TRANSPORT OF SMALL LIVE JUVENILE REDCLAW
Broad Aim: To find an ideal method of transporting juveniles
Specific Objectives: To determine the level of post transport and in transport survival
of small (approx 2gm.) redclaw transported in a water bag filled with oxygen.
Need:
The Redclaw Industry is presently in the throes of adopting a mature outlook towards the practice
of juveniles being produced in specialised hatcheries with controlled
breeding protocols, rather than the present haphazard practice of every
farm rearing its own.
Successful transport of juveniles is seen to be a major stumbling block
to this advance and the ability to transport small animals would limit their production cost
Method:
Pack animals as above and simulate transport conditions for 24, 36 and 48
hours.
Release to holding tank and observe. Note any mortalities upon release and in subsequent days.
Compare with control batch not transported. If this successful, extend transport time until limit is determined.
Resources:
Packing boxes, liner bags, oxygen, holding tanks, approx 50k of 2gm.
redclaw
Outcomes:
To prove or eliminate this method of transport as a preferable alternative
to present methods.
To possibly pave the way for modernisation of the industry.
TRANSPORT OF LIVE REDCLAW WITH OXYGEN
Broad Aim:
To delermine the benefit of oxygen in transport
Specific Objectives:
To compare the survival level and vitality of crayfish transported
in oxygen,
to other means of packaging
Need:
Successful exploitation of lucrative export enquires have been hampered by
the difficulty in complying
with customers requirements that the redclaw be able to be displayed
live following delivery, A transport method needs to be perfected
so that these enquires can be handled with confidence.
Method:
This experiment can best be run in parallel with "Packaging 01", either as an alternative
or addition to the methods described therein- Oxygen can be introduced
into the box
after packing through a tube inserted through a small hole in the lid to the bottom of the box,
another being made in the lid to vent the air. Both holes are sealed
after introduction of oxygen.
Resources: Foam boxes, oxygen, redclaw,
Outcomes: To optimise packaging of redclaw, particularly for extended periods of transport.
DETERMINE EFFECTIVENESS OF PACKAGING FOR LIVE REDCLAW
Proponents: QCFA
Broad Aim: To optimise the packaging for the transport of live Redclaw.
Specific Objectives:
To assess the effect of ice pack size and placement on the core temperature
of live crayfish over typical transport times.
To assess the effect of pre-cooling on the core temperature of live crayfish.
To gauge the effect of temperature on the survival and vitality during transit.
To provide growers with best practice information.
A large proportion of Redclaw is transported live. There has been a history
of some mortality
during and after live transport. In addition, vitality is very important to buyers
but is suppressed by over cooling in transit. There is a need to optimise
the packing techniques and package configuration to maximise the yield to the grower.
Methods:
Conduct a literature search and summarise the available information.
Assess the vitality of Redclaw as a function of time and core temperature.
Generate a best practice manual for packaging of live Redclaw.
Resources required:
Access to crayfish prior to shipment.
Temperature and humidity data loggers.
Facility to pre-cool crayfish shipments.
Expected Outcomes:
An understanding of how the core temperature of crayfish is influenced by
the packing technique.
An understanding of the effect of core temperature and air humidity on
crayfish vitality during transport.
A best practice manual for packaging of live Redclaw.
REDCLAW HABITAT - REVIEW EXISTING USE IN FARMS
Proponents: QCFA
Broad Aim:
To gain an understanding of the habitat currently used by farmers.
Specific Objectives:
To document a cross section of the Redclaw industry of habitat types and
quantities used,
and correlate with farm output.
Survey farmers on what is currently used and canvas opinions on what is
most effective.
To document any trials that farmers have conducted in the past.
To ensure current knowledge is shared within the industry and researchers.
The development of suitable habitat has been identified a critical factor in the success of the Redclaw industry.
Development work should not proceed until the current state of knowledge is assessed.
Methods:
Use the DPI benchmarking information to select farms.
Visit farms and document habitat used and trial work undertaken.
Summarise data and analyse for trends.
Hold workshops on the results.
Resources required:
Access to the DPI benchmarking work and extension officers.
Access to farmer's time and facilities.
Travel and telephone.
Expected Outcomes:
A summary of habitat types and quantities and indications of their costs and effectiveness.
Recommendations of the work required for habitat development
REDCLAW TRACKING PROJECT
FEEDING:
Experiment:
Determine from what distance an average commercial feed (eg Ridleys) is detected.
Outcomes:
Knowledge of necessity for feed distribution Optimum trap spacing
Experiment:
Compare response to different feeds, eg various commercial diets; grains; other such as potato
Outcomes:
Determine usefulness of various attractants used in commercial diets
Compare artificial attractants to natural food source
Experiment:
Examine time response to scattered feed, feed at intervals and feed at central point.
Outcomes:
Knowledge of degree of stability in water necessary
Experiment:
Feed at different intervals and different times of day.
Outcomes:
Knowledge of degree of interest in feed at different intervals and optimum time of day to feed.
HABITAT:
Experiment:
Distribute various habitat types - (tyres; bread box stacks; mesh bundles -fine and prawn net;
pipe stacks - backed/unbacked - holed/solid - mesh/solid - black/coloured - smooth/convoluted -
various sizes - Formosa commercial; milk bottle bundles) throughout the pond and up to the water line,
and where applicable, (bread box stacks and mesh bundles) up to the surface
Outcomes:
Preference for hide type - day/nite
Preference for hide position - day/nite
Preference for hide type with respect to cray size
Overall habitat usage with respect to day/nite, hunger etc
Usage of water column - how near to surface/ far from bottom are crays comfortable?
FURTHER WORK ON THE EFFECTS OF PURGING ON SURVIVAL
Broad Aim: To maximise post purge survival
Specific Objectives:
To extend the objectives in "Purging 01" to determine minimum purging times for different
commercial sizes of redclaw
To determine the subsequent effect on survival of redclaw subjected to low oxygen and high ammonia
levels during purging
To examine those animals that die and those that survive for the presence of SMV or other
factors that may influence their resistance to purging stress, such as
proximity to moult cycle
Need: As production levels increase, more demands will be placed on farm purging facilities and the
minimum time redclaw need to be in the tanks will become critical.
The conditions in the purge tank are known to be an important factor for post purge survival,
but no quantitative acceptable levels have been established, nor has the
benefit of disease free animals been established-
Method:
Purge samples of various commercial size grades of crayfish and examine gut contents at intervals
Subject crayfish to varying degrees of less than ideal conditions and determine acceptable levels
Comparison of least robust animals with survivors by DPI and JCU pathologists
Resources: Purge tanks and crayfish
Outcomes: Additional information to add to the Best Practice manual compiled in "Purging 01"-
Determining the benefit of disease free animals with regard to withstanding purging stress
GENERAL BEHAVIOUR
Experiment:
General observations in the course of the experiment
Outcomes:
Information gained regarding:-
General usage of pond - day/nite
Does pond "age" effect areas of pond and habitat usage deteriation of pond bottom condition)
Degree of crapusculance
General grazing between meals
Avoidance of predators
BE ON THE LOOKOUT FOR ANYTHING TO TALLY THE UNEXPECTED!!!!!!
Increased knowledge, awareness and interest of habitat by farmers.
