Spadenose shark
Encyclopedia
The spadenose shark is a species
of requiem shark
, family
Carcharhinidae, and the only member of its genus
. It is common in the tropical Indian
and western Pacific Ocean
s, where it forms large schools
in shallow water. A small shark reaching a length of 74 cm (29.1 in), the spadenose shark is named for its distinctively flattened, triangular snout. It is a predator of small bony fishes and invertebrate
s. This species exhibits the most advanced mode of viviparity of any fish
, in which the developed embryo
s form a highly complex placenta
l connection to the mother at a very small size. Females breed year-round, giving birth to 6–18 pups after a gestation period
of 5–6 months. The spadenose shark is harmless to humans and is valued by artisanal
and commercial fishers
for its meat and fins. Its abundance ensures that it forms a significant component of many fisheries in South
and Southeast Asia
. The International Union for Conservation of Nature (IUCN) has assessed this species as Near Threatened
.
and Friedrich Gustav Jakob Henle
, in their Systematische Beschreibung der Plagiostomen. The holotype
is presumed to be a 42 cm (16.5 in) long stuffed specimen in the Zoologisches Museum of Berlin
. The generic name Scoliodon is derived from the Greek skolex ("worm") and odon ("tooth"), while the specific epithet laticaudus comes from the Latin
latus ("broad" or "wide") and cauda ("tail"). Other common name
s used for this species include Indian dog shark, sharp nosed shark, trowel nose shark, and yellow dog shark.
Phylogenetic analyses
based on morphological
and molecular data indicate that the spadenose shark is one of the most basal
members of its family, along with the related genus Rhizoprionodon
and Galeocerdo, the tiger shark. In addition, anatomical similarities suggest this species to be the closest living relative of the hammerhead shark
s, which diverged from the other carcharhinids some time before the Middle Eocene (48.6–37.2 Ma).
from Tanzania
to South
and Southeast Asia
, as far east as Java
and Borneo
and as far north as Taiwan
and Japan
. It is typically found close to the coast in water 10–13 m (32.8–42.7 ft) deep, often close to rocky bottoms. This shark is frequently reported from the lower reaches of rivers in Malaysia, Sumatra
, and Borneo, though whether this species is capable of tolerating fresh water
like the bull shark
(Carcharhinus leucas) is unclear due to a lack of salinity
data from these areas.
-shaped snout. The eyes and nares are small. The corners of the mouth are well behind the eyes and have poorly developed furrows at the corners. There are 25–33 tooth rows in the upper jaw and 24–34 tooth rows in the lower jaw; each tooth has a single slender, blade-like, oblique cusp without serrations. The first dorsal fin
is positioned closer to the pelvic than the pectoral fins, which are very short and broad. The second dorsal fin is much smaller than the anal fin. There is no ridge between the dorsal fins. The back is bronze-gray in color, and the belly is white. The fins are plain but may be darker than the body. The maximum known length is 74 cm (29.1 in), though there are unsubstantiated reports of individuals reaching 1.2 m (3.9 ft).
. It feeds mainly on small bony fishes, including anchovies
, codlets, burrowing gobies, and Bombay ducks. Shrimp
, crab
s, cuttlefish
, and stomatopods are also sometimes taken. Known parasites of this shark include the tapeworm Ruhnkecestus latipi, and the larva
e of ascaridid
roundworms.
The spadenose shark has the most advanced form of placenta
l viviparity known in fish, as measured by the complexity of the placental connection and the difference in weight between the egg
and the newborn young. Newly ovulated
eggs measure only 1 mm (0.0393700787401575 in) in diameter, while the developing embryo
s become dependent on their mother for sustenance at a length of only 3 mm (0.118110236220472 in). The placental stalk, formed from the yolk sac
, has an unusual columnar structure and is covered by numerous long appendiculae that support a massive capillary
network, providing a large surface area for gas exchange
. The placental tissue contacts the uterine wall
in a unique structure called the "trophonematal cup", where nutrients are transferred from the mother's blood
stream into the placenta.
Female spadenose sharks probably mate at least once per year, and breeding takes place year-round. The gestation period
of the spadenose shark is 5–6 months long, and the young are born at a length of 12–15 cm (4.7–5.9 in). The litter size is 6–18. Males mature sexually at a length of 24 –, and females at a length of 33 –. Estimates of the age at maturity range from six months to 1–2 years. The lifespan
may be five years for males and six years for females.
and commercial fisheries
across its range, using floating and fixed gillnet
s, longlines, bottom nets, fish trap
s, trawls, and hook-and-line. The meat is eaten or used as bait for other fishes, the fins are valued for shark fin soup
, and the carcasses are processed into fishmeal. The meat can also be processed with glacial acetic acid to obtain a gel
powder that can be used as a protein supplement
in cereal
foods, a biodegradable film for wrapping seafood
, or a binder in sausage
s and other foods.
Despite its commercial importance, overall fishery statistics for the spadenose shark are lacking. A 1996 report found that this was the most common coastal shark on Chinese
markets, and it is also one of the most common sharks caught off northern Australia
. Substantial numbers are caught by India
n and Pakistan
i fisheries; from 1979–81, an average of 823 tons were caught annually off Verval, India. The spadenose shark is also caught as bycatch
, particularly in gillnet fisheries off Kalimantan
. The International Union for Conservation of Nature (IUCN) has assessed this species as Near Threatened
; the spadenose shark's relatively short reproductive cycle may render it more resilient to fishing pressure than other sharks, though its low fecundity
still merits caution. This shark may also be negatively affected by coastal development, due to its inshore habitat preferences.
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 requiem shark
Requiem shark
Requiem sharks are a family, Carcharhinidae, of sharks in the order Carcharhiniformes, containing migratory, live-bearing sharks of warm seas such as the tiger shark, the blue shark, the bull shark, and the milk shark.The name may be related to the French word for shark, "requin", itself of...
, 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...
Carcharhinidae, and the only member of its genus
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
. It is common in the tropical Indian
Indian Ocean
The Indian Ocean is the third largest of the world's oceanic divisions, covering approximately 20% of the water on the Earth's surface. It is bounded on the north by the Indian Subcontinent and Arabian Peninsula ; on the west by eastern Africa; on the east by Indochina, the Sunda Islands, and...
and western Pacific Ocean
Pacific Ocean
The Pacific Ocean is the largest of the Earth's oceanic divisions. It extends from the Arctic in the north to the Southern Ocean in the south, bounded by Asia and Australia in the west, and the Americas in the east.At 165.2 million square kilometres in area, this largest division of the World...
s, where it forms large schools
Shoaling and schooling
In biology, any group of fish that stay together for social reasons are said to be shoaling , and if, in addition, the group is swimming in the same direction in a coordinated manner, they are said to be schooling . In common usage, the terms are sometimes used rather loosely...
in shallow water. A small shark reaching a length of 74 cm (29.1 in), the spadenose shark is named for its distinctively flattened, triangular snout. It is a predator of small bony fishes and invertebrate
Invertebrate
An invertebrate is an animal without a backbone. The group includes 97% of all animal species – all animals except those in the chordate subphylum Vertebrata .Invertebrates form a paraphyletic group...
s. This species exhibits the most advanced mode of viviparity of any fish
Fish
Fish are a paraphyletic group of organisms that consist of all gill-bearing aquatic vertebrate animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish, as well as various extinct related groups...
, in which the developed 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 form a highly complex placenta
Placenta
The placenta is an organ that connects the developing fetus to the uterine wall to allow nutrient uptake, waste elimination, and gas exchange via the mother's blood supply. "True" placentas are a defining characteristic of eutherian or "placental" mammals, but are also found in some snakes and...
l connection to the mother at a very small size. Females breed year-round, giving birth to 6–18 pups after 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:...
of 5–6 months. The spadenose shark is harmless to humans and is valued by 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 fishers
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...
for its meat and fins. Its abundance ensures that it forms a significant component of many fisheries in South
South Asia
South Asia, also known as Southern Asia, is the southern region of the Asian continent, which comprises the sub-Himalayan countries and, for some authorities , also includes the adjoining countries to the west and the east...
and Southeast Asia
Southeast Asia
Southeast Asia, South-East Asia, South East Asia or Southeastern Asia is a subregion of Asia, consisting of the countries that are geographically south of China, east of India, west of New Guinea and north of Australia. The region lies on the intersection of geological plates, with heavy seismic...
. The International Union for Conservation of Nature (IUCN) has assessed this species as Near Threatened
Near Threatened
Near Threatened is a conservation status assigned to species or lower taxa that may be considered threatened with extinction in the near future, although it does not currently qualify for the threatened status...
.
Taxonomy and phylogeny
The first scientific description of the spadenose shark was published in 1838 by the German biologists Johannes Peter MüllerJohannes Peter Müller
Johannes Peter Müller , was a German physiologist, comparative anatomist, and ichthyologist not only known for his discoveries but also for his ability to synthesize knowledge.-Early years and education:...
and Friedrich Gustav Jakob Henle
Friedrich Gustav Jakob Henle
Friedrich Gustav Jakob Henle was a German physician, pathologist and anatomist. He is credited with the discovery of the loop of Henle in the kidney. His essay "On Miasma and Contagia" was an early argument for the germ theory of disease...
, in their Systematische Beschreibung der Plagiostomen. The holotype
Holotype
A holotype is a single physical example of an organism, known to have been used when the species was formally described. It is either the single such physical example or one of several such, but explicitly designated as the holotype...
is presumed to be a 42 cm (16.5 in) long stuffed specimen in the Zoologisches Museum of Berlin
Berlin
Berlin is the capital city of Germany and is one of the 16 states of Germany. With a population of 3.45 million people, Berlin is Germany's largest city. It is the second most populous city proper and the seventh most populous urban area in the European Union...
. The generic name Scoliodon is derived from the Greek skolex ("worm") and odon ("tooth"), while the specific epithet laticaudus comes 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...
latus ("broad" or "wide") and cauda ("tail"). Other common name
Common name
A common name of a taxon or organism is a name in general use within a community; it is often contrasted with the scientific name for the same organism...
s used for this species include Indian dog shark, sharp nosed shark, trowel nose shark, and yellow dog shark.
Phylogenetic analyses
Phylogenetics
In biology, phylogenetics is the study of evolutionary relatedness among groups of organisms , which is discovered through molecular sequencing data and morphological data matrices...
based on morphological
Morphology (biology)
In biology, morphology is a branch of bioscience dealing with the study of the form and structure of organisms and their specific structural features....
and molecular data indicate that the spadenose shark is one of the most basal
Basal (phylogenetics)
In phylogenetics, a basal clade is the earliest clade to branch in a larger clade; it appears at the base of a cladogram.A basal group forms an outgroup to the rest of the clade, such as in the following example:...
members of its family, along with the related genus Rhizoprionodon
Rhizoprionodon
Rhizoprionodon is a genus of requiem sharks, family Carcharhinidae, commonly known as sharpnose sharks because of their long, pointed snouts.-Species:* Rhizoprionodon acutus...
and Galeocerdo, the tiger shark. In addition, anatomical similarities suggest this species to be the closest living relative of the hammerhead shark
Hammerhead shark
The hammerhead sharks are a group of sharks in the family Sphyrnidae, so named for the unusual and distinctive structure of their heads, which are flattened and laterally extended into a "hammer" shape called a "cephalofoil". Most hammerhead species are placed in the genus Sphyrna while the...
s, which diverged from the other carcharhinids some time before the Middle Eocene (48.6–37.2 Ma).
Distribution and habitat
The spadenose shark is found in the western Indo-PacificIndo-Pacific
The Indo-Pacific is a biogeographic region of the Earth's seas, comprising the tropical waters of the Indian Ocean, the western and central Pacific Ocean, and the seas connecting the two in the general area of Indonesia...
from Tanzania
Tanzania
The United Republic of Tanzania is a country in East Africa bordered by Kenya and Uganda to the north, Rwanda, Burundi, and the Democratic Republic of the Congo to the west, and Zambia, Malawi, and Mozambique to the south. The country's eastern borders lie on the Indian Ocean.Tanzania is a state...
to South
South Asia
South Asia, also known as Southern Asia, is the southern region of the Asian continent, which comprises the sub-Himalayan countries and, for some authorities , also includes the adjoining countries to the west and the east...
and Southeast Asia
Southeast Asia
Southeast Asia, South-East Asia, South East Asia or Southeastern Asia is a subregion of Asia, consisting of the countries that are geographically south of China, east of India, west of New Guinea and north of Australia. The region lies on the intersection of geological plates, with heavy seismic...
, as far east as Java
Java
Java is an island of Indonesia. With a population of 135 million , it is the world's most populous island, and one of the most densely populated regions in the world. It is home to 60% of Indonesia's population. The Indonesian capital city, Jakarta, is in west Java...
and Borneo
Borneo
Borneo is the third largest island in the world and is located north of Java Island, Indonesia, at the geographic centre of Maritime Southeast Asia....
and as far north as Taiwan
Taiwan
Taiwan , also known, especially in the past, as Formosa , is the largest island of the same-named island group of East Asia in the western Pacific Ocean and located off the southeastern coast of mainland China. The island forms over 99% of the current territory of the Republic of China following...
and Japan
Japan
Japan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...
. It is typically found close to the coast in water 10–13 m (32.8–42.7 ft) deep, often close to rocky bottoms. This shark is frequently reported from the lower reaches of rivers in Malaysia, Sumatra
Sumatra
Sumatra is an island in western Indonesia, westernmost of the Sunda Islands. It is the largest island entirely in Indonesia , and the sixth largest island in the world at 473,481 km2 with a population of 50,365,538...
, and Borneo, though whether this species is capable of tolerating 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...
like the bull shark
Bull shark
The bull shark, Carcharhinus leucas, also known as Zambezi shark or unofficially known as Zambi in Africa and Nicaragua shark in Nicaragua, is a shark common worldwide in warm, shallow waters along coasts and in rivers...
(Carcharhinus leucas) is unclear due to a lack of 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...
data from these areas.
Description
A small, stocky species, the spadenose shark has a broad head with a distinctive highly flattened, trowelTrowel
A trowel is one of several similar hand tools used for digging, smoothing, or otherwise moving around small amounts of viscous or particulate material.-Hand tools:...
-shaped snout. The eyes and nares are small. The corners of the mouth are well behind the eyes and have poorly developed furrows at the corners. There are 25–33 tooth rows in the upper jaw and 24–34 tooth rows in the lower jaw; each tooth has a single slender, blade-like, oblique cusp without serrations. The first 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...
is positioned closer to the pelvic than the pectoral fins, which are very short and broad. The second dorsal fin is much smaller than the anal fin. There is no ridge between the dorsal fins. The back is bronze-gray in color, and the belly is white. The fins are plain but may be darker than the body. The maximum known length is 74 cm (29.1 in), though there are unsubstantiated reports of individuals reaching 1.2 m (3.9 ft).
Biology and ecology
Abundant in many areas, spadenose sharks often form large schoolsShoaling and schooling
In biology, any group of fish that stay together for social reasons are said to be shoaling , and if, in addition, the group is swimming in the same direction in a coordinated manner, they are said to be schooling . In common usage, the terms are sometimes used rather loosely...
. It feeds mainly on small bony fishes, including anchovies
Anchovy
Anchovies are a family of small, common salt-water forage fish. There are 144 species in 17 genera, found in the Atlantic, Indian, and Pacific Oceans. Anchovies are usually classified as an oily fish.-Description:...
, codlets, burrowing gobies, and Bombay ducks. Shrimp
Shrimp
Shrimp are swimming, decapod crustaceans classified in the infraorder Caridea, found widely around the world in both fresh and salt water. Adult shrimp are filter feeding benthic animals living close to the bottom. They can live in schools and can swim rapidly backwards. Shrimp are an important...
, crab
Crab
True crabs are decapod crustaceans of the infraorder Brachyura, which typically have a very short projecting "tail" , or where the reduced abdomen is entirely hidden under the thorax...
s, cuttlefish
Cuttlefish
Cuttlefish are marine animals of the order Sepiida. They belong to the class Cephalopoda . Despite their name, cuttlefish are not fish but molluscs....
, and stomatopods are also sometimes taken. Known parasites of this shark include the tapeworm Ruhnkecestus latipi, and the larva
Larva
A larva is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle...
e of ascaridid
Ascaridida
The order Ascaridida includes several families of parasitic roundworms with three "lips" on the anterior end. They were formerly placed in the subclass Rhabditia by some, but morphological and DNA sequence data rather unequivocally assigns them to the Spiruria...
roundworms.
The spadenose shark has the most advanced form of placenta
Placenta
The placenta is an organ that connects the developing fetus to the uterine wall to allow nutrient uptake, waste elimination, and gas exchange via the mother's blood supply. "True" placentas are a defining characteristic of eutherian or "placental" mammals, but are also found in some snakes and...
l viviparity known in fish, as measured by the complexity of the placental connection and the difference in weight between the egg
Egg (biology)
An egg is an organic vessel in which an embryo first begins to develop. In most birds, reptiles, insects, molluscs, fish, and monotremes, an egg is the zygote, resulting from fertilization of the ovum, which is expelled from the body and permitted to develop outside the body until the developing...
and the newborn young. Newly ovulated
Ovulation
Ovulation is the process in a female's menstrual cycle by which a mature ovarian follicle ruptures and discharges an ovum . Ovulation also occurs in the estrous cycle of other female mammals, which differs in many fundamental ways from the menstrual cycle...
eggs measure only 1 mm (0.0393700787401575 in) in diameter, while 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 become dependent on their mother for sustenance at a length of only 3 mm (0.118110236220472 in). The placental stalk, formed from the yolk sac
Yolk sac
The yolk sac is a membranous sac attached to an embryo, providing early nourishment in the form of yolk in bony fishes, sharks, reptiles, birds, and primitive mammals...
, has an unusual columnar structure and is covered by numerous long appendiculae that support a massive capillary
Capillary
Capillaries are the smallest of a body's blood vessels and are parts of the microcirculation. They are only 1 cell thick. These microvessels, measuring 5-10 μm in diameter, connect arterioles and venules, and enable the exchange of water, oxygen, carbon dioxide, and many other nutrient and waste...
network, providing a large surface area for gas exchange
Gas exchange
Gas exchange is a process in biology where gases contained in an organism and atmosphere transfer or exchange. In human gas-exchange, gases contained in the blood of human bodies exchange with gases contained in the atmosphere. Human gas-exchange occurs in the lungs...
. The placental tissue contacts the uterine wall
Uterus
The uterus or womb is a major female hormone-responsive reproductive sex organ of most mammals including humans. One end, the cervix, opens into the vagina, while the other is connected to one or both fallopian tubes, depending on the species...
in a unique structure called the "trophonematal cup", where nutrients are transferred from the mother's blood
Blood
Blood is a specialized bodily fluid in animals that delivers necessary substances such as nutrients and oxygen to the cells and transports metabolic waste products away from those same cells....
stream into the placenta.
Female spadenose sharks probably mate at least once per year, and breeding takes place year-round. The 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:...
of the spadenose shark is 5–6 months long, and the young are born at a length of 12–15 cm (4.7–5.9 in). The litter size is 6–18. Males mature sexually at a length of 24 –, and females at a length of 33 –. Estimates of the age at maturity range from six months to 1–2 years. The lifespan
Maximum life span
Maximum life span is a measure of the maximum amount of time one or more members of a population has been observed to survive between birth and death.Most living species have at least one upper limit on the number of times cells can divide...
may be five years for males and six years for females.
Human interactions
The spadenose shark is harmless to humans. This common species is taken by artisanalArtisan 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...
across its range, using floating and fixed gillnet
Gillnet
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...
s, longlines, bottom nets, fish trap
Fish trap
A fish trap is a trap used for fishing. Fish traps may have the form of a fishing weir or a lobster trap. A typical trap might consist of a frame of thick steel wire in the shape of a heart, with chicken wire stretched around it. The mesh wraps around the frame and then tapers into the inside of...
s, trawls, and hook-and-line. The meat is eaten or used as bait for other fishes, the fins are valued for shark fin soup
Shark fin soup
Shark fin soup is a popular soup item of Chinese cuisine usually served at special occasions such as weddings and banquets, or as a luxury item in Chinese culture. The shark fins provide texture while the taste comes from the other soup ingredients.There is controversy over the practice of shark...
, and the carcasses are processed into fishmeal. The meat can also be processed with glacial acetic acid to obtain a gel
Gel
A gel is a solid, jelly-like material that can have properties ranging from soft and weak to hard and tough. Gels are defined as a substantially dilute cross-linked system, which exhibits no flow when in the steady-state...
powder that can be used as a protein supplement
Protein supplement
Protein supplement may refer to:* Dietary supplements**Bodybuilding supplement* Protein bar...
in cereal
Cereal
Cereals are grasses cultivated for the edible components of their grain , composed of the endosperm, germ, and bran...
foods, a biodegradable film for wrapping seafood
Seafood
Seafood is any form of marine life regarded as food by humans. Seafoods include fish, molluscs , crustaceans , echinoderms . Edible sea plants, such as some seaweeds and microalgae, are also seafood, and are widely eaten around the world, especially in Asia...
, or a binder in sausage
Sausage
A sausage is a food usually made from ground meat , mixed with salt, herbs, and other spices, although vegetarian sausages are available. The word sausage is derived from Old French saussiche, from the Latin word salsus, meaning salted.Typically, a sausage is formed in a casing traditionally made...
s and other foods.
Despite its commercial importance, overall fishery statistics for the spadenose shark are lacking. A 1996 report found that this was the most common coastal shark on Chinese
China
Chinese civilization may refer to:* China for more general discussion of the country.* Chinese culture* Greater China, the transnational community of ethnic Chinese.* History of China* Sinosphere, the area historically affected by Chinese culture...
markets, and it is also one of the most common sharks caught off northern 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...
. Substantial numbers are caught by India
India
India , officially the Republic of India , is a country in South Asia. It is the seventh-largest country by geographical area, the second-most populous country with over 1.2 billion people, and the most populous democracy in the world...
n and Pakistan
Pakistan
Pakistan , officially the Islamic Republic of Pakistan is a sovereign state in South Asia. It has a coastline along the Arabian Sea and the Gulf of Oman in the south and is bordered by Afghanistan and Iran in the west, India in the east and China in the far northeast. In the north, Tajikistan...
i fisheries; from 1979–81, an average of 823 tons were caught annually off Verval, India. The spadenose shark is also 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...
, particularly in gillnet fisheries off Kalimantan
Kalimantan
In English, the term Kalimantan refers to the Indonesian portion of the island of Borneo, while in Indonesian, the term "Kalimantan" refers to the whole island of Borneo....
. The International Union for Conservation of Nature (IUCN) has assessed this species as Near Threatened
Near Threatened
Near Threatened is a conservation status assigned to species or lower taxa that may be considered threatened with extinction in the near future, although it does not currently qualify for the threatened status...
; the spadenose shark's relatively short reproductive cycle may render it more resilient to fishing pressure than other sharks, though its low fecundity
Fecundity
Fecundity, derived from the word fecund, generally refers to the ability to reproduce. In demography, fecundity is the potential reproductive capacity of an individual or population. In biology, the definition is more equivalent to fertility, or the actual reproductive rate of an organism or...
still merits caution. This shark may also be negatively affected by coastal development, due to its inshore habitat preferences.