Prevention
Animal quarantine
NARRATOR: Disease has the potential to devastate the aquaculture and fishing
industries, slashing profits and in some cases closing the industry. It is vital that we
all act responsibly to prevent the introduction of disease into Australian fisheries.
Movement of live animals
NARRATOR: History has shown repeatedly that the main way to introduce disease
into an aquaculture industry is through the movement of live animals. The spread of
first white spot disease and now taura syndrome throughout the prawn farming
industries in South-East Asia clearly shows that the irresponsible movement of
aquatic animals will inevitably lead to the spread of disease.
LEIGH OWENS, James Cook University: It really comes down to the movement of
live animals. There’s not been a lot of evidence of animals moving in the wild, say
from one country to another country, taking an exotic disease. It’s usually been man’s
intervention, carrying product or carrying live animals from one site to another. So the
fishery can be protected by having strict controls over the movement of live animals.
Purchasing stock
NARRATOR: Stock should only be purchased from reliable suppliers, known to be
disease free and preferably all new stock should come with a health certificate
attesting that they are free from important diseases and pests.
Examination
NARRATOR: When receiving delivery of new stock, check them carefully and reject
batches displaying obvious disease signs.
BRUCE ZIPPEL, Oyster Farmer, Smoky Bay, SA: It’s important that operators
involved with oyster farming ensure that any spat that they have imported has the
proper protocols in place, to ensure that it has the proper documentation and is from
an authorised source. It’s also importation for any of spat, even if it’s from another
bay, or the shifting of oysters between bays, to make sure that there’s nothing being
transported with those oysters.
Containment
NARRATOR: Quarantine procedures in the transport of all fish should be rigorously
enforced, whether they are arrivals from another farm or simply transfers between
ponds or tanks. New animals should be held separately in tanks or ponds to allow for
observation and detection of infections.
Treatment
NARRATOR: In some cases, preventative measures such as salt water treatment
at five to ten parts per million can be undertaken to kill ectoparasites and promote
the healing of wounds caused by capture.
Daily observation of fish appearance, behaviour and feeding activity allows early
detection of problems when they do occur so that a diagnosis can be made before
the majority of the population becomes sick. The most obvious sign of sick fish is the
presence of dead or dying animals. However, the careful observer can usually tell
that fish are sick before they start dying because sick fish often stop feeding and may
appear lethargic. Healthy fish should eat aggressively if fed at regularly scheduled
times. If treatment is indicated, it will be most successful if it is implemented early in
the course of the disease while the fish are still in good shape. It is important to
remember that disease does not occur just because the pathogen is present in the
environment, but is a function of the animal itself, its environment and the pathogen.
COLIN JOHNSTON, Aquatic Animal Health, Primary Industry and Resources,
South Australia: Disease in aquatic animals is not a simple process. It’s a complex
interaction of factors involving the animals themselves, the environment that they live
in and also the presence of the pathogen. It would be extremely rare for just the
presence of a disease agent to cause a disease in aquaculture species. Much more
commonly, there are a number of environmental factors, or host factors, that will
render the animals more susceptible to a particular pathogen.
Understanding the three circles of the importance of the host—the animal—the
importance of the environment and the presence of the pathogen gives you a very
basic approach to some of the things you need to consider if you’re trying to prevent
entry and spread of disease on a farm. You’ve got farm management practices, that
is, how you look after your animals. You want to ensure high water quality at all times
and you want to ensure that the management husbandry procedures are not stressful
on the animals. The second one is the environment, making sure that your facilities
are ensuring good water quality and monitoring that water quality at all times. The
third is obviously you try and prevent the ingress of a pathogen onto your farm or
facility. Here we’re talking fairly basic farm level hygiene practices.
MARK CRANE, Australian Fish Diseases Laboratory at the CSIRO:
If the farm is managed well, you do reduce the risk of disease. Even in the presence
of infectious agents, the fish can be infected but don’t show signs of disease. You
keep the levels of stress down though low handling, good feed, good water quality,
you can reduce the impact of that infectious agent and you may not in fact have and
outbreak of disease in the presence of that organism.
NARRATOR: If disease occurs, seek the advice of a fish health professional as early
as possible.
END