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Ref:576/03 |
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AUSTRALIA
- Mar 5, 2003 |
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Steel Fish Cages to Hold Fish
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Steel cages may be the
answer to the Yellowtail Kingfish industry overcoming
the number of escapees from existing nets, but
problems associated with damage to the fish will need
to be looked into before local farmers give the go
ahead for their installation.
The steel cages, manufactured by One Steel, are
similar in appearance to a chain-link fence (like the
mesh surrounding most tennis courts) but have about 12
times the amount of zinc coating to slow the rusting
effect.
The cages are strong enough to keep even the biggest
sharks from making holes in the net, which in turn
means the number of escapes would be kept to a
minimum.
The problem with the cages, according to Clean Seas
Aquaculture, Arno Bay, is that the fish will rub up
against the abrasive surface to try and rid themselves
of the Skin and Gill Fluke (parasite) which will
damage their skin which makes them less attractive
when sold.
Skin and Gill Fluke are naturally occurring parasites
which are endemic to Yellow Tail Kingfish, both wild
and farmed.
The Fluke live on the fish and their eggs are laid on
the weed build up on the cages. When the larvae are
big enough they then attach themselves onto the fish.
"Although our company thinks the steel cages are
marvellous and have been talking about a trial, we'd
have to get over this issue of fish rubbing against
the steel cage," Clean Seas manager Stephen Clark
said. He said one advantage the steel cages have shown
in early tests over traditional nylon nets is that the
weed doesn't tend to build up as much on the steel
cages which obviously means fewer Fluke building up.
He said he'd like to see the cages tested by Primary
Industries and Resources to see if the problem could
be overcome before the private operators used the
cages.
Mr Clark said a 40 metre steel cage, which could last
about three years, cost around $30,000 which compared
to the traditional nylon net, however the nylon nets
last for about six or seven years.
Reports of escaped Yellow Tail Kingfish have been
plaguing the industry for some months now, with South
Australia's peak recreational fishing body – South
Australian Recreational Fishing Advisory Council (SARFAC)
last week claiming up to 18,000 fish have escaped from
pens within South Australia. This claim however was
refuted by the State Government who said the figure is
closer to 9000.
(A One Steel representative was contacted but didn't
return calls in time for publication.) |
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