65.6 ft) and as deep as 300 m (984.3 ft).
Description
The greenback stingaree has a diamond-shaped pectoral fin disc wider than long, with broadly rounded outer corners. The leading margins of the disc are nearly straight, and converge at an obtuse angle on the fleshy snout. The tip of the snout protrudes slightly past the disc. The eyes are large and followed by comma-shaped 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 with rounded posterior margins. There is a skirt-shaped curtain of skin between the nostrils, with a finely fringed posterior margin; the posterior corners of the nasal curtain are extended into small lobes. The medium-sized mouth contains 4–7 variably shaped papillae (nipple-like structures) on the floor; additional papillae are found in a narrow strip on the lower jaw. The teeth are small with roughly oval bases, and the 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 are short. The pelvic fins are small and rounded on their trailing margins.
The tail is flattened at the base and measures 75–91% as long as the disc; a prominent skin fold runs along each side, and a deep, lance-shaped caudal fin is found at the end. The upper surface of the tail bears a serrated stinging spine about halfway along its length; there is no dorsal fin
Dorsal fin
A dorsal fin is a fin located on the backs of various unrelated marine and freshwater vertebrates, including most fishes, marine mammals , and the ichthyosaurs...
. The skin entirely lacks dermal denticles. This species is a plain light green above, becoming lighter towards the edge of the disc, and off-white below, becoming purplish or pinkish towards the lateral margins of the disc; the ventral, lateral disc margins may also have a dark brown edge or blotches. The caudal fin is colored dark brown in juveniles and olive in adults. Some individuals are dark beneath the tail and/or on the tip of the snout. The maximum recorded length is 51 cm (20.1 in).
Biology and ecology
The greenback stingaree preys mainly on polychaete worms and crustaceanCrustacean
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. It is known to be parasitized by a species of 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....
n in the genus Calicotyle. Like other stingrays, it is aplacental viviparous 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 via histotroph ("uterine milk") produced by the mother. Females produce 1–3 pups per year, following a gestation period
Gestation period
For mammals the gestation period is the time in which a fetus develops, beginning with fertilization and ending at birth. The duration of this period varies between species.-Duration:...
lasting 10–12 months. Males and females attain sexual maturity
Sexual maturity
Sexual maturity is the age or stage when an organism can reproduce. It is sometimes considered synonymous with adulthood, though the two are distinct...
at approximately 28 cm (11 in) and 26–31 cm (10.2–12.2 in) long respectively; rays found around Lakes Entrance, Victoria apparently have a smaller maturation size than those elsewhere.
Human interactions
The greenback stingaree and the sandyback stingaree (U. bucculentus) are the most common stingarees in the trawl bycatchBycatch
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...
of the Southern and Eastern Scalefish and Shark Fishery (SESSF), operating on the upper continental slope off 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...
. The New South Wales Oceanic Prawn Trawl Fishery and the 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...
East Coast Trawl Fishery also operate within the geographical and depth range of this species. Because of its deepwater habits, the greenback stingaree is unlikely to survive capture, and the process also often causes it to abort any gestating young. Though specific data is lacking, between 1976–77 and 1996–97, stingaree numbers on New South Wales upper slope fell by some two-thirds. Given these declines and the continuing intensity of fishing activities within its range, the International Union for Conservation of Nature (IUCN) has assessed this ray 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:...
. It would potentially benefit from the implementation of the 2004 Australian National Plan of Action for the Conservation and Management of Sharks.