Download Silver Perch (Bidyanus bidyanus) fact sheet

THREATENED SPECIES AND COMMUNITIES OF THE ACT
Fact Sheet No. 26
SILVER PERCH
(Bidyanus bidyanus)
An endangered species
The Silver Perch (Bidyanus bidyanus) is a
moderate to large fish (maximum length of
about 500 mm and a maximum weight of about
8 kg) which commonly reaches 300-400mm in
rivers and 0.5-1.5kg. The body is elongate and
slender in juvenile and immature fish,
becoming deeper and compressed in adults.
The head is relatively small, jaws are equal in
length and eyes and mouth are small. The
scales are thin and small and the tail is weakly
forked. The lateral line follows the profile of
the back. Colour is generally silvery grey to
black on the body with the dorsal, anal and
caudal fins also grey. The pelvic fins are
whitish.
There are anecdotal angler records of the
species from the Molonglo River in the 1940s
and 1950s but no contemporary records exist
for this river (other than stocked fish). In the
Canberra region, Silver Perch are also known
from stocked populations at four locations:
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Conservation threats
The major threats to the continued survival of
native fish species in freshwater habitats
include:
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Illustration: Murray-Darling Basin Commission
Googong Reservoir on the Queanbeyan
River;
Yass weir pool on the Yass River;
Lake George; and
Burrinjuck Reservoir.
alteration or destruction of fish habitat;
alteration of flow regimes;
barriers to fish movement;
impacts of introduced fish species; and .
overfishing.
All of these threats are thought to have
impacted on populations of Silver Perch.
The species was formerly widespread over
much of the Murray-Darling Basin (excluding
the cooler upper reaches) but has declined over
most of its range. Little is currently known of
the species’ habitat requirements.
The exotic EHN virus, which is widespread
throughout the ACT region, is lethal to Silver
Perch in laboratory studies and may also
constitute a severe threat to wild populations.
In the Canberra region the species has been
recorded from the Murrumbidgee River,
generally downstream of Kambah Pool.
Formerly, Silver Perch from Lake Burrinjuck
migrated upstream to the lower reaches of the
Murrumbidgee River in the ACT in spring and
summer, however, this migration has not been
recorded since the late 1970s to early 1980s.
Conservation threats will be addressed through
the following strategies:
Conservation actions
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There are still occasional angler reports of
Silver Perch from the Murrumbidgee River in
the ACT, but the species has not been recorded
in the ACT Government fish monitoring
program since the 1980’s.
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Improving understanding of the biology
and ecology of the species as the basis for
managing its habitat;
Protecting sites and habitats that are
critical to the survival of the species;
Managing activities in the Murrumbidgee
catchment in the ACT to minimise or
eliminate threats to fish populations; and
Increasing community awareness of the
need to protect fish and their habitats.
The primary source of information for this Fact Sheet is
the conservation Action Plan No. 26 where a full
bibliography is available. Action Plans are available
from the Environment ACT Website:
www.environment.act.gov.au
Environment ACT Helpline: (02) 6207 9777