Stout whiting
Encyclopedia
The stout whiting, Sillago robusta (also known as the yellow-cheek whiting and school whiting), is a species
of benthic marine
fish
in the smelt-whiting family Sillaginidae
. Like other sillaginids, it is an elongate, slightly compressed fish, growing to a maximum known length of 30 cm. The stout whiting is endemic to Australia
, with the species divided into western and eastern populations, with the western population ranging from Shark Bay
to Fremantle
and the eastern population from Bustard Head, Queensland
to northern New South Wales
. The species inhabits deep, sand
y continental shelf
regions to a depth of at least 70 m. The stout whiting is a benthic carnivore
, consuming a variety of polychaetes and crustaceans. The species grows rapidly, and sexual maturity
is reached at a length of 13 cm, with spawning
occurring between December and March. Juveniles of the eastern population move to protected inshore waters, while those of the western population remain offshore their entire life. Stout whiting are the subject of a major export
fishery
operating out of southern Queensland and to a lesser extent New South Wales, with fishery authorities limiting the yearly catch to 1000 tonnes in Queensland. Most of the catch is exported frozen to a number of Asia
n countries, although small quantities are sold in Australia, with the net worth of the fishery values at around 3 million Australian dollar
s per year.
in the genus
Sillago
, which is one of three divisions of the smelt whiting family
Sillaginidae
. The smelt-whitings are Perciformes
in the suborder Percoidea
.
The species was first scientifically described by Stead in 1908 based on a specimen collected from Rose Bay
in Port Jackson
, New South Wales, which was designated to be the holotype
. After this description and naming, the species was once again described and named by William Ogilby
in 1910 as Sillago auricomis, based on a specimen taken from near Hervey Bay in Queensland
. This is considered to be junior synonym under ICZN
naming rules and has subsequently been discarded. During a comprehensive revision of the sillaginids in 1985, Roland McKay noted that the eastern and western populations of fish varied slightly in their fin osteology
and swimbladder morphology, but recommended a full osteological comparison before placing them in subspecies
ranks. McKay also postulates that the two populations became separated during the last ice age, when a land bridge
closed the Torres Strait
to the movement of the species.
The species is most commonly
known as the 'stout whiting', and is recognised as such by the Australian Government. The species is occasionally called the 'yellow-cheek whiting' and also 'school whiting', a broad name applied to a number of Australian sillaginids.
and swimbladder
morphology the best identification features. It is a small fish, reaching a known maximum length of 30 cm, but more commonly seen below 23 cm. Like most sillaginids, the stout whiting has a slightly more convex dorsal profile compared to the ventral profile, reflecting the benthic nature of the species. The dorsal fin is composed of 2 sections; the first consisting of 11 spines and the second of 1 spine followed by 16 to 18 soft rays. Large specimens show a distinct anterior keel
on the first spine of the first dorsal fin, with this feature being more pronounced in the eastern population. The anal fin is similar to the second dorsal fin, having 2 spines followed by 16 or 19 soft rays. The lateral line
has 65-70 scale
s, whilst the cheek has 2 to 3 rows of cteniod scales, and there are 33 vertebrae in total. The swimbladders of the two populations are slightly different, with the eastern population having small anterolateral extensions, while the western population lack these. There is a single tapering posterior extension and a duct like process which runs from the ventral surface to the urogenital opening.
In life, the stout whiting is a creamy yellow to sandy pink colour dorsally, with a silvery white with mauve
reflections ventrally. The dorsal and ventral colours are sharply separated by a silvery mid lateral
band that is often only weakly visible. The body and fins are devoid of any dark markings, with the only breaks in colouration being yellow blotches on the cheeks and a yellow blotch on the base of the first dorsal fin. The first dorsal fin has a white base, becoming darker dorsally, while the anal fin is white, becoming more yellow at the base of the fin. The caudal fin is a pale lemon yellow with a speckled margin, the pelvic fins are white to hyaline
and the pectoral fins are hyaline. There have been records of geographical variation in colour amongst the species, especially within Shark Bay. The Shark Bay fish may have faint gold bars trending 50 degrees above the mid lateral silvery band, and may have black dusting on the dorsal and anal fins.
, the other on the western seaboard. The eastern population has a wider distribution, inhabiting waters from Bustard Head, Queensland
to southern New South Wales
. The western population exists from Shark Bay
in the north to Fremantle
in the south. In his 1985 revision of the Sillaginidae, McKay reported the species from as far north as the Gulf of Carpentaria
, but did not mention any specimen from this far north in his follow-up catalogue for the FAO
.
Stout whiting are found in deeper waters than other Australian sillaginids, inhabiting sand
y substrates
at depths of 10 to 70 m. juvenile
fish of the eastern population inhabit shallower waters for the first year of life, often in large bay
s and near surf beaches. The fish of the western population spend their entire lives offshore. In northern Australia, the same offshore niche is occupied by the mud whiting
, Sillago lutea. In southern Queensland, where it coexists in deeper waters with S. flindersi
, the stout whiting shows preference for deep sandy strata with a riverine influence.
, a number of detailed studies have been undertaken to determine the reproductive and growth characteristics of the species in southern Queensland, while a series of studies in southern Western Australia have focused on the diet and movements of the species in relation to the ecology
of coexisting sillaginids. Like most smelt-whitings, the stout whiting is a schooling species, occasionally associating with S. vitttata
, S. burrus
and S. bassensis
in southern Western Australia and with S. flindersi in southern Queensland. The species is thought to form large schools mostly at dawn and dusk.
s to 'suck up' prey from the substrate. Research conducted in southern Queensland indicates the species preys mostly on crustacean
s and polychaete
worms. Individuals less than 10 cm predominantly consume small crustaceans such as copepod
s and mysids, while older fish took more polychaetes. Amphipods and the shrimp
genus Callianassa
were also commonly taken in this study. In southern Queensland, there is also a strong temporal control on the diet, with summer months showing much higher polychaete intake compared to crustaceans and vice versa in winter. A detailed study in southern Western Australia indicated amphipods and polychaetes are the two primary components of this population's diet. Penaeids, ostracod
s, ophiuroid echinoderm
s and a variety of molluscs also make up a significant part of the species diet in this area. Once again, larger fish took more polychaetes, and in general broadened their diet with increasing age. This resulted in a low dietary overlap with other coexisting sillaginids present in the same area.
The stout whiting is also a major prey species itself for a number of species, with seal
s, dolphin
s and larger fish known predators of the species.
by the end of its second year of life, with around 50% of fish accomplishing this after only one year. The fish are around 13 cm once they reach sexual maturity.
The patterns of spawning
and movement of the juveniles differs between the eastern and western populations. In the western population, unlike many co-occurring sillaginids, stout whiting do not move inshore to spawn and the juveniles do not make their way to shallower waters; instead they spawn offshore, with the fish spending their entire lives in this environment. In contrast, the eastern population do use inshore nursery areas for the juveniles including bay
s and surf beaches, with this difference between populations attributed to increased competition between sillaginids by some authors. In both populations, spawning occurs over summer, with the fish spawning multiple times between December and March.
Stout whiting are fast growers in comparison to most other smelt-whitings, reaching 80% of its final length after 2 years of life. The species is known to reach a maximum age of 7 years, although most individuals do not survive more than 3 years.
, although have soft flesh which results in a tendency to bruise
easily. Due to their mostly offshore nature and small size, they are rarely targeted or caught by recreational fishermen
, who take an estimated 1 tonne
per year. They are however are a major target for commercial operators, especially in southern Queensland.
The Queensland fishery
originated in 1981, after a single operator began targeting eastern school whiting, S. flindersi. It was soon discovered that stout whiting were highly abundant in the surrounding region and the fishery began to shift towards the species. The original operator who realised the potential of the fishery continued after the market took a downfall, upgrading equipment with a new snap freezing facility, which became essential for exporting the fish. There was a rapid expansion in the fishery between 1989 and 1990, with 10 operators recording a 1789 tonne haul in 1990. In 1991 the market once again took a downfall due to low demand
, and the fishery is now closely monitored by fishery authorities, with a 1000 tonne limit on the total yearly catch in place since 2000. This limit includes the fish taken as bycatch
in other fisheries such as prawn
trawling, which means often a sizable amount must be discarded.
In New South Wales, stout whiting were mostly discarded by trawlers until an export
market developed in the 1970s. Substantial amounts are taken and mostly discarded by prawn trawlers, and the catch has been stable at around 300-500 tonnes per year since 2000. The western population is not highly exploited.
The fishery is worth a reported 3 million Australian dollars annually (around $2.80 per kg in 1999), with the fish exported to Thailand
, China
, Vietnam
, Japan
and Taiwan
. These exported fish compete with local Asian sillaginids, especially northern whiting
and Japanese whiting
, resulting in substantial price fluctuations. Few fish make their way to local markets where they are sold as butterfly fillet
s.
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 benthic marine
Marine biology
Marine biology is the scientific study of organisms in the ocean or other marine or brackish bodies of water. Given that in biology many phyla, families and genera have some species that live in the sea and others that live on land, marine biology classifies species based on the environment rather...
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 the smelt-whiting family Sillaginidae
Sillaginidae
The Sillaginidae, commonly known as the smelt-whitings, whitings, sillaginids, sand borers and sand-smelts, are a family of benthic coastal marine fishes in the order Perciformes. The smelt-whitings inhabit a wide region covering much of the Indo-Pacific, from the west coast of Africa east to Japan...
. Like other sillaginids, it is an elongate, slightly compressed fish, growing to a maximum known length of 30 cm. The stout whiting is endemic to 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...
, with the species divided into western and eastern populations, with the western population ranging from Shark Bay
Shark Bay, Western Australia
Shark Bay is a World Heritage Site in the Gascoyne region of Western Australia. It is an area centred approximately on , 800 kilometres north of Perth, on the westernmost point of Australia. An expedition led by Dirk Hartog happened upon the area in 1616, becoming the second group of Europeans...
to Fremantle
Fremantle, Western Australia
Fremantle is a city in Western Australia, located at the mouth of the Swan River. Fremantle Harbour serves as the port of Perth, the state capital. Fremantle was the first area settled by the Swan River colonists in 1829...
and the eastern population from Bustard Head, 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 northern 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 species inhabits deep, sand
Sand
Sand is a naturally occurring granular material composed of finely divided rock and mineral particles.The composition of sand is highly variable, depending on the local rock sources and conditions, but the most common constituent of sand in inland continental settings and non-tropical coastal...
y 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,...
regions to a depth of at least 70 m. The stout whiting is a benthic carnivore
Carnivore
A carnivore meaning 'meat eater' is an organism that derives its energy and nutrient requirements from a diet consisting mainly or exclusively of animal tissue, whether through predation or scavenging...
, consuming a variety of polychaetes and crustaceans. The species grows rapidly, and 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...
is reached at a length of 13 cm, with spawning
Spawn (biology)
Spawn refers to the eggs and sperm released or deposited, usually into water, by aquatic animals. As a verb, spawn refers to the process of releasing the eggs and sperm, also called spawning...
occurring between December and March. Juveniles of the eastern population move to protected inshore waters, while those of the western population remain offshore their entire life. Stout whiting are the subject of a major export
Export
The term export is derived from the conceptual meaning as to ship the goods and services out of the port of a country. The seller of such goods and services is referred to as an "exporter" who is based in the country of export whereas the overseas based buyer is referred to as an "importer"...
fishery
Fishery
Generally, a fishery is an entity engaged in raising or harvesting fish which is determined by some authority to be a fishery. According to the FAO, a fishery is typically defined in terms of the "people involved, species or type of fish, area of water or seabed, method of fishing, class of boats,...
operating out of southern Queensland and to a lesser extent New South Wales, with fishery authorities limiting the yearly catch to 1000 tonnes in Queensland. Most of the catch is exported frozen to a number of Asia
Asia
Asia is the world's largest and most populous continent, located primarily in the eastern and northern hemispheres. It covers 8.7% of the Earth's total surface area and with approximately 3.879 billion people, it hosts 60% of the world's current human population...
n countries, although small quantities are sold in Australia, with the net worth of the fishery values at around 3 million Australian dollar
Australian dollar
The Australian dollar is the currency of the Commonwealth of Australia, including Christmas Island, Cocos Islands, and Norfolk Island, as well as the independent Pacific Island states of Kiribati, Nauru and Tuvalu...
s per year.
Taxonomy and naming
The stout whiting is one of 29 speciesSpecies
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...
in the 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...
Sillago
Sillago
Sillago is one of three genera in the family Sillaginidae containing the smelt-whitings, and contains 29 species, making Sillago the only non-monotypic genus in the family. Distinguishing among Sillago species can be difficult, with many similar in appearance and colour, forcing the use of swim...
, which is one of three divisions of the smelt whiting 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...
Sillaginidae
Sillaginidae
The Sillaginidae, commonly known as the smelt-whitings, whitings, sillaginids, sand borers and sand-smelts, are a family of benthic coastal marine fishes in the order Perciformes. The smelt-whitings inhabit a wide region covering much of the Indo-Pacific, from the west coast of Africa east to Japan...
. The smelt-whitings are Perciformes
Perciformes
The Perciformes, also called the Percomorphi or Acanthopteri, is one of the largest orders of vertebrates, containing about 40% of all bony fish. Perciformes means perch-like. They belong to the class of ray-finned fish and comprise over 7,000 species found in almost all aquatic environments...
in the suborder Percoidea
Percoidea
Percoidea is a superfamily of fish of the order Perciformes....
.
The species was first scientifically described by Stead in 1908 based on a specimen collected from Rose Bay
Rose Bay, New South Wales
Rose Bay is a harbourside, eastern suburb of Sydney, in the state of New South Wales, Australia. Rose Bay is located 7 kilometres east of the Sydney central business district, in the local government areas of Waverley Municipal Council and Woollahra Council .Rose Bay has views of both the Sydney...
in 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...
, New South Wales, which was designated to be 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...
. After this description and naming, the species was once again described and named by William Ogilby
William Ogilby
William Ogilby was an Irish barrister and naturalist.Ogilby was honorary secretary of the Zoological Society of London from 1839 to 1846....
in 1910 as Sillago auricomis, based on a specimen taken from near Hervey 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...
. This is considered to be junior synonym under ICZN
International Code of Zoological Nomenclature
The International Code of Zoological Nomenclature is a widely accepted convention in zoology that rules the formal scientific naming of organisms treated as animals...
naming rules and has subsequently been discarded. During a comprehensive revision of the sillaginids in 1985, Roland McKay noted that the eastern and western populations of fish varied slightly in their fin osteology
Osteology
Osteology is the scientific study of bones. A subdiscipline of anatomy, anthropology, and archeology, osteology is a detailed study of the structure of bones, skeletal elements, teeth, morphology, function, disease, pathology, the process of ossification , the resistance and hardness of bones , etc...
and swimbladder morphology, but recommended a full osteological comparison before placing them in subspecies
Subspecies
Subspecies in biological classification, is either a taxonomic rank subordinate to species, ora taxonomic unit in that rank . A subspecies cannot be recognized in isolation: a species will either be recognized as having no subspecies at all or two or more, never just one...
ranks. McKay also postulates that the two populations became separated during the last ice age, when a land bridge
Land bridge
A land bridge, in biogeography, is an isthmus or wider land connection between otherwise separate areas, over which animals and plants are able to cross and colonise new lands...
closed the Torres Strait
Torres Strait
The Torres Strait is a body of water which lies between Australia and the Melanesian island of New Guinea. It is approximately wide at its narrowest extent. To the south is Cape York Peninsula, the northernmost continental extremity of the Australian state of Queensland...
to the movement of the species.
The species is most commonly
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...
known as the 'stout whiting', and is recognised as such by the Australian Government. The species is occasionally called the 'yellow-cheek whiting' and also 'school whiting', a broad name applied to a number of Australian sillaginids.
Description
The stout whiting is similar in appearance to a number of Australian sillaginids, with dorsal finDorsal 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...
and swimbladder
Gas bladder
The swim bladder, gas bladder, fish maw or air bladder is an internal gas-filled organ that contributes to the ability of a fish to control its buoyancy, and thus to stay at the current water depth without having to waste energy in swimming...
morphology the best identification features. It is a small fish, reaching a known maximum length of 30 cm, but more commonly seen below 23 cm. Like most sillaginids, the stout whiting has a slightly more convex dorsal profile compared to the ventral profile, reflecting the benthic nature of the species. The dorsal fin is composed of 2 sections; the first consisting of 11 spines and the second of 1 spine followed by 16 to 18 soft rays. Large specimens show a distinct anterior keel
Keel
In boats and ships, keel can refer to either of two parts: a structural element, or a hydrodynamic element. These parts overlap. As the laying down of the keel is the initial step in construction of a ship, in British and American shipbuilding traditions the construction is dated from this event...
on the first spine of the first dorsal fin, with this feature being more pronounced in the eastern population. The anal fin is similar to the second dorsal fin, having 2 spines followed by 16 or 19 soft rays. The lateral line
Lateral line
The lateral line is a sense organ in aquatic organisms , used to detect movement and vibration in the surrounding water. Lateral lines are usually visible as faint lines running lengthwise down each side, from the vicinity of the gill covers to the base of the tail...
has 65-70 scale
Scale (zoology)
In most biological nomenclature, a scale is a small rigid plate that grows out of an animal's skin to provide protection. In lepidopteran species, scales are plates on the surface of the insect wing, and provide coloration...
s, whilst the cheek has 2 to 3 rows of cteniod scales, and there are 33 vertebrae in total. The swimbladders of the two populations are slightly different, with the eastern population having small anterolateral extensions, while the western population lack these. There is a single tapering posterior extension and a duct like process which runs from the ventral surface to the urogenital opening.
In life, the stout whiting is a creamy yellow to sandy pink colour dorsally, with a silvery white with mauve
Mauve
Mauve is a pale lavender-lilac color, one of many in the range of purples. The color mauve is named after the mallow flower....
reflections ventrally. The dorsal and ventral colours are sharply separated by a silvery mid lateral
Anatomical terms of location
Standard anatomical terms of location are designations employed in science that deal with the anatomy of animals to avoid ambiguities that might otherwise arise. They are not language-specific, and thus require no translation...
band that is often only weakly visible. The body and fins are devoid of any dark markings, with the only breaks in colouration being yellow blotches on the cheeks and a yellow blotch on the base of the first dorsal fin. The first dorsal fin has a white base, becoming darker dorsally, while the anal fin is white, becoming more yellow at the base of the fin. The caudal fin is a pale lemon yellow with a speckled margin, the pelvic fins are white to hyaline
Hyaline
The term hyaline denotes a substance with a glass-like appearance.-Histopathology:In histopathological medical usage, a hyaline substance appears glassy and pink after being stained with haematoxylin and eosin — usually it is an acellular, proteinaceous material...
and the pectoral fins are hyaline. There have been records of geographical variation in colour amongst the species, especially within Shark Bay. The Shark Bay fish may have faint gold bars trending 50 degrees above the mid lateral silvery band, and may have black dusting on the dorsal and anal fins.
Distribution and habitat
Stout whiting are endemic to Australia, and consist of two apparently disjunct populations; one on the eastern seaboardCoast
A coastline or seashore is the area where land meets the sea or ocean. A precise line that can be called a coastline cannot be determined due to the dynamic nature of tides. The term "coastal zone" can be used instead, which is a spatial zone where interaction of the sea and land processes occurs...
, the other on the western seaboard. The eastern population has a wider distribution, inhabiting waters from Bustard Head, 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 southern 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 western population exists from Shark Bay
Shark Bay
Shark Bay is a World Heritage listed bay in Western Australia. The term may also refer to:* the locality of Shark Bay, now known as Denham* Shark Bay Marine Park* Shark Bay , a shark exhibit at Sea World, Gold Coast, Australia* Shire of Shark Bay...
in the north to Fremantle
Fremantle, Western Australia
Fremantle is a city in Western Australia, located at the mouth of the Swan River. Fremantle Harbour serves as the port of Perth, the state capital. Fremantle was the first area settled by the Swan River colonists in 1829...
in the south. In his 1985 revision of the Sillaginidae, McKay reported the species from as far north as the Gulf of Carpentaria
Gulf of Carpentaria
The Gulf of Carpentaria is a large, shallow sea enclosed on three sides by northern Australia and bounded on the north by the Arafura Sea...
, but did not mention any specimen from this far north in his follow-up catalogue for the FAO
Fão
Fão is a town in Esposende Municipality in Portugal....
.
Stout whiting are found in deeper waters than other Australian sillaginids, inhabiting sand
Sand
Sand is a naturally occurring granular material composed of finely divided rock and mineral particles.The composition of sand is highly variable, depending on the local rock sources and conditions, but the most common constituent of sand in inland continental settings and non-tropical coastal...
y substrates
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....
at depths of 10 to 70 m. juvenile
Juvenile (organism)
A juvenile is an individual organism that has not yet reached its adult form, sexual maturity or size. Juveniles sometimes look very different from the adult form, particularly in terms of their colour...
fish of the eastern population inhabit shallower waters for the first year of life, often in large 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 and near surf beaches. The fish of the western population spend their entire lives offshore. In northern Australia, the same offshore niche is occupied by the mud whiting
Mud whiting
The mud whiting, Sillago lutea, is a species of coastal marine fish in the smelt-whiting family Sillaginidae. The mud whiting was first described in 1985 and is currently known from the north west coast of Australia and the Indian coast....
, Sillago lutea. In southern Queensland, where it coexists in deeper waters with S. flindersi
Eastern school whiting
The eastern school whiting, Sillago flindersi , is a species of benthic marine fish of the smelt-whiting family Sillaginidae...
, the stout whiting shows preference for deep sandy strata with a riverine influence.
Biology
Due to the emergence of stout whiting as a major east coast fisheryFishery
Generally, a fishery is an entity engaged in raising or harvesting fish which is determined by some authority to be a fishery. According to the FAO, a fishery is typically defined in terms of the "people involved, species or type of fish, area of water or seabed, method of fishing, class of boats,...
, a number of detailed studies have been undertaken to determine the reproductive and growth characteristics of the species in southern Queensland, while a series of studies in southern Western Australia have focused on the diet and movements of the species in relation to the ecology
Ecology
Ecology is the scientific study of the relations that living organisms have with respect to each other and their natural environment. Variables of interest to ecologists include the composition, distribution, amount , number, and changing states of organisms within and among ecosystems...
of coexisting sillaginids. Like most smelt-whitings, the stout whiting is a schooling species, occasionally associating with S. vitttata
Western school whiting
The western school whiting, Sillago vittata , is a species of benthic marine fish in the smelt-whiting family Sillaginidae. The species is one of three 'school whiting' that inhabit southern Australia and share a very similar appearance...
, S. burrus
Western trumpeter whiting
The western trumpeter whiting, Sillago burrus, is a species of marine fish of the smelt whiting family Sillaginidae that is commonly found along the northern coast of Australia and in southern Indonesia and New Guinea...
and S. bassensis
Southern school whiting
The southern school whiting, Sillago bassensis, is a common species of coastal marine fish of the smelt-whiting family that inhabits the south and south-west coasts of Australia...
in southern Western Australia and with S. flindersi in southern Queensland. The species is thought to form large schools mostly at dawn and dusk.
Diet and feeding
Stout whiting are benthic predators that forage the sea floor using their protrusile jawJaw
The jaw is any opposable articulated structure at the entrance of the mouth, typically used for grasping and manipulating food. The term jaws is also broadly applied to the whole of the structures constituting the vault of the mouth and serving to open and close it and is part of the body plan of...
s to 'suck up' prey from the substrate. Research conducted in southern Queensland indicates the species preys mostly 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
Polychaete
The Polychaeta or polychaetes are a class of annelid worms, generally marine. Each body segment has a pair of fleshy protrusions called parapodia that bear many bristles, called chaetae, which are made of chitin. Indeed, polychaetes are sometimes referred to as bristle worms. More than 10,000...
worms. Individuals less than 10 cm predominantly consume small crustaceans such as copepod
Copepod
Copepods are a group of small crustaceans found in the sea and nearly every freshwater habitat. Some species are planktonic , some are benthic , and some continental species may live in limno-terrestrial habitats and other wet terrestrial places, such as swamps, under leaf fall in wet forests,...
s and mysids, while older fish took more polychaetes. Amphipods and the 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...
genus Callianassa
Callianassa
Callianassa can refer to:*Callianassa, one of the Nereids*Callianassa , a genus of mud-shrimp including**C. filholi**C. subterranea**C. tyrrhena...
were also commonly taken in this study. In southern Queensland, there is also a strong temporal control on the diet, with summer months showing much higher polychaete intake compared to crustaceans and vice versa in winter. A detailed study in southern Western Australia indicated amphipods and polychaetes are the two primary components of this population's diet. Penaeids, ostracod
Ostracod
Ostracoda is a class of the Crustacea, sometimes known as the seed shrimp because of their appearance. Some 65,000 species have been identified, grouped into several orders....
s, ophiuroid echinoderm
Echinoderm
Echinoderms are a phylum of marine animals. Echinoderms are found at every ocean depth, from the intertidal zone to the abyssal zone....
s and a variety of molluscs also make up a significant part of the species diet in this area. Once again, larger fish took more polychaetes, and in general broadened their diet with increasing age. This resulted in a low dietary overlap with other coexisting sillaginids present in the same area.
The stout whiting is also a major prey species itself for a number of species, with seal
Pinniped
Pinnipeds or fin-footed mammals are a widely distributed and diverse group of semiaquatic marine mammals comprising the families Odobenidae , Otariidae , and Phocidae .-Overview: Pinnipeds are typically sleek-bodied and barrel-shaped...
s, dolphin
Dolphin
Dolphins are marine mammals that are closely related to whales and porpoises. There are almost forty species of dolphin in 17 genera. They vary in size from and , up to and . They are found worldwide, mostly in the shallower seas of the continental shelves, and are carnivores, mostly eating...
s and larger fish known predators of the species.
Reproduction and growth
The stout whiting reaches sexual maturitySexual 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...
by the end of its second year of life, with around 50% of fish accomplishing this after only one year. The fish are around 13 cm once they reach sexual maturity.
The patterns of spawning
Spawn (biology)
Spawn refers to the eggs and sperm released or deposited, usually into water, by aquatic animals. As a verb, spawn refers to the process of releasing the eggs and sperm, also called spawning...
and movement of the juveniles differs between the eastern and western populations. In the western population, unlike many co-occurring sillaginids, stout whiting do not move inshore to spawn and the juveniles do not make their way to shallower waters; instead they spawn offshore, with the fish spending their entire lives in this environment. In contrast, the eastern population do use inshore nursery areas for the juveniles including 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 and surf beaches, with this difference between populations attributed to increased competition between sillaginids by some authors. In both populations, spawning occurs over summer, with the fish spawning multiple times between December and March.
Stout whiting are fast growers in comparison to most other smelt-whitings, reaching 80% of its final length after 2 years of life. The species is known to reach a maximum age of 7 years, although most individuals do not survive more than 3 years.
Relationship to humans
Stout whiting, like most of the smelt-whitings are considered to be good quality table fishFish (food)
Fish is a food consumed by many species, including humans. The word "fish" refers to both the animal and to the food prepared from it. Fish has been an important source of protein for humans throughout recorded history.-Terminology:...
, although have soft flesh which results in a tendency to bruise
Bruise
A bruise, also called a contusion, is a type of relatively minor hematoma of tissue in which capillaries and sometimes venules are damaged by trauma, allowing blood to seep into the surrounding interstitial tissues. Bruises can involve capillaries at the level of skin, subcutaneous tissue, muscle,...
easily. Due to their mostly offshore nature and small size, they are rarely targeted or caught by recreational fishermen
Angling
Angling is a method of fishing by means of an "angle" . The hook is usually attached to a fishing line and the line is often attached to a fishing rod. Fishing rods are usually fitted with a fishing reel that functions as a mechanism for storing, retrieving and paying out the line. The hook itself...
, who take an estimated 1 tonne
Tonne
The tonne, known as the metric ton in the US , often put pleonastically as "metric tonne" to avoid confusion with ton, is a metric system unit of mass equal to 1000 kilograms. The tonne is not an International System of Units unit, but is accepted for use with the SI...
per year. They are however are a major target for commercial operators, especially in southern Queensland.
The Queensland fishery
Fishery
Generally, a fishery is an entity engaged in raising or harvesting fish which is determined by some authority to be a fishery. According to the FAO, a fishery is typically defined in terms of the "people involved, species or type of fish, area of water or seabed, method of fishing, class of boats,...
originated in 1981, after a single operator began targeting eastern school whiting, S. flindersi. It was soon discovered that stout whiting were highly abundant in the surrounding region and the fishery began to shift towards the species. The original operator who realised the potential of the fishery continued after the market took a downfall, upgrading equipment with a new snap freezing facility, which became essential for exporting the fish. There was a rapid expansion in the fishery between 1989 and 1990, with 10 operators recording a 1789 tonne haul in 1990. In 1991 the market once again took a downfall due to low demand
Demand
- Economics :*Demand , the desire to own something and the ability to pay for it*Demand curve, a graphic representation of a demand schedule*Demand deposit, the money in checking accounts...
, and the fishery is now closely monitored by fishery authorities, with a 1000 tonne limit on the total yearly catch in place since 2000. This limit includes the fish 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 other fisheries such as prawn
Prawn
Prawns are decapod crustaceans of the sub-order Dendrobranchiata. There are 540 extant species, in seven families, and a fossil record extending back to the Devonian...
trawling, which means often a sizable amount must be discarded.
In New South Wales, stout whiting were mostly discarded by trawlers until an export
Export
The term export is derived from the conceptual meaning as to ship the goods and services out of the port of a country. The seller of such goods and services is referred to as an "exporter" who is based in the country of export whereas the overseas based buyer is referred to as an "importer"...
market developed in the 1970s. Substantial amounts are taken and mostly discarded by prawn trawlers, and the catch has been stable at around 300-500 tonnes per year since 2000. The western population is not highly exploited.
The fishery is worth a reported 3 million Australian dollars annually (around $2.80 per kg in 1999), with the fish exported to Thailand
Thailand
Thailand , officially the Kingdom of Thailand , formerly known as Siam , is a country located at the centre of the Indochina peninsula and Southeast Asia. It is bordered to the north by Burma and Laos, to the east by Laos and Cambodia, to the south by the Gulf of Thailand and Malaysia, and to the...
, China
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...
, Vietnam
Vietnam
Vietnam – sometimes spelled Viet Nam , officially the Socialist Republic of Vietnam – is the easternmost country on the Indochina Peninsula in Southeast Asia. It is bordered by China to the north, Laos to the northwest, Cambodia to the southwest, and the South China Sea –...
, 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...
and 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...
. These exported fish compete with local Asian sillaginids, especially northern whiting
Northern whiting
The northern whiting, Sillago sihama , is a marine fish, the most widespread and abundant member of the smelt-whiting family Sillaginidae. The northern whiting was the first species of sillaginid scientifically described and is therefore the type species of both the family Sillaginidae and the...
and Japanese whiting
Japanese whiting
The Japanese whiting, Sillago japonica, is a common species of coastal marine fish belonging to the smelt-whiting family, Sillaginidae...
, resulting in substantial price fluctuations. Few fish make their way to local markets where they are sold as butterfly fillet
Fillet (cut)
A fillet is a cut or slice of boneless meat or fish.- Meat :In the case of beef, in the USA, the term most often refers to beef tenderloin, especially filet mignon.- Chicken :...
s.