Macquarie perch
Encyclopedia
The Macquarie perch is an Australia
n native freshwater fish
of the Murray-Darling river system
. It is a member of the Percichthyidae family and is closely related to the golden perch
(Macquaria ambigua).
The Macquarie perch derives its scientific name from the Macquarie River where the first scientifically described specimen was collected (Macquaria) and a derivation of the Latin
word for "southern" (australasica).
Macquarie perch are a medium sized fish, commonly 30–40 cm and 1.0–1.5 kg. Maximum size is about 2.5 kg and 50 cm. Their body is elongated, deep, and laterally compressed. The caudal fin, anal fin and soft dorsal fin
are rounded. Spiny dorsal fin medium height and strong. Mouth and eyes are relatively small. Colouration can vary from tan to (more commonly) dark purplish-grey to black. The irises of the eyes are distinctly silver.
Macquarie perch are a relatively placid native fish species with the bulk of their diet consisting of aquatic invertebrate
s such as caddisfly, stonefly and mayfly
species, with a small quantity of terrestrial insect
s taken as well.
.
Macquarie perch appear to have inherited the sexual dimorphism of other Macquaria species where females reach a larger maximum size than males. Females also reach sexual summat at older, larger sizes than males.
Maximum ages for Macquarie perch are not clear but it is possible they are similar to their relative the golden perch (maximum age 26 years). The extremely limited work done on ageing Macquarie perch has only recorded fish to around 11 years of age so far.
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.
, has been proven to be fatal to Macquarie perch, and may have contributed to the decline of some populations of Macquarie perch in upland impoundments. What has become clear however is that total domination of the Macquarie perch's upland habitats by introduced brown trout
(Salmo trutta) and rainbow trout
(Oncorhynchus mykiss) have also been a major cause of decline. Indeed, Macquarie perch populations have failed in significant stretches of relatively pristine upland river that offer excellent habitat, are not silted, dammed or overfished, and where there are no possible explanations for their demise except introduced trout species. Dietary studies have documented significant overlap between the diet of Macquarie perch and introduced trout species, and anglers have observed predation of Macquarie perch juveniles by introduced trout species. Several publications in the 1940s through to the 1960s by the director of the Victorian Fisheries and Game Department (A.D.Butcher) documents predation on juvenile trout cod, Macquarie perch and other upland native fish species by introduced trout species, and major dietary overlaps. Recent research (Lintermans, 2006) records dietary overlaps that are significant by scientific criteria between Macquarie perch and introduced trout species.
Over the last 20 or 30 years, the last few remaining Macquarie perch populations in upland habitats have faltered. All of these populations appear to be in extinction vortices and may disappear completely over the next couple of decades.
Macquarie perch have proved difficult but not impossible to breed. However, no Australian government agency is breeding Macquarie perch, and some government agencies are stocking upland habitats containing remnant Macquarie perch populations with introduced trout species. Not only do these stockings threaten Macquarie perch by competition and predation, but rainbow trout
fingerlings have been shown to carry significant levels of EHN virus.
Australia
Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...
n native freshwater fish
Fish
Fish are a paraphyletic group of organisms that consist of all gill-bearing aquatic vertebrate animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish, as well as various extinct related groups...
of the Murray-Darling river system
Murray-Darling Basin
The Murray-Darling basin is a large geographical area in the interior of southeastern Australia, whose name is derived from its two major rivers, the Murray River and the Darling River. It drains one-seventh of the Australian land mass, and is currently by far the most significant agricultural...
. It is a member of the Percichthyidae family and is closely related to the golden perch
Golden perch
The golden perch, Macquaria ambigua, is an Australian native freshwater fish, primarily of the Murray-Darling river system. It is not a true perch of the genus Perca....
(Macquaria ambigua).
The Macquarie perch derives its scientific name from the Macquarie River where the first scientifically described specimen was collected (Macquaria) and a derivation of the Latin
Latin
Latin is an Italic language originally spoken in Latium and Ancient Rome. It, along with most European languages, is a descendant of the ancient Proto-Indo-European language. Although it is considered a dead language, a number of scholars and members of the Christian clergy speak it fluently, and...
word for "southern" (australasica).
Description and diet
Dorsal fin
A dorsal fin is a fin located on the backs of various unrelated marine and freshwater vertebrates, including most fishes, marine mammals , and the ichthyosaurs...
are rounded. Spiny dorsal fin medium height and strong. Mouth and eyes are relatively small. Colouration can vary from tan to (more commonly) dark purplish-grey to black. The irises of the eyes are distinctly silver.
Macquarie perch are a relatively placid native fish species with the bulk of their diet consisting of aquatic invertebrate
Invertebrate
An invertebrate is an animal without a backbone. The group includes 97% of all animal species – all animals except those in the chordate subphylum Vertebrata .Invertebrates form a paraphyletic group...
s such as caddisfly, stonefly and mayfly
Mayfly
Mayflies are insects which belong to the Order Ephemeroptera . They have been placed into an ancient group of insects termed the Palaeoptera, which also contains dragonflies and damselflies...
species, with a small quantity of terrestrial insect
Insect
Insects are a class of living creatures within the arthropods that have a chitinous exoskeleton, a three-part body , three pairs of jointed legs, compound eyes, and two antennae...
s taken as well.
Breeding and biology
The Macquarie perch is an upland native fish and has a breeding biology clearly adapted to flowing upland rivers and streams. (For this reason, the species has proven difficult to breed artificially, as captive females do not produce ripe eggs when kept in still broodponds or tanks). Macquarie perch breed in late spring at temperatures of 15 to 16 °C, in flowing water over unsilted cobble and gravel substrate. The demersal (sinking) eggs fall into the interstices (spaces) between the gravel and cobble, where they lodge and are then protected and incubated until hatching. This is a breeding strategy similar to that used by introduced species of troutTrout
Trout is the name for a number of species of freshwater and saltwater fish belonging to the Salmoninae subfamily of the family Salmonidae. Salmon belong to the same family as trout. Most salmon species spend almost all their lives in salt water...
.
Macquarie perch appear to have inherited the sexual dimorphism of other Macquaria species where females reach a larger maximum size than males. Females also reach sexual summat at older, larger sizes than males.
Maximum ages for Macquarie perch are not clear but it is possible they are similar to their relative the golden perch (maximum age 26 years). The extremely limited work done on ageing Macquarie perch has only recorded fish to around 11 years of age so far.
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 codTrout Cod
The trout cod or bluenose cod, Maccullochella macquariensis, is a large predatory freshwater fish of the Maccullochella genus and the Percichthyidae family which was originally found in the south-east corner of the Murray-Darling river system in Australia...
and one or both of the blackfish
Two-spined blackfish
The two-spined blackfish, Gadopsis bispinosus, is an Australian native freshwater fish. It is a speciated, more specialised upland variant of the river blackfish, Gadopsis marmoratus....
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
Golden perch
The golden perch, Macquaria ambigua, is an Australian native freshwater fish, primarily of the Murray-Darling river system. It is not a true perch of the genus Perca....
, 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
Yarra River
The Yarra River, originally Birrarung, is a river in east-central Victoria, Australia. The lower stretches of the river is where the city of Melbourne was established in 1835 and today Greater Melbourne dominates and influences the landscape of its lower reaches...
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.
Conservation
Murray-Darling Macquarie perch are now listed as endangered on state and Commonwealth listings. Gross overfishing by anglers, habitat degradation through siltation, and regulation of flow and "thermal pollution" by dams have all been major causes of decline. A mysterious but endemic disease called Epizootic Haemotopoeitic Necrosis virus (EHN virus), now vectored by introduced redfin perchPerch
Perch is a common name for fish of the genus Perca, freshwater gamefish belonging to the family Percidae. The perch, of which there are three species in different geographical areas, lend their name to a large order of vertebrates: the Perciformes, from the Greek perke meaning spotted, and the...
, has been proven to be fatal to Macquarie perch, and may have contributed to the decline of some populations of Macquarie perch in upland impoundments. What has become clear however is that total domination of the Macquarie perch's upland habitats by introduced brown trout
Brown trout
The brown trout and the sea trout are fish of the same species....
(Salmo trutta) and rainbow trout
Rainbow trout
The rainbow trout is a species of salmonid native to tributaries of the Pacific Ocean in Asia and North America. The steelhead is a sea run rainbow trout usually returning to freshwater to spawn after 2 to 3 years at sea. In other words, rainbow trout and steelhead trout are the same species....
(Oncorhynchus mykiss) have also been a major cause of decline. Indeed, Macquarie perch populations have failed in significant stretches of relatively pristine upland river that offer excellent habitat, are not silted, dammed or overfished, and where there are no possible explanations for their demise except introduced trout species. Dietary studies have documented significant overlap between the diet of Macquarie perch and introduced trout species, and anglers have observed predation of Macquarie perch juveniles by introduced trout species. Several publications in the 1940s through to the 1960s by the director of the Victorian Fisheries and Game Department (A.D.Butcher) documents predation on juvenile trout cod, Macquarie perch and other upland native fish species by introduced trout species, and major dietary overlaps. Recent research (Lintermans, 2006) records dietary overlaps that are significant by scientific criteria between Macquarie perch and introduced trout species.
Over the last 20 or 30 years, the last few remaining Macquarie perch populations in upland habitats have faltered. All of these populations appear to be in extinction vortices and may disappear completely over the next couple of decades.
Macquarie perch have proved difficult but not impossible to breed. However, no Australian government agency is breeding Macquarie perch, and some government agencies are stocking upland habitats containing remnant Macquarie perch populations with introduced trout species. Not only do these stockings threaten Macquarie perch by competition and predation, but rainbow trout
Rainbow trout
The rainbow trout is a species of salmonid native to tributaries of the Pacific Ocean in Asia and North America. The steelhead is a sea run rainbow trout usually returning to freshwater to spawn after 2 to 3 years at sea. In other words, rainbow trout and steelhead trout are the same species....
fingerlings have been shown to carry significant levels of EHN virus.