Sillaginodes punctatus és una espècie de peix de la família dels sil·lagínids i l'única del gènere Sillaginodes.
Els mascles poden assolir els 72 cm de longitud total.[2]
Es troba a Austràlia Meridional.[2]
Sillaginodes punctatus és una espècie de peix de la família dels sil·lagínids i l'única del gènere Sillaginodes.
The King George whiting (Sillaginodes punctatus), also known as the spotted whiting or spotted sillago, 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.[1] The King George whiting is the only member of the genus Sillaginodes and the largest member of the smelt-whiting family Sillaginidae, growing to a length of 80 cm and 4.8 kg in weight. The species is readily distinguishable from other Australian whitings by its unique pattern of spots, as well as its highly elongate shape. King George whiting are often found in bays and protected waterways over sand and seagrass beds, also venturing out onto deep continental shelf reefs during adulthood. The species is a benthic carnivore, consuming a variety of crustaceans, polychaete worms, molluscs and fish. The King George whiting forms the basis of one of southern Australia's most important commercial fisheries, reportedly worth over five million Australian dollars per year. The species is also heavily targeted by recreational anglers, who value the whiting for its sporting and eating qualities.
The King George whiting is the only species nested in the genus Sillaginodes, which itself is in the family Sillaginidae, containing all the smelt whitings.[2] The Sillaginidae are part of the Percoidei, a suborder of the order Perciformes.[3] The King George whiting was first officially named by Cuvier in 1829 as Sillago punctata, based on an individual taken from King George Sound in Western Australia.[4] In 1861, Theodore Gill created the monotypic genus Sillaginodes based on a number or morphological characteristics and assigned S. punctatus to it. A number of synonyms have been applied after the initial correct naming, apparently due to Cuvier not designating a holotype, or it being lost. A lectotype was finally designated by McKay in 1985.[5] The species has a variety of common names (many now obsolete), with the most common, “King George whiting”, taken from the name of the body of water where the initial description was made. It is also often called the spotted whiting in reference to its obliquely positioned bars of brown spots, with other names used in markets, especially outside of Australia.[5]
The King George whiting has the same overall profile as the rest of the sillaginid fishes, an elongate, slightly compressed body with a tapering head and terminal mouth. The genus Sillaginodes is distinguished by a first dorsal fin with twelve or thirteen spines and the second dorsal fin with a single spine and 25 to 27 soft rays.[1] The vertebrae number between 42 and 44 in the genus.[4]
The King George whiting is the only member of the genus Sillaginodes and is further distinguished from any other possible taxa assigned to that genus by a number of distinct anatomical features. It is the largest of the Sillaginid fishes with 129 to 147 lateral line scales, and like all fishes in the family is best distinguished by the shape of its swim bladder. In plan view, the swim bladder has a land slug-like appearance, with a posteriorly tapering extension and two anterolateral extensions or ‘horns’. There are no duct-like processes on the ventral surface unlike taxa in the genus Sillago.[4]
In situations where identification is needed quickly, the colour of the King George whiting is also very distinctive, with a pale golden brown to olive brown top colour and white to silver colour on its underside. The species also as distinct obliquely positioned rows of brown spots running the length of its body, which are apparent to see even after removal from the water and after death. The caudal, anal and pectoral fins are usually a light brown, with some having olive green caudal fins.[6]
It is the largest member of Sillaginidae, growing to a maximum length of 72 cm long and 4.8 kg in weight.[6]
The King George whiting is endemic to Southern Australia, ranging lower Western Australia, South Australia, Victoria and occasionally even lower New South Wales. The westernmost reported capture was in Jurien Bay and the furthest east King George whiting have been reported from is Botany Bay in New South Wales (although this appears to be a rare occurrence).[4]
King George whiting are most commonly found in tidal bays, estuaries and creeks along the coast of the mainland and numerous islands scattered throughout the species’ range. There is a distinct difference in habitat between the adult and juvenile fish, with the juveniles more inclined to inhabit shallower waters in protected bays, creeks and estuaries.[7] A favourite habitat of young fish appears to be Zostera and Posidonia seagrass beds in protected bays, apparently using the seagrass as protection and for foraging purposes.[8] Juveniles tend to form schools of varying sizes, occasionally schooling with other species, including other members of the family Sillaginidae.[6] Adults tend to be solitary and found in deeper water in a range of habitats including bays, offshore surf gutters, broken bottom and deep reef, also venturing into shallower water on occasion.
The King George whiting's distinctive body shape and mouth placement is an adaptation to bottom feeding, which is the predominant method of feeding for all whiting species. All larger whiting feed by using their protrusile jaws and tube-like mouths to suck up various types of prey from in, on or above the ocean substrate.[9] There is a large body of evidence that shows whiting do not rely on visual cues when feeding, instead using a system based on the vibrations emitted by their prey.[10]
Studies of gut content have shown that the primary food items of King George whiting are amphipods, copepods and polychaete worms.[11] Unlike any of its relatives, the King George whiting does not appear to feed on molluscs, which is unusual because in many parts of Southern Australia, the main bait used by recreational fishers to catch whiting is the cockle; a mollusc, but then, it has been deshelled. An excellent bait for catching King George Whiting is raw king prawn, such as banana prawn. They are better bought in the shell and peeled shortly before using, as this keeps the bait fresh. Also rare in the diet are echinoderms, which are frequent prey for other species of Sillago. This may be a function of niche partitioning, as in many areas the King George whiting's habitat overlaps with other species of the genus Sillago.[9] Other minor components of the diet include crustaceans such as carids, leptostracans, stomatopods, crabs, tanaids, cumaceans and isopods as well as other fish and benthic algae.
As previously mentioned, younger fish tend to school when foraging, and have been known to forage in groups with other species such as silver trevally, tarwhine and other species of whiting.[6] Larger fish tend to occupy areas with larger species such as Australasian snapper, blue morwong and larger trevally.
King George whiting, especially juveniles, are known to be common prey for a number of larger inshore fishes and wading birds. The most prominent inshore predators are Australian salmon, members of the flathead family, the barracouta (a snake mackerel), snook as well as various species of sharks and rays.[12] Various species of diving birds, particularly the pied cormorant are also common predators of the species,[13] as are marine mammals such as bottlenose and common dolphins.[14]
King George whiting reach sexual maturity at three to four years of age, with males reaching 30 cm in length and females 34 cm. These lengths are used as guides when setting minimum legal lengths for the species, allowing adequate time for an individual to reproduce before being taken.[15] Spawning occurs in a range of areas, depending on the geographic locality of the individual; some spawning in deeper water up to 9 m deep, others in estuaries.[16] May and June are the most common times for spawning, with some spawning events recorded as early as February and as late as July.[3] Juvenile fish are recruited to areas by ocean currents, with studies showing the species is too weak a swimmer to be able to undertake long distance journeys.[17] The location of spawning also has implications for the location of the juveniles, as with some estuary breeding individuals.
The King George whiting is a highly rated food fish and is common in southern Australia and so has become a major component of the commercial and recreational fisheries in this region, with aquaculture potential still being explored but apparently of low value.[1]
The main commercial King George whiting fishery is centred on South Australia from Ceduna in the west to Gulf St Vincent in the east. Smaller fisheries are present in Victoria and south west Western Australia. Common catching practices include haul seine nets, gill nets as well as longline and handline methods. This fishery is one of the most important in the country, reportedly worth five million Australian dollars a year,[4] as King George whiting fetch premium price in markets. This single species alone was reported as comprising 60% of the total annual catch in South Australia during the late 1980s.[18] The fish are sold either whole or as fillets and are generally rated as one of the very best quality Australian fish for the table, and are ubiquitous in Fish and chips shops.
In Southern Australia, the King George whiting is often the sole target for fishermen who seek it for its high quality eating.[1] A number of coastal towns rely heavily on the species as a tourism drawcard for anglers seeking a range of fish and crustacean species, but King George whiting is often the most desired catch.[19] They are a relatively easy species to catch, with no special baits, rigs or techniques required and are often caught from jetties, beaches and rocks; meaning a boat is not necessary. Simple rigs such varieties of running ball sinker or paternoster rigs are commonly used, with a fixed sinker employed in area of high tidal movement.[20] As mentioned previously, molluscs, particularly the Goolwa cockle are common bait, with varieties of worms, gents, squid, cuttlefish, fish pieces and especially raw king prawn are commonly successful. The larger fish inhabiting deep reefs are often caught on whole pilchards while fishing for snapper and morwong.[20]
The King George whiting has differing size and bag limits for anglers in different states. In Victoria, there is a minimum size limit of 27 cm and a bag limit of 20 per person.[21] South Australia is divided into two zones concerning the taking of this species, with fish caught east of longitude 136° restricted to a minimum length of 32 cm and fish caught to the west of longitude 136° having a minimum length of 30 cm. In both divisions, the bag limit is 10 fish per person.[22] Western Australia has set a minimum legal limit of 28 cm and a bag limit of 8 per person.[23]
Due to the King George whitings’ popularity as a food fish, extensive investigations into the viability of the species as an aquaculture species have occurred, with most initial investigations indicating the long larval cycle is a major barrier to the successful farming of the fish. Other problems have arisen in a parasite previously unknown in the species only affecting the fish in captivity. Thyroid growth hormones may be used in the future to hasten growth of larvae and make such ventures more feasible.[24]
The King George whiting (Sillaginodes punctatus), also known as the spotted whiting or spotted sillago, is a coastal marine fish of the smelt-whitings family Sillaginidae. The King George whiting is endemic to Australia, inhabiting the south coast of the country from Jurien Bay, Western Australia to Botany Bay, New South Wales in the east. The King George whiting is the only member of the genus Sillaginodes and the largest member of the smelt-whiting family Sillaginidae, growing to a length of 80 cm and 4.8 kg in weight. The species is readily distinguishable from other Australian whitings by its unique pattern of spots, as well as its highly elongate shape. King George whiting are often found in bays and protected waterways over sand and seagrass beds, also venturing out onto deep continental shelf reefs during adulthood. The species is a benthic carnivore, consuming a variety of crustaceans, polychaete worms, molluscs and fish. The King George whiting forms the basis of one of southern Australia's most important commercial fisheries, reportedly worth over five million Australian dollars per year. The species is also heavily targeted by recreational anglers, who value the whiting for its sporting and eating qualities.
Sillaginodes punctatus es una especie de peces de la familia Sillaginidae en el orden de los Perciformes.
Los machos pueden llegar alcanzar los 72 cm de longitud total.[1]
Se encuentra en Australia Meridional.
Sillaginodes punctatus es una especie de peces de la familia Sillaginidae en el orden de los Perciformes.
Sillaginodes punctatus Sillaginodes generoko animalia da. Arrainen barruko Sillaginidae familian sailkatzen da.
Sillaginodes punctatus Sillaginodes generoko animalia da. Arrainen barruko Sillaginidae familian sailkatzen da.
Sillaginodes punctatus is een straalvinnige vissensoort uit de familie van witte baarzen (Sillaginidae).[1] De wetenschappelijke naam van de soort is voor het eerst geldig gepubliceerd in 1829 door Cuvier.
Bronnen, noten en/of referenties
ダイオウギス(Sillaginodes punctatus)はキスの一種。オーストラリア南岸固有種である。全長72cm・体重4.8kgに達するキス科の最大種である。細長い体型と独特な斑点から同定は容易である。波の少ない湾内などの砂地・アマモ場などに生息するが、成魚はより深い大陸棚にも進出する。底生の肉食魚で、甲殻類・多毛類・貝類・魚などを食べる。オーストラリア南部の商業漁業において最も重要な魚種の一つで、年間500万豪ドル以上の漁獲高があると報告されている。釣りやすさと味の良さから釣りの対象ともなる。
Sillaginodes 属唯一の種である[1][2]。1829年、キング・ジョージ・サウンド産の標本を基にジョルジュ・キュヴィエによりSillago punctataとして記載された[3]。1861年、Theodore Gillは形態的特徴から単型属Sillaginodesを創設し、本種を置いた。キュヴィエがホロタイプを指定しなかったか、紛失したため多くのシノニムが命名されたが、1985年、McKayによりレクトタイプが指定された[4]。様々な英名があるが、最初の標本の採集地に由来する“King George whiting”が一般に用いられている。斜めに並んだ体側の斑点に由来するspotted whitingなど、特にオーストラリア外の市場では他の名が用いられることもある[4]。
基本的な形態は他のキス類と同じであり、細長く側扁した体、先細りになった口を持つ。Sillaginodes属の特徴として、第一背鰭が12-13棘条であること、第二背鰭が1棘25-27軟条であること、脊椎骨数は42-44であることが挙げられる[3]。キス類の最大種であるため、側線鱗数が129-147と多いことも特徴である。他のキス類と確実に区別できる形質としては、鰾の形態が挙げられる。鰾の後方は先細りとなっており、背面の前方には角のような1対の突起がある。キス属のような、鰾の下面から伸びた管状突起はない[3]。
体色も特徴的であり、背面は薄いキツネ色から緑褐色、腹面は白-銀色。体側を斜めに走る茶色い斑点の列があるが、死ぬと消失する。尾鰭・臀鰭・胸鰭は明褐色で、尾鰭には濃緑色の斑点がある場合もある[5]。
全長72cm・体重4.8kgになる[5]。
オーストラリア南部固有種であり、西オーストラリア州南部・南オーストラリア州・ビクトリア州、稀にニューサウスウェールズ州南部でも見られる。西限は西オーストラリア州のJurien Bay、東限はニューサウスウェールズ州のボタニー湾と報告されている[3]。
本土の海岸線や点在する島々の内湾・三角江・入江で最もよく見られる。成魚と稚魚では生息場所に差があり、稚魚はより浅い場所に出現する[6]。餌場と外敵からの保護を得られるため、若魚は湾内のアマモ場を好む[7]。稚魚は他のキス類などと共に群れを作ることがある[5]。成魚は群れを作らず、沖合の深みに移動するが、稀に浅部に出現することもある。
他のキスのように底生生物の捕食に適応している。大型のキス類は全て、突き出す顎と管状の口で、堆積物の上・内部の餌を吸い込むように捕食するという方法をとる[8]。捕食時には視覚に頼らず、獲物が発する振動を感知していることが示されている[9]。
消化管内容物の調査では、主に端脚類・カイアシ・多毛類を食べることが示された[10]。オーストラリア南西部での調査では、他のキス類と異なり、軟体動物を全く食べないことが示された。また、棘皮動物を餌とするキス類は多いが、本種はあまり食べない。本種とシロギス属の数種は生息地が重複しているため、これはニッチ分割の一例とみなせるかもしれない[8]。他には様々な甲殻類・他の魚・底生藻類などが餌となる。
上で述べたように、若魚はシマアジ・ヘダイ・他のキス類などとともに群れを作って摂餌することが知られる[5]。大型個体はゴウシュウマダイ（英語版）・ギンタカノハ（英語版）・大型アジ類などの大型魚と同所に棲息するようになる。
本種、特に稚魚は渉禽類や大型の魚類の獲物となる。マルスズキ（英語版）・コチ科・クロタチカマス科・ホソカマス・サメ・エイなどが主な捕食者である[11]。様々な潜水鳥類（特にマミジロウ（英語版））[12]、海獣（ハンドウイルカ・マイルカ）も本種を獲物とする[13]。
生後3-4年、雄は30cm・雌は34cmで性成熟する。これは漁獲が許可されている最低の大きさであり、漁獲前に繁殖できるように考慮されている[14]。繁殖場所は地域によって変わり、河口で繁殖する場所もあれば、9 m程度の深みで繁殖する場所もある[15]。繁殖は2-7月で記録されているが、5-6月が最も活発である[16]。稚魚は遊泳力が低く、長距離を海流に乗って運ばれて定着する[17]。
味がよいため、オーストラリア南部では漁業・遊漁共に広く利用されている重要な魚種である。養殖の研究も行われているが、あまり成果は上がっていない。
主な商業漁業は、西のCedunaから東のセントビンセント湾まで行われている。また、ビクトリア州や西オーストラリア南西部でも小規模な漁業が営まれている。漁獲には底曳網・刺し網や延縄・手釣りが用いられる。この漁業はオーストラリアで最も重要なものであり、年間500万豪ドルの漁獲高があり[3]、市場で高く売買されている。1980年代後半を通じて、本種は南オーストラリア州の漁獲量の60%を占めていた[18]。
味がよいため、オーストラリア南部ではよく釣りの対象とされる。沿岸域の多くの街は、本種を目当てにした釣り人によって観光収入を得ている[19]。容易に釣ることができ、特殊な餌や釣具は必要ない。釣り船も不要で、防波堤・砂浜・岩場から釣ることができる[20]。餌は主に ピピガイ（英語版）が用いられるが、ゴカイ・蛆・イカ・切り身・他の貝類なども用いることができる。深部に住む大型個体は、イワシを餌にしたタイやギンタカノハ狙いの釣りで釣れることがある[20]。
州ごとに全長・匹数に応じて捕獲制限が行われている。ビクトリア州では一人あたり20匹まで、全長27 cm以上に制限されている[21] 。 南オーストラリア州では、一人あたり12匹まで、全長は東経136°以東では31 cm、以西では30 cm以上に[22]、西オーストラリア州では一人あたり8匹まで、全長28 cm以上に制限されている[23]。
価値が高いため、養殖の可能性が検討されているが、長い幼生期がその実現を阻んでいる。他の問題としては、飼育下でのみ発生する未知の寄生虫がある。甲状腺ホルモンによって幼生の成長を促進する手法を用いることができるかもしれない[24]。
ダイオウギス(Sillaginodes punctatus)はキスの一種。オーストラリア南岸固有種である。全長72cm・体重4.8kgに達するキス科の最大種である。細長い体型と独特な斑点から同定は容易である。波の少ない湾内などの砂地・アマモ場などに生息するが、成魚はより深い大陸棚にも進出する。底生の肉食魚で、甲殻類・多毛類・貝類・魚などを食べる。オーストラリア南部の商業漁業において最も重要な魚種の一つで、年間500万豪ドル以上の漁獲高があると報告されている。釣りやすさと味の良さから釣りの対象ともなる。
