Yellowfin whiting
Encyclopedia
The yellowfin whiting, Sillago schomburgkii, (also known as the western sand whiting and fine-scaled whiting) is a species
of inshore marine
fish
in the smelt-whiting family Sillaginidae
. The species is endemic to the eastern Indian Ocean
, ranging from Dampier, Western Australia
to Gulf St Vincent in South Australia
, with an apparent division in the populations of the two states. Yellowfin whiting inhabit relatively shallow waters for their entire life, often found on tidal flats and creeks, as well as large estuaries. It is one of the largest members of the smelt-whiting family, growing to 42 cm, and can be distinguished by a number of anatomical and colour related features. Yellowfin whiting are benthic carnivores, preying predominantly on polychaete
worms, with minor amounts of copepod
s, amphipods and bivalves also commonly taken. The species shows a change in diet with age, and also dietary differences with other sillaginids presumably to minimize competition
. Reproduction occurs at different times throughout its range, generally focused around summer, with up to 217,000 egg
s produced per season. Yellowfin whiting reach sexual maturity
at around 20 cm, with each individual spawning
more than once. The species forms the basis of major fisheries in both Shark Bay, Western Australia
and the two Gulfs of South Australia, with around 260 tonnes of fish taken each year. They are also a popular target for shore based anglers, with a reputation as a very good table fish.
in the genus
Sillago
, which is one of three divisions of the smelt whiting family
Sillaginidae
. The smelt-whitings are Perciformes
in the suborder Percoidei
.
The species was first recognised and scientifically described by the German
naturalist
Wilhelm Peters
in 1864 based on the holotype
collected from the waters near Adelaide
, the capital city of South Australia. Peters assigned the species name schomburgkii in honor of the German]] explorer and botanist Moritz Richard Schomburgk
, who became the second Director of the Adelaide Botanic Garden
s. Schomburgk collected the specimen and sent it to Peters, who was by then the curator of the Berlin Zoological Museum, an institution for which Schomburgk had collected extensively before in the past during expeditions to British Guiana
.
Prior to Peter's description, the yellowfin whiting was at first confused with the similar Sillago bassensis, which also occurs within the same range. The species was also independently renamed twice after the initial naming, first by Francis de Castelnau
in 1873 as Sillago bostockii, and then Gilbert Percy Whitley
in 1944 who named the species Sillago frazeri (or S. fraseri). These two names are considered to be junior synonyms under the ICZN
naming rules, and are considered invalid.
The species is known primarily as the 'yellowfin whiting' or 'yellow-finned whiting' in reference to the yellow pectoral, anal and caudal fins, and is recognised as such by the Australian Government. In Western Australia, the species is usually referred to as the 'western sand whiting' due to its close similarity with the sand whiting
(Sillago ciliata) of Eastern Australia, with the name 'fine-scaled whiting' rarely used.
. The body is elongate and compressed, with the dorsal profile more arched than the ventral. The mouth is small and oblique, having a broad band of villiform teeth in each jaw. There are two slightly separated dorsal fin
s, the first consisting of 10 to 12 spines and the second of 1 spine followed by 19 to 22 soft rays. The anal fin consists of 2 spines followed by 17 to 20 soft rays, the ventral of 1 spine and 5 soft rays and the pectoral of 15 to 16 rays. The caudal fin is emarginate, and is made up of 17 rays. The body is covered in small ctenoid scales
extending to the upper head and nostrils of the fish, also present behind each ray of the dorsal and anal fins. The lateral line
has 66 to 76 scales, and the cheek has 4 or 5 rows of scales, all of which are ctenoid. There is a total of 37 vertebrae in the species. The swimbladder has an incised anterior margin with no median or anterolateral projections and there is a single tapering posterior extension which rapidly narrows to a slender tube. A duct like process is present on the ventral surface of the swimbladder.
The yellowfin whiting is a sandy brown to pale silvery grey colour, with a darker dorsal surface and paler underside. There is a narrow silver mid-lateral
band with a brownish band above, although these bands may be pale or indistinct. The dorsal fins are both hyaline
with rows of small brown spots and the anal fins are pale yellow with a cream margin. The ventral fins are also yellowish, and the pectoral fin is pale yellow to hyaline with a fine dusting and lacks a dark spot at the base. As yellowfin whiting grow, the yellow colour of the fins often fades and in large specimens may be completely absent. The caudal fin is greyish.
off south west Australia
, and is believed to exist as two separate populations, one in Western Australia
and the other in South Australia
.
The western population extends from Dampier
, south to Albany
, with no records of the species between Albany and Spencer Gulf
further west. The southern population occurs in Spencer Gulf and Gulf St Vincent, extending eastward to the Fleurieu Peninsula
. Tagging
studies have found that the populations in each of South Australia's Gulfs are isolated from each others, but no genetics
studies have been undertaken to clarify this.
Yellowfin whiting primarily inhabit shallow protected inshore waters in depths of less than 10 m, often moving across tidal flats less than a meter deep. They are commonly found on sand flats, bars and spits, as well as mangrove
lined tidal creeks, mud flats, seagrass
beds and estuaries. Yellowfin whiting move with the tide
, pushing into the shallows of creeks and flats to forage at high tide and moving back to the sandy hollows of deeper slopes of channels and banks as the tide falls. In Western Australia, they often enter large, sandy estuaries such as the Swan
and Leschenault Estuary
where they many penetrate the limits of brackish water, indicating they can survive in low salinity
environments. Conversely, they have been recorded in the extremely saline waters of upper Spencer Gulf and Shark Bay
, suggesting a wide tolerance to salinity. Juveniles inhabit the same environments as adults in South Australia, but in Western Australia adults move from the tidal creeks and seagrass beds to more sand dominated environments including high energy beach
es.
species, with its movements highly controlled by tidal phases, with the species often moving over shallow sand banks with the rising tide. Where it occurs with other species of sillaginids, it is unique in that it remains in the shallow protected inshore waters, while other species move offshore
as they grow. This is likely a response to reduce interspecific competition
between sillaginids. The dietary and reproductive biology
of the yellowfin whiting has been extensively studied in Western and South Australia, where it comprises a major part of the fishery
. As with a number of other sillaginids, the species has been recorded 'burrowing' in the substrate
to avoid predators.
s that can be protruded to 'suck up' and capture its prey from the seafloor. Studies on the mouth morphology
of a range of sillaginids concluded that the mouth morphology of most species has little influence on the type of prey caught, with differences in diet more likely due to variations in the foraging
behavior. Studies conducted in southwest Western Australia found the species predominantly takes polychaetes as its main prey item, although crustacean
s, particularly amphipods and penaeids also make up a large portion of its diet. Items taken infrequently or in lesser amounts include small teleost fish, bivalve molluscs, marine plant material and other crustaceans such as tanaids, decapods
and cumaceans. Modeling with the stable isotopes 13C and 15N indicate that seagrass
and epiphytic algae
were the primary initial sources of energy and nutrition that flow into the fish via detritivore
s which the species preys on, with salt marsh
plants and macroalgae contributing in some settings.
The species is known to undergo a dietary shift as it grows to adulthood. Young individuals less than 10 cm in length consume considerable volumes of copepods and minor amounts of polychaetes, but once they reach around 10 cm, the diet shifts to a polychaete-dominated one. Further growth sees an increase in the volume of amphipods, small fish and oligochaetes taken. These changes appear to be unrelated to mouth morphology, instead the fish becomes more mobile and possesses a larger mouth to be able to take these prey. The yellowfin whitings' diet also varies spatially and temporally, which appears to be a function of prey availability at different sites and periods of the year. There is little resource partitioning between the small individuals of sillaginids which inhabit shallow inshore habitats, with Sillago vittata, S. burrus and Sillaginodes punctatus also taking copepods as their primary prey in southwest Western Australia. This changes as each species grows, with S. vittata and S burrus moving to deeper waters to avoid interspecific competition
, whilst the remaining S. schomburgkii and Sillaginodes punctatus partition the resources, with S. punctatus consuming more decapods and shrimp
s.
at a length of 200 mm in male
s and 230 mm in female
s, with the majority of both sexes reaching this length by the end of their second year of life. The timing of spawning
varies over the species range, a trait found in a number of other sillaginids. In the northern most part of its range in Shark Bay, spawning occurs between August and December, while further south off southern Western Australia, spawning occurs between December and February. The South Australian population also spawns between December and February, with this event preceded by the movement of fish into shallow tidal and estuarine regions where spawning occurs. Ripe fish then break off the main schooling body to form smaller spawning schools, where the egg
s are shed. There is conflicting data concerning the pattern of spawning in yellowfin whiting, with an earlier Shark Bay study finding the species to be a single spawner, whilst recent studies in the south indicate they are multiple spawners. In South Australia, once spawning has occurred the fish disperse and move further offshore once again.
Females release between 170,000 and 217,000 eggs per season, with these eggs being pelagic and spherical, with a diameter of 0.6 mm. The development and morphology of the newly hatched larva
e has been extensively described in the ichthyological literature. By the time they reach 2.7 mm, the mouth and gut are functional, the eyes are pigment
ed, a gas bladder
is present, and yolk absorption is complete. The larvae are elongate, having 36 to 38 myomere
s, with flexion
occurring by 4.8 mm. The juveniles appear in Western Australian estuaries during March, with subsequent growth being fairly rapid. However, the yellowfin whiting is one of the slower growing sillaginids, but reaches a much larger maximum size than most of its relatives, with a known maximum length of 42 cm. On average, individuals measure 8 cm after their first year and weigh between 60 and 190 g, while by the end of their second year they have attained 24 cm, with females thought to grow slightly faster than males. The oldest known individual taken was a 12 year old female that measured 35 cm, while the oldest known male was at least 7 years old and measured 34.8 mm.
, but often considered slightly inferior to the King George whiting
, which often occurs in similar areas. Due to its popularity and abundance in both South and Western Australia, it has become a major target for commercial and recreational fishermen
, although major declines in population numbers have limited the resources. Roland McKay has also suggested the species has aquaculture
potential, especially with its high tolerance to varying salinity levels.
estuary, Geographe Bay
, the Leschenault Estuary
and Cockburn Sound
. Fishing methods employed commonly include beach seines, bottom set gill nets along creek edges, ring nets, and long gill nets set on sand banks. Nets are usually set in the mornings in South Australia, when fish often move from the tidal flats back into the deeper channels. The two major fishery areas have produced very large numbers of fish in the past, with the South Australian catch representing up to 65% of the entire catch from the gulfs in the late 1970s. In Shark Bay, the largest known annual catch was 204 tonne
s during 1961. This has dropped substantially, and current Shark Bay catches have fluctuated between 100 and 130 tonnes per year since 1990, with the 2003 catch around 110 tonnes. Including the minor fisheries catches of Western Australia, the total WA yellowfin whiting catch was 131.4 tonnes, and made up over 95% of the total whiting catch in the state. South Australia has similar modern catch numbers, with the fishery recovering from a major downturn in the late 1980s, when the catch dropped below 20 tonnes per year for an unknown reason. Concerns were raised about previous over-exploitation, but catch numbers have since recovered to levels of around 150–170 tonnes per year.
, with a boat
not necessary for their capture. Yellowfin whiting are actually most commonly targeted from beaches, estuaries and jetties constructed over shallow waters, with good catches often made on the ingoing and outgoing period of the tide. Due to their easily spooked nature, tackle used to capture the fish is usually very light, with lines
kept below 6 kg, hooks below size 4, and sinker
s to an absolute minimum as heavy lines and sinkers often scare away the fish. Specialist whiting fishermen often attach a red bead
or piece of tubing directly above the hook to attract the fish, although the usefulness of this is debated. The most common bait used is 'beach worms', which may be from a variety of families, with prawn
s, cockle
s and squid
occasionally taking good catches also. Lure
and fly fishing
for the species is poorly developed, with their shy nature preventing these methods from being effectively used.
The recreational catch often is greater than the commercial catch in some areas, with a survey carried out in Blackwood River
indicating 120 700 fish were taken in a year by anglers. A similar survey conducted in the South Australian Gulfs found recreational fishermen accounted for 28% of the entire yellowfin whiting taken during the 2000/2001 period, representing over 50 tonnes of fish. Recreational bag limits have been put in place to prevent over-exploitation by anglers in both states, with South Australia imposing a minimum size limit of 24 cm and a bag limit of 20 fish on anglers. In Western Australia, there is no minimum size limit, but a bag limit of 40 fish in combination with school whitings (Sillago bassensis and Sillago vittata).
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 inshore marine
Marine (ocean)
Marine is an umbrella term. As an adjective it is usually applicable to things relating to the sea or ocean, such as marine biology, marine ecology and marine geology...
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...
. The species is endemic to the eastern Indian Ocean
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...
, ranging from Dampier, Western Australia
Dampier, Western Australia
Dampier is a major industrial port in the north-west of Western Australia. The Dampier Port is part of the Dampier Archipelago. The port services petrochemical, salt, iron ore and natural gas export industries. Rio Tinto exports large volumes of iron ore through the port, and in September 2010...
to Gulf St Vincent in South Australia
South Australia
South Australia is a state of Australia in the southern central part of the country. It covers some of the most arid parts of the continent; with a total land area of , it is the fourth largest of Australia's six states and two territories.South Australia shares borders with all of the mainland...
, with an apparent division in the populations of the two states. Yellowfin whiting inhabit relatively shallow waters for their entire life, often found on tidal flats and creeks, as well as large estuaries. It is one of the largest members of the smelt-whiting family, growing to 42 cm, and can be distinguished by a number of anatomical and colour related features. Yellowfin whiting are benthic carnivores, preying predominantly on 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, with minor amounts of 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, amphipods and bivalves also commonly taken. The species shows a change in diet with age, and also dietary differences with other sillaginids presumably to minimize 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...
. Reproduction occurs at different times throughout its range, generally focused around summer, with up to 217,000 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...
s produced per season. Yellowfin whiting reach 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 around 20 cm, with each individual 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...
more than once. The species forms the basis of major fisheries in both Shark Bay, Western Australia
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...
and the two Gulfs of South Australia, with around 260 tonnes of fish taken each year. They are also a popular target for shore based anglers, with a reputation as a very good table fish.
Taxonomy and naming
The yellowfin 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 Percoidei
Percoidei
Percoidei is one of eighteen suborders of bony fish in the order Perciformes. Many commercially harvested fish species are contained in this suborder, including the snappers, jacks, whitings, groupers, bass, perches and porgies.-Divisions:...
.
The species was first recognised and scientifically described by the German
Germany
Germany , officially the Federal Republic of Germany , is a federal parliamentary republic in Europe. The country consists of 16 states while the capital and largest city is Berlin. Germany covers an area of 357,021 km2 and has a largely temperate seasonal climate...
naturalist
Naturalist
Naturalist may refer to:* Practitioner of natural history* Conservationist* Advocate of naturalism * Naturalist , autobiography-See also:* The American Naturalist, periodical* Naturalism...
Wilhelm Peters
Wilhelm Peters
Wilhelm Karl Hartwich Peters was a German naturalist and explorer.He was assistant to Johannes Peter Müller and later curator of the Berlin Zoological Museum. In September 1842 he travelled to Mozambique via Angola. He returned to Berlin with an enormous collection of natural history specimens...
in 1864 based on 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...
collected from the waters near Adelaide
Adelaide
Adelaide is the capital city of South Australia and the fifth-largest city in Australia. Adelaide has an estimated population of more than 1.2 million...
, the capital city of South Australia. Peters assigned the species name schomburgkii in honor of the German]] explorer and botanist Moritz Richard Schomburgk
Moritz Richard Schomburgk
Moritz Richard Schomburgk was a German botanist.In 1844 he went on the Prussian-British expedition to Guyana and Brazil, led by his brother Robert. He collected for the Museum of the University of Berlin. After the political turmoil in Europe in 1848, he emigrated to Gawler, South Australia...
, who became the second Director of the Adelaide Botanic Garden
Adelaide Botanic Garden
The Adelaide Botanic Garden is a public garden at the north-east corner of the Adelaide city centre, in the Adelaide Park Lands. It encompasses a fenced garden on North Terrace and behind it the Botanic Park...
s. Schomburgk collected the specimen and sent it to Peters, who was by then the curator of the Berlin Zoological Museum, an institution for which Schomburgk had collected extensively before in the past during expeditions to British Guiana
British Guiana
British Guiana was the name of the British colony on the northern coast of South America, now the independent nation of Guyana.The area was originally settled by the Dutch at the start of the 17th century as the colonies of Essequibo, Demerara, and Berbice...
.
Prior to Peter's description, the yellowfin whiting was at first confused with the similar Sillago bassensis, which also occurs within the same range. The species was also independently renamed twice after the initial naming, first by Francis de Castelnau
François Louis de la Porte, comte de Castelnau
François Louis Nompar de Caumont LaPorte, comte de Castelnau was a French naturalist, known also as François Laporte or Francis de Castelnau.-Life:Born in London, he studied natural history in Paris...
in 1873 as Sillago bostockii, and then Gilbert Percy Whitley
Gilbert Percy Whitley
Gilbert Percy Whitley was a British-born Australian ichthyologist and malacologist who was Curator of Fishes at the Australian Museum in Sydney for about 40 years. He was born at Swaythling, Southampton, England, and was educated at King Edward VI School, Southampton and Osborne House...
in 1944 who named the species Sillago frazeri (or S. fraseri). These two names are considered to be junior synonyms under the 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 are considered invalid.
The species is known primarily as the 'yellowfin whiting' or 'yellow-finned whiting' in reference to the yellow pectoral, anal and caudal fins, and is recognised as such by the Australian Government. In Western Australia, the species is usually referred to as the 'western sand whiting' due to its close similarity with the sand whiting
Sand whiting
The sand whiting, Sillago ciliata, is a common species of coastal marine fish of the family Sillaginidae, the smelt-whitings...
(Sillago ciliata) of Eastern Australia, with the name 'fine-scaled whiting' rarely used.
Description
The yellowfin whiting has a similar body profile to most other Australian sillaginids, with colour and swimbladder morphology the simplest identifying features. It is one of the largest members of the Sillaginidae, growing to a known maximum known length of 42 cm and a weight of 860 gGram
The gram is a metric system unit of mass....
. The body is elongate and compressed, with the dorsal profile more arched than the ventral. The mouth is small and oblique, having a broad band of villiform teeth in each jaw. There are two slightly separated 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...
s, the first consisting of 10 to 12 spines and the second of 1 spine followed by 19 to 22 soft rays. The anal fin consists of 2 spines followed by 17 to 20 soft rays, the ventral of 1 spine and 5 soft rays and the pectoral of 15 to 16 rays. The caudal fin is emarginate, and is made up of 17 rays. The body is covered in small ctenoid scales
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...
extending to the upper head and nostrils of the fish, also present behind each ray of the dorsal and anal fins. 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 66 to 76 scales, and the cheek has 4 or 5 rows of scales, all of which are ctenoid. There is a total of 37 vertebrae in the species. The swimbladder has an incised anterior margin with no median or anterolateral projections and there is a single tapering posterior extension which rapidly narrows to a slender tube. A duct like process is present on the ventral surface of the swimbladder.
The yellowfin whiting is a sandy brown to pale silvery grey colour, with a darker dorsal surface and paler underside. There is a narrow silver 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 with a brownish band above, although these bands may be pale or indistinct. The dorsal fins are both 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...
with rows of small brown spots and the anal fins are pale yellow with a cream margin. The ventral fins are also yellowish, and the pectoral fin is pale yellow to hyaline with a fine dusting and lacks a dark spot at the base. As yellowfin whiting grow, the yellow colour of the fins often fades and in large specimens may be completely absent. The caudal fin is greyish.
Distribution and habitat
The yellowfin whiting is endemic to the waters of the eastern Indian OceanIndian 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...
off south west 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...
, and is believed to exist as two separate populations, one in 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...
and the other in South Australia
South Australia
South Australia is a state of Australia in the southern central part of the country. It covers some of the most arid parts of the continent; with a total land area of , it is the fourth largest of Australia's six states and two territories.South Australia shares borders with all of the mainland...
.
The western population extends from Dampier
Dampier, Western Australia
Dampier is a major industrial port in the north-west of Western Australia. The Dampier Port is part of the Dampier Archipelago. The port services petrochemical, salt, iron ore and natural gas export industries. Rio Tinto exports large volumes of iron ore through the port, and in September 2010...
, south to Albany
Albany, Western Australia
Albany is a port city in the Great Southern region of Western Australia, some 418 km SE of Perth, the state capital. As of 2009, Albany's population was estimated at 33,600, making it the 6th-largest city in the state....
, with no records of the species between Albany and Spencer Gulf
Spencer Gulf
The Spencer Gulf is the westernmost of two large inlets on the southern coast of Australia, in the state of South Australia, facing the Great Australian Bight. The Gulf is 322 km long and 129 km wide at its mouth. The western shore of the Gulf is the Eyre Peninsula, while the eastern side is the...
further west. The southern population occurs in Spencer Gulf and Gulf St Vincent, extending eastward to the Fleurieu Peninsula
Fleurieu Peninsula
The Fleurieu Peninsula is a peninsula located south of Adelaide in South Australia, Australia. It was named after the French explorer and hydrographer Charles Pierre Claret de Fleurieu by the French explorer Nicolas Baudin as he mapped the south coast of Australia in 1802.Towns of interest in the...
. Tagging
Electronic tagging
Electronic tagging is a form of non-surreptitious surveillance consisting of an electronic device attached to a person or vehicle, especially certain criminals, allowing their whereabouts to be monitored. In general, devices locate themselves using GPS and report their position back to a control...
studies have found that the populations in each of South Australia's Gulfs are isolated from each others, but no genetics
Genetics
Genetics , a discipline of biology, is the science of genes, heredity, and variation in living organisms....
studies have been undertaken to clarify this.
Yellowfin whiting primarily inhabit shallow protected inshore waters in depths of less than 10 m, often moving across tidal flats less than a meter deep. They are commonly found on sand flats, bars and spits, as well as mangrove
Mangrove
Mangroves are various kinds of trees up to medium height and shrubs that grow in saline coastal sediment habitats in the tropics and subtropics – mainly between latitudes N and S...
lined tidal creeks, mud flats, seagrass
Seagrass
Seagrasses are flowering plants from one of four plant families , all in the order Alismatales , which grow in marine, fully saline environments.-Ecology:...
beds and estuaries. Yellowfin whiting move with the tide
Tide
Tides are the rise and fall of sea levels caused by the combined effects of the gravitational forces exerted by the moon and the sun and the rotation of the Earth....
, pushing into the shallows of creeks and flats to forage at high tide and moving back to the sandy hollows of deeper slopes of channels and banks as the tide falls. In Western Australia, they often enter large, sandy estuaries such as the Swan
Swan River (Western Australia)
The Swan River estuary flows through the city of Perth, in the south west of Western Australia. Its lower reaches are relatively wide and deep, with few constrictions, while the upper reaches are usually quite narrow and shallow....
and Leschenault Estuary
Leschenault Estuary
Leschenault Estuary is an estuarine lagoon that lies to the north of Bunbury, Western Australia.It had in the past met the Indian Ocean at the Leschenault Inlet - but that has been altered by harbour works for Bunbury, and the creation of The Cut north of the historical inlet location.The estuary...
where they many penetrate the limits of brackish water, indicating they can survive in low 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...
environments. Conversely, they have been recorded in the extremely saline waters of upper Spencer Gulf and 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...
, suggesting a wide tolerance to salinity. Juveniles inhabit the same environments as adults in South Australia, but in Western Australia adults move from the tidal creeks and seagrass beds to more sand dominated environments including high energy 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.
Biology
The yellowfin whiting is a 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...
species, with its movements highly controlled by tidal phases, with the species often moving over shallow sand banks with the rising tide. Where it occurs with other species of sillaginids, it is unique in that it remains in the shallow protected inshore waters, while other species move offshore
Shore
A shore or shoreline is the fringe of land at the edge of a large body of water, such as an ocean, sea, or lake. In Physical Oceanography a shore is the wider fringe that is geologically modified by the action of the body of water past and present, while the beach is at the edge of the shore,...
as they grow. This is likely a response to reduce interspecific competition
Interspecific competition
Interspecific competition, in ecology, is a form of competition in which individuals of different species compete for the same resource in an ecosystem...
between sillaginids. The dietary and reproductive biology
Reproductive biology
Reproductive biology is a study mainly involving the reproductive system and sex organs. It is closely related to reproductive endocrinology and infertility. also is miotosis and miosis...
of the yellowfin whiting has been extensively studied in Western and South Australia, where it comprises a major part of the 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,...
. As with a number of other sillaginids, the species has been recorded 'burrowing' in the substrate
Substrate (marine biology)
Stream substrate is the material that rests at the bottom of a stream. There are several classification guides. One is:*Mud – silt and clay.*Sand – Particles between 0.06 and 2 mm in diameter.*Granule – Between 2 and 4 mm in diameter....
to avoid predators.
Diet and feeding
The yellowfin whiting is a benthic predator, using its well developed eyesight and a downward pointing 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 that can be protruded to 'suck up' and capture its prey from the seafloor. Studies on the mouth morphology
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....
of a range of sillaginids concluded that the mouth morphology of most species has little influence on the type of prey caught, with differences in diet more likely due to variations in the foraging
Foraging
- Definitions and significance of foraging behavior :Foraging is the act of searching for and exploiting food resources. It affects an animal's fitness because it plays an important role in an animal's ability to survive and reproduce...
behavior. Studies conducted in southwest Western Australia found the species predominantly takes polychaetes as its main prey item, although 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, particularly amphipods and penaeids also make up a large portion of its diet. Items taken infrequently or in lesser amounts include small teleost fish, bivalve molluscs, marine plant material and other crustaceans such as tanaids, decapods
Decapoda
The decapods or Decapoda are an order of crustaceans within the class Malacostraca, including many familiar groups, such as crayfish, crabs, lobsters, prawns and shrimp. Most decapods are scavengers. It is estimated that the order contains nearly 15,000 species in around 2,700 genera, with...
and cumaceans. Modeling with the stable isotopes 13C and 15N indicate that seagrass
Seagrass
Seagrasses are flowering plants from one of four plant families , all in the order Alismatales , which grow in marine, fully saline environments.-Ecology:...
and epiphytic algae
Epiphyte
An epiphyte is a plant that grows upon another plant non-parasitically or sometimes upon some other object , derives its moisture and nutrients from the air and rain and sometimes from debris accumulating around it, and is found in the temperate zone and in the...
were the primary initial sources of energy and nutrition that flow into the fish via detritivore
Detritivore
Detritivores, also known as detritophages or detritus feeders or detritus eaters or saprophages, are heterotrophs that obtain nutrients by consuming detritus . By doing so, they contribute to decomposition and the nutrient cycles...
s which the species preys on, with salt marsh
Salt marsh
A salt marsh is an environment in the upper coastal intertidal zone between land and salt water or brackish water, it is dominated by dense stands of halophytic plants such as herbs, grasses, or low shrubs. These plants are terrestrial in origin and are essential to the stability of the salt marsh...
plants and macroalgae contributing in some settings.
The species is known to undergo a dietary shift as it grows to adulthood. Young individuals less than 10 cm in length consume considerable volumes of copepods and minor amounts of polychaetes, but once they reach around 10 cm, the diet shifts to a polychaete-dominated one. Further growth sees an increase in the volume of amphipods, small fish and oligochaetes taken. These changes appear to be unrelated to mouth morphology, instead the fish becomes more mobile and possesses a larger mouth to be able to take these prey. The yellowfin whitings' diet also varies spatially and temporally, which appears to be a function of prey availability at different sites and periods of the year. There is little resource partitioning between the small individuals of sillaginids which inhabit shallow inshore habitats, with Sillago vittata, S. burrus and Sillaginodes punctatus also taking copepods as their primary prey in southwest Western Australia. This changes as each species grows, with S. vittata and S burrus moving to deeper waters to avoid interspecific competition
Interspecific competition
Interspecific competition, in ecology, is a form of competition in which individuals of different species compete for the same resource in an ecosystem...
, whilst the remaining S. schomburgkii and Sillaginodes punctatus partition the resources, with S. punctatus consuming more decapods and 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.
Reproduction and growth
Yellowfin whiting reach 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...
at a length of 200 mm in male
Male
Male refers to the biological sex of an organism, or part of an organism, which produces small mobile gametes, called spermatozoa. Each spermatozoon can fuse with a larger female gamete or ovum, in the process of fertilization...
s and 230 mm in female
Female
Female is the sex of an organism, or a part of an organism, which produces non-mobile ova .- Defining characteristics :The ova are defined as the larger gametes in a heterogamous reproduction system, while the smaller, usually motile gamete, the spermatozoon, is produced by the male...
s, with the majority of both sexes reaching this length by the end of their second year of life. The timing 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...
varies over the species range, a trait found in a number of other sillaginids. In the northern most part of its range in Shark Bay, spawning occurs between August and December, while further south off southern Western Australia, spawning occurs between December and February. The South Australian population also spawns between December and February, with this event preceded by the movement of fish into shallow tidal and estuarine regions where spawning occurs. Ripe fish then break off the main schooling body to form smaller spawning schools, where 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...
s are shed. There is conflicting data concerning the pattern of spawning in yellowfin whiting, with an earlier Shark Bay study finding the species to be a single spawner, whilst recent studies in the south indicate they are multiple spawners. In South Australia, once spawning has occurred the fish disperse and move further offshore once again.
Females release between 170,000 and 217,000 eggs per season, with these eggs being pelagic and spherical, with a diameter of 0.6 mm. The development and morphology of the newly hatched 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 has been extensively described in the ichthyological literature. By the time they reach 2.7 mm, the mouth and gut are functional, the eyes are 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, 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...
is present, and yolk absorption is complete. The larvae are elongate, having 36 to 38 myomere
Myomere
Myomere are the blocks of skeletal muscle tissue found commonly in chordates. They are commonly zig-zag, "W" or "V"-shaped muscle fibers. The myomeres are separated from adjacent myomere by connective tissues and most easily seen in larval fishes or in the olm...
s, with flexion
Flexion
In anatomy, flexion is a position that is made possible by the joint angle decreasing. The skeletal and muscular systems work together to move the joint into a "flexed" position. For example the elbow is flexed when the hand is brought closer to the shoulder...
occurring by 4.8 mm. The juveniles appear in Western Australian estuaries during March, with subsequent growth being fairly rapid. However, the yellowfin whiting is one of the slower growing sillaginids, but reaches a much larger maximum size than most of its relatives, with a known maximum length of 42 cm. On average, individuals measure 8 cm after their first year and weigh between 60 and 190 g, while by the end of their second year they have attained 24 cm, with females thought to grow slightly faster than males. The oldest known individual taken was a 12 year old female that measured 35 cm, while the oldest known male was at least 7 years old and measured 34.8 mm.
Relationship to humans
The yellowfin whiting is a highly rated 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:...
, but often considered slightly inferior to the 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...
, which often occurs in similar areas. Due to its popularity and abundance in both South and Western Australia, it has become a major target for commercial and 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...
, although major declines in population numbers have limited the resources. Roland McKay has also suggested the species has aquaculture
Aquaculture
Aquaculture, also known as aquafarming, is the farming of aquatic organisms such as fish, crustaceans, molluscs and aquatic plants. Aquaculture involves cultivating freshwater and saltwater populations under controlled conditions, and can be contrasted with commercial fishing, which is the...
potential, especially with its high tolerance to varying salinity levels.
Commercial fishery
There are two major fisheries in operation for yellowfin whiting; one in the Gulfs of South Australia and another in Shark Bay, Western Australia. There are also up to four minor fisheries in Western Australia, centered in the Blackwood RiverBlackwood River
The Blackwood River is a major river and catchment in the South West of Western Australia.The river begins at the junction of Arthur River and Balgarup River near Quelarup and travels in a south westerly direction through the town of Bridgetown then through Nannup until it discharges into the...
estuary, Geographe Bay
Geographe Bay
Geographe Bay is located in the South West of Western Australia around 220 km southwest of Perth.The bay was named in May 1801 by French explorer Nicolas Baudin; Baudin named the bay after his ship, Géographe. The bay is a wide curve of coastline extending from Cape Naturaliste past the towns...
, the Leschenault Estuary
Leschenault Estuary
Leschenault Estuary is an estuarine lagoon that lies to the north of Bunbury, Western Australia.It had in the past met the Indian Ocean at the Leschenault Inlet - but that has been altered by harbour works for Bunbury, and the creation of The Cut north of the historical inlet location.The estuary...
and Cockburn Sound
Cockburn Sound
Cockburn Sound is an inlet of the Indian Ocean on the coast of Western Australia. It extends from the south of the mouth of the Swan River at Fremantle for about 25 km to Cape Peron near Rockingham and is located at...
. Fishing methods employed commonly include beach seines, bottom set gill nets along creek edges, ring nets, and long gill nets set on sand banks. Nets are usually set in the mornings in South Australia, when fish often move from the tidal flats back into the deeper channels. The two major fishery areas have produced very large numbers of fish in the past, with the South Australian catch representing up to 65% of the entire catch from the gulfs in the late 1970s. In Shark Bay, the largest known annual catch was 204 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...
s during 1961. This has dropped substantially, and current Shark Bay catches have fluctuated between 100 and 130 tonnes per year since 1990, with the 2003 catch around 110 tonnes. Including the minor fisheries catches of Western Australia, the total WA yellowfin whiting catch was 131.4 tonnes, and made up over 95% of the total whiting catch in the state. South Australia has similar modern catch numbers, with the fishery recovering from a major downturn in the late 1980s, when the catch dropped below 20 tonnes per year for an unknown reason. Concerns were raised about previous over-exploitation, but catch numbers have since recovered to levels of around 150–170 tonnes per year.
Recreational fishery
Yellowfin whiting have become a major target for anglers in both South and Western Australia for a number of reasons: they are very good table fish, they provide good sport on light line, and are easily accessible from beaches and jettiesJetty
A jetty is any of a variety of structures used in river, dock, and maritime works that are generally carried out in pairs from river banks, or in continuation of river channels at their outlets into deep water; or out into docks, and outside their entrances; or for forming basins along the...
, with a boat
Boat
A boat is a watercraft of any size designed to float or plane, to provide passage across water. Usually this water will be inland or in protected coastal areas. However, boats such as the whaleboat were designed to be operated from a ship in an offshore environment. In naval terms, a boat is a...
not necessary for their capture. Yellowfin whiting are actually most commonly targeted from beaches, estuaries and jetties constructed over shallow waters, with good catches often made on the ingoing and outgoing period of the tide. Due to their easily spooked nature, tackle used to capture the fish is usually very light, with lines
Fishing line
A fishing line is a cord used or made for angling. Important parameters of a fishing line are its length, material, and weight...
kept below 6 kg, hooks below size 4, and sinker
Sinker (fishing)
A fishing sinker or knoch is a weight used in conjunction with a fishing lure or hook to increase its rate of sink, anchoring ability, and/or casting distance. Fishing sinkers may be as small as 1/32 of an ounce for applications in shallow water, and even smaller for fly fishing applications, or as...
s to an absolute minimum as heavy lines and sinkers often scare away the fish. Specialist whiting fishermen often attach a red bead
Bead
A bead is a small, decorative object that is usually pierced for threading or stringing. Beads range in size from under to over in diameter. A pair of beads made from Nassarius sea snail shells, approximately 100,000 years old, are thought to be the earliest known examples of jewellery. Beadwork...
or piece of tubing directly above the hook to attract the fish, although the usefulness of this is debated. The most common bait used is 'beach worms', which may be from a variety of families, with 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, cockle
Cockle (bivalve)
Cockle is the common name for a group of small, edible, saltwater clams, marine bivalve molluscs in the family Cardiidae.Various species of cockles live in sandy sheltered beaches throughout the world....
s and squid
Squid
Squid are cephalopods of the order Teuthida, which comprises around 300 species. Like all other cephalopods, squid have a distinct head, bilateral symmetry, a mantle, and arms. Squid, like cuttlefish, have eight arms arranged in pairs and two, usually longer, tentacles...
occasionally taking good catches also. Lure
Fishing lure
A fishing lure is an object attached to the end of a fishing line which is designed to resemble and move like the prey of a fish. The purpose of the lure is to use movement, vibration, and colour to catch the fish's attention so it bites the hook...
and fly fishing
Fly fishing
Fly fishing is an angling method in which an artificial 'fly' is used to catch fish. The fly is cast using a fly rod, reel, and specialized weighted line. Casting a nearly weightless fly or 'lure' requires casting techniques significantly different from other forms of casting...
for the species is poorly developed, with their shy nature preventing these methods from being effectively used.
The recreational catch often is greater than the commercial catch in some areas, with a survey carried out in Blackwood River
Blackwood River
The Blackwood River is a major river and catchment in the South West of Western Australia.The river begins at the junction of Arthur River and Balgarup River near Quelarup and travels in a south westerly direction through the town of Bridgetown then through Nannup until it discharges into the...
indicating 120 700 fish were taken in a year by anglers. A similar survey conducted in the South Australian Gulfs found recreational fishermen accounted for 28% of the entire yellowfin whiting taken during the 2000/2001 period, representing over 50 tonnes of fish. Recreational bag limits have been put in place to prevent over-exploitation by anglers in both states, with South Australia imposing a minimum size limit of 24 cm and a bag limit of 20 fish on anglers. In Western Australia, there is no minimum size limit, but a bag limit of 40 fish in combination with school whitings (Sillago bassensis and Sillago vittata).