Home' Know How : KnowHow Issue 2 Contents 26 KnowHow magazine
New tools in the fight
against fish ferals
Dr Dean Gilligan (above) leads the
Invasive Animals CRC’s inland water pest program.
Inset and below: Australia’s carp crisis.
DNA detection and virus research are two tools being
used by scientists battling to control the proliferation
of feral fish in Australian waters, reports Rosslyn Beeby.
“They dig around in the bottom of rivers, pull out
vegetation, stir up mud and generally trash the
habitat for native species. They’re also bullies.”
THEY’RE KNOWN AS the
rabbits of Queensland’s rivers.
Tilapia were introduced into
Australia in the 1970s through the
aquarium trade, and these African
exotics are now one of the country’s
most destructive pest fish.
“ They’re like little bulldozers
in a river,’’ says aquatic ecosystems
biologist Dr Dean Gilligan. “ They dig
around in the bottom of rivers, pull out
vegetation, stir up mud and generally
trash the habitat for native species.
They’re also bullies. They’re extremely
aggressive toward native fish – and,
unfortunately, can breed up into
a very large biomass, just like carp.”
Gilligan is a senior fisheries research
scientist with the NSW Department of
Primary Industries, and leads the CRC’s
inland water pests research program,
whose focus is to develop new technologies
to detect and better control pest fish.
With researchers at the University
of Notre Dame in Illinois, US, scientists
from the Queensland Department of
Agriculture, Fisheries and Forestry and
James Cook University have been
working to develop a DNA surveillance
technique to detect the presence of
tilapia in creeks and other waterways.
The spread of tilapia has so far been
confined to Queensland, where their range
includes one of the state’s biggest river
systems – the Burdekin. Several outbreaks
in West Australian rivers near Geraldton
were controlled thanks to early detection.
Preventing the spread of the fish,
particularly to the Murray-Darling
Basin, is a key concern of the CRC.
Tilapia can thrive in polluted and
degraded waterways, and are fast, prolific
breeders. Several were added to an
ornamental pond at a hotel golf course
in Port Douglas, near Cairns. Two years
later, an eradication program removed
16 tonnes of tilapia from the pond.
Gilligan says the DNA surveillance
technique being developed by the
Invasive Animals CRC will enable
fisheries officers to more efficiently
detect pest fish, even in low numbers.
“Instead of sending a whole team
of people out with a boat, nets and
a pile of equipment for several days,
we can send one person, with a bucket,
to collect around nine to 10 litres of
water from a river,’’ Gilligan says.
The water is filtered, using fine filter
paper, and when filtration is complete,
the paper is analysed using a standard
polymerase chain reaction laboratory
test to detect DNA fragments.
“It’s not instantaneous. It takes a couple
of days to filter the water and run the
test, but it’s a much faster, more reliable
[method] of measuring pest fish incursions
in a river than using nets, lines and boats.
Once the test result is back, we can run
a risk assessment and
move on to developing
an eradication program.”
The DNA surveillance
technique was originally developed
in the US to detect carp, which are
now among Australia’s most destructive
environmental pests. The CRC is also
evaluating a naturally occurring virus
found overseas as a biological control agent
to reduce carp impact. Dr Ken McColl,
a veterinary virologist at the CSIRO
Australian Animal Health Laboratory
in Geelong, is leading the research.
McColl is conducting tests to confirm
the findings that this carp herpes virus is
effective and that it is safe for release into
Australia’s waterways to control carp
without affecting humans or native species.
If successful, the strategic control program
will open up new areas of research.
“ We’d see unprecedented massive fish
kills of carp in rivers, so we need to look
at ways to manage collection and disposal
of thousands of dead carp,” says Gilligan.
“Do they go to council tips as landfill, or
could they be ploughed into paddocks as
fertiliser? That ’s all part of the challenge
of developing an eradication technique.”
Links Archive KnowHow Issue 3 KnowHow Issue 1 Navigation Previous Page Next Page