Sillago
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| Sillago Fossil range: Early Oligocene to Present[1] |
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 Sillago argentifasciata being sold in a Philippine supermarket.
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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 bladder morphology as a definitive feature. All whiting species are benthic in nature and generally live in shallow, protected waters, although there are exceptions. Minor fisheries exist around various species of Sillago, making them of minor importance in most of their range.
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[edit] Taxonomy
The genus Sillago is one of three genera in the family Sillaginidae, itself part of the Percoidea, a suborder of the Perciformes. McKay (1985) further divided Sillago into three subgenera based primarily on the morphology of the swim bladder.[2]
- Silliganopodys: Swimbladder greatly reduced, with no duct-like process and no haemal funnel
- Sillago: A double post-coelomic extension penetrating the tail region
- Parasillago: A single post-coelomic extension of the swimbladder
These subgenera are not universally used; for example, FishBase does not currently use them.
The name Sillago is derived from a locality or region within Australia,[3] possibly after Sillago Reef near Whitsunday Island in Queensland.[4]
[edit] Anatomy
All species in the genus Sillago are similar to other members of the Sillaginidae family in profile, with the distinctive compressed, long, tapering body common to all species. The definitive characteristic for Sillago is the presence of a swim bladder, in all but one case (Sillago chondropus) having a duct-like process from the ventral surface to near the anus. Their swim bladders are often complex, further distinguishing them from the genera Sillaginodes and Sillaginopsis (which often lacks a swim bladder entirely).[5]
Members of the genus usually have a silver to gold-brown colour depending on their habitat, with shallow sand flat fish having a more silver appearance, while estuary and silt bottom dwellers having a darker brown colour.
[edit] Range and habitat
With 29 species, the genus Sillago has the widest distribution of any smelt-whiting genus, spanning much of the Indo-Pacific. The genus ranges from the east coast of Africa to Japan in the east and Southern Australia in the south, with most species concentrated around South East Asia, the Indonesian Archipelago and Australia. Many species have overlapping distribution, often making positive identification hard.[5]
Sillagos are generally coastal fishes, inhabiting a variety of shallow water habitats including open sand flats, muddy substrates and beaches with moderately strong wave action. Some species enter estuaries and even penetrate fresh water for considerable periods, especially during vulnerable stages of their life cycle. Shallow water of a few centimetres is also occupied by juvenile sillagos, especially in the vicinity of cover such as seagrass beds or mangroves. A few species are known to inhabit deeper offshore waters, with fish known from trawls up to 180 m (600 ft) deep.[5]
[edit] Importance to humans
Various species of Sillago represent minor local fisheries in their ranges, with many having commercial importance. Fish are taken by a variety of methods including seine, gill and cast nets as well as by line. Recreational fishing for Sillago is common, especially in Australia where they are valued as food fish or for live bait for larger species. Estuarine aquaculture in India, Japan and Taiwan has utilized sillagos as an important species, and similar trials have been conducted in Australia.[5]
[edit] References
- ^ Sepkoski, Jack (2002). "A compendium of fossil marine animal genera". Bulletins of American Paleontology 364: p.560.
- ^ McKay, R.J. (1985), “A revision of the fishes of the family Sillaginidae”, Mem. Queensland Mus. 23: 1-73
- ^ Fishbase, Sillago, <http://www.fishbase.org/Eschmeyer/GeneraSummary.cfm?ID=Sillago>. Retrieved on 22 July 2007
- ^ Great Barrier Reef Marine Park Authority, Whitsunday Plan of Management Area boundary map, <http://www.gbrmpa.gov.au/__data/assets/pdf_file/0005/1688/pipi_map_whit.pdf>. Retrieved on 22 July 2007
- ^ a b c d McKay, R.J. (1992). FAO Species Catalogue: Vol. 14. Sillaginid Fishes Of The World. Rome: Food and Agricultural Organisation of the United Nations, 22. ISBN 0014-5602.
