Southern school whiting
Encyclopedia
The southern school whiting, Sillago bassensis, (also known as the silver whiting or trawl whiting) is a common species
of coastal marine fish
of the smelt-whiting
family that inhabits the south and south-west coasts of Australia
. Its distribution overlaps a number of other common sillaginids, with careful observation of anatomical
features occasionally needed to distinguish between species. The southern school whiting is closely related to the eastern school whiting
, Sillago flindersi, and initially were thought to be all one species. The species inhabits both shallow inshore sand
y waters, as well as deeper offshore waters, with a transition of habitats occurring with increasing age. It is a predatory fish, taking a variety of crustacean
s, polychaete
s and bivalves as prey. It reaches sexual maturity
at three years of age, and spawns multiple times between December and April. The southern school whiting is commonly caught by commercial
and recreational
fishermen, often while fishing for related species, especially the sought after King George whiting
. The species is market
ed fresh in southern Australia.
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 examined and named Sillago bassensis by Georges Cuvier
in 1829 from the holotype
specimen
collected in Western Port
of Victoria
, which lies on the Bass Strait
. A number of re-examinations of the fish commonly called 'school whiting' during the 1980s confirmed the presence of two possible subspecies
, which were termed by McKay Sillago bassensis bassensis and Sillago bassensis flindersi, the Western school whiting and Eastern school whiting
respectively. McKay hypothesized the two species diverged during the last ice age
which left a land bridge
from mainland Australia
to Tasmania
open during the Pleistocene
, effectively isolating two pockets of fish, allowing genetic divergence
. These two subspecies are now treated as separate species, despite a relatively young divergence time.
The identification of a further species of school whiting from Western Australia
, Sillago vittata, caused the common name 'western school whiting
' to applied to this species, while S. bassensis is now referred to as the 'Southern school whiting', causing some confusion. The species is often termed the 'silver whiting' by recreational fishermen
in reference to the bright silvery longitudinal strip on the fish, while the name 'trawl whiting' refers to the fact large quantities are taken in commercial trawls.
, with a slightly compressed, elongate body tapering toward the terminal mouth
. The dorsal fin is moderately arched, while the ventral profile is straight. The species is known to grow to a maximum size of 33 cm and around 0.3 kg weight. The colouration of the species is also very similar to a number of other Sillago species which have an overlapping distribution
, and in most circumstances, a more detailed analysis must be done to determine the species.
The fin
anatomy
is highly useful for identification purposes, with the species having 10 to 12 spines in the first dorsal fin
, with one spine and 18 or 19 soft rays on the second dorsal fin. The anal fin has two spines with 18 to 20 soft rays posterior to the spines. Lateral line
scale
s and cheek
scales are also distinctive, with southern school whiting possessing 63 to 70 lateral line scales and cheek scales positioned in 3-4 rows, all of which are ctenoid. The amount of vertebrae are also diagnostic, having 33 to 35 in total. The swim bladder has a short, blunt anterior median projection with no posterior projection.
The southern school whiting has a body colour of creamy brown to rusty above, before an abrupt transition to a silvery white below, with a brilliant longitudinal
silver band separating the colours. A narrow rusty brown horizontal band is positioned above the silver band, with irregular red-brown oblique
blotches and broken stripes positioned on the back and upper sides, much like Sillago maculata. The dorsal fins have rows of rusty brown or red-orange spots, the anal fins are yellow to hyaline
in colour, while all other fins are pale cream, white or hyaline in appearance. There is no black blotch at the base of the pectoral fin.
, ranging from Geraldton
, Western Australia
in the west to Western Port, Victoria
in the east of the country. There have been no reports from Tasmania
. Older literature often refers to S. bassensis recorded as far north as Moreton Bay, Queensland, but these reports are due to misidentification of S. flindersi, as it was unknown there were two species of school whiting when these reports were made.
The species is predominantly found over sand
substrate in variable wave
and tidal activity zones, often in protected bay
s. They often frequent the quiet waters of sand flats, the surf zone
s of beach
es, as well as inhabiting deeper offshore waters to at least 55 m and possibly much deeper where they are taken by commercial trawlers over sand. Juveniles are usually found in a few centimeters of water on calm sand flats, in association with accumulations of detached macrophytes
in the surf,
but do not enter estuarine waters like many of their closest relatives,
although they often occupy the sandflats at the entrances of large estuaries.
similar to other whiting species, although the exact composition differs between species inhabiting the same region, allowing competition
to be avoided. Crustaceans make up the bulk of the species food, with calanoids, cladocerans and carids the dominant crustaceans eaten. Other small teleosts, polychaete
s and bivalves are also common prey. Prey items change over the range
of S. bassensis, and also seasonally as different prey becomes available. A transition is also seen from juvenile to adult stages as at less than 50 mm in length, the species prey consists almost entirely of small plankton
ic prey, such calanoid copepod
s and cladocerans, whereas that of the largest fish (100–169 mm) is dominated by more benthic prey, such as polychaetes and carid shrimp
s, echinoderm
s, as well as teleosts in some cases. This transition in diet occurs as the older, larger fish move to deeper offshore waters where different prey becomes available to the fish. Throughout its life cycle
, S. bassensis usually has some dietary overlap with co-occurring sillaginids, however the diet is still varied enough not to have any negative effects.
until the end of their third year of life, but those individuals that reach maturity early are significantly longer lived than those that do not reach maturity at the same age. The species often reaches 7 years of age, with a known maximum life span
of 10 years.
S. bassensis is known to spawn
at three periods during the year, with the period between December and March the most common spawning time, with some individuals also spawning between September and November and in March and April. The presence of oocyte
s that range widely in size and development, as well as post-ovulatory follicles
, suggest that the species is a multiple spawner.
The larva
e of the species have a functional mouth
and gut
by 2.3 mm in length, with pigment
ed eyes and a gas bladder
. By this time, the yolk absorption is complete. The snout of recently hatched larvae is concave, but changes to straight or slightly concave during development, as the mouth retracts from below the center of the eye to the anterior margin of the eye in older fish. The fins develop in sequence from caudal to pectoral, anal, 1st dorsal, 2nd dorsal and finally the pelvic fin. Scales are first visible around the gut and mid lateral line by 16 mm. The larvae of S. bassensis are the least pigmented of the whiting inhabiting southern Australia
, with the lower jaw containing the only pigment for a long period of time. Juveniles migrate inshore to their nursery areas in surf
zones and tidal flats, where they remain until reaching around 50 mm in length.
As southern school whiting mature, they move from their shallow near shore habitats to deeper offshore waters 20 to 35 m deep and within 20 km of the shore where spawning occurs.
has the largest fishery
for the species, however only 1,275 kg of fish are taken annually, which is small compared to other species. The species is often sold fresh in Australia as school or silver whiting, where it is considered a fine eating fish and fetches good prices at market
, although not as high as the related King George whiting
. It is also exported to Japan
with other species of whiting.
The species is often taken by recreational fishermen
, who do not normally target the species, often taking it amongst other deeper water whiting species such as S. robusta and Sillaginodes punctatus. The juveniles are often taken from the shore along beaches of variable wave action while fishing for species such as S. schomburgkii. Southern school whiting are taken on a variety of baits, with their natural prey such as marine worms
, molluscs, prawn
s and sardine
s often used. Due to their schooling nature, many fish can be caught in a single fishing period, although most authorities ask for excess fish to be returned to the water alive. In Western Australia, southern school whiting and yellowfin whiting
have a combined bag limit of 40 per person with no size restrictions, with no regulations applying elsewhere.
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 coastal marine fish
Coastal fish
Coastal fish, also called offshore fish or neritic fish, are fish that inhabit the sea between the shoreline and the edge of the continental shelf. Since the continental shelf is usually less than 200 metres deep, it follows that pelagic coastal fish are generally epipelagic fish, inhabiting the...
of the smelt-whiting
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...
family that inhabits the south and south-west coasts of 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...
. Its distribution overlaps a number of other common sillaginids, with careful observation of anatomical
Anatomy
Anatomy is a branch of biology and medicine that is the consideration of the structure of living things. It is a general term that includes human anatomy, animal anatomy , and plant anatomy...
features occasionally needed to distinguish between species. The southern school whiting is closely related to the eastern school whiting
Eastern school whiting
The eastern school whiting, Sillago flindersi , is a species of benthic marine fish of the smelt-whiting family Sillaginidae...
, Sillago flindersi, and initially were thought to be all one species. The species inhabits both shallow inshore 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 waters, as well as deeper offshore waters, with a transition of habitats occurring with increasing age. It is a predatory fish, taking a variety of crustacean
Crustacean
Crustaceans form a very large group of arthropods, usually treated as a subphylum, which includes such familiar animals as crabs, lobsters, crayfish, shrimp, krill and barnacles. The 50,000 described species range in size from Stygotantulus stocki at , to the Japanese spider crab with a leg span...
s, 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...
s and bivalves as prey. It reaches sexual maturity
Sexual maturity
Sexual maturity is the age or stage when an organism can reproduce. It is sometimes considered synonymous with adulthood, though the two are distinct...
at three years of age, and spawns multiple times between December and April. The southern school whiting is commonly caught by commercial
Commercial fishing
Commercial fishing is the activity of catching fish and other seafood for commercial profit, mostly from wild fisheries. It provides a large quantity of food to many countries around the world, but those who practice it as an industry must often pursue fish far into the ocean under adverse conditions...
and recreational
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...
fishermen, often while fishing for related species, especially the sought after King George whiting
King George whiting
The King George whiting, Sillaginodes punctatus , is a coastal marine fish of the smelt-whitings family Sillaginidae. The King George whiting is endemic to Australia, inhabiting the south coast of the country from Jurien Bay, Western Australia to Botany Bay, New South Wales in the east...
. The species is market
Market
A market is one of many varieties of systems, institutions, procedures, social relations and infrastructures whereby parties engage in exchange. While parties may exchange goods and services by barter, most markets rely on sellers offering their goods or services in exchange for money from buyers...
ed fresh in southern Australia.
Taxonomy and naming
The southern school 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 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 examined and named Sillago bassensis by Georges Cuvier
Georges Cuvier
Georges Chrétien Léopold Dagobert Cuvier or Jean Léopold Nicolas Frédéric Cuvier , known as Georges Cuvier, was a French naturalist and zoologist...
in 1829 from 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...
specimen
Specimen
A specimen is a portion/quantity of material for use in testing, examination, or study.BiologyA laboratory specimen is an individual animal, part of an animal, a plant, part of a plant, or a microorganism, used as a representative to study the properties of the whole population of that species or...
collected in Western Port
Western Port
Western Port, is sometimes called "Western Port Bay", is a large tidal bay in southern Victoria, Australia opening into Bass Strait. It is the second largest bay in Victoria. Geographically, it is dominated by the two large islands; French Island and Phillip Island. Contrary to its name, it lies to...
of Victoria
Victoria (Australia)
Victoria is the second most populous state in Australia. Geographically the smallest mainland state, Victoria is bordered by New South Wales, South Australia, and Tasmania on Boundary Islet to the north, west and south respectively....
, which lies on the Bass Strait
Bass Strait
Bass Strait is a sea strait separating Tasmania from the south of the Australian mainland, specifically the state of Victoria.-Extent:The International Hydrographic Organization defines the limits of the Bass Strait as follows:...
. A number of re-examinations of the fish commonly called 'school whiting' during the 1980s confirmed the presence of two possible 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...
, which were termed by McKay Sillago bassensis bassensis and Sillago bassensis flindersi, the Western school whiting and Eastern school whiting
Eastern school whiting
The eastern school whiting, Sillago flindersi , is a species of benthic marine fish of the smelt-whiting family Sillaginidae...
respectively. McKay hypothesized the two species diverged during the last ice age
Ice age
An ice age or, more precisely, glacial age, is a generic geological period of long-term reduction in the temperature of the Earth's surface and atmosphere, resulting in the presence or expansion of continental ice sheets, polar ice sheets and alpine glaciers...
which left 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...
from mainland 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...
to Tasmania
Tasmania
Tasmania is an Australian island and state. It is south of the continent, separated by Bass Strait. The state includes the island of Tasmania—the 26th largest island in the world—and the surrounding islands. The state has a population of 507,626 , of whom almost half reside in the greater Hobart...
open during the Pleistocene
Pleistocene
The Pleistocene is the epoch from 2,588,000 to 11,700 years BP that spans the world's recent period of repeated glaciations. The name pleistocene is derived from the Greek and ....
, effectively isolating two pockets of fish, allowing genetic divergence
Genetic divergence
Genetic divergence is the process in which two or more populations of an ancestral species accumulate independent genetic changes through time, often after the populations have become reproductively isolated for some period of time...
. These two subspecies are now treated as separate species, despite a relatively young divergence time.
The identification of a further species of school whiting from Western Australia
Western Australia
Western Australia is a state of Australia, occupying the entire western third of the Australian continent. It is bounded by the Indian Ocean to the north and west, the Great Australian Bight and Indian Ocean to the south, the Northern Territory to the north-east and South Australia to the south-east...
, Sillago vittata, caused the common name 'western school whiting
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...
' to applied to this species, while S. bassensis is now referred to as the 'Southern school whiting', causing some confusion. The species is often termed the 'silver whiting' 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...
in reference to the bright silvery longitudinal strip on the fish, while the name 'trawl whiting' refers to the fact large quantities are taken in commercial trawls.
Description
The southern school whiting has a very similar profile to other members of the genus SillagoSillago
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...
, with a slightly compressed, elongate body tapering toward the terminal mouth
Mouth
The mouth is the first portion of the alimentary canal that receives food andsaliva. The oral mucosa is the mucous membrane epithelium lining the inside of the mouth....
. The dorsal fin is moderately arched, while the ventral profile is straight. The species is known to grow to a maximum size of 33 cm and around 0.3 kg weight. The colouration of the species is also very similar to a number of other Sillago species which have an overlapping distribution
Range (biology)
In biology, the range or distribution of a species is the geographical area within which that species can be found. Within that range, dispersion is variation in local density.The term is often qualified:...
, and in most circumstances, a more detailed analysis must be done to determine the species.
The fin
Fin
A fin is a surface used for stability and/or to produce lift and thrust or to steer while traveling in water, air, or other fluid media, . The first use of the word was for the limbs of fish, but has been extended to include other animal limbs and man-made devices...
anatomy
Anatomy
Anatomy is a branch of biology and medicine that is the consideration of the structure of living things. It is a general term that includes human anatomy, animal anatomy , and plant anatomy...
is highly useful for identification purposes, with the species having 10 to 12 spines in 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...
, with one spine and 18 or 19 soft rays on the second dorsal fin. The anal fin has two spines with 18 to 20 soft rays posterior to the spines. 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...
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 and cheek
Cheek
Cheeks constitute the area of the face below the eyes and between the nose and the left or right ear. They may also be referred to as jowls. "Buccal" means relating to the cheek. In humans, the region is innervated by the buccal nerve...
scales are also distinctive, with southern school whiting possessing 63 to 70 lateral line scales and cheek scales positioned in 3-4 rows, all of which are ctenoid. The amount of vertebrae are also diagnostic, having 33 to 35 in total. The swim bladder has a short, blunt anterior median projection with no posterior projection.
The southern school whiting has a body colour of creamy brown to rusty above, before an abrupt transition to a silvery white below, with a brilliant longitudinal
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...
silver band separating the colours. A narrow rusty brown horizontal band is positioned above the silver band, with irregular red-brown oblique
Oblique
Oblique may refer to:*Oblique angle, in geometry, an angle that is not a multiple of 90 degrees*Oblique angle, synonym for Dutch angle, a cinematographic technique*Oblique , by jazz vibraphonist Bobby Hutcherson...
blotches and broken stripes positioned on the back and upper sides, much like Sillago maculata. The dorsal fins have rows of rusty brown or red-orange spots, the anal fins are yellow 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...
in colour, while all other fins are pale cream, white or hyaline in appearance. There is no black blotch at the base of the pectoral fin.
Distribution and habitat
The southern school whiting inhabits the south and south western coastlines of AustraliaAustralia
Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...
, ranging from Geraldton
Geraldton, Western Australia
Geraldton is a city and port in Western Australia located north of Perth in the Mid West region. Geraldton has an estimated population at June 2010 of 36,958...
, Western Australia
Western Australia
Western Australia is a state of Australia, occupying the entire western third of the Australian continent. It is bounded by the Indian Ocean to the north and west, the Great Australian Bight and Indian Ocean to the south, the Northern Territory to the north-east and South Australia to the south-east...
in the west to Western Port, Victoria
Victoria (Australia)
Victoria is the second most populous state in Australia. Geographically the smallest mainland state, Victoria is bordered by New South Wales, South Australia, and Tasmania on Boundary Islet to the north, west and south respectively....
in the east of the country. There have been no reports from Tasmania
Tasmania
Tasmania is an Australian island and state. It is south of the continent, separated by Bass Strait. The state includes the island of Tasmania—the 26th largest island in the world—and the surrounding islands. The state has a population of 507,626 , of whom almost half reside in the greater Hobart...
. Older literature often refers to S. bassensis recorded as far north as Moreton Bay, Queensland, but these reports are due to misidentification of S. flindersi, as it was unknown there were two species of school whiting when these reports were made.
The species is predominantly found over 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...
substrate in variable wave
Wave
In physics, a wave is a disturbance that travels through space and time, accompanied by the transfer of energy.Waves travel and the wave motion transfers energy from one point to another, often with no permanent displacement of the particles of the medium—that is, with little or no associated mass...
and tidal activity zones, often in protected 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. They often frequent the quiet waters of sand flats, the surf zone
Surf zone
As ocean surface waves come closer to shore they break, forming the foamy, bubbly surface we call surf. The region of breaking waves defines the surf zone. After breaking in the surf zone, the waves continue to move in, and they run up onto the sloping front of the beach, forming an uprush of...
s of beach
Beach
A beach is a geological landform along the shoreline of an ocean, sea, lake or river. It usually consists of loose particles which are often composed of rock, such as sand, gravel, shingle, pebbles or cobblestones...
es, as well as inhabiting deeper offshore waters to at least 55 m and possibly much deeper where they are taken by commercial trawlers over sand. Juveniles are usually found in a few centimeters of water on calm sand flats, in association with accumulations of detached macrophytes
Seaweed
Seaweed is a loose, colloquial term encompassing macroscopic, multicellular, benthic marine algae. The term includes some members of the red, brown and green algae...
in the surf,
but do not enter estuarine waters like many of their closest relatives,
although they often occupy the sandflats at the entrances of large estuaries.
Diet
The southern school whiting has a dietDiet (nutrition)
In nutrition, diet is the sum of food consumed by a person or other organism. Dietary habits are the habitual decisions an individual or culture makes when choosing what foods to eat. With the word diet, it is often implied the use of specific intake of nutrition for health or weight-management...
similar to other whiting species, although the exact composition differs between species inhabiting the same region, allowing competition
Competition
Competition is a contest between individuals, groups, animals, etc. for territory, a niche, or a location of resources. It arises whenever two and only two strive for a goal which cannot be shared. Competition occurs naturally between living organisms which co-exist in the same environment. For...
to be avoided. Crustaceans make up the bulk of the species food, with calanoids, cladocerans and carids the dominant crustaceans eaten. Other small teleosts, 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...
s and bivalves are also common prey. Prey items change over the range
Range (biology)
In biology, the range or distribution of a species is the geographical area within which that species can be found. Within that range, dispersion is variation in local density.The term is often qualified:...
of S. bassensis, and also seasonally as different prey becomes available. A transition is also seen from juvenile to adult stages as at less than 50 mm in length, the species prey consists almost entirely of small plankton
Plankton
Plankton are any drifting organisms that inhabit the pelagic zone of oceans, seas, or bodies of fresh water. That is, plankton are defined by their ecological niche rather than phylogenetic or taxonomic classification...
ic prey, such calanoid 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 cladocerans, whereas that of the largest fish (100–169 mm) is dominated by more benthic prey, such as polychaetes and carid 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...
s, 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, as well as teleosts in some cases. This transition in diet occurs as the older, larger fish move to deeper offshore waters where different prey becomes available to the fish. Throughout its life cycle
Biological life cycle
A life cycle is a period involving all different generations of a species succeeding each other through means of reproduction, whether through asexual reproduction or sexual reproduction...
, S. bassensis usually has some dietary overlap with co-occurring sillaginids, however the diet is still varied enough not to have any negative effects.
Life cycle
Southern school whiting do not usually reach 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...
until the end of their third year of life, but those individuals that reach maturity early are significantly longer lived than those that do not reach maturity at the same age. The species often reaches 7 years of age, with a known maximum life span
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...
of 10 years.
S. bassensis is known to spawn
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...
at three periods during the year, with the period between December and March the most common spawning time, with some individuals also spawning between September and November and in March and April. The presence of oocyte
Oocyte
An oocyte, ovocyte, or rarely ocyte, is a female gametocyte or germ cell involved in reproduction. In other words, it is an immature ovum, or egg cell. An oocyte is produced in the ovary during female gametogenesis. The female germ cells produce a primordial germ cell which undergoes a mitotic...
s that range widely in size and development, as well as post-ovulatory follicles
Ovarian follicle
Ovarian follicles are the basic units of female reproductive biology, each of which is composed of roughly spherical aggregations of cells found in the ovary. They contain a single oocyte . These structures are periodically initiated to grow and develop, culminating in ovulation of usually a single...
, suggest that the species is a multiple spawner.
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 the species have a functional mouth
Mouth
The mouth is the first portion of the alimentary canal that receives food andsaliva. The oral mucosa is the mucous membrane epithelium lining the inside of the mouth....
and gut
Gut (zoology)
In zoology, the gut, also known as the alimentary canal or alimentary tract, is a tube by which bilaterian animals transfer food to the digestion organs. In large bilaterians the gut generally also has an exit, the anus, by which the animal disposes of solid wastes...
by 2.3 mm in length, with pigment
Pigment
A pigment is a material that changes the color of reflected or transmitted light as the result of wavelength-selective absorption. This physical process differs from fluorescence, phosphorescence, and other forms of luminescence, in which a material emits light.Many materials selectively absorb...
ed eyes and a gas bladder
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...
. By this time, the yolk absorption is complete. The snout of recently hatched larvae is concave, but changes to straight or slightly concave during development, as the mouth retracts from below the center of the eye to the anterior margin of the eye in older fish. The fins develop in sequence from caudal to pectoral, anal, 1st dorsal, 2nd dorsal and finally the pelvic fin. Scales are first visible around the gut and mid lateral line by 16 mm. The larvae of S. bassensis are the least pigmented of the whiting inhabiting southern 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 lower jaw containing the only pigment for a long period of time. Juveniles migrate inshore to their nursery areas in surf
Breaking wave
In fluid dynamics, a breaking wave is a wave whose amplitude reaches a critical level at which some process can suddenly start to occur that causes large amounts of wave energy to be transformed into turbulent kinetic energy...
zones and tidal flats, where they remain until reaching around 50 mm in length.
As southern school whiting mature, they move from their shallow near shore habitats to deeper offshore waters 20 to 35 m deep and within 20 km of the shore where spawning occurs.
Relationship to humans
Being that the southern school whiting is quite prevalent along the south western coastline of Australia, it is taken in minor quantities by trawlers working deep, sandy waters of this region. Western AustraliaWestern Australia
Western Australia is a state of Australia, occupying the entire western third of the Australian continent. It is bounded by the Indian Ocean to the north and west, the Great Australian Bight and Indian Ocean to the south, the Northern Territory to the north-east and South Australia to the south-east...
has the largest 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,...
for the species, however only 1,275 kg of fish are taken annually, which is small compared to other species. The species is often sold fresh in Australia as school or silver whiting, where it is considered a fine eating fish and fetches good prices at market
Market
A market is one of many varieties of systems, institutions, procedures, social relations and infrastructures whereby parties engage in exchange. While parties may exchange goods and services by barter, most markets rely on sellers offering their goods or services in exchange for money from buyers...
, although not as high as the related King George whiting
King George whiting
The King George whiting, Sillaginodes punctatus , is a coastal marine fish of the smelt-whitings family Sillaginidae. The King George whiting is endemic to Australia, inhabiting the south coast of the country from Jurien Bay, Western Australia to Botany Bay, New South Wales in the east...
. It is also exported to 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...
with other species of whiting.
The species is often taken 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 do not normally target the species, often taking it amongst other deeper water whiting species such as S. robusta and Sillaginodes punctatus. The juveniles are often taken from the shore along beaches of variable wave action while fishing for species such as S. schomburgkii. Southern school whiting are taken on a variety of baits, with their natural prey such as marine worms
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...
, molluscs, 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...
s and sardine
Sardine
Sardines, or pilchards, are several types of small, oily fish related to herrings, family Clupeidae. Sardines are named after the Mediterranean island of Sardinia, around which they were once abundant....
s often used. Due to their schooling nature, many fish can be caught in a single fishing period, although most authorities ask for excess fish to be returned to the water alive. In Western Australia, southern school whiting and yellowfin whiting
Yellowfin whiting
The yellowfin whiting, Sillago schomburgkii, is a species of inshore marine fish in the smelt-whiting family Sillaginidae...
have a combined bag limit of 40 per person with no size restrictions, with no regulations applying elsewhere.