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| The average weight of Carp is 4-5 kg. Their maximum
size is 120 cm and weighing 60 kg. |
Native to Asia Minor, Carp were first introduced to Australia in 1850
and they are now widespread throughout the Murray-Darling Basin. They
are present in bodies of water that are located below 800 metres. However,
they are also very common in water
bodies below 500 metres. Carp are considered to be the most widely-distributed freshwater fish.
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IN THE PAST
Carp were introduced into Australia in 3 stages; in 1850, 1876
and in 1961. Since the 1960s, Carp numbers have become large and they
have become very widespread. Their rapid spread was probably helped along
by the large floods that occurred in 1974-1975. |
TODAY
Carp are extremely abundant in the Basin and they are the most
commonly caught fish in inland waters. Carp make up over 80% of the fish
found in the Basin. |
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| SLOPES & TABLELANDS |
PLAINS |
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| LAKES
AND DAMS |
Carp are present in all but the highest mountain regions,
but they can thrive in cool water environments. Carp are very tolerant
to poorly-oxygenated water.
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| AQUATIC PLANT BEDS |
| Carp prefer still or slow-flowing water and where there
are lots of aquatic plants. |
MATING
Carp mature early
in some areas, males at one year and females at two years. |
SPAWNING
Carp spawn in
shallow water in spring (September-December) when water temperatures
reach 17-25°C. Females release large numbers of eggs. Between 100,000
and 300,000 per kilo of their bodyweight can be produced. |
EGGS
Sticky Carp eggs are deposited over on any plant material in shallow
water. They hatch after only a few days. |
JUVENILES
Young Carp grow rapidly in warm water that contains great amounts
of zooplankton.
After one year Carp are 18 cm long, and they reach 50-70 cm long within
two years. |
| Carps’ diets are variable and include aquatic molluscs, crustaceans, insect
larvae, soft plant material and detritus (during
winter when other food is unavailable). They feed by sucking in water
and then filtering out food using their gill rakers. |
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| Carp may migrate to
newly-flooded billabongs to
spawn. In rivers they may move large distances to escape low water flow
and rising temperatures. Any other movements that Carp make may be only
short and not made very often. Carp are active swimmers and can swim
in very strong river flows, jumping over obstacles that are up to 1 metre
in height. |
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IN THE PAST
There is no historical fishery because numbers of Carp have
only reached reasonable catching levels since the 1960s. |
TODAY
Carp are a viable commercial fishing
proposition. Carp fisheries are expanding in New South Wales, Victoria
and South Australia. Current uses of Carp include fertilisers, pet food
and dead bait. |
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IN THE PAST
Carp are not traditionally a species targeted by fishers. |
TODAY
Most fishers consider Carp a pest, however some catch them
because they like their flavour. |
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LEGAL SIZES
There are no size limits on Carp that can be caught. This applies
to all States of Australia. |
CATCH LIMITS
There are no limits on the number of Carp that can be caught
each day. This applies to all States of Australia. |
CLOSED SEASONS
Carp can be caught all year round in all States of Australia. |
BAIT
Carp are not generally targeted by fishers, but they are caught
using bait and lures.
They are considered pests in most States so they cannot be used as
live bait. |
| River
regulation has created conditions that favour the fast breeding
and spreading of Carp. Only large-scale removal of them or other control
measures appear to threaten this species. |
REMEDIES?
Carp are considered to be one of the most harmful of the alien species
of fish found in the Basin. They are called 'underwater rabbits' because
of their numbers are in plague proportions. Carp are currently the target
of active control programs in every State of Australia. |
CONTROL PLANS
Although there is wide agreement that Carp numbers should be reduced,
control efforts are being hampered by the lack of information on the
impact of Carp on the environment, how they are dying out, and details
of their reproductive habits. Nonetheless, there are several options
for reducing Carp, and each has its benefits, disadvantages and costs.
Effective control of Carp will require the application of a combination
of techniques which include:
- Environmental Rehabilitation - This includes
taking actions that will increase the numbers
of native fish,
such as creating fishways,
and
revegetating river banks, re-snagging rivers
and looking at ways to release warmer water
from dams. These are viewed as a necessary
part of river management, but their direct
effects on Carp are unknown.
- Physical Removal - Catching large number of
Carp is already under way on a small scale
and more licences are being issued. To be
effective, at least 98% of carp must be
removed, which may be very expensive, or
impossible to achieve. Methods include
netting and electrofishing.
- Reduce Carp Reproduction - This strategy
involves reducing the numbers of Carp eggs
that have been laid in shallow habitats such
as billabongs and wetlands where most
spawning activity occurs. This technique
involves lowering the level of water by 45-60
cm to expose and dry out the Carp eggs. The
technique is being researched and could
work well in wetland and billabong habitats.
- Chemical Poisoning: - While this is possibly
an effective method, poisoning is very
expensive and may only work in small or
closed bodies of water. In addition, chemical
poisoning would not be acceptable for the
general environment, and would only be able
to be used in habitats such as irrigation
channels where the water quality is poor and
the environment is no good.
- Biological Techniques - These include
pathogens (usually viruses), immuno-
contraception (interfering with reproduction)
and interfering with the genetic make-up of
the Carp. None of these techniques are
currently being used, but they are currently
the subject of research and management
studies. |
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