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ACCURATE DATA
Disease Awareness and Control
These observations should be recorded daily, for all stages, including date, time, tank number, broodstock (where there are more than one) and food source. Dates and times of tank and water changes, pipe flushing/back-flushing and/or disinfections, should also be recorded. Ideally, these records should be checked (signed
off) regularly by the person responsible for maintaining the facility. For pond or
net/cage sites, observations that need to be recorded include:
These should be recorded with date, site location and any relevant activities (e.g., sample collection for laboratory examination). As elsewhere, the person responsible for the facility
should check these records regularly. Human activities should also be recorded on
an "as it happens" basis, since there may be time-lag
effects. In all cases, date and time should be recorded, as parameters
such as temperature and pH can vary markedly during the day, particularly
in open ponds and inter-tidal sites. All movements of fish into and out of a hatchery or site should be recorded, including:
Such records are also applicable (but less critical) to movements between tanks, ponds, and cages within a site. Where possible, animals from different sources
should not be mixed. If mixing is unavoidable, keep strict records
of which sources are mixed and dates of new introductions into the
holding site or system. Environmental issues must also be monitored on a regular basis. This is most applicable to open water sites, but should also be included in land-based systems with flow-through or well-based water sources. The minimum essential data that should be recorded
is:
The frequency of these observations will vary with site. Where salinity or turbidity rarely vary, records may only be required during rainy seasons or exceptional weather conditions. Temperate climates will require more frequent
water temperature monitoring than tropical climates. Human activity should be logged on an "as it happens" basis for reference if no infections or natural environmental changes can be attributed to a disease situation. For Crustacean Hatchery operations, the minimum essential information that should be recorded/ logged includes:
These observations should be recorded on a daily basis for all stages, and include date, time, tank, broodstock (where there are more than one) and food-source (e.g., brine shrimp culture batch or other food-source). Dates and times for tank and water changes should also be noted, along with dates and times for pipe flushing and/or disinfections. Ideally, the person responsible should check these logs regularly for the site/animals.
These should be recorded with date, site location and any action taken (e.g., sample collection for laboratory examination). It is important to understand that rates of change for these parameters are essential for assessing the cause of any disease outbreak. This means levels have to be logged on a regular and consistent basis in order to detect patterns over time. Ideally, the person responsible for the site/animals should check these logs regularly. If an outbreak does occur, the collection of accurate data that can be passed on to the lab, could mean the difference between a quick and effective diagnosis; and therefore a remedy; or a total loss of all animals!
ANIMAL
SAMPLES "Normal behaviour" of the animals should be observed from day one to establish and describe the "normal" situation. Any change from this normal behaviour should be a cause for concern and warrants further investigation. With finfish, abnormal behaviour includes fish swimming near the surface, sinking to the bottom, loss of balance, flashing, corkscrewing or air gulping (non air-breathers) or any sign which deviates from normal behaviour. Bursts of abnormal activity are often associated with a generalised lethargy. If losses persist or increase, samples should be sent for laboratory analysis. Mortalities that are unusual, or cannot be explained should be examined immediately and environmental factors during, pre- and post-mortality recorded. Some jurisdictions require farmers to report such mortalities. It is difficult to observe behavioural changes in molluscs in open-water, however, close attention can be made of behaviour of both broodstock and larvae in hatcheries. In Crustaceans such as prawns, this may be a subtle change in feeding behaviour, swimming movement or unusual aggregations. Even predator activity can provide clues to more "hidden" changes such as when fish- or shrimp-eating birds congregate round affected ponds. Since disease situations can erupt very quickly under hatchery conditions, regular and close monitoring is essential; for example, feeding behaviour of larval molluscs is a good indicator of general health. Mortalities that spread from one area to another may suggest the presence of an infectious disease agent and should be sampled immediately. Affected animals should be kept (isolated) as far away as possible from unaffected animals until the cause of the mortalities can be established.
A Contingency Plans will help clarify whether handling stress, change of environment or infectious agents are causes for concern. It will also help speed up diagnosis, risk assessment, and husbandry management and treatment recommendations. The most important factors associated with collection
of specimens for surveillance are:
Environmental changes (rapid water quality changes, such as turbidity fluxes, saltwater incursion into freshwater ponds, unusual weather events, etc.) should also be noted and information on these events should be included with the specimens. It's critical to establish, and record, normal behaviour and appearance to compare with observations made during disease events. Accurate record keeping is, therefore, an essential
component of effective aquatic animal health management.
Disease Awareness and Control
Some aquaculture farmers may hesitate to report the first signs of health problems, due to concern that it may reflect on their production capability, or that it will result in failure in the competitive market place. Hiding or denying health problems, however, can be as destructive to aquatic animals as it is in other agriculture endeavors. It is important to recognise that disease is a challenge that everyone has to face, and having the resources that can effectively deal with it, are the primary weapons against misplaced ignorance and fear. Every State Government has a representative that can be contacted if an exotic or other disease is suspected. In Western Australia and in Tasmania the State Governments provide a diagnostic framework and encourage farmers to make them the first port of call. There are also local vets, commercial laboratories and specialists at many of the TAFE and University based training Institutions, and of course AFFA from the Australian Government. The main thing is to act responsibly…and
quickly!
Disease Awareness and Control All samples submitted for disease diagnosis should include as much supporting information as possible including:
This information will help clarify whether handling stress; change of environment or infectious agents may be a factor in the observed abnormalities/mortalities. Such information is necessary for both rapid and accurate diagnosis, since it helps focus the investigative procedures required. If being shipped by air also indicate "HOLD AT AIRPORT AND CALL FOR PICK-UP" In some cases, samples may be unable to be delivered live to a diagnostic laboratory due to distance or slow transport connections. In such cases, diagnostic requirements should be discussed with laboratory personnel before you collected your samples. Shipping of non-preserved tissues or dead specimens may require precautions to prevent contamination or decay. In any event animals that are putrid, or have been dead for any significant length of time, will generally not be suitable for diagnosis. The laboratory should be informed of the estimated time of arrival of the sample, in order to ensure that the they have all the materials required for processing prepared before the fish arrive. It is worth noting that many postal services and transport companies (especially air couriers) have strict regulations regarding shipping chemicals, including preserved samples. If the tissues have been adequately fixed, most fixative or storage solution can be drained from the sample for shipping purposes. As long as sufficient solution is left to keep the tissues from drying out, this will minimise the quantity of chemical solution being shipped. The carrier should be consulted before samples are collected to ensure they are processed and packed according to shipping rules. In the case of live samples, clearly indicate the name and telephone number of the person responsible for picking up the package, or receiving it at the laboratory. Where possible, ship early in the week to avoid delivery during the weekend which may lead to improper storage and loss of samples. Call the lab first to ensure that the samples are
properly collected and packaged and that the samples are expected.
Inform the contact person as soon as the shipment has been sent
and provide the name of the carrier, flight number, and waybill
number and estimated time of arrival, as appropriate.
Disease Awareness and Control |
