Range
Macquarie perch were originally found in the larger upland rivers and streams in the south-eastern corner of the Murray-Darling system, which they usually co-inhabited with trout cod and one or both of the blackfish species.
Macquarie perch continue a pattern found in native freshwater fish of the Murray-Darling system of specialisation into lowland and upland stream inhabitants. Macquarie perch are a speciated, more specialised upland version of the golden perch, which is primarily a lowland fish. (Having said this, the primarily lowland golden perch, being highly adaptable species, still extend a significant distance into upland habitats).
Macquarie perch, like many other Murray-Darling native fish, have managed to cross the Great Dividing Range into eastern coastal systems through natural river capture events. They are found in the eastern coastal Shoalhaven and Hawkesbury-Nepean river systems. Although the situation has been blurred with translocations of Murray-Darling fish into these eastern coastal systems, it appears that, as with other naturally occurring populations of Murray-Darling native fish in eastern coastal systems, these Macquarie perch are almost certainly separate species due to isolation from parent populations, genetic drift and selective forces. The taxonomy for Macquarie perch has not been updated to reflect this. Major differences between the eastern coastal species and the Murray-Darling species are that the eastern coastal species displays a far smaller average and maximum size (15 and 20 cm respectively) and are reported to have one less vertebra than the Murray-Darling species. Recent evidence suggest the Shoalhaven species may be close to or at extinction due to damming of their habitat and subsequent encroachment of legally and illegally stocked fish species. The Hawkesbury-Nepean species appears to be threatened by introduced trout and other exotic fish, river damming and regulation, siltation, and urban encroachment, but does not appear to be as critically threatened as the Murray-Darling species. Information on this page relates primarily to the Murray-Darling species.
There is also a translocated self-sustaining breeding population of Macquarie Perch located in the middle and upper reaches of the Yarra River on the outskirts of Melbourne. They highest numbers are found lowest reaches, which also support a mix of translocated native and introduced fish including trout. In this stretch however no fish species is particularly dominant, and introduced trout are not numerous.
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