The yellowfin whiting (''Sillago schomburgkii''), also known as the western sand whiting or fine-scaled whiting, is a
species
A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...
of
inshore
A coast (coastline, shoreline, seashore) is the land next to the sea or the line that forms the boundary between the land and the ocean or a lake. Coasts are influenced by the topography of the surrounding landscape and by aquatic erosion, su ...
marine fish
A fish (: fish or fishes) is an aquatic animal, aquatic, Anamniotes, anamniotic, gill-bearing vertebrate animal with swimming fish fin, fins and craniate, a hard skull, but lacking limb (anatomy), limbs with digit (anatomy), digits. Fish can ...
in the smelt-whiting family
Sillaginidae
The Sillaginidae, commonly known as the smelt-whitings, whitings, sillaginids, sand borers and sand-smelts, are a family (biology), family of benthic coastal Marine (ocean), marine fish historically classified in the order (biology), order Percif ...
. The species is
endemic
Endemism is the state of a species being found only in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also foun ...
to the eastern
Indian Ocean
The Indian Ocean is the third-largest of the world's five oceanic divisions, covering or approximately 20% of the water area of Earth#Surface, Earth's surface. It is bounded by Asia to the north, Africa to the west and Australia (continent), ...
, ranging from
Dampier, Western Australia
Dampier is a major industrial port in the Pilbara region in the northwest of Western Australia. It is located near the city of Karratha and Port Walcott.
Dampier Port is part of the Dampier Archipelago and is primarily a port for the export ...
to
Gulf St Vincent
Gulf St Vincent, sometimes referred to as St Vincent Gulf, St Vincent's Gulf or Gulf of St Vincent, is the eastern of two large inlets of water on the southern coast of Australia, in the state of South Australia, the other being the larger Sp ...
in
South Australia
South Australia (commonly abbreviated as SA) is a States and territories of Australia, state in the southern central part of Australia. With a total land area of , it is the fourth-largest of Australia's states and territories by area, which in ...
, 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 flat
Mudflats or mud flats, also known as tidal flats or, in Ireland, slob or slobs, are coastal wetlands that form in intertidal areas where sediments have been deposited by tides or rivers. A global analysis published in 2019 suggested that tidal ...
s and creeks, as well as large
estuaries
An estuary is a partially enclosed coastal body of brackish water with one or more rivers or streams flowing into it, and with a free connection to the open sea. Estuaries form a transition zone between river environments and maritime environm ...
. 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
A carnivore , or meat-eater (Latin, ''caro'', genitive ''carnis'', meaning meat or "flesh" and ''vorare'' meaning "to devour"), is an animal or plant whose nutrition and energy requirements are met by consumption of animal tissues (mainly mu ...
, preying predominantly on
polychaete
Polychaeta () is a paraphyletic class of generally marine Annelid, annelid worms, common name, commonly called bristle worms or polychaetes (). Each body segment has a pair of fleshy protrusions called parapodia that bear many bristles, called c ...
worms, with minor amounts of
copepod
Copepods (; meaning 'oar-feet') are a group of small crustaceans found in nearly every freshwater and saltwater habitat (ecology), habitat. Some species are planktonic (living in the water column), some are benthos, benthic (living on the sedimen ...
s,
amphipod
Amphipoda () is an order of malacostracan crustaceans with no carapace and generally with laterally compressed bodies. Amphipods () range in size from and are mostly detritivores or scavengers. There are more than 10,700 amphipod species cur ...
s and
bivalve
Bivalvia () or bivalves, in previous centuries referred to as the Lamellibranchiata and Pelecypoda, is a class (biology), class of aquatic animal, aquatic molluscs (marine and freshwater) that have laterally compressed soft bodies enclosed b ...
s also commonly taken. The species shows a change in diet with age, and also dietary differences with other sillaginids presumably to minimize
competition
Competition is a rivalry where two or more parties strive for a common goal which cannot be shared: where one's gain is the other's loss (an example of which is a zero-sum game). Competition can arise between entities such as organisms, indi ...
. Reproduction occurs at different times throughout its range, generally focused around summer, with up to 217,000
egg
An egg is an organic vessel grown by an animal to carry a possibly fertilized egg cell (a zygote) and to incubate from it an embryo within the egg until the embryo has become an animal fetus that can survive on its own, at which point the ...
s produced per season. Yellowfin whiting reach
sexual maturity
Sexual maturity is the capability of an organism to reproduce. In humans, it is related to both puberty and adulthood. ''Puberty'' is the biological process of sexual maturation, while ''adulthood'', the condition of being socially recognized ...
at around 20 cm, with each individual
spawning
Spawn is the Egg cell, eggs and Spermatozoa, sperm released or deposited into water by aquatic animals. As a verb, ''to spawn'' refers to the process of freely releasing eggs and sperm into a body of water (fresh or marine); the physical act is ...
more than once. The species forms the basis of major
fisheries
Fishery can mean either the enterprise of raising or harvesting fish and other aquatic life or, more commonly, the site where such enterprise takes place ( a.k.a., fishing grounds). Commercial fisheries include wild fisheries and fish farm ...
in both
Shark Bay, Western Australia
Shark Bay () is a World Heritage Site in the Gascoyne region of Western Australia. The area is located approximately north of Perth, on the westernmost point of the Australian continent.
UNESCO's listing of Shark Bay as a World Heritage S ...
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 over 30 species in the genus ''
Sillago
''Sillago'' is a genus of fish in the family (biology), family Sillaginidae and the only non-monotypic genus in the family. Distinguishing the species can be difficult, with many similar in appearance and colour, forcing the use of swim bladder ...
'',
which is one of five genera belonging to the smelt whiting family
Sillaginidae
The Sillaginidae, commonly known as the smelt-whitings, whitings, sillaginids, sand borers and sand-smelts, are a family (biology), family of benthic coastal Marine (ocean), marine fish historically classified in the order (biology), order Percif ...
, this family was previously considered to be part of the
Percoidea
Percomorpha () is an extremely large and diverse clade of ray-finned fish. With more than 17,000 known species (including tuna, seahorses, gobies, cichlids, flatfish, wrasse, perches, anglerfish, and pufferfish) known from both marine and fresh ...
, a
suborder
Order () is one of the eight major hierarchical taxonomic ranks in Linnaean taxonomy. It is classified between family and class. In biological classification, the order is a taxonomic rank used in the classification of organisms and recognized ...
of the
Perciformes
Perciformes (), also called the Acanthopteri, is an order or superorder of ray-finned fish in the clade Percomorpha. ''Perciformes'' means " perch-like". Among the well-known members of this group are perches and darters ( Percidae), and als ...
.
[ The 5th edition of '']Fishes of the World
''Fishes of the World'' is a standard reference for the systematics of fishes. It was first written in 1976 by the American ichthyologist Joseph S. Nelson (1937–2011). Now in its fifth edition (2016), the work is a comprehensive overview of t ...
'' classifies the Sillaginidae in the order Spariformes
Spariformes is an order of ray-finned fishes consisting of six families within the series Percomorpha.
Taxonomy
Spariformes was first used as a taxonomic term in 1860 by the Dutch physician, herpetologist and ichthyologist Pieter Bleeker. Trad ...
.
The species was first recognised and scientifically described
A species description is a formal scientific description of a newly encountered species, typically articulated through a scientific publication. Its purpose is to provide a clear description of a new species of organism and explain how it diffe ...
by the German
German(s) may refer to:
* Germany, the country of the Germans and German things
**Germania (Roman era)
* Germans, citizens of Germany, people of German ancestry, or native speakers of the German language
** For citizenship in Germany, see also Ge ...
naturalist
Natural history is a domain of inquiry involving organisms, including animals, fungi, and plants, in their natural environment, leaning more towards observational than experimental methods of study. A person who studies natural history is cal ...
Wilhelm Peters
Wilhelm Karl Hartwich (or Hartwig) Peters (22 April 1815 – 20 April 1883) was a German natural history, naturalist and explorer.
He was assistant to the anatomist Johannes Peter Müller and later became curator of the Natural History Museum, ...
in 1864 based on the holotype
A holotype (Latin: ''holotypus'') is a single physical example (or illustration) of an organism used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of s ...
collected from the waters near Adelaide
Adelaide ( , ; ) is the list of Australian capital cities, capital and most populous city of South Australia, as well as the list of cities in Australia by population, fifth-most populous city in Australia. The name "Adelaide" may refer to ei ...
, the capital city of South Australia. Peters assigned the species name ''schomburgkii'' in honor of the German explorer
Exploration is the process of exploring, an activity which has some Expectation (epistemic), expectation of Discovery (observation), discovery. Organised exploration is largely a human activity, but exploratory activity is common to most organis ...
and botanist
Botany, also called plant science, is the branch of natural science and biology studying plants, especially Plant anatomy, their anatomy, Plant taxonomy, taxonomy, and Plant ecology, ecology. A botanist or plant scientist is a scientist who s ...
Moritz Richard Schomburgk
Moritz Richard Schomburgk (5 October 1811 – 24 March 1891), generally known as Richard Schomburgk, was a German botanist and curator of the Adelaide Botanic Garden.
Family
Schomburgk was born in Freyburg, Saxony, the son of Johann Friedrich L ...
, who became the second Director of the 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 (between Lot Fourteen, the site of the old Royal Adelaide Hospit ...
s. Schomburgk collected the specimen and sent it to Peters, who was by then the curator of the Berlin Zoological Museum (in the present day the Berlin's Natural History Museum), an institution for which Schomburgk had collected extensively before in the past during expeditions to British Guiana
British Guiana was a British colony, part of the mainland British West Indies. It was located on the northern coast of South America. Since 1966 it has been known as the independent nation of Guyana.
The first known Europeans to encounter Guia ...
.
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
Francis may refer to:
People and characters
*Pope Francis, head of the Catholic Church (2013–2025)
*Francis (given name), including a list of people and fictional characters
*Francis (surname)
* Francis, a character played by YouTuber Boogie29 ...
in 1873 as ''Sillago bostockii'', and then Gilbert Percy Whitley
Gilbert Percy Whitley (9 June 1903 – 18 July 1975) was a British-born Australian ichthyologist and malacologist who was curator of fishes at the Australian Museum in Sydney for about 40 years.
Early life and education
Gilbert Percy Whitley ...
in 1944 who named the species ''Sillago frazeri'' (or ''S. fraseri''). These two names are considered to be junior synonym
In taxonomy, the scientific classification of living organisms, a synonym is an alternative scientific name for the accepted scientific name of a taxon. The botanical and zoological codes of nomenclature treat the concept of synonymy differently.
...
s under the ICZN
The International Code of Zoological Nomenclature (ICZN) is a widely accepted convention in zoology that rules the formal scientific naming of organisms treated as animals. It is also informally known as the ICZN Code, for its formal author, t ...
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
The Australian Government, also known as the Commonwealth Government or simply as the federal government, is the national executive government of Australia, a federal parliamentary constitutional monarchy. The executive consists of the pr ...
. In Western Australia, the species is usually referred to as the 'western sand whiting' due to its close similarity with the sand whiting
The sand whiting (''Sillago ciliata''), also known as the summer whiting, yellowfin whiting or blue-nose whiting, is a common species of coastal marine fish of the family Sillaginidae, the smelt-whitings. It is a slender, slightly compressed fish ...
(''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
The swim bladder, gas bladder, fish maw, or air bladder is an internal gas-filled organ in bony fish that functions to modulate buoyancy, and thus allowing the fish to stay at desired water depth without having to maintain lift via swimming, w ...
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 g. The body is elongate and compressed, with the dorsal
Dorsal (from Latin ''dorsum'' ‘back’) may refer to:
* Dorsal (anatomy), an anatomical term of location referring to the back or upper side of an organism or parts of an organism
* Dorsal, positioned on top of an aircraft's fuselage
The fus ...
profile more arched than the ventral
Standard anatomical terms of location are used to describe unambiguously the anatomy of humans and other animals. The terms, typically derived from Latin or Greek roots, describe something in its standard anatomical position. This position prov ...
. The mouth is small and oblique, having a broad band of villiform teeth in each jaw. There are two slightly separated dorsal fin
A dorsal fin is a fin on the back of most marine and freshwater vertebrates. Dorsal fins have evolved independently several times through convergent evolution adapting to marine environments, so the fins are not all homologous. They are found ...
s, the first consisting of 10 to 12 spines and the second of 1 spine followed by 19 to 22 soft rays
Fish anatomy is the study of the form or morphology of fish. It can be contrasted with fish physiology, which is the study of how the component parts of fish function together in the living fish. In practice, fish anatomy and fish physiology co ...
. The anal fin
Fins are moving appendages protruding from the body of fish that interact with water to generate thrust and help the fish swim. Apart from the tail or caudal fin, fish fins have no direct connection with the back bone and are supported o ...
consists of 2 spines followed by 17 to 20 soft rays, the ventral
Standard anatomical terms of location are used to describe unambiguously the anatomy of humans and other animals. The terms, typically derived from Latin or Greek roots, describe something in its standard anatomical position. This position prov ...
of 1 spine and 5 soft rays and the pectoral
Pectoral may refer to:
* The chest region and anything relating to it.
* Pectoral cross, a cross worn on the chest
* a decorative, usually jeweled version of a gorget
* Pectoral (Ancient Egypt), a type of jewelry worn in ancient Egypt
* Pectora ...
of 15 to 16 rays. The caudal fin
Fins are moving appendages protruding from the body of fish that interact with water to generate thrust and help the fish swim. Apart from the tail or caudal fin, fish fins have no direct connection with the back bone and are supported only ...
is emarginate, and is made up of 17 rays. The body is covered in small ctenoid
A fish scale is a small rigid plate that grows out of the skin of a fish. The skin of most jawed fishes is covered with these protective scales, which can also provide effective camouflage through the use of reflection and colouration, as w ...
scales
Scale or scales may refer to:
Mathematics
* Scale (descriptive set theory), an object defined on a set of points
* Scale (ratio), the ratio of a linear dimension of a model to the corresponding dimension of the original
* Scale factor, a number ...
extending to the upper head and nostrils of the fish, also present behind each ray of the dorsal and anal fins. The lateral line
The lateral line, also called the lateral line organ (LLO), is a system of sensory organs found in fish, used to detect movement, vibration, and pressure gradients in the surrounding water. The sensory ability is achieved via modified epithelia ...
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
Each vertebra (: vertebrae) is an irregular bone with a complex structure composed of bone and some hyaline cartilage, that make up the vertebral column or spine, of vertebrates. The proportions of the vertebrae differ according to their spinal ...
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
A hyaline substance is one with a glassy appearance. The word is derived from , and .
Histopathology
Hyaline cartilage is named after its glassy appearance on fresh gross pathology. On light microscopy of H&E stained slides, the extracellula ...
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
Endemism is the state of a species being found only in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also foun ...
to the waters of the eastern Indian Ocean
The Indian Ocean is the third-largest of the world's five oceanic divisions, covering or approximately 20% of the water area of Earth#Surface, Earth's surface. It is bounded by Asia to the north, Africa to the west and Australia (continent), ...
off south west Australia
Australia, officially the Commonwealth of Australia, is a country comprising mainland Australia, the mainland of the Australia (continent), Australian continent, the island of Tasmania and list of islands of Australia, numerous smaller isl ...
, and is believed to exist as two separate populations, one in Western Australia
Western Australia (WA) is the westernmost state of Australia. It is bounded by the Indian Ocean to the north and west, the Southern Ocean to the south, the Northern Territory to the north-east, and South Australia to the south-east. Western Aust ...
and the other in South Australia
South Australia (commonly abbreviated as SA) is a States and territories of Australia, state in the southern central part of Australia. With a total land area of , it is the fourth-largest of Australia's states and territories by area, which in ...
.
The western population extends from Dampier, south to Albany, with no records of the species between Albany and Spencer Gulf
The Spencer Gulf is the westernmost and larger of two large inlets (the other being Gulf St Vincent) on the southern coast of Australia, in the state of South Australia, facing the Great Australian Bight. It spans from the Cape Catastrophe an ...
further west. The southern population occurs in Spencer Gulf and Gulf St Vincent
Gulf St Vincent, sometimes referred to as St Vincent Gulf, St Vincent's Gulf or Gulf of St Vincent, is the eastern of two large inlets of water on the southern coast of Australia, in the state of South Australia, the other being the larger Sp ...
, extending eastward to the Fleurieu Peninsula
The Fleurieu Peninsula ( ; locally mainly ) is a peninsula in the Australian state of South Australia located south of the state capital of Adelaide city centre, Adelaide.
History
Before British colonisation of South Australia, the western s ...
.
Yellowfin whiting primarily inhabit shallow protected inshore waters in depths of less than 10 m, often moving across tidal flat
Mudflats or mud flats, also known as tidal flats or, in Ireland, slob or slobs, are coastal wetlands that form in intertidal areas where sediments have been deposited by tides or rivers. A global analysis published in 2019 suggested that tidal ...
s less than a meter deep. They are commonly found on sand flats, bars and spits, as well as mangrove
A mangrove is a shrub or tree that grows mainly in coastal saline water, saline or brackish water. Mangroves grow in an equatorial climate, typically along coastlines and tidal rivers. They have particular adaptations to take in extra oxygen a ...
lined tidal creeks, mud flats, seagrass
Seagrasses are the only flowering plants which grow in marine (ocean), marine environments. There are about 60 species of fully marine seagrasses which belong to four Family (biology), families (Posidoniaceae, Zosteraceae, Hydrocharitaceae and ...
beds and estuaries
An estuary is a partially enclosed coastal body of brackish water with one or more rivers or streams flowing into it, and with a free connection to the open sea. Estuaries form a transition zone between river environments and maritime environm ...
. Yellowfin whiting move with the tide
Tides are the rise and fall of sea levels caused by the combined effects of the gravitational forces exerted by the Moon (and to a much lesser extent, the Sun) and are also caused by the Earth and Moon orbiting one another.
Tide tables ...
, 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
Swans are birds of the genus ''Cygnus'' within the family Anatidae. The swans' closest relatives include the goose, geese and ducks. Swans are grouped with the closely related geese in the subfamily Anserinae where they form the tribe (biology) ...
and Leschenault Estuary where they many penetrate the limits of brackish
Brackish water, sometimes termed brack water, is water occurring in a natural environment that has more salinity than freshwater, but not as much as seawater. It may result from mixing seawater (salt water) and fresh water together, as in estuari ...
water, indicating they can survive in low salinity
Salinity () is the saltiness or amount of salt (chemistry), salt dissolved in a body of water, called saline water (see also soil salinity). It is usually measured in g/L or g/kg (grams of salt per liter/kilogram of water; the latter is dimensio ...
environments. Conversely, they have been recorded in the extremely saline waters of upper Spencer Gulf and Shark Bay
Shark Bay () is a World Heritage Site in the Gascoyne region of Western Australia. The area is located approximately north of Perth, on the westernmost point of the Australian continent.
UNESCO's listing of Shark Bay as a World Heritage S ...
, 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
A beach is a landform alongside a body of water which consists of loose particles. The particles composing a beach are typically made from Rock (geology), rock, such as sand, gravel, shingle beach, shingle, pebbles, etc., or biological s ...
es.
Biology
The yellowfin whiting is a schools
A school is the educational institution (and, in the case of in-person learning, the building) designed to provide learning environments for the teaching of students, usually under the direction of teachers. Most countries have systems of ...
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
Interspecific competition, in ecology, is a form of competition in which individuals of ''different'' species compete for the same resources in an ecosystem (e.g. food or living space). This can be contrasted with mutualism, a type of symbiosis. ...
between sillaginids. The dietary and reproductive biology
Reproductive biology includes both sexual and asexual reproduction.
Reproductive biology includes a wide number of fields:
* Reproductive systems
* Endocrinology
* Sexual development (Puberty)
* Sexual maturity
* Reproduction
* Fertility
H ...
of the yellowfin whiting has been extensively studied in Western and South Australia, where it comprises a major part of the fishery
Fishery can mean either the enterprise of raising or harvesting fish and other aquatic life or, more commonly, the site where such enterprise takes place ( a.k.a., fishing grounds). Commercial fisheries include wild fisheries and fish far ...
. As with a number of other sillaginids, the species has been recorded 'burrowing' in the substrate
Substrate may refer to:
Physical layers
*Substrate (biology), the natural environment in which an organism lives, or the surface or medium on which an organism grows or is attached
** Substrate (aquatic environment), the earthy material that exi ...
to avoid predator
Predation is a biological interaction in which one organism, the predator, kills and eats another organism, its prey. It is one of a family of common List of feeding behaviours, feeding behaviours that includes parasitism and micropredation ...
s.
Diet and feeding
The yellowfin whiting is a benthic
The benthic zone is the ecological region at the lowest level of a body of water such as an ocean, lake, or stream, including the sediment surface and some sub-surface layers. The name comes from the Ancient Greek word (), meaning "the depths". ...
predator, using its well developed eyesight and a downward pointing jaw
The jaws are a pair of opposable articulated structures 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 ...
s that can be protruded to 'suck up' and capture its prey from the seafloor
The seabed (also known as the seafloor, sea floor, ocean floor, and ocean bottom) is the bottom of the ocean. All floors of the ocean are known as seabeds.
The structure of the seabed of the global ocean is governed by plate tectonics. Most of ...
. Studies on the mouth morphology
Morphology, from the Greek and meaning "study of shape", may refer to:
Disciplines
*Morphology (archaeology), study of the shapes or forms of artifacts
*Morphology (astronomy), study of the shape of astronomical objects such as nebulae, galaxies, ...
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 is searching for wild food resources. It affects an animal's fitness because it plays an important role in an animal's ability to survive and reproduce. Foraging theory is a branch of behavioral ecology that studies the foraging behavi ...
behavior. Studies conducted in southwest Western Australia found the species predominantly takes polychaetes
Polychaeta () is a paraphyletic class of generally marine annelid worms, commonly called bristle worms or polychaetes (). Each body segment has a pair of fleshy protrusions called parapodia that bear many bristles, called chaetae, which are m ...
as its main prey item, although crustacean
Crustaceans (from Latin meaning: "those with shells" or "crusted ones") are invertebrate animals that constitute one group of arthropods that are traditionally a part of the subphylum Crustacea (), a large, diverse group of mainly aquatic arthrop ...
s, particularly amphipod
Amphipoda () is an order of malacostracan crustaceans with no carapace and generally with laterally compressed bodies. Amphipods () range in size from and are mostly detritivores or scavengers. There are more than 10,700 amphipod species cur ...
s and penaeid
Penaeidae is a family of marine crustaceans in the suborder Dendrobranchiata, which are often referred to as penaeid shrimp or penaeid prawns. The Penaeidae contain many species of economic importance, such as the tiger prawn, whiteleg shrimp, ...
s also make up a large portion of its diet. Items taken infrequently or in lesser amounts include small teleost fish, bivalve
Bivalvia () or bivalves, in previous centuries referred to as the Lamellibranchiata and Pelecypoda, is a class (biology), class of aquatic animal, aquatic molluscs (marine and freshwater) that have laterally compressed soft bodies enclosed b ...
mollusc
Mollusca is a phylum of protostome, protostomic invertebrate animals, whose members are known as molluscs or mollusks (). Around 76,000 extant taxon, extant species of molluscs are recognized, making it the second-largest animal phylum ...
s, marine plant material and other crustaceans such as tanaids, decapods
The Decapoda or decapods, from Ancient Greek δεκάς (''dekás''), meaning "ten", and πούς (''poús''), meaning "foot", is a large order (biology), order of crustaceans within the class Malacostraca, and includes crabs, lobsters, crayfis ...
and cumaceans. Modeling with the stable isotopes 13C and 15N indicate that seagrass
Seagrasses are the only flowering plants which grow in marine (ocean), marine environments. There are about 60 species of fully marine seagrasses which belong to four Family (biology), families (Posidoniaceae, Zosteraceae, Hydrocharitaceae and ...
and epiphytic algae were the primary initial sources of energy and nutrition that flow into the fish via detritivore
Detritivores (also known as detrivores, detritophages, detritus feeders or detritus eaters) are heterotrophs that obtain nutrients by consuming detritus (decomposing plant and animal parts as well as feces). There are many kinds of invertebrates, ...
s which the species preys on, with salt marsh
A salt marsh, saltmarsh or salting, also known as a coastal salt marsh or a tidal marsh, is a coastal ecosystem in the upper coastal intertidal zone between land and open saltwater or brackish water that is regularly flooded by the tides. I ...
plants and macroalgae
Seaweed, or macroalgae, refers to thousands of species of Macroscopic scale, macroscopic, Multicellular organism, multicellular, ocean, marine algae. The term includes some types of ''Rhodophyta'' (red), ''Brown algae, Phaeophyta'' (brown) and ...
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 oligochaete
Oligochaeta () is a subclass of soft-bodied animals in the phylum Annelida, which is made up of many types of aquatic and terrestrial worms, including all of the various earthworms. Specifically, oligochaetes comprise the terrestrial megadril ...
s 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
In ecology, a niche is the match of a species to a specific environmental condition.
Three variants of ecological niche are described by
It describes how an organism or population responds to the distribution of resources and competitors (for e ...
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, in ecology, is a form of competition in which individuals of ''different'' species compete for the same resources in an ecosystem (e.g. food or living space). This can be contrasted with mutualism, a type of symbiosis. ...
, whilst the remaining ''S. schomburgkii'' and ''Sillaginodes punctatus'' partition the resources, with ''S. punctatus'' consuming more decapods and shrimp
A shrimp (: shrimp (American English, US) or shrimps (British English, UK)) is a crustacean with an elongated body and a primarily Aquatic locomotion, swimming mode of locomotion – typically Decapods belonging to the Caridea or Dendrobranchi ...
s.
Reproduction and growth
Yellowfin whiting reach sexual maturity
Sexual maturity is the capability of an organism to reproduce. In humans, it is related to both puberty and adulthood. ''Puberty'' is the biological process of sexual maturation, while ''adulthood'', the condition of being socially recognized ...
at a length of 200 mm in male
Male (Planet symbols, symbol: ♂) is the sex of an organism that produces the gamete (sex cell) known as sperm, which fuses with the larger female gamete, or Egg cell, ovum, in the process of fertilisation. A male organism cannot sexual repro ...
s and 230 mm in female
An organism's sex is female ( symbol: ♀) if it produces the ovum (egg cell), the type of gamete (sex cell) that fuses with the male gamete (sperm cell) during sexual reproduction.
A female has larger gametes than a male. Females and ...
s, with the majority of both sexes reaching this length by the end of their second year of life. The timing of spawning
Spawn is the Egg cell, eggs and Spermatozoa, sperm released or deposited into water by aquatic animals. As a verb, ''to spawn'' refers to the process of freely releasing eggs and sperm into a body of water (fresh or marine); the physical act is ...
varies over the species range, a trait found in a number of other sillaginids. In the northernmost 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
An egg is an organic vessel grown by an animal to carry a possibly fertilized egg cell (a zygote) and to incubate from it an embryo within the egg until the embryo has become an animal fetus that can survive on its own, at which point the ...
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
The pelagic zone consists of the water column of the open ocean and can be further divided into regions by depth. The word ''pelagic'' is derived . The pelagic zone can be thought of as an imaginary cylinder or water column between the sur ...
and spherical, with a diameter of 0.6 mm. The development and morphology of the newly hatched larva
A larva (; : larvae ) is a distinct juvenile form many animals undergo before metamorphosis into their next life stage. Animals with indirect development such as insects, some arachnids, amphibians, or cnidarians typically have a larval phase ...
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
A pigment is a powder used to add or alter color or change visual appearance. Pigments are completely or nearly solubility, insoluble and reactivity (chemistry), chemically unreactive in water or another medium; in contrast, dyes are colored sub ...
ed, a gas bladder
The swim bladder, gas bladder, fish maw, or air bladder is an internal gas-filled organ in bony fish that functions to modulate buoyancy, and thus allowing the fish to stay at desired water depth without having to maintain lift via swimming, ...
is present, and yolk
Among animals which produce eggs, the yolk (; also known as the vitellus) is the nutrient-bearing portion of the egg whose primary function is to supply food for the development of the embryo. Some types of egg contain no yolk, for example bec ...
absorption is complete. The larvae are elongate, having 36 to 38 myomere
Myomeres are blocks of skeletal muscle tissue arranged in sequence, commonly found in aquatic chordates. Myomeres are separated from adjacent myomeres by fascia consisting of connective tissue, known as myosepta. Myomere counts are sometimes us ...
s, with flexion
Motion, the process of movement, is described using specific anatomical terminology, anatomical terms. Motion includes movement of Organ (anatomy), organs, joints, Limb (anatomy), limbs, and specific sections of the body. The terminology used de ...
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 fish, 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
Aquaculture (less commonly spelled aquiculture), also known as aquafarming, is the controlled cultivation ("farming") of aquatic organisms such as fish, crustaceans, mollusks, algae and other organisms of value such as aquatic plants (e.g. Nelu ...
potential, especially with its high tolerance to varying salinity levels.
Commercial fishery
There are two major fisheries
Fishery can mean either the enterprise of raising or harvesting fish and other aquatic life or, more commonly, the site where such enterprise takes place ( a.k.a., fishing grounds). Commercial fisheries include wild fisheries and fish farm ...
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 River
The Blackwood River is a major river and catchment in the South West (Western Australia), South West of Western Australia.
Course
The river begins at the junction of Arthur River (Western Australia), Arthur River and Balgarup River near Que ...
estuary, Geographe Bay
Geographe Bay is in the south-west of Western Australia, around southwest of Perth.
The bay was named in May 1801 by French explorer Nicolas Baudin, after his ship, ''Géographe''. It is a wide curve of coastline extending from Cape Natur ...
, the Leschenault Estuary and 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 to Point Peron near Rockingham. The total area of the sound is about .
It ...
. Fishing methods employed commonly include beach seine
The Seine ( , ) is a river in northern France. Its drainage basin is in the Paris Basin (a geological relative lowland) covering most of northern France. It rises at Source-Seine, northwest of Dijon in northeastern France in the Langres plat ...
s, bottom set gill net
Gillnetting is a fishing method that uses gillnets: vertical panels of netting that hang from a line with regularly spaced floaters that hold the line on the surface of the water. The floats are sometimes called "corks" and the line with corks is ...
s 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
The tonne ( or ; symbol: t) is a unit of mass equal to 1,000 kilograms. It is a non-SI unit accepted for use with SI. It is also referred to as a metric ton in the United States to distinguish it from the non-metric units of the s ...
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
Overexploitation, also called overharvesting or ecological overshoot, refers to harvesting a renewable resource to the point of diminishing returns. Continued overexploitation can lead to the destruction of the resource, as it will be unable t ...
, 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
Sport is a physical activity or game, often Competition, competitive and organization, organized, that maintains or improves physical ability and skills. Sport may provide enjoyment to participants and entertainment to spectators. The numbe ...
on light line, and are easily accessible from beaches and jetties
A jetty is a man-made structure that protrudes from land out into water. A jetty may serve as a breakwater, as a walkway, or both; or, in pairs, as a means of constricting a channel. The term derives from the French word ', "thrown", signif ...
, with a boat
A boat is a watercraft of a large range of types and sizes, but generally smaller than a ship, which is distinguished by its larger size or capacity, its shape, or its ability to carry boats.
Small boats are typically used on inland waterways s ...
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, hook
A hook is a tool consisting of a length of material, typically metal, that contains a portion that is curved/bent back or has a deeply grooved indentation, which serves to grab, latch or in any way attach itself onto another object. The hook's d ...
s below size 4, and sinkers to an absolute minimum as heavy lines and sinkers often scare away the fish. Specialist whiting fishermen often attach a red bead
A bead is a small, decorative object that is formed in a variety of shapes and sizes of a material such as stone, bone, shell, glass, plastic, wood, or pearl and with a small hole for threading or stringing. Beads range in size from under 1 ...
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 is a common name for small aquatic crustaceans with an exoskeleton
An exoskeleton () . is a skeleton that is on the exterior of an animal in the form of hardened integument, which both supports the body's shape and protects the intern ...
s, cockles and squid
A squid (: squid) is a mollusc with an elongated soft body, large eyes, eight cephalopod limb, arms, and two tentacles in the orders Myopsida, Oegopsida, and Bathyteuthida (though many other molluscs within the broader Neocoleoidea are also ...
occasionally taking good catches also. Lure and fly fishing
Fly fishing is an angling technique that uses an ultra-lightweight lure called an artificial fly, which typically mimics small invertebrates such as flying and aquatic insects to attract and catch fish. Because the mass of the fly lure is in ...
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
The Blackwood River is a major river and catchment in the South West (Western Australia), South West of Western Australia.
Course
The river begins at the junction of Arthur River (Western Australia), Arthur River and Balgarup River near Que ...
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'').
References
External links
Fishbase page for yellowfin whiting
Encyclopedia of life page
Western Angler page (Yellowfin and school whiting)
Fishing WA: Fishing methods for whiting
{{Taxonbar, from=Q2277027
yellowfin whiting
Marine fish of Western Australia
yellowfin whiting
yellowfin whiting