- Endangered, Protected
NSW - Vulnerable, Protected
VIC - Endangered Though limited take allowed from some
National - Endangered, listed under the EPBC Act
on image for larger version
courtesy - Jim Tait
Perch (Macquaria australasica) are medium sized (~2.5
kg max) native fish found in the Murray-Darling system. They
are in the Macquaria genus that also contains Golden Perch,
Australian Bass and Estuary Perch, and they are closely related
to Golden Perch. Macquarie Perch reflect a pattern present in
several other Murray-Darling native fish of speciating into
upland species and lowland species, Macquarie Perch being the
upland species and their relative the Golden Perch being the
lowland species. Macquarie Perch used to be caught regularly
by anglers using bait and artificials including Trout anglers
using fly gear. They were renowned as a strong and exciting
sportfish and an excellent table fish. They are now totally
protected in most states, though some Victorian populations
including one translocated to the Yarra still form part of a
Distribution and Habitat
the term "upland" suggests, Macquarie Perch are primarily
a species of the larger sub-alpine rivers and streams in the
SE corner of the Murray-Darling system. Due to the broad temperature
tolerances all native fish possess, Macquarie Perch where occasionally
recorded from the lowland reaches of the Murray River and southern
tributaries in previous decades. However Macquarie Perch have
an upper temperature limit of 26 degrees and their primary habitat
is the cool, clear, flowing upland rivers and streams now generally
considered prime Trout habitat.
Perch Distribution. Click on map for larger version.
Perch like most native fish are long-lived fish. Extreme longevity
is a survival strategy for native fish in our harsh environment,
as they survive many years to capitalise on exceptional conditions
for spawning and recruitment, when those conditions occur. There
is some uncertainly about their maximum age, but their close
relative the Golden Perch regularly reaches ages of 20 years,
with a maximum recorded age of 26 years and Macquarie Perch
may reach similar ages.
Macquarie Perch have a maximum size of approximately 50 cm and
2.5 kg but fish over 2kg are rare. A more common size for Murray-Darling
Macquarie Perch is 0.5 - 1.5 kg. Like the other species in the
Macquaria genus female Macquarie Perch grow much larger than
male Macquarie Perch and all large Macquarie Perch are females.
Perch spawn in November or December, when water temperatures
reach 15 or 16 degrees. The fecundity of Macquarie Perch is
surprisingly low compared to their relative the Golden Perch,
with a reported egg count of 32,000 eggs per kilogram of fish
weight (i.e. 1.0 kg fish, 32,000 eggs, 2.0 kg fish 64,000 eggs).
Spawning takes place at the head or tail of pools with strongly
flowing water and clean gravel or cobble. The male fertilises
the eggs with a cloud of milt as the female sheds them. The
eggs sink into gaps and cracks in the gravel or cobble where
they are protected until they hatch. Eggs are reported to take
13 - 18 days to hatch depending on temperature.
Perch are not as aggressive predators as Murray Cod, Trout Cod
and Golden Perch. While they will occasionally take small fish,
they are generally aquatic insect eaters. Aquatic insect larvae
such as mayfly, caddisfly and dragonfly larvae make up the bulk
of their diet, with a small amount of terrestrial insects also
taken. Studies have shown that there is a very strong overlap
between the diet of the introduced Trout species and Macquarie
and Causes of Decline
main causes of decline are habitat destruction (particularly
siltation), overfishing, competition and predation by introduced
Trout species, altered flow and temperatures associated with
reservoirs, and possibly disease.
clearing, grazing pressure, associated soil erosion, destruction
of riparian (river-bank) vegetation, and the trampling of river
banks by domestic stock has led to severe siltation of rivers
and streams throughout the Murray-Darling Basin. Like many larger
native predatory fish Macquarie Perch are reliant on deep unsilted
pools as their main habitat. Macquarie Perch also rely on clean
and unsilted gravel and cobble in flowing areas for spawning
sites. Severe siltation can destroy both of these critical areas.
The branches and leaves of native riparian vegetation contributed
to upland rivers and streams are a critical part of the food
chain. Destruction of riparian vegetation results in impacts
to the food chain and food resources for fish in these habitats.
Perch, whether in impoundments or in undammed rivers, will make
strong upstream migrations in late spring or early summer prior
to spawning. There have been shocking slaughters of Macquarie
Perch in the early 1900s by fishermen using both lines and nets
in tributaries of Eildon Dam including the Goulburn River. Catches
exceeding several tons from one pool in one day have been recorded.
(Macquarie Perch populations in Eildon Dam have long since collapsed).
In more recent times anglers have exploited the spawning run
of Macquarie Perch in Dartmouth Dam (now in the process of collapsing
for various reasons), and illegal netters jeopardise remnant
Macquarie Perch populations in several rivers with set nets
that exploit the Macquarie Perch's upstream migrations.
Trout species also significantly impact on Macquarie Perch,
and the Trout Cod often found with Macquarie Perch in upland
rivers and streams.
prey heavily on small fish of any species and cause mortality
of juvenile Macquarie Perch. (NSW Fisheries literature states
that Trout are "known to prey on juvenile Macquarie Perch
and Trout Cod"). With a significantly higher egg count
Macquarie Perch have survived this impact better than Trout
Cod, and have managed to hang on in a few Trout dominated upland
rivers/streams. Many of these populations are now collapsing,
suggesting that over the longer term Macquarie Perch do not
survive well in upland rivers/streams holding introduced Trout.
Trout also compete heavily with Macquarie Perch at all sizes,
juvenile and adult, for food resources, feeding sites and habitat.
Studies have shown that there is a very strong overlap between
the diet of the introduced Trout species and Macquarie Perch.
is not known how much cryptic mortality there may be with juvenile
Macquarie Perch from predation by adult Trout or from intense
competition for food and shelter from juvenile Trout. Saturation
stockings of Trout are likely to be particularly damaging in
Darling Basin Macquarie Perch have no Trout-free habitats. Introduced
Trout species are found in every single larger upland river
and stream in the Murray-Darling system, which were the primary
habitat for Macquarie Perch.
a species conservation perspective there is a strong case for
removing introduced Trout from some large upland rivers/streams
to create upland native fish reserves and re-establishing Macquarie
Perch and other vulnerable natives such as Trout Cod in these
rivers/streams. Unique catch-and-release fisheries could be
another aim of these areas.
flow and temperatures from reservoirs
have a devastating effect on all native fish species including
Macquarie Perch for the same reasons. Dams replace the seasonally
varying temperature regime in a natural upland river with an
artificial uniformly frigid temperature regime due to low level
(deepwater) outlet releases. This interferes with cues for roe
development and spawning, interferes with actual spawning, and
reduces survival and growth of juvenile native fish. In extreme
cases rivers or streams are too cold for native fish to even
live in, though this is not such a problem with the cold-adapted
Macquarie perch. Contrary to popular belief, such an artificial
frigid temperature regime will also usually (depending on the
exact stretch of river) lead to an impoverished invertebrate
population and therefore reduced food resources for fish. Dams
also reduce the height of flood flow peaks experienced in downstream
reaches which are important for flushing out accumulated silt
and 'resetting' instream habitat conditions.
EHN virus is a virus carried by the introduced Redfin Perch.
Research suggests EHN virus was a dormant "native"
virus without a host until Redfin Perch were introduced in the
1860s. Research has proven that it readily infects Macquarie
Perch which have an almost 100% fatality rate. Anecdotally it
has been noted that as redfin expand into areas inhabited by
Macquarie Perch their populations often undergo major reductions
(i.e. lower Murrumbidgee). Fortunately overlap between Macquarie
Perch and Redfin Perch is largely limited to impoundments as
Redfin Perch dislike fast flowing river environments which remain
the primary strong hold for Macquarie Perch. In some instances
fish passage barriers have also been beneficial for halting
the spread of redfin in Macquarie Perch habitats. Of more concern
is research that has shown EHN virus is present in a significant
proportion of Rainbow Trout fingerlings produced in Australia.
Rainbow Trout stockings into remnant Macquarie Perch habitat
may not just be threatening Macquarie Perch through competition
and predation but also through the introduction of EHN virus.
Macquarie Perch species
occurring Macquarie Perch populations are also found in the
coastal Hawkesbury-Nepean and Shoalhaven river systems. These
coastal populations of Macquarie Perch are the result of an
ancient "river capture" events where eastern coastal
catchments have cut westwards into inland drainages. Research
has shown there are now significant taxonomic and genetic differences
between these coastal Macquarie Perch and Murray-Darling Macquarie
Perch, and suggesting that the coastal Macquarie Perch are now
a separate species.
Macquarie Perch appear to inhabit the upper reaches of these
coastal river systems upstream of the main Bass-holding areas.
They exhibit a far smaller maximum size than Murray-Darling
Macquarie Perch of around 15 - 18 centimetres.
situation with the coastal Macquarie Perch species has been
confused by at least two translocations of Murray-Darling species
Macquarie Perch into these coastal catchments. Coastal Macquarie
Perch are reported as being abundant in some areas of the two
coastal systems in which they occur - the conservation situation
with these species may not be as critical as with the Murray-Darling
Perch have largely been forsaken by those that previously loved
them (including rec fishers) and are sliding closer to extinction
every day. While recovery plans are being initiated at a commonwealth
and state (NSW) level, no Fisheries Department is breeding them,
and major knowledge gaps and problems remain for the successful
artificial breeding and recovery of Macquarie Perch. One of
the key challenges is that Macquarie Perch do not respond to
artificial hormone induction techniques used successfully to
breed many other native fish. They appear to require 'natural'
stream flow conditions to 'roe up' and the development of dedicated
facilities with constructed flow chambers may provide one option.
to the limited wild populations of Macquarie Perch remaining,
the production of fingerlings is critically important and could
support several key initiatives including:
Research - particularly on the susceptibility of fish to EHN
virus and also on competitive interactions with trout
Conservation stocking into suitable habitat where the species
has been lost or numbers have become critically low
Establishment of a limited recreational fishery by stocking
into selected impoundments.
option 3, establishment of limited recreational fishery is currently
a much lower priority than conservation and research needs,
limited recreational fisher access in stocked impoundments as
has been done for other endangered species (i.e. the Mary River
Cod in Queensland) would serve to reintroduce recreational fishers
to the species and garnish their support for further investment
in the full rehabilitation of the species.
recreational fishers (in NSW, ACT, Vic) are keen to see this
species rehabilitated they should write to their relevant State
ministers seeking increased investment in the rehabilitation
of Macquarie Perch, particularly the development of successful
artificial breeding techniques. Full recovery of the species
could see this once popular recreational species re-established
as a recreational target in streams as well as impoundments.
Without such concerted efforts the future does not look positive
for Macquarie Perch.
of Environment & Water Resouces