| Golden Perch |
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| percichthyidae | |
| freshwater fish of australia | |
The Golden Perch, '''''Macquaria ambigua''''' is an Australia n native freshwater Fish , primarily of the Murray - Darling river system. Their genus name derives from the Macquarie River (=''Macquaria'') where the first species of the ''Macquaria'' genus was obtained, while their specific name derives from the original meaning of the Latin word ''ambigua'' which is 'two sides'. This is a reference to the strong lateral compression adult Golden Perch display. DESCRIPTION Golden Perch are medium sized fish, commonly 30–40cm and 1.0–2.0 kg in rivers. Fish from rivers are smaller and somewhat streamlined - fish in man-made impoundments are much deeper-bodied and show much greater average and maximum sizes. In rivers, has been recorded to 9.0 kg, in impoundments to 15.0 kg. Golden Perch have an elongated deep body, laterally compressed, with a sizable mouth, small to moderate sized eyes and distinct curve to the forehead and "hump" above the head. The Caudal Fin , soft Dorsal Fin and Anal Fin are rounded. The spiny dorsal fin is short to moderate in length and strong. Golden Perch vary from in colour from pale silvery-gold (turbid waters) to deep yellow/gold or bronze-black (very clear waters). RANGE The Golden Perch, '''''Macquaria ambigua''''' is an Australia n native freshwater Fish , primarily of lowland reaches of the Murray - Darling river system, but also known to push some way into upland reaches as well. In the Murray-Darling system Golden Perch are often found in Sympatry ("together with") Murray Cod (''Maccullochella peelii peelii''). The ''Macquaria'' perches, of which Golden perch are one, continue the trend present in native fish genera of the Murray-Darling system of speciating into a Lowland species and a specialist Upland species. Golden perch, ''Macquaria ambigua'', are the Lowland species while the closely related Macquarie Perch , ''Macquaria australasica'', are the speciated, more specialised Upland species which used to inhabit the Upland reaches of the southern Murray-Darling basin. Like many Murray-Darling native fish, Golden Perch have crossed into eastern coastal river catchments through natural river capture events. Golden Perch are found naturally in the Fitzroy-Dawson River in central Queensland . Golden Perch have also entered the internal Lake Eyre - Coopers Creek drainage system of Central Australia . Both of these separate populations are likely to be separate species due to isolation from parent Murray-Darling populations, genetic drift and natural selection. The taxonomy of Golden Perch has not been updated to reflect this, although the term ''Macquaria ambigua oriens'', denoting sub-species status, has recently appeared in literature discussing the Fitzroy-Dawson population. SPAWNING AND BIOLOGY Golden Perch have a flexible breeding strategy but generally need a spring or summer flood or "fresh" to stimulate spawning. Like most primarily lowland native fish species of the Murray-Darling river system, these floods or freshes appear to be necessary for good survival and recruitment of spawned fish. The Golden Perch is highly fecund with egg counts frequently exceeding 500,000. The eggs are semi-planktonic, and hatch fairly quickly (24-36 hours). Like other ''Macquaria'' species, Sexual Dimorphism is present, with females reaching much larger maximum sizes than males. Females also reach sexual maturity at older, larger sizes than males. Golden Perch continue the trend of native fish of southeast Australia being incredibly long-lived. Longevity is a survival strategy in the often challending Australian environment to ensure that most adults participate in at least one exceptional spawning and recruitment event, which are often linked to unusually wet '' La Niña '' years and may only every one or two decades. Maximum recorded age is 26 years. DIET Golden Perch are a predator, taking Yabbies , Shrimp s, Frog s, small fish and aquatic Invertebrate s. CONSERVATION Wild populations have declined significantly, especially in upper reaches of rivers, due to dams and weirs blocking migration, mitigating floods and freshes, regulating flows and releasing un-naturally cold water ("thermal pollution"), all of which interfere with migration, spawning and recruitment. Golden Perch are extremely migratory and migration appears to have been important in maintaining populations in some reaches of river, usually the upper reaches. The species is however bred in hatcheries in large numbers and stocked. Concerns over genetic diversity issues are growing however. REFERENCES
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