Colares stingray
Encyclopedia
The Colares stingray, Dasyatis colarensis, is a species
of stingray
in the family
Dasyatidae, native to the shallow brackish water
s of the Amazon River
estuary
in northern Brazil
. This species inhabits inshore bays during the dry season
and moves away from the coast in the rainy season. It is characterized by a rhomboid pectoral fin disk, elongated snout, and a dark band on the lower lip. A fairly large species, males and females attain disk widths of 63 cm (24.8 in) and 91 cm (35.8 in) respectively. Females give birth to 1–4 young, possibly annually. Colares stingrays are both targeted and caught as bycatch
by Brazilian artisanal
and commercial fisheries
; these pressures coupled with its small range and slow reproductive rate has led the International Union for Conservation of Nature (IUCN) to list this species as Vulnerable
.
Zootaxa. The specific epithet refers to Colares Island in Marajó Bay, where the type specimen, a 2.07 m (6.8 ft) long mature male, was caught.
in northern Brazil
, in the estuarine
area affected by the river's freshwater
discharge; it may also occur in adjacent areas as far as Venezuela
. Found to a depth of 6 m (19.7 ft), this species conducts annual movements that are influenced by salinity
: in the dry season
it is found in the coastal bays such as Marajó, while in the rainy season it leaves the bays and shifts offshore.
s. There is a flap of skin between the nares with a fringed rear margin and rounded corners. The lower lip is bow-shaped and lined by a distinctive straight, dark band. The dentition is sexually dimorphic: males have pointed, recurved teeth in 43–45 upper tooth rows and 45–60 lower tooth rows, while females have flat-crowned teeth in 66–77 upper tooth rows and 75–77 lower tooth rows. There are 3–4 papilla
e in a transverse row on the floor of the mouth, which may have forked tips. The pelvic fins are triangular, with the pointed tips extending past the disk. The tail is long and whip-like, measuring more than twice the disk length. A stinging spine with 69–70 serrations and sometimes a low keel are positioned on top of the tail, while a low fin fold runs underneath.
Small, flattened tubercles are randomly arranged along the dorsal midline from the base of the tail to between the eyes, thinning out towards the tip of the snout. Females also have tubercles on the underside. The dorsal coloration is a uniform light brown, becoming darker on the tail and claspers (in males), and with a light trailing margin on the pelvic fins. The underside is pale, darkening towards the fin margins. Males reach 2.07 m (6.8 ft) long and 63 cm (24.8 in) across, while females reach 2.61 m (8.6 ft) long and 91 cm (35.8 in) across.
, citing its limited geographic distribution, likely slow reproductive rate, and susceptibility to fishing
gear. This species is abundant in Marajó Bay during the dry season. It is taken as bycatch
in artisanal
and commercial fisheries
targeting catfish
in the Amazon estuary. In addition, industrial fishing vessels from the Brazilian state of Pará
began to fish directly for this species in the 2000s, with their catches exported to Europe
. The IUCN has recommended that Brazil implement habitat conservation and fishery management schemes.
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, native to the shallow 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 of the Amazon River
Amazon River
The Amazon of South America is the second longest river in the world and by far the largest by waterflow with an average discharge greater than the next seven largest rivers combined...
estuary
Estuary
An estuary is a partly enclosed coastal body of water with one or more rivers or streams flowing into it, and with a free connection to the open sea....
in northern Brazil
Brazil
Brazil , officially the Federative Republic of Brazil , is the largest country in South America. It is the world's fifth largest country, both by geographical area and by population with over 192 million people...
. This species inhabits inshore bays during the dry season
Dry season
The dry season is a term commonly used when describing the weather in the tropics. The weather in the tropics is dominated by the tropical rain belt, which oscillates from the northern to the southern tropics over the course of the year...
and moves away from the coast in the rainy season. It is characterized by a rhomboid pectoral fin disk, elongated snout, and a dark band on the lower lip. A fairly large species, males and females attain disk widths of 63 cm (24.8 in) and 91 cm (35.8 in) respectively. Females give birth to 1–4 young, possibly annually. Colares stingrays are both targeted and caught as 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...
by Brazilian artisanal
Artisan fishing
Artisan fishing is a term used to describe small scale low-technology commercial or subsistence fishing practices. The term particularly applies to coastal or island ethnic groups using traditional techniques such as rod and tackle, arrows and harpoons, throw nets and drag nets, and traditional...
and commercial fisheries
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...
; these pressures coupled with its small range and slow reproductive rate has led the International Union for Conservation of Nature (IUCN) to list this species 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 Colares stingray was described by Hugo Santos, Ulisses Gomes, and Patricia Charvet-Almeida in 2004, in the scientific journalScientific 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...
Zootaxa. The specific epithet refers to Colares Island in Marajó Bay, where the type specimen, a 2.07 m (6.8 ft) long mature male, was caught.
Distribution and habitat
The range of the Colares stingray appears restricted to the mouth of the Amazon RiverAmazon River
The Amazon of South America is the second longest river in the world and by far the largest by waterflow with an average discharge greater than the next seven largest rivers combined...
in northern Brazil
Brazil
Brazil , officially the Federative Republic of Brazil , is the largest country in South America. It is the world's fifth largest country, both by geographical area and by population with over 192 million people...
, in the estuarine
Estuary
An estuary is a partly enclosed coastal body of water with one or more rivers or streams flowing into it, and with a free connection to the open sea....
area affected by the river's freshwater
Freshwater
Fresh water is naturally occurring water on the Earth's surface in ice sheets, ice caps, glaciers, bogs, ponds, lakes, rivers and streams, and underground as groundwater in aquifers and underground streams. Fresh water is generally characterized by having low concentrations of dissolved salts and...
discharge; it may also occur in adjacent areas as far as Venezuela
Venezuela
Venezuela , officially called the Bolivarian Republic of Venezuela , is a tropical country on the northern coast of South America. It borders Colombia to the west, Guyana to the east, and Brazil to the south...
. Found to a depth of 6 m (19.7 ft), this species conducts annual movements that are influenced by salinity
Salinity
Salinity is the saltiness or dissolved salt content of a body of water. It is a general term used to describe the levels of different salts such as sodium chloride, magnesium and calcium sulfates, and bicarbonates...
: in the dry season
Dry season
The dry season is a term commonly used when describing the weather in the tropics. The weather in the tropics is dominated by the tropical rain belt, which oscillates from the northern to the southern tropics over the course of the year...
it is found in the coastal bays such as Marajó, while in the rainy season it leaves the bays and shifts offshore.
Description
The Colares stingray has a diamond-shaped pectoral fin disk about as long as wide, with rounded margins and a long snout that tapers to a point. The snout of the female is shorter than that of the male, and snout edges dip in slightly near the tip. The eyes are small and followed by large 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. There is a flap of skin between the nares with a fringed rear margin and rounded corners. The lower lip is bow-shaped and lined by a distinctive straight, dark band. The dentition is sexually dimorphic: males have pointed, recurved teeth in 43–45 upper tooth rows and 45–60 lower tooth rows, while females have flat-crowned teeth in 66–77 upper tooth rows and 75–77 lower tooth rows. There are 3–4 papilla
Papilla (fish mouth structure)
The papilla, in certain kinds of fish, particularly rays, sharks, and catfish, are small lumps of dermal tissue found in the mouth, where they are "distributed uniformly on the tongue, palate, and pharynx"...
e in a transverse row on the floor of the mouth, which may have forked tips. The pelvic fins are triangular, with the pointed tips extending past the disk. The tail is long and whip-like, measuring more than twice the disk length. A stinging spine with 69–70 serrations and sometimes a low keel are positioned on top of the tail, while a low fin fold runs underneath.
Small, flattened tubercles are randomly arranged along the dorsal midline from the base of the tail to between the eyes, thinning out towards the tip of the snout. Females also have tubercles on the underside. The dorsal coloration is a uniform light brown, becoming darker on the tail and claspers (in males), and with a light trailing margin on the pelvic fins. The underside is pale, darkening towards the fin margins. Males reach 2.07 m (6.8 ft) long and 63 cm (24.8 in) across, while females reach 2.61 m (8.6 ft) long and 91 cm (35.8 in) across.
Biology and ecology
Like other stingrays, the Colares stingray is aplacental viviparous; only recently impregnated females can be found inshore, suggesting that the annual movements of this species may relate to reproduction. Observed litter sizes range from 1 to 4, and the reproductive cycle may last one year.Human interactions
The International Union for Conservation of Nature (IUCN) has assessed the Colares stingray as VulnerableVulnerable species
On 30 January 2010, the IUCN Red List of Threatened Species identified 9694 Vulnerable species, subspecies and varieties, stocks and sub-populations.-References:...
, citing its limited geographic distribution, likely slow reproductive rate, and susceptibility to fishing
Fishing
Fishing is the activity of trying to catch wild fish. Fish are normally caught in the wild. Techniques for catching fish include hand gathering, spearing, netting, angling and trapping....
gear. This species is abundant in Marajó Bay during the dry season. It is taken as 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...
in artisanal
Artisan fishing
Artisan fishing is a term used to describe small scale low-technology commercial or subsistence fishing practices. The term particularly applies to coastal or island ethnic groups using traditional techniques such as rod and tackle, arrows and harpoons, throw nets and drag nets, and traditional...
and commercial fisheries
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...
targeting catfish
Catfish
Catfishes are a diverse group of ray-finned fish. Named for their prominent barbels, which resemble a cat's whiskers, catfish range in size and behavior from the heaviest and longest, the Mekong giant catfish from Southeast Asia and the second longest, the wels catfish of Eurasia, to detritivores...
in the Amazon estuary. In addition, industrial fishing vessels from the Brazilian state of Pará
Pará
Pará is a state in the north of Brazil. It borders the Brazilian states of Amapá, Maranhão, Tocantins, Mato Grosso, Amazonas and Roraima. To the northwest it also borders Guyana and Suriname, and to the northeast it borders the Atlantic Ocean. The capital is Belém.Pará is the most populous state...
began to fish directly for this species in the 2000s, with their catches exported to Europe
Europe
Europe is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally 'divided' from Asia to its east by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas, and the waterways connecting...
. The IUCN has recommended that Brazil implement habitat conservation and fishery management schemes.