Redclaw Crayfish Aquaculture

Redclaw Crayfish Aquaculture

Edited by CM Jones

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C.M. Jones (editor)

Recommended Practices for Redclaw Crayfish Aquaculture based on Research and Development Activities, 1988 through 2000. Northern Fisheries Centre, Department of Primary Industries and Fisheries Cairns Q 4870, Australia [email protected]

mailto:[email protected]

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PREFACE Interest in the aquaculture of redclaw crayfish has continued to be strong since initial assessments of this species were made in the late 1980's, through both Industry trials and Department of Primary Industries and Fisheries research. Considerable Industry development has occurred since that time, although with limited success. Unlike the development of most other Australian aquaculture industries for which existing technologies established elsewhere have been transferred, redclaw aquaculture has developed independently. This is primarily because existing crayfish aquaculture technologies are not suitable for redclaw. In virtually every aspect of the production technology for redclaw, there have been no established procedures or standards. It is the development and definition of these procedures and standards which constituted the broad goal of redclaw research activities at the Freshwater Fisheries and Aquaculture Centre, Walkamin, through to 2000. This work has been financially supported by the Fisheries Research and Development Corporation (FRDC), the Australian Centre for International Agricultural Research (ACIAR), and Queensland Department of Primary Industries and Fisheries who have all contributed to the research program. An integral part of this program is the transfer of information and technology to industry. This has been achieved through a variety of means, the most direct being the presentation of seminars. This publication represents background notes for these seminars as they were presented through the late 1990’s. I would like to acknowledge all those who made contributions which led to the preparation of this publication. Jo Grady (DPI&F Walkamin) and Greg Love (crayfish farmer) provided presentations at the seminar. Thanks also to Peter Long, Millin Curtis, Ian Ross, Colin Bendall, Andrew Hinton and Maurice Downing (all of the DPI&F&F) who provided information and /or assistance with the preparation of the notes. Clive Jones

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CONTENTS PREFACE ............................................................................................................................................... III CONTENTS ............................................................................................................................................IV FIGURES ................................................................................................................................................VI TABLES..................................................................................................................................................VI A SITE ASSESSMENT FOR SUITABILITY OF FARMING REDCLAW............................................ 1

Summary .............................................................................................................................................. 1 Location and Services.......................................................................................................................... 1 Climate and Water Quality.................................................................................................................. 1 Soil Types............................................................................................................................................. 2 Alternative Crops................................................................................................................................. 3 Water Resources Comment.................................................................................................................. 3 Charleville Redclaw Farm................................................................................................................... 3 Local Issues ......................................................................................................................................... 4

INTRODUCTION TO REDCLAW ......................................................................................................... 6 Introduction ......................................................................................................................................... 6 Historical Perspective ......................................................................................................................... 6 Biological Characteristics ................................................................................................................... 7 Feeding Characteristics....................................................................................................................... 8 Growth Rate......................................................................................................................................... 8 Reproduction ....................................................................................................................................... 9 Life Cycle............................................................................................................................................. 9 Disease and Parasites ....................................................................................................................... 10 Farming Technology.......................................................................................................................... 10 Summary ............................................................................................................................................ 10

SITE REQUIREMENTS........................................................................................................................ 12 Site Requirements .............................................................................................................................. 12 Site Suitability Criteria ...................................................................................................................... 12

POND AND CONSTRUCTION ENGINEERING ISSUES .................................................................. 15 Water Supply...................................................................................................................................... 15 Construction Materials...................................................................................................................... 15 Pond Design ...................................................................................................................................... 15 Pond Details ...................................................................................................................................... 16 Lining Materials ................................................................................................................................ 16 Basic steps in Pond Construction ...................................................................................................... 17

PRODUCTION TECHNIQUES FOR REDCLAW ............................................................................... 18 Introduction ....................................................................................................................................... 18 Farm Layout Considerations............................................................................................................. 19 Juvenile Supply .................................................................................................................................. 19 Stock Management............................................................................................................................. 21 Harvesting ......................................................................................................................................... 22 Feeding .............................................................................................................................................. 22 Pond Management............................................................................................................................. 23 Outcome............................................................................................................................................. 24

FARM MANAGEMENT ....................................................................................................................... 26 1. Your Objective ............................................................................................................................... 26 2. Recognising the Processes............................................................................................................. 26 3. Developing the Strategy................................................................................................................. 26 4. Allocating Resources ..................................................................................................................... 28 5. Setting Timetables.......................................................................................................................... 28 6. Identifying Assessment Criteria and Standards............................................................................. 29 7. Assessing Performance.................................................................................................................. 29 Conclusion ......................................................................................................................................... 30

WATER QUALITY ............................................................................................................................... 31 Pond Preparation .............................................................................................................................. 31 Managing plankton............................................................................................................................ 34

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Pond dynamics................................................................................................................................... 35 Record Keeping ................................................................................................................................. 38

REDCLAW ECONOMICS.................................................................................................................... 39 Summary ............................................................................................................................................ 39 Introduction ....................................................................................................................................... 40 Results................................................................................................................................................ 40 Sensitivity analysis............................................................................................................................. 48 Provision of Initial Stock ................................................................................................................... 50

INDUSTRY OVERVIEW (1994) .......................................................................................................... 54 REDCLAW MARKETING ................................................................................................................... 56

Introduction ....................................................................................................................................... 56 Overseas Markets .............................................................................................................................. 56 Domestic Market................................................................................................................................ 58 Product Issues.................................................................................................................................... 58 Pricing & Its Implications ................................................................................................................. 60 Promotion .......................................................................................................................................... 60 Summary ............................................................................................................................................ 60

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FIGURES FIGURE 1. DIAGRAM OF REDCLAW LIFE CYCLE.......................................................................................... 9 FIGURE 2. LAYOUT OF A HYPOTHETICAL REDCLAW FARM CONSISTING OF FORTY 1,000M2 PRODUCTION

PONDS. ........................................................................................................................................... 19 FIGURE 3. ESTIMATING AGRICULTURAL LIME APPLICATION RATE. (MODIFIED FROM BOYD, 1990). ........ 33 FIGURE 4. TYPICAL CHANGES IN PLANKTON DENSITY AFTER POND FILLING IN WELL MANAGED PONDS. . 34 FIGURE 5. TYPICAL WATER TEMPERATURES OVER 24 HOURS IN A REDCLAW POND IN NORTH

QUEENSLAND DURING SUMMER..................................................................................................... 35 FIGURE 6. TYPICAL PH LEVELS OVER 24 HOURS IN A REDCLAW POND IN NORTH QUEENSLAND. LEVELS

ARE GIVEN FOR LOW ALKALINITY (<20PPM) AND HIGH ALKALINITY (>50PPM) WATER.................. 36 FIGURE 7. TYPICAL DISSOLVED OXYGEN LEVELS OVER 24 HOURS IN A REDCLAW POND IN NORTH

QUEENSLAND. ............................................................................................................................... 37 FIGURE 8. ACCUMULATIVE CASH FLOW OVER TIME FOR A MODEL REDCLAW FARM WITH 53 X 750M2

PONDS. ........................................................................................................................................... 51 FIGURE 9. PERCENTAGE BREAKDOWN ON OVERHEADS FOR MODEL REDCLAW FARM WITH 53 X 750M2

PONDS. ........................................................................................................................................... 52 FIGURE 10. PRICE AND RETURN TO CAPITAL AND MANAGEMENT FOR A MODEL REDCLAW FARM WITH 53 X

750M2 PONDS. ................................................................................................................................ 52 FIGURE 11. TOTAL POND AREA VERSUS RETURN TO CAPITAL AND MANAGEMENT FOR A MODEL REDCLAW

FARM WITH 53 X 750M2 PONDS. ..................................................................................................... 53

TABLES TABLE 1. ESTIMATED WATER TEMPERATURES FOR AQUACULTURE PONDS AT CUNNAMULLA. .................. 2 TABLE 2. PREFERRED RANGE OF SELECTED WATER QUALITY PARAMETERS OF SOURCE WATER, FOR

REDCLAW AQUACULTURE. ............................................................................................................. 13 TABLE 3. WATER QUALITY PARAMETERS, THEIR PREFERRED RANGE AND MEASUREMENT FOR REDCLAW

AQUACULTURE............................................................................................................................... 24 TABLE 4. LIMING AND NON-LIMING COMPOUNDS USED FOR AQUACULTURE PONDS. ............................... 31 TABLE 5. ESTIMATED FEED COSTS FOR A MODEL REDCLAW FARM WITH 53 X 750M2 PONDS. .................. 41 TABLE 6. ALLOCATION AND COSTS OF HIRED LABOUR FOR REDCLAW FARMS OF VARYING SIZE.............. 42 TABLE 7. TOTAL CAPITAL COSTS FOR A MODEL REDCLAW FARM WITH 53 X 750M2 PONDS...................... 43 TABLE 8. DISCOUNTED CASH FLOW FOR MODEL REDCLAW FARM WITH 53 X 750M2 PONDS WITH POND

LINERS. .......................................................................................................................................... 45 TABLE 9. DISCOUNTED CASH FLOW FOR MODEL REDCLAW FARM WITH 53 X 750M2 PONDS WITHOUT POND

LINERS. .......................................................................................................................................... 46 TABLE 10. SUMMARY OF ECONOMIC ANALYSIS FOR A MODEL REDCLAW FARM WITH 53 X 750M2 PONDS,

USING A FARM-GATE PRICE OF $10.00/KG. ..................................................................................... 47 TABLE 11. VARIATIONS IN FARM-GATE PRICE ON RETURN TO MANAGEMENT FOR A MODEL REDCLAW

FARM WITH 53 X 750M2 PONDS. ..................................................................................................... 48 TABLE 12. VARIATIONS IN REDCLAW YIELDS ON RETURN TO MANAGEMENT FOR A MODEL REDCLAW

FARM WITH 53 X 750M2 PONDS. ..................................................................................................... 49 TABLE 13. COST OF PRODUCTION AND RETURN TO MANAGEMENT FOR REDCLAW AQUACULTURE WITH

VARIOUS TOTAL POND AREA. ......................................................................................................... 50 TABLE 14. COST AND POND ALLOCATION FOR STOCKING A MODEL REDCLAW FARM WITH 53 X 750M2

PONDS. ........................................................................................................................................... 51

REDCLAW CRAYFISH AQUACULTURE 1

A SITE ASSESSMENT FOR SUITABILITY OF FARMING REDCLAW Peter Long

Summary In July 1994, a preliminary assessment of redclaw production in South-West Queensland was undertaken. Information was gathered on environmental conditions, soil characteristics, local services available, land-holder interest, government agency comments, Paroo Shire support and existing redclaw production experiences. Five interested land-holders were interviewed at length, which provided a fruitful exchange of ideas and concepts. The Paroo Shire Council representatives certainly provided a positive hearing and one producer of 18 months experience (Charleville) provided some insights into his local production experiences.

Location and Services Cunnamulla (population 1700) is located some 807km from Brisbane and 197km from Charleville (population 3500), the closest major town. The community is serviced by aircraft twice a week, rail twice a week and bus three times a week. The office of the Paroo Shire is headquartered in Cunnamulla and ongoing support for the project has been provided by both Suzette Beresford, Shire Chief Executive Officer and Paroo Shire Chairman, Darby Land. Cunnamulla is located on the Warrego River (Murray-Darling Catchment). The Cunnamulla Weir, adjacent to the town was completed in 1992 and provides an annual yield of in excess of 3000Ml with a 92% reliability factor.

Climate and Water Quality The annual rainfall of the district ranges from 300 to 350mm (November-March) and Cunnamulla's altitude is 189 metres. The net evaporation rate (Cunnamulla Post Office) is 2.55m a year. Mean maximum daily temperatures range from 18.9°C in July to 35.6°C in January with minimums of 5.5°C in July to 25.4°C in January. Using the pond temperature model (Australian Fisheries, November 1990), based on ponds at Walkamin Research Station, the following pond water temperatures could be predicted at Cunnamulla.

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Table 1. Estimated water temperatures for aquaculture ponds at Cunnamulla.

Month Pond temp. (°C) Max. Pond Bottom Temp.

(°C) January February March April May June July August September October November December

31.5 29.5 26.8 20.6 14.3 11.3 10.2 13.1 17.0 22.0 25.5 27.5

34.5 32.5 28.8 24.6 19.3 16.3 15.2 17.1 21.0 25.5 29.5 30.5

As quoted previously, 2600Ml is available for allocation from the Cunnamulla Weir. Water Resources are at present finalising allocations. Several land holders adjacent to the weir hold 30-100Ml annual allocations, some of which is used to irrigate pasture crops. The bulk of the water allocation is in one parcel, and will be used to irrigate either cotton or table grape production, depending on the successful applicant. The Council has requested an E.I.A., if cotton production is to proceed, and there is a degree of unease with this crop's production in the district. Water Resources have withheld 300Ml of allocation for future Council use and additions to present allocations of small licence holders. Both artesian and sub-artesian waters are available in the region, the quality of which varies. The majority of South-West Queensland sits over the Great Artesian Basin (G.A.B.), this water supply has traditionally provided stock and domestic supplies throughout the region. Three conductivity reports sighted ranged from 700 to 4000 uS/cm with a pH in the range of 7.8 to 8.5. In general most artesian water around Cunnamulla is regarded as drinkable and of good quality, (unscientific, but some measure of quality is reflected). Volumes from bores were quoted up to 1.3Ml per day and the water pressure does not vary.

Soil Types A preliminary assessment of the soil types divides the district into 3 "simple" categories - black (heavy clays), red (light clays) and river loams. Drawing on the property dam construction experience, there appears to be few problems with black and red soils, but comments about the river loams would suggest potential difficulties. Sand and gravel run through the soil profile in some of the flood plain areas.

REDCLAW CRAYFISH AQUACULTURE 3 Alternative Crops South-West Queensland by and large is considered to have a depressed rural income due, to a greater part, to depressed wool prices. Both the state and Commonwealth Governments are supporting a "Mulga Land Strategy" to underpin the region with income support, property rationalisation and investigations of alternative production systems. As discussed previously, cotton and table grape production are serious candidates along with garlic and native plant production. The first three require irrigation, and would, in the case of Cunnamulla, be limited by water allocations from the weir. Artesian water is unsuitable for sustained irrigation usage. There was also a suggestion of limited expansion of pasture crop production, again based on the weir water allocations.

Water Resources Comment Mr Lachlan Hanley, Water Resources Engineer, Charleville, was consulted and provided the following observations. There are three water sources in this region - surface (Cunnamulla Weir), sub-artesian and artesian (G.A.B.) As previously discussed the allocation of water from the weir is at present in the final stages of negotiation and is committed, with flood harvesting of the Warrego committed for at least 2 years. Possible flood harvesting requires off-stream storage and can be unreliable in this region. The present weir allocations have a 92% reliability. Water of the G.A.B. flows at different rates depending on the bore and vary in quality through the region. (A Water Resources survey of G.A.B. water quality of the Warrego region is available). Bores presently provide for domestic and stock purposes. If the water was to be used for aquaculture a permit would need to be applied for along with a $55.00 application charge. Water usage from the G.A.B. is becoming increasingly sensitive, a bore capping program is under way and Government support for pipe replacement of bore drains is under way. There is a national program to reduce usage of these waters. Historically a lot of artesian water has run to waste, down bore drains. Lachlan advised to apply for a reasonable G.B.A. allocation for aquaculture as allocations are made with the "bigger picture" of the whole basin in mind. Sub-artesian water is available in areas and is not subject to the same process of approval, a decision can be made at the district office based on the local water table and demand levels.

Charleville Redclaw Farm Mr Roy Bignell is at present experimenting with seven ponds on the outskirts of Charleville. He is using both artesian and sub-artesian waters. The sub-artesian water has a conductivity of 3000-4000 with the artesian water around 1000-1200. He has developed the technique of blending the waters. Reasonable "blooms" were observed in several on the ponds and he claimed the crayfish, first stocked in February 1993 were doing very well and reproducing at a good rate.


No pond bottom drains were installed and I would suggest he had some pond bottom problems. Crayfish were observed with tail blisters and tail sections missing in some ponds. Chook pellets were used and small juveniles were noted at the time of visit. This redclaw farm illustrated to me the possibility of redclaw production in G.A.B. waters. Pond management may need to be modified to produce good blooms and thus provide a good pond environment.

Local Issues The Cunnamulla district is within the "channel country" and as such is relatively flat, floods spread out from the major streams/Warrego and Paroo Rivers and cover large tracts of country. Both from economic loss and permit requirement considerations, all ponds need to be above flood height. This issue would need to be addressed in any presentation. Future marketing opportunities will be limited by the lack of seafood marketing licence holders in the South-West. This could be overcome if a number of producers established and agreed to cooperate in marketing their crayfish, with possibilities of a unique South-West Queensland identity for such a product being marketed through a single market (and licence) group. The possibility of a good local market was raised by several people, with a regular flow of tourists, but this market would only take small quantities in my opinion. Artesian water has a temperature of 45-55°C at the bore head, and it was suggested that this quality could be used to warm ponds in winter. It was explained that flow-through ponds don't provide the optimum conditions in crayfish ponds, but considerations could be given to heat exchange methods (e.g. piping in ponds). The cost may be questionable, but the warm water is available and an experiment may be worthwhile. It is reported that the local crayfish population is well distributed and in good numbers. It should be highlighted to intending producers that the local yabbies and redclaw don't mix and ponds will need to be kept free of this species if successful production levels are to be achieved. Fencing and netting of ponds also needs to be highlighted, as there was some what of a local sceptical reaction to the suggested destruction by predators, both land-based and birds. In the short time on the ground, and Graham's comments a local "industry" of 4-6 producers with upwards of 20 ponds may be possible in the next 2 years. The ponds will be based on both surface and bore water and as well as normal redclaw production skills. Bore water pond management may require a slightly different approach. Cunnamulla is a long way from the coast and some planning needs to be undertaken to service an "established" redclaw industry in the South-West. The Department has a real role and this needs to be addressed. I believe Agribusiness (both QDPI&F and DPI&FE) could and should be involved in the marketing stage of the industry of it

REDCLAW CRAYFISH AQUACULTURE 5 gets off the ground. A "volume" of redclaw from a unique location could be well suited to a niche marketing exercise. A third stage of any industry development would be the visiting and exposure of potential producers to established redclaw enterprises. This could take the form of a visit to a region of several redclaw enterprises to allow exposure to different production methods and farm sizes, the QDPI&F could facilitate such a trip in arranging existing producer contacts. Several interested producers have already visited one or more enterprises. Another impression that needs to be addressed is that it is a low-cost industry to establish, again the typical approach of many about redclaw - dig a hole - throw them in - and harvest at the end of twelve months. The message about costs and system management needs to be highlighted and reinforced at the proposed seminar. However, a couple of individuals impressed me with the seriousness of their approach. The issue of aquaculture permits would need to be covered and some suggestion of where to turn to for assistance and for explanations, again QDPI&F.


INTRODUCTION TO REDCLAW Clive Jones

Introduction Freshwater crayfish are relatively common throughout the world, and several species in the northern hemisphere are utilised for food by way of either wild fisheries or farming. In the southern hemisphere, there is a single family of freshwater crayfish, which in Australia represents over 100 species. Most Australians have some recollection of catching yabbies in the local creek, however, commercial exploitation of our native crayfish has been quite limited and interest in farming crayfish has arisen in only the past 10 to 15 years. The most dramatic introduction to Australia's crayfish is by way of the giant Tasmanian crayfish (Astacopsis gouldi) which can reach in excess of 4 kilograms, although such specimens are likely to be very old. Two other relatively familiar species are the Marron from Western Australia and the true Yabbie from several states in southern and central Australia. The yabbie, Cherax destructor, is the species local to the Southwest of Queensland. Considerable quantities of yabbies are taken from the wild each year, much of which is sold into fish markets in NSW and Victoria. Farming of both these species is undertaken in various parts of southern Australia, although total production is relatively small, particularly for marron. Redclaw (Cherax quadricarinatus), is a warmwater species distributed throughout the river systems of northern Queensland and the Northern Territory flowing to the Gulf of Carpentaria. It also occurs in southern parts of New Guinea. Within this distribution, redclaw inhabits turbid, slow-moving waters usually in clay-lined billabongs with over-hanging vegetation. Because of the remote distribution, there was very little interest in redclaw until the early 1980's. Recreational fishing was limited to isolated areas adjacent to towns and of very little significance. Interest from an aquaculture perspective has only arisen in recent years.

Historical Perspective Farming of freshwater crayfish in Queensland began as a carry-over from marron (Cherax tenuimanus) farming in Western Australia. Despite the involvement of many farmers over a considerable period, marron farming had achieved little commercial success. Enterprising farmers from south-east Queensland felt that marron would perform better in the sub-tropical climate of Queensland. Juvenile marron were shipped across in 1979, and over several years, a small industry began to emerge primarily producing juveniles, but in some instances involving several growout ponds. In 1986, the short-lived success was suddenly terminated as higher than average summer temperatures killed off the bulk of marron held. Just prior to the demise of marron in Queensland, several farmers had begun trials with redclaw which, being a native of the State, they though would be better suited to

REDCLAW CRAYFISH AQUACULTURE 7 the south-east Queensland climate. In an effort to protect their capital investment, all the surviving marron farmers switched to redclaw. In 1987, the Queensland Department of Primary Industries Fisheries Branch proposed a two-year research program to assess the aquaculture potential of redclaw. This research was conducted at the Fisheries Research Station at Walkamin, adjacent to natural redclaw populations. The results of this work indicated that redclaw was indeed an ideal candidate for aquaculture. With the losses incurred by the Queensland marron farmers, and the general scepticism concerning aquaculture, development of the redclaw farming industry has been slow. Nevertheless, those involved are optimistic primarily because this species possesses so many advantageous characteristics in regard to its biology, the farming technology required and its marketing. That optimism is now translating into considerable production and substantial industry growth.

Biological Characteristics The considerable biological advantages of this species are primarily attributable to its natural habitat which necessitates broad tolerance of physical extremes. The still waters of a billabong in north-western Queensland will often display characteristics which many freshwater species would find lethal. Redclaw thrives in this environment. Specific experimentation of growth in relation to temperature indicated tolerance to a broad range of temperatures. Optimal growth was achieved over the range 23 to 31°C and lethal levels were estimated to be 10 and 35°C. By way of comparison, the temperature/growth relationship of the giant freshwater prawn (or Mitchell River Prawn), Macrobrachium rosenbergii, indicated a much narrower tolerance to temperature. The range over which redclaw will grow well represents temperatures which prevail throughout much of Queensland. Similar experimentation of salinity tolerance indicated that redclaw will tolerate reasonably high salinities (up to 12 parts per thousand) for extended periods. This tolerance has two advantages. Firstly, farming in brackish water may be feasible, and secondly the physiological impact of saline treatment brings about a significant improvement in flavour. Redclaw also display an extraordinary tolerance of low dissolved oxygen concentrations. Naturally, as with all aquatic species, production is optimal when dissolved oxygen is close to 100% saturation. However, when dissolved oxygen falls, redclaw remain active and healthy at concentrations as low as 1 ppm (parts per million). The physiological mechanism involved is similar to that which operates in vertebrates, and will sustain the animal for some hours, until oxygen levels are increased. Although this characteristic should not preclude good pond management practices, it is comforting to know that if oxygen levels do drop suddenly, redclaw are likely to survive. Under similar circumstances, most fish and other crustaceans would suffer mass mortalities.


Although specific assessment of redclaw's tolerance to other physical parameters has not been made, it is clear from general experience amongst farmers and researchers, that this species is broadly physiologically robust and will tolerate extremes that many other species would find lethal.

Feeding Characteristics The feeding characteristics of redclaw are also advantageous. Under natural circumstances redclaw have a broad diet ranging from the simplest organic materials associated with decaying plant and animal material, the detritus, through to fresh animal and plant material, when available. The microbial organisms associated with decaying organic material, primarily fungi and bacteria, are highly nutritious. Consequently, simple organic materials added to a normal earthen pond environment where natural microbial populations are present can provide adequate nutrition. To provide optimal nutrition, a specific feed formulation is necessary. The development of such a feed for redclaw is one of the primary research activities at present.

Growth Rate Growth of crayfish is dependant on a process known as moulting. This involves a sequence of stages including; shedding of the external shell; swelling of the body with water while the new shell hardens; expelling the water; tissue growth until the new shell is full; and so the process continues. Newly hatched crayfish moult every few days, but the frequency slowly diminishes to once every few months in large crayfish. Newly moulted crayfish which are soft are particularly vulnerable to predation by other crayfish. For this reason, ample shelter, particularly for juveniles, is essential. Growth of redclaw is dependant on the prevailing physical conditions (primarily temperature) and the type of nutrition. In addition, there is considerable variability in growth rate between individuals. In general terms however, redclaw will achieve a size of between 50 and 100 grams within twelve months. Although a maximum size in excess of 400 grams is possible, growth rate slows appreciably after the first 12 to 18 months and commercial production of crayfish larger than 150 grams is currently not commercially viable. Increasing growth rate and the uniformity of growth are also primary objectives of research. Significant gains are likely to be achieved through nutritional research and selective breeding programs.


Reproduction The reproductive characteristics of redclaw are well suited to aquaculture. Both males and females mature at 6 to 9 months of age and will mate and spawn continuously while suitable temperature conditions prevail. In north Queensland, egg-bearing females are found year round although there is a considerable decline in reproductive activity from May through July. For the other nine months, females may have successive broods. After mating, the fertilised eggs are carried beneath the tail of the female who carefully maintains and nurtures them during the incubation. Incubatory period is also temperature dependent, and may range from 6 to 10 weeks. The number of eggs carried is dependant on the size of the female and will vary from around 300 to 1,000 per brood.

Life Cycle The Redclaw life cycle is very simple. From a farming perspective, the technology involved in accommodating and managing this life cycle can therefore also be simple. Figure 1 below provides a summary of this cycle. After mating the fertilised eggs are carefully nurtured for about 6 to 10 weeks at which time they hatch to produce a small crayfish (about 12mm long) of adult-form, i.e. there is no free-living larval stage.

Figure 1. Diagram of redclaw life cycle.

MATING

HATCHLINGS

JUVENILES

MATURE ADULTS

incubation6 to 10 weeks

adult form0.02g300-1000/fem

rapid growth3 months

5 to 15g50 -100/female

rapid growth6-12 monthssimple food

adults may growto over 400gin 4-5 years

The hatchlings grow rapidly when provided with an adequate diet (preferably zooplankton) and within 3 months will achieve a size of 5 to 15 grams. They are now past their most vulnerable stage and will feed on detritus and grow to an average of approximately 70 grams (ranging from 50 to 100g) over the next 6 to 12 months. During this period they mature and continue the cycle.


Disease and Parasites Several potentially serious disease causing organisms have been identified in redclaw including a couple of viruses, which could potentially cause major mortalities. This has been the case with prawn aquaculture, where viruses have caused severe losses and the demise of large industries. It is clear that the influence of the disease causing organisms is directly related to crayfish condition. That is, stress-free crayfish, held in good water quality conditions are unlikely to be affected by disease. Maintenance of optimal conditions is therefore crucial. The only other significant health issues are in regard to organisms fouling the shell. There are a variety of species which will attach themselves to the outer shell or inside the gill chambers, but most will not cause direct damage. Those occurring most commonly include species of flat-worms (Temnocephalans), eggs of water bugs and various protozoans. They can be controlled through pond management or if need be with a saline bath.

Farming Technology The biological characteristics of redclaw provide technical advantages in regard to its cultivation, particularly when considered in comparison with aquaculture of other species. A significant advantage is conferred simply because the species is physically robust. It can be handled out of water with little adverse affect and without a requirement for specialised handling procedures as are often necessary for fish species. This is particularly advantageous for sampling and moving crayfish around the farm. Redclaw breed so readily in normal pond conditions, there is no requirement for specialised hatcheries with environmental control and intensive management. The larval phase of the crayfish is entirely contained in the egg, precluding the requirement for sophisticated larval rearing facilities as are required for prawns and other species. The entire breeding, hatching and nursery phases can be managed within an earthern pond system. This permits large scale juvenile production with a minimum of capital expenditure and minimum of technical expertise. A specific and highly advantageous characteristic of redclaw in regard to harvesting is its response to water current. Like many freshwater species, redclaw respond to moving water by migrating upstream. This response is particularly strong and has been harnessed by the development of flow traps. These traps are of various designs, but all work on the principle of attracting crayfish into a trap by way of a water current.

Summary It is clear that redclaw is an ideal aquaculture species. It will achieve substantial size, is attractive in colour and form, has a good flesh recovery rate and compares well in flavour and texture with the most sought after crustaceans.

REDCLAW CRAYFISH AQUACULTURE 11 Its physiological tolerance to extremes of environment is great, particularly in regard to temperature, dissolved oxygen and salinity. Growth is rapid and sufficient to achieve a commercially acceptable size within twelve months. Feeding requirements are such that a relatively cheap diet will enable significant production in the order of 1.5 to 3 tonnes per hectare. The species is relatively non-aggressive and will perform well at densities of 5 to 10 per square metre. It displays behavioural characteristics which lend themselves to efficient harvesting practices. Redclaw can be induced to spawn with relative ease. Handling of broodstock and incubation of eggs requires no specialised facilities. The larval stage is entirely contained in the egg which is carefully nurtured by the maternal parent. The reproductive capacity of the species is relatively high. Juvenile crayfish, although fragile, are resilient and respond well to intensive pond production with appropriate food and shelter. Throughout all stages of the production cycle, crayfish can be handled easily and with a minimum of specialised procedures and facilities. At this stage, disease and health are not major issues. The physical (including climatic) requirements for cultivation of redclaw are broad and reasonably non-restrictive. The geographic potential for the species is therefore significant, and extends throughout tropical regions where sufficient water is available.


SITE REQUIREMENTS Millin Curtis

Site Requirements The potential of redclaw for aquaculture can only be achieved by providing the right conditions for good growth and reproduction. Redclaw may survive under poor conditions, but will not grow rapidly enough to sustain the commercial viability of an operation. In reaching a decision of where and how to establish a farm, it is important to consider all the factors, maximising favourable characteristics and minimising any negative aspects. There is no such thing as the perfect site for freshwater crayfish farming. Site suitability is usually judged on the basis of satisfying given criteria.

Site Suitability Criteria Climate Temperature is the most important factor in maximising the growth potential of redclaw. The site should maximise the period each year when pond temperatures remain between 23 to 31°C. Mortalities may occur if pond temperatures remain below 10°C or above 35°C for extended periods. Some sub-tropical regions may present suitable conditions for most of the year, but as per Table 1, low winter and high summer temperatures may cause some problems. Management strategies which alleviate these extremes may need to be devised. Besides growth, successful reproduction also requires sustained periods of warm temperatures. Water Availability An abundant supply of good quality water, which can be sourced from a surface flowing stream, an irrigation channel or from underground is essential for aquaculture. The supply of water must be guaranteed, even during the most severe drought. The quality of the water is just as important as the quantity. Chemical laboratories can test samples to determine if the sources of an appropriate quality for aquaculture. The water supply must be free from chemicals such as heavy metals, oils, pesticides, herbicides, chlorine, methane, hydrogen sulphide, high iron content, and extremes of pH. High turbidity, caused by suspended silt or clay colloids, should be avoided as it may inhibit natural pond production and possibly cause stress through deposition on gills by reducing the ability of the crayfish to respire. Additions of a liming agent and fertilisers would be routine practice in pond management.

REDCLAW CRAYFISH AQUACULTURE 13 Caution should be exercised when the utilisation of surface water is proposed as present and previous land management practice involving pesticide application is undesirable. Similarly, upstream discharge of industrial effluents or contamination by dead livestock would be incompatible with crayfish farming. Bore water, and sometimes artesian water, can be excellent sources for aquaculture. Underground supplies are free of pathogens, predators, pollution and have a relatively constant temperature year round. The quality of underground water must always be checked as it can be deficient in oxygen, or contain excessive levels of carbon dioxide, hydrogen sulphide or iron. Generally, these limitations can be overcome by storing the water in a reservoir and aerating vigorously prior to use.

Table 2. Preferred range of selected water quality parameters of source water, for redclaw aquaculture.

Parameter Acceptable range Comments

Temperature 23 to 31°C Growth will be optimised within this range

Dissolved oxygen > 5.0 mg/l

pH 6.5 to 8.5 Waters should be well buffered.

Total alkalinity > 50 mg/l as CaCO3 < 500 mg/l

Total hardness > 50 mg/l as CaCO3 < 500 mg/l

Ammonia < 0.05 mg/l total NH3 Toxicity increases with rising pH and temperature

Nitrite < 0.05 mg/l

Turbidity Nil

Iron < 0.1 mg/l

Hydrogen sulphide < 0.002 mg/l Soil Type In order to hold water, ponds must be constructed from soils containing a high proportion of clay. If clay soil predominates across a site then ponds can be constructed with a minimum of earthmoving. If clay soil is only present in pockets, it may not be cost effective to construct ponds because of the expense of earthmoving.


Soil surveys are advisable to determine if there are sand or gravel layers that could interfere with pond construction or limit water retention. Soil samples should be taken from any potential sites for pesticide residue analysis as previous agricultural activity may have involved application of persistent pesticides which are incompatible with crayfish farming. Topography The land should be gently sloping to enable gravity flow of water, minimise pumping costs and facilitate simplicity of pond construction. The land should not be susceptible to flooding. Miscellaneous Other aspects of site requirements which should be considered include: • Proximity to necessary infrastructure such as workforce, technical expertise,

electricity, supplies (hardware, mechanical, feed, fertiliser), processing • Ability to secure the site against predators and poachers • Desirability of the area as a place to live • Future developments which may impact on crayfish farming • Proximity to both domestic and international markets


POND AND CONSTRUCTION ENGINEERING ISSUES Clive Jones, Ian Ross and Colin Bendall

Water Supply As discussed under Site Requirements, the water supply is one of the most important requirements for a successful aquaculture project. The source must be guaranteed of supplying sufficient volume during the most severe drought conditions. Points to consider include: • Is sufficient volume on-hand to provide pond fill (e.g. for a pond surface area of

1000m2 volume required is approximately 1.2 Ml). • The water supply must be sufficiently reliable to provide year round

replenishment of evaporation and seepage losses. For example, the volume for evaporation losses for a 1000m2 pond is approximately 2.5 Ml for the Cunnamulla district.

• Is water of suitable quality? See recommendations elsewhere. • Does pond effluent need to be stored as part of discharge permit? • Can water be recycled to reduce volume of water required?

Construction Materials Materials on site need to be investigated to determine their suitability for pond construction. Clay soils provide the lowest permeability and therefore little or no seepage losses. Sandy clay soils may be suitable for pond construction providing steps are taken to minimise seepage. Sands, silts and structured clays are all quite permeable and therefore require the installation of clay or synthetic liners.

Pond Design The layout of the ponds is generally determined by the topography. Factors to be considered include: • On sloping sites ponds are constructed as hillside storages i.e. banks on three

sides. • On flat sites ponds are constructed as excavated tanks i.e. banks on four sides. • Flat sites are not desirable due to the difficulty in fully draining ponds for

effective harvesting and drying. • Sloping sites provide better pond drainage opportunities by using gravity. • Slopes of around 2 to 5% (1:5m to 1:2m) provide the best storage to excavation

ratio, i.e.the least amount of earthworks to provide the storage required. • Surface drainage may be required to exclude runoff from surrounding areas. • It is important to consider all aspects of the project before commencing pond

construction so that best use of topography and existing facilities can be achieved.


Pond Details • Ponds are usually rectangular in shape. • Surface area can vary from approximately 700 to 2000m2, with the average

around 1000m2, i.e. 50m x 20m at water level. • Batters 2.5:1 outside, 2:5:1 inside, for dozer construction. • Batters 2.5:1 outside, 3.5:1 inside, short end, for scraper construction in clay. • If lining is required, 3:1 inside, 2.5:1 outside. • Min Base dimension - 30m x 6m for scraper construction. Smaller bases can be

achieved with dozer construction. • Min Crest width of 2.5m for construction equipment safety on crest. • Base of pond should slope to drainage outlet to allow full drainage of pond. • Recommended depth of 1.2m (shallow end) to 1.8m (deep end). • Inlet pipe around 100mm for fast filling and topping up. • Outlet pipe 200mm diameter (minimum) for effective drain harvest. • Inlet and outlet pipes at opposite ends of pond. • Concrete or loose rock pads are required at inlet and outlet to prevent erosion. • Galvanised steel sheet "Water Rat" wall to be placed around pond - 600mm high. • Predator proof netting supported above ponds by timber posts and steel cable.

Lining Materials Clay Soils • Strip topsoil and stock pile for placement on constructed embankment. • Construct embankment using suitable clay material with correct moisture content. • Compacted central clay core and cutoff will prevent loss of water through

seepage. • Use thin layers (200mm Max) to be compacted by sheeps foot roller. • Outlet pipe to be installed using baffles around pipe to prevent seepage. Clay Lining • Is suitable clay material available on site or is cartage from elsewhere required. • If cartage is required - placement and compaction with moisture control may

result in greater cost than synthetic liner e.g. Clay Liner - Walkamin area $7.50/ m3 or $2500 for 1000m2 pond.

• Batters 3:1 to 3.5:1 inside to allow spreading and compaction of lining material. • 300mm minimum liner thickness. • Minor seepage will still occur with clay lining. Synthetic lining • Many types and thicknesses available. • Materials - Polythene/P.V.C/HDPE. • Mechanical strength (resistance to puncture and tearing) increases with type and

thickness of material. • Materials come in rolls 1.4 to 8m in width

REDCLAW CRAYFISH AQUACULTURE 17 • Joining of strips is by hot welding or adhesive tapes. • Priced from $1.10 to $4.00 per square metre depending on material. • Surface to be lined should be free from rocks and sticks. • Sand bedding may be required if soil surface too rough or stony or higher grade of

lining material should be used. • Liner is anchored in excavated trench, approximately 300mm deep at edge of

crest. • HDPE type materials require deeper trench to be located up to 0.5m from edge of

crest to resist expansion / contraction forces. • 300mm minimum lining of top soil over liner required to protect liner from U.V.

and to provide a natural environment for crayfish. • Subsurface drainage may be required to prevent soil water pressure from lifting

liner.

Basic steps in Pond Construction • Clear the site area of vegetation, including stumps and roots. • Strip the pond and surrounding bank area of topsoil and stockpile it for later use. • Excavate the core trench in the middle of the proposed surrounding embankments

at least 3 metres wide and at least 0.3 metres deep into impermeable clay beneath the bank.

• Excavate and install the outlet pipes under the proposed embankments ensuring to carefully compact the backfill clay around the pipes and baffles.

• Refill the core trench with layers of compacted clay originating from the excavated pond, ensuring each successive layer is no more than 0.2 metres thick.

• Preferably site construction plant should include a scraper, sheepsfoot roller and water truck..

• Continue construction of the clay core and outer embankment zones until the design crest height is reached.

• Excavate ponds to designed depth and shape, then compact base and sides of pond with sheepsfoot roller.

• Spread a minimum topsoil cover of 100 millimetres over total pond and surrounding embankment area.

• Quickly establish a dense ground cover of suitable holding grass i.e. kikuyu, couch, pangola, African star etc. on crest and exposed batters of the ponds to stabilise the soils and reduce erosion.


PRODUCTION TECHNIQUES FOR REDCLAW Clive Jones

Introduction There is a common misconception that farming of redclaw involves nothing much more than throwing a few crayfish into a dam. Redclaw aquaculture is an intensive farming activity requiring daily management of a range of processes. Consequently, to achieve efficiency and maximise productivity, and therefore maximise success and profit, the various processes should be streamlined and linked together. A systematic approach must be taken. Naturally every farm is unique and every farmer has there own way of doing things. The following concepts are therefore of a general nature and would need to be modified and adapted to suit each individual farm. It should be noted that there are many redclaw enthusiasts who have taken a quite different approach to that outlined here. Their approach generally takes the form of managing semi-natural populations of redclaw in ponds which are never (or infrequently) drained. Crayfish are continually harvested by traps and natural reproduction in the pond takes care of re-stocking. While this approach will produce crayfish, it is not considered commercially viable as a dedicated farming activity. For this discussion, I have also deliberately omitted any considerations of post-harvest, marketing and business issues, not because they're not important, on the contrary, they're so important and so numerous, that they justify separate consideration. The farming of redclaw can effectively be considered an amalgamation of the following processes. • Supply of juveniles (farm production, purchased) • Stock management (broodstock, culling, health/disease, predators) • Harvesting (partial, total) • Feeding (what, when, how much, how often) • Pond management (pond preparation, water quality, environment) • Post-Harvest • Marketing • Application of good business principles (book-keeping, costs, income) To illustrate the development and operation of a redclaw farm I will use a hypothetical model farm. Naturally for the purposes of this introduction these notes are quite general. More comprehensive and detailed considerations will be necessary before embarking on a commercial operation. I have assumed that a suitable site has been selected as discussed previously. The model farm includes 40 by 1,000m2 growout ponds (i.e. a production capacity of 4 hectares), 15 by 1,000m2 juvenile production ponds and other facilities as marked in the diagram.


Figure 2. Layout of a hypothetical redclaw farm consisting of forty 1,000m2 production ponds.

SETTLINGDAM

SUPPLYDAMGROWOUT

PONDS

JUVENILE PRODUCTION PONDS The ponds, as discussed previously under 'Pond Construction', should be 1 to 2 metres deep, with good slope from shallow to deep end, and a large bore drainage pipe at the deepest point, running through the pond wall. Quick (approximately 24 hours) and complete drainage is essential.

Farm Layout Considerations • positioning of ponds (optimising use of slope, minimising materials e.g. pipes,

fencing, netting, allowing flexibility for expansion) • position of central facilities (minimise travel distances); tanks (for holding

harvested crayfish), feed storage, general storage, electricity supply, blower, sorting/packing area, office, etc.)

• supply and settling ponds • drainage (gravity drainage of all ponds is recommended) • netting (essential to prevent bird predation) • fencing (essential to prevent rat predation, and to prevent migration of crayfish) • aeration (essential to maintain dissolved oxygen levels and to provide pond

circulation)

Juvenile Supply


There are two options for obtaining a supply of juvenile crayfish; purchase them from another grower, or produce them on the farm. Given the ease with which redclaw will breed and rear offspring, production on the farm is the usual choice. This may change in time when specialist juvenile production farms ('hatcheries') with superior genetic stock are established. Although a typical female of average size may lay and incubate between 300 and 1,000 eggs, there is considerable attrition before these offspring achieve a size of between 2 and 20g when they are referred to as advanced juveniles, and are ready for stocking to growout ponds. As a rule of thumb, each female is considered capable of producing 50 advanced juveniles per brood. Juvenile production ponds are usually of the same specification as growout ponds, although they are managed a little differently, particularly in regard to provision of suitable shelter and planktonic food. Our model farm ponds of 1,000m2 would normally be stocked with around 100 mature females and between 25 and 100 males (carefully selected as the best of the stock available). On the basis of 50 advanced juveniles per female this pond would therefore produce 5,000 juveniles for stocking to the growout ponds. This number is suitable for a complete stocking of one growout pond at 5 crayfish per square metre, a standard stocking density. Under North Queensland conditions, a juvenile production pond, stocked as specified, would be ready for harvest in 4 months. Thus, the 15 juvenile production ponds, producing 3 times per year can supply 45 batches (5,000 in each) of advanced juveniles per year. This is sufficient, with some excess, for the 40 growout ponds. This strategy will necessitate a juvenile pond harvest about once every week. To maximise survival and growth of the juvenile redclaw, an abundance of shelter in the ponds is essential. This is usually provided in the form of bundles of synthetic mesh, tied onto a line with a weight at one end and a float at the other. Arranged in this manner, these bundles extend from the pond floor up into the water column providing many spaces and surfaces for the juveniles to utilise. In the 1,000m2 model ponds, at least 200 mesh bundles are required. Juvenile production ponds are carefully managed to provide an abundance of planktonic organisms which the juvenile crayfish utilise as food. These planktonic organisms are the microscopic creatures which live in the water, and include both plants (phytoplankton) and animals (zooplankton). It is primarily the zooplankton which are consumed by the juvenile crayfish. As they grow, they progressively consume less plankton and more detrital food which occurs on the surface of the shelter material and more particularly on the mud surface. Maintaining high levels of plankton involves regular checking of water quality and periodic fertilisation of the water. Harvesting of the juveniles (about 4 months after stocking) can be achieved by a number of methods. Individual mesh shelters can be removed and the juveniles shaken out. However, the most effective method is to employ the flow trap, the design and operation of which is explained elsewhere. With this method, the pond is

REDCLAW CRAYFISH AQUACULTURE 21 completely drained and all the crayfish are attracted into a trap. From here they can be removed to the central tank facility and sorted, counted and then stocked to the growout ponds. Generally speaking, there will be some excess juveniles. The best (i.e. the largest and healthiest) should be selected for stocking, and the remainder removed from the farm (sold to other farms or to the bait market) or destroyed. The juveniles to be stocked to the growout pond should be transferred to the growout pond late in the afternoon or early in the evening.

Stock Management Stock management primarily concerns the growout stage. As mentioned above, growout ponds are normally stocked with advanced juveniles at around 5/m2. For our model ponds, this means 5,000 juveniles. Shelter is again important. For the growout stage some mesh shelters may be used as well as some of different specification. For our model farm we will use mesh shelters and 'highrise' shelters made from agricultural drainage pipe. Each highrise shelter consists of 150mm lengths of 50mm pipe clipped together in a stack 10 wide by 3 high. This will provide adequate shelter for at least 30 crayfish. One hundred mesh shelters and 100 highrise will be used in each growout pond. The growout phase would normally be in the order of 12 months. Some farmers harvest more frequently to enable culling of runts and staging of crayfish into uniform size groups for further growout. This can be beneficial, but is dependant to some extent on total number of ponds and available labour. For the purposes of our model farm we will work on the basis of 12 months growout per pond. Consequently, there will be 40 growout pond harvests per year, or one approximately every 9 days. In order to gauge crayfish size (for determining feeding rates) and health/condition (to ensure pond management is optimal), regular sampling of each growout pond is recommended. For this model farm we will stipulate 3 samples per year for each growout pond, meaning a sample every 3 days. The sample can be taken by retrieving a few of the shelters, or by baited traps. The captured crayfish should be weighed, and the results used to adjust the feeding schedule. The condition of the crayfish can be observed with particular attention paid to tail blistering, growths on the shell and general vitality of the animals. Any problems should be addressed by a review of water quality and appropriate adjustments. The 12 month growout period is sufficient for the entire crop to achieve market size (i.e. >50g). At harvest, the crayfish will initially be sorted into 3 groupings. The fastest growers, i.e. the largest will be selected out as breeding stock. As indicated above, about 100 females and up to 100 males will be required per juvenile production pond. So, the best 100 females and males from the growout harvest will be used for breeding. All crayfish down to 50g will be separated for market. These may require further size and quality grading prior to leaving the farm. All crayfish under 50g are considered runts and unwanted juveniles. If they can be sold to other farms or other markets, well and good. Otherwise they must be destroyed.


Another important facet of stock management is prevention or minimisation of predators. This will primarily be achieved by the netting and fencing installed during farm construction. However, on-going observation for indications of predator activity is important. Both water rats and birds will leave tell-tale signs of their presence. Such signs should prompt closer inspection of nets and fences for holes and gaps etc.. A small number of predators can achieve significant damage over time. Eels are also a major concern, but only in coastal areas.

Harvesting As indicated above, the harvesting timetable involves 45 juvenile production ponds per year and 40 growout ponds per year. On the basis of continuous year-round production, there will be a harvest of both a juvenile and growout pond every week to 9 days. For both juveniles and growout, the flow trap harvesting technique will be employed. The design and operation of the flow trap is well explained in a video available from the DPI&F&F (contact Clive Jones). It involves a trap which harnesses the redclaws strong response to flowing water. It is very efficient and ensures crayfish remain in optimal condition. The trapping occurs while the pond is being completely drained, usually overnight. Harvested crayfish (both juvenile and grown out) are taken from the trap in the pond immediately to a tank holding facility. The post-harvest procedures of sorting, grading, re-stocking, or packaging for transport are completed here. Crayfish from the juvenile production ponds should be sorted quickly and released into a growout pond, preferably on the same day. This will necessitate previous preparation of a growout pond (see below).

Feeding As indicated in the previous discussion of crayfish feeding habit, the food consumed by post-juvenile and adult crayfish is primarily the decaying organic material on the pond mud surface, referred to as the detritus. To maximise the availability and nutritional quality of this food source, organic materials are added to the pond on a regular basis. This is usually in the form of a pellet. Nutritional research is proceeding towards developing optimal diets in pellet form. At present, adequate diets are available from several feed manufacturers throughout the State. Chicken pellets should be avoided. A specific crayfish pellet with a protein content of around 20% is recommended. The amount of feed provided to the pond is based on the biomass, that is, the total weight of stock in the pond calculated from the number of crayfish and their average size. At first stocking of growout ponds feed is provided at about 12% of biomass 3 times per week (equivalent to 5% per day). This equates to about 6kg of food for each feed in the 1,000m2 ponds. As the crayfish grow a smaller percentage of the biomass is fed, down to about 5% of biomass 3 times per week (equivalent to 2% per day). Close to harvest, this would mean about 10kg of food at each feed. The schedule

REDCLAW CRAYFISH AQUACULTURE 23 prepared is a rough rule of thumb. Adjustments up or down must be made on the basis of regular observation of ponds for uneaten food, and according to the size of the crayfish as measured from regular sampling. For our model farm feed will be purchased in bulk and stored in a small silo. Approximately 48 tonnes of feed per year would be required. Fresh feed can be purchased every month, requiring a silo capacity of 4 tonnes. Distribution of feed to each pond (3 times per week) will be achieved with a small blower mounted on a 4-wheel bike. Smaller farms would distribute the feed by hand from a bucket. Feeding of juvenile production ponds is substantially different to growout ponds. Planktonic food is required, and a more intensive management of the pond water is therefore required. Appropriate pond preparation (discussed below) is critical, followed by frequent assessment of plankton density (secchi disk readings) and plankton type. The bloom of plankton is maintained through regular applications of fertilisers, both organic and inorganic. Some application of pellet food to the pond is also necessary to provide detrital food for the juvenile crayfish as they grow and change their diet. As a rule of thumb about 2kg 3 times per week would be sufficient.

Pond Management Management of the pond is primarily an issue of water quality management. Some understanding of the chemical and biological dynamics of pond water is required. The parameters which are generally measured and managed include pH, dissolved oxygen, plankton density, water temperature, alkalinity, hardness, ammonia and nitrite. Table 3 below gives some further details of these parameters and their measurement. Adjustment of the these parameters when they move outside the optimal range may involve additions of various materials such as fertiliser or lime, or flushing of the pond with new water. Dissolved oxygen levels are maintained by aeration. This can be achieved using a variety of mechanical devices. Our preferred method for the model farm is using airlift aerators. Briefly, this involves running low pressure air from a mechanical blower to the ponds, injecting the air into the base of PVC pipes which are held onto the pond floor with a weight. The air rises to the surface, thereby holding the pipe up at the surface, and water is displaced out of the top. The action of the airlift provides oxygenation of the water and circulation.


Table 3. Water quality parameters, their preferred range and measurement for redclaw aquaculture.

Parameter Description Optimal

Range Measuring

Device Frequency of Measurement

pH acid/alkaline balance

7.0 to 8.5 pH meter, or test kit

1 to 3 x/week (am)

Dissolved Oxygen

Oxygen dissolved in the water

> 4.0ppm, or > 80% satur.

Dissolved oxygen meter

1 to 3 x/week (am)

Plankton density

Abundance of plankton

30 to 70cm Secchi disk 1 to 3 x/week

Temperature Maximum & minimum

Max. 31C Min. 20C

Max/min thermometer

1 x/week

Alkalinity Buffering capacity of water

>40ppm Test kit, or lab analysis

1 x/year

Hardness Concentration of Ca and Mg

>40ppm Test kit, or lab analysis

1 x/year

Ammonia Toxic waste product

<1.0ppm Test kit as necessary

Nitrite Toxic by-product

<1.0ppm Test kit as necessary

Other aspects of pond management include pond preparation, checking of source water and pond drying. Pond preparation mainly involves additions of lime, and inorganic and organic fertilisers. A typical application for the model ponds may be 100kg of lime, 20kg DAP and 150kg of lucerne chaff. However, the application rates will vary in relation to each ponds' soil characteristics. Once these materials are added the pond is filled and then left for about a week prior to stocking with juveniles. Depending on the source of the water used for the farm, annual or more frequent assessment of the source waters' quality should be made, particularly for pesticide residues and other potentially toxic materials (e.g. heavy metals). Such analysis would be conducted by a laboratory. Good pond management should include regular drying of the pond soil. For both the juvenile production ponds and the growout ponds, one to two weeks of drying prior to the next stocking is required.

Outcome Given the strategies suggested here, a production rate of between 1,500 and 3,000kg per hectare (i.e. 150 to 300 kg/pond) may be achieved. Newly constructed ponds tend to have relatively low production, improving substantially over the first few seasons. As research work generates better feed, and management practices, further gains beyond 3,000kg/ha are likely.

REDCLAW CRAYFISH AQUACULTURE 25 It should be clear from these notes that redclaw farming is an intensive farming activity which requires daily attention, a broad range of skills and knowledge and a commitment to a range of principles. If this approach is adopted, the potential returns can be very attractive (see Economics section). Because of the skills and knowledge required, those interested in starting a redclaw farming operation should obtain as much information as possible. Crayfish farming Associations operating throughout the State will provide access to existing farmers whose experience will assist those new to this enterprise.


FARM MANAGEMENT Clive Jones I have defined 7 steps to a systematic approach to redclaw farm management.

1. Your Objective Firstly, if you're serious about a systems approach to farming, you need to have set some overall Objective, a Mission Statement which sums up what you plan to achieve. This objective might be something like: To create and operate a redclaw farm where facilities and operations are organised to optimise efficiency and to maximise output of premium product and financial return.

2. Recognising the Processes Next, you need to recognise the various processes which collectively make-up redclaw farming. • Supply of juveniles (farm production, purchased) • Stock management (broodstock, culling, health/disease, predators) • Harvesting (partial, total) • Feeding (what, when, how much, how often) • Pond management (pond preparation, water quality, environment) • Post-Harvest • Marketing • Application of good business principles (book-keeping, costs, cash flow, repairs &

maintenance)

3. Developing the Strategy The third step is to develop a strategy of how you plan to carry out these processes. For example your strategy for supplying juveniles to your farm may be to produce 100,000 x10g male only crayfish in your own dedicated juvenile production ponds each year on a continuous basis. Strategies for all the processes should be defined. i) Farm Layout (see Figure 2) • positioning of ponds (optimising use of slope, minimising materials e.g. pipes,

fencing, netting, allowing flexibility for expansion) • position of central facilities (minimise travel distances); tanks, feed storage,

general storage, electricity supply, blower, sorting/packing area, office, etc.) • supply and settling ponds • drainage

REDCLAW CRAYFISH AQUACULTURE 27 • netting • fencing • aeration ii) Juvenile Production • produced on farm • farm requires 200,000 advanced (5-20g) juveniles per year (based on stocking

densities given below) • farm requires 4,000 breeding females (+ appropriate number of males) to generate

juveniles (based on production of 50 advanced juveniles per female) • breeding ponds to be stocked at 100 females (25 to 100 males)(to generate 5,000

advanced juveniles) • juveniles to be sold only if excess available iii) Stock Management • breeding and growout will be managed as separate processes • broodstock will be actively selected from each growout harvest (i.e. best 100

female and male) • everything under 15g at growout harvest will be destroyed/discarded • crayfish 15 to 50g sold to juvenile market (e.g. other farmers or overseas) • all crayfish 50g + to be sold to market, all year round • health and disease status will be monitored • predation proofing will be applied iv) Harvesting • growout ponds to be harvested by total drainage and flow-trapping (once every

year) • breeding ponds to be harvested by total drainage and flow-trapping (every 3

months) • pond water directed to settling pond, re-used v) Feeding • good quality pellets to be used (15-20% protein) • feed to be stored in bulk silo (4 tonne capacity) • feed purchased in bulk • requirement for 48 tonnes of feed per year (based on feed conversion ratio of 4,

and production rate of 3 tonnes per hectare) vi) Pond Management • pond preparation to include liming (100kg/pond), DAP (20kg/pond), lucerne chaff

(150kg/pond) • water quality will be measured in all ponds including pH, dissolved oxygen and

secchi (3x/wk), hardness and alkalinity (once/yr), ammonia and nitrite (as necessary)


• water quality of source water will be measured annually by full analysis, including pesticides and heavy metals

• the pond environment will be maintained by keeping pond depth at full, regular additions of fertiliser, or flushing as determined by water quality

• ponds will be dried for at least 2 weeks between crops

4. Allocating Resources Your strategies should be realistic in regard to the resources you have on hand, e.g. ponds, water supply, capacity to handle crayfish etc. Your resources must be allocated in a way which makes optimal use of them. For example, it is not much use producing 200,000 juveniles if you have no facility to handle them or there are no ponds ready to be stocked. • Ponds. Each breeding pond to be managed to produce juveniles for one growout

pond. Harvesting breeding ponds every 4 months (3x/yr). 15 breeding ponds will service 40 growout ponds, with some excess. It is important to note here that even though there are 55 ponds, only 40 (4ha) are for growout production, and production rates are based on these.

• Water. 5.5 hectares of water (including all ponds) at 1.5m average depth = 82,500 cubic metres = 82.5 Megalitres. Anticipate evaporative loss of 2.5 metres per year (for South-West Qld.) = 137.5ML. Harvesting each growout pond once per year = 60ML. Harvesting each breeding pond 3 times per year = 67.5ML. Plus seepage and other uses = 10ML. Water required 297.5ML for the first year, and 215ML/yr for successive years. Factor water required into supply dam size, pump capacity etc. Clearly, savings can be made by re-using water at harvest.

• Air Blower, sufficient to run 6x100mm airlifts per pond, i.e. approximately 33,000l/min capacity

• Habitats. Highrise and mesh bundles. Minimum of 100 of each per pond. • Flowtrap. One is sufficient. Possibly a second with different specifications for

juvenile harvesting. • Scoopnets • Crates, enough to handle at least one total harvest (300kg), at 10kg per crate = 30

crates. • Tanks, enough to hold at least one total harvest (300kg), at 10kg/m2 = 30m2. 6

tanks 2.5m diameter. • Feed, silo with 4 tonne capacity • Buckets, sufficient for feed distribution • Scales, for weighing harvested crayfish and feed quantities, maximum capacity

50kg • Balance, for weighing individual crayfish • Water quality equipment, pH meter, dissolved oxygen meter, secchi disk, reagent

test kits for hardness, alkalinity, ammonia, nitrite. • Store-room, for fertiliser, hay/chaff, lime, boxes, general equipment

5. Setting Timetables Because there is a certain amount of predictability to growth rates of crayfish, or preparation time for new ponds etc., it is both possible and extremely desirable to map

REDCLAW CRAYFISH AQUACULTURE 29 out activities in relation to time. For example, if the strategy is to provide 50 to 90g crayfish to the market all year round, then a harvesting timetable which permits this is essential. • Juvenile Production, all year round • Stock Management, sampling growout ponds 3x per year each, to check

health/condition and to gauge size (relate back to feeding rate) • Harvesting, each of 15 breeding ponds to be harvested 3 time per year, i.e.

approximately 1 every week; each of 40 growout ponds to be harvested once per year, i.e. approximately every 9 days

• Feeding, feed purchased in bulk every month to maintain freshness/quality. Feed provided every day at dusk. Feed silo cleaned out once per year to prevent fungal contamination

• Pond Management, water quality measured twice per week (pH, DO, secchi). Aeration provided midnight to 8am

6. Identifying Assessment Criteria and Standards To ensure that all activities and processes are operating optimally, you need standards against which to measure your performance. It should be possible to set some criteria or value for most processes on the farm. An obvious example is water quality. You should already be aware that dissolved oxygen should always be above 4 parts per million, or that pH should be between 7.0 and 8.5. Similarly, standards should be set on all processes. • Juvenile Production, minimum of 5,000 5 to 15g juveniles to be produced from

each breeding pond • Stock Management, Broodstock selected - lively, >120g (at 12 months age),

colour etc.; Growout stock health/condition - external growths, tail blistering, disease symptoms; Growout production of 150 to 300 kg per pond

• Harvesting, percentage of crayfish caught by flowtrap Vs percentage left behind (95:5), number of mortalities, time taken to retrieve harvested crayfish

• Feeding, quality of feed - fungal growth, odour, clumping, dust. Quantity of feed per pond based on prepared schedule, adjusted relative to sampling results

• Pond Management, water quality levels (pH 7.0-8.5, DO >4.0, secchi 50-70cm, hardness/alkalinity 20-100ppm, ammonia/nitrite <1.0ppm), blue-green or other algae

7. Assessing Performance This is clearly the next step after identifying assessment criteria. It revolves around good record keeping. Measuring and recording all processes so they can be compared against the assessment criteria previously set. For example, the quantity of feed used for a particular pond. If optimal feeding efficiency is desired, some measure of the feed required to achieve a certain crop size is essential, if adjustments are to be made in search of improvement. Measuring of performance is all about feedback. Processes/parameters are measured or observed in relation to the criteria and standards set. Where a discrepancy occurs,


some action should be taken. For example, pH is greater than 9.0, flush the pond. Hardness is less than 20ppm, add lime. The flowtrap catches only 80% of the crop, review the procedure.

Conclusion This listing is reasonably comprehensive, but is by no means the whole story. However, it should give you a start in developing your own systematic approach to redclaw farming. Some of you may have recognised that this Systems Approach is similar to the concept of Total Quality Management (TQM), and that the setting of criteria and standards to measure performance is effectively Quality Assurance (QA). It's true, just different terminology. The practices of TQM and QA are most commonly applied to the post-harvest and market sectors. Whatever they may be called, the value of these philosophies for the production chain is also clear. Many farmers may suggest that this Systems Approach is too involved and impractical. It has to be something you as a farmer are committed to and feel comfortable with. I accept that many of the aspects I have covered might be observed rather than measured, and might be remembered rather than written down. Nevertheless, the likelihood of achieving your objective, your mission, will be vastly improved if a methodical, clearly defined systematic approach is applied.


WATER QUALITY Millin Curtis A basic understanding of some of the properties and dynamics of the pond water is essential for maximising crop yield. Measurement of water quality does not replace observation of the crayfish stock, but provides additional data to foster informed decision making. The quality of water in ponds has a direct effect on crayfish health and performance. If water quality deteriorates, crayfish become predisposed to retarded growth, disease and migration. Proper management of the water commences with pond preparation and continues throughout the life of the pond. Good pond managers will be able to predict when water quality deterioration may occur and take remedial action. Reacting to poor water conditions as they occur or after the fact is not good practice.

Pond Preparation Liming Liming deals with problems associated with the acid - base relationship in soils or water. Liming is not fertilising but may increase the response of fertilisation by mobilising nutrients.

Table 4. Liming and non-liming compounds used for aquaculture ponds.

Formula Compound Common Names Neutralising Value

(%) CaCO3 Calcium Carbonate Agricultural

limestone 100

Ca(OH)2 Calcium Hydroxide Hydrated lime Builders lime Slaked lime Caustic lime

136

CaO Calcium Oxide Quick lime Unslaked lime Burnt lime

179

CaMg(CO3)2 Calcium Carbonate / Magnesium Carbonate blend

Dolomite Calmag

109

CaSO4.2H2O Calcium Sulphate Gypsum nil

Al2(SO4)3 Aluminium Sulphate Alum nil The neutralising value of agricultural lime depends upon the fineness of the particles. Finer particles cause a stronger pH response. Agricultural lime has an arbitrary neutralising value of 100, against which all other liming agents are compared.


Hydrated lime is caustic and care should be taken where there is potential for exposure to the skin or eyes. It can be used to remove high carbon dioxide levels commonly experienced after plankton crashes or in bore water. Quick lime is highly caustic and can easily burn the skin, particularly if there is any perspiration. If applied to water, this material will generate bubbles as it transforms to calcium hydroxide. Detoxification of very acid pond bottoms is best achieved by applying quick lime to moist mud. Dolomite is a calcium-magnesium carbonate blend. Besides effective liming, this product provides magnesium in addition to calcium, necessary for shell growth. Gypsum is a good source of calcium but will not effect pH. Application of gypsum is useful when the water is deficient in calcium (soft water) but has a high pH. Outcomes of liming ponds include: • pH of the water is raised to acceptable levels for crayfish production • pH of the mud substrate is raised so that important nutrients such as nitrogen,

phosphorus and potassium are mobilised and produce plankton blooms • the alkalinity or buffering capacity of pond waters is increased, preventing large

daily swings in the pH value. Increased alkalinity has been attributed to significant production increases in penaeid prawn culture. Many people incorrectly use the term 'alkaline' to refer to non-acid waters, although alkaline waters commonly have a higher pH

• calcium (and magnesium) are provided as a nutrient source. These nutrients are essential for shell growth

• the decomposition process of organic matter is accelerated, providing a potential food source more rapidly

• pond bottoms are detoxified between growout cycles. A build up of uneaten feeds and crayfish wastes on the pond bottom contributes to anaerobic conditions in the substrate. Liming in conjunction with sun drying effectively conditions ponds for re-use.

Lime requirements The amount of lime required during pond preparation is complex and dependent upon many factors. The two main factors are pH of the bottom mud (this can be quite different from pond or source water pH) and soil type (Figure 3). Mud pH can be determined by inserting a pH probe directly into a well mixed solution containing equal parts of distilled (but not de-ionised) water and mud. The more acidic the mud, the more lime it will require. Similarly, heavier soils will require more lime than sandy soils. If the selected rate is adequate, total alkalinity and hardness will remain above 20 mg/l CaCO3 after 3 or 4 weeks.


Figure 3. Estimating agricultural lime application rate. (modified from Boyd, 1990).

kg/ha

0

2000

4000

6000

8000

10000

12000

14000

16000

heavy loamor clay

sandyloam

sand

4.0 4.5 5.0 5.5 6.0 6.5 7.0

pH OF MUD Fertilisers Fertilisers can increase the productivity of a pond. The two types of fertilisers are : • Chemical: these are compounds that dissolve in water releasing nutrients • Organic: these are manures or agricultural by-products that slowly release

nutrients when decomposing Phosphorus is the main limiting nutrient in most aquaculture systems. Lime should be added to ponds well before phosphate based fertilisers to displace phosphates from colloidal mud. Nitrogen is the second most limiting nutrient. Application of a fertiliser that contains a good balance of both these nutrients will increase the likelihood of establishing and maintaining a good plankton bloom. The appropriate amount of fertiliser to add to each pond is largely dependent upon the available nutrient content of the existing soil. Variation of conditions between and within farms precludes any "recipe approach" to pond fertilising. Initial applications of around 200 kg/ha of DAP and various amounts of lucerne pellets, chaff and chicken manure hung in sacks have been successfully used at Walkamin to promote plankton growth. Fertilising should not be carried out when overcast weather inhibits phytoplankton growth as nutrients will become bound in the bottom mud. Blooms take 9 to 14 days to peak at about 35 to 60 cm secchi depth at Walkamin. Subsequent fertiliser applications become necessary when blooms drop below about 70 cm.


Managing plankton Ponds are fertilised to stimulate a phytoplankton bloom that provides an abundant food source for zooplankton to feed on. Phytoplankton are the microscopic plants (algae) inhabiting the water column that give the pond colour, provided there is no interference from clay turbidity. A secchi disk may be used to measure plankton density. There are many advantages of maintaining phytoplankton communities in ponds. Like all plants, the phytoplankton photosynthesise to generate oxygen in the presence of sunlight. Due to higher oxygen levels, ponds with healthy phytoplankton blooms can support a greater biomass of crayfish than clear ponds. Phytoplankton can raise the pH to levels more conducive to crayfish culture and the dark shading cover that it provides may encourage foraging behaviour outside of regular feeding times. Zooplankton are microscopic animals that can sometimes be seen moving around the pond in cloud-like formations. Zooplankton numbers will rapidly increase until there is no more available food. Re-fertilising the pond to provide nutrients for phytoplankton before they become eaten out by zooplankton will cause an equilibrium to occur between the two communities (Figure 4). Zooplankton may also feed on the microbial communities associated with organic matter. Zooplankton is an excellent source of cheap natural food that is nutritious for crayfish, especially juveniles.

Figure 4. Typical changes in plankton density after pond filling in well managed ponds.

phytoplankton

zooplankton

PLANKTONDENSITY

High

Low

TIME (weeks)

1 2 3 4

fertilise

fertilise

Bacteria populations proliferate in the presence of organic matter. However, bacterial breakdown of organic matter reduces oxygen levels substantially. Organic matter additions should only be undertaken when oxygen levels can be maintained at acceptable levels.

REDCLAW CRAYFISH AQUACULTURE 35 Pond dynamics The changes to water quality conditions in a pond over a 24 hour period can be quite dramatic. The following figures illustrate typical changes to the most important water quality parameters - temperature (Figure 5), pH (Figure 6) and dissolved oxygen (Figure 7). Crayfish growth is largely dependent upon temperature. Redclaw have a broad temperature range over which close to maximum growth occurs. A maxima-minima thermometer can be used to measure the temperature range over any time period. These cost about $30 and can be purchased from any scientific supplies. Temperature (and all other water quality parameters) should be measured just above the pond bottom, where crayfish predominantly occur.

Figure 5. Typical water temperatures over 24 hours in a redclaw pond in north Queensland during summer.

dawn noon dusk midnight dawn20

22

24

26

28

30Temperature (C)

LIGHT DARK

Morning temperatures in the pond steadily rise from just after daybreak reaching their peak around dusk and then steadily decline throughout the night until dawn. Water density is dependent upon temperature. Ponds become thermally stratified when the water is not well mixed and the bottom is appreciably colder and denser than the top. Installation of a series of air-lift pumps serviced by a blower is a cost effective method of de-stratifying ponds. pH may be quite low before dawn (Figure 6). On a sunny day, a steady increase will occur after dawn as phytoplankton remove carbon dioxide from the water during photosynthesis. The pH will remain high after sunset until the effects of plant and


animal respiration result in net carbon dioxide production, causing a steady decline in pH until dawn. Low pH levels can be treated by liming and dangerously high pH levels can be reduced by flushing. The addition of organic matter can also reduce pH as acids are released during decomposition. However, this may reduce oxygen to dangerously low levels and may contribute to shell staining.

Figure 6. Typical pH levels over 24 hours in a redclaw pond in north Queensland. Levels are given for low alkalinity (<20ppm) and high alkalinity (>50ppm) water.

pH

Low Alkalinity

Moderate Alkalinity

dawn noon dusk midnight dawn One of the dangers of high pH levels in ponds that have a large crayfish biomass and high feeding rates, is ammonia toxicity. The major source of ammonia is from crayfish excreta. Ammonia exists in two basic forms, unionised (NH3-highly toxic) and ionised (NH4). As a general rule of thumb, ammonia toxicity increases tenfold with every one unit rise in pH and doubles with every 10 degree Celsius rise in temperature. Potential danger situations occur in the late afternoon or evening when temperature and pH are elevated. This problem may be exacerbated in poorly buffered ponds, where daily pH swings are greater. Documented studies indicate that ammonia concentrations as low as 0.09 mg/l may reduce growth in freshwater crustaceans. An average quality pH meter will cost around $200.

REDCLAW CRAYFISH AQUACULTURE 37 Figure 7. Typical dissolved oxygen levels over 24 hours in a redclaw pond in north Queensland.

DO (mg/l)

LIGHT DARK

dawn noon dusk midnight dawn Dissolved oxygen (DO) is lowest in the morning and steadily rises to a peak in the late afternoon - evening (Figure 7). Clearly, the potential danger period for crayfish is during the night and very early morning. Although redclaw are extremely hardy and can survive long periods at very low DO concentrations, commercial growth rates cannot be achieved under these conditions. DO levels should be maintained above 5 mg/l. Natural oxygen generation from wind and phytoplankton is insufficient to sustain long term commercial production of a large biomass of redclaw. Supplementary aeration should be provided. Supplying oxygenated new water while discharging poorer quality bottom waters will provide some relief to crayfish when DO levels drop. DO meters are very expensive (at least $1500 for a reliable one) and require regular maintenance. DO should be measured very early in the morning as this is when it is lowest. A low oxygen situation may be indicated by crayfish rolling on their side in shallow water exposing their gills to the air-water interface, crayfish emerging from the water, or dead animals found in baited traps. Pond DO concentrations are most often lowest on the bottom, where the crayfish live.


Conditions which commonly occur before a potential oxygen crash are hot, still, cloudy days where there is little oxygen generation from phytoplankton or mixing of the water column and elevated temperatures reduce the ability of the water body to contain dissolved oxygen. Plankton die-off will also result in a reduction in available oxygen as bacteria use large quantities of DO to decompose the dead plankton. Additions of excess organic matter will cause the same result.

Record Keeping Keeping accurate records of water quality measurements for each pond is an effective way to rapidly increase understanding of pond dynamics. It also assists you to become proficient at predicting deterioration of water quality by comparing with conditions and outcomes previously recorded. Prevention is cheaper than cure.


REDCLAW ECONOMICS Andrew Hinton and Clive Jones This paper was prepared originally for a farm diversification project for Atherton Tablelands farmers. The project named 'Choices', examined alternative crops for Tobacco farmers. While specific reference is made to conditions prevailing in the Mareeba-Dimbulah district, the economic analysis is applicable to redclaw aquaculture throughout its existing range of operation in Australia. Costs are in Australian dollars as at 1994.

Summary At present the redclaw industry in Australia is undergoing rapid change as it expands and is still at an infant stage. This analysis is based on data collected from existing redclaw farms. Census data was used to help prepare profitability figures for model redclaw farms that have 53 ponds with each pond measuring an area of 750m2 which is equivalent to 4 hectares of pond area. According to existing farmers this size operation is considered sufficient to support a family-based operation. Two model redclaw farms are presented in this paper. Many farms from the Mareeba-Dimbulah region have sandy soils and it is recommended that these farms use pond lining. Farms with clay based ponds do not require lining since levels of water seepage is usually low. Pond lining is expensive and for this reason two scenarios are presented - a model farm with pond lining and one without pond lining. To set up a redclaw farm with 53x750m2 ponds costs $376,012 including pond liners and $217,078 without pond lining. These large up-front costs plus the uncertainty that is associated with a new industry presents barriers for new entrants. The large establishment costs may however be reduced through the use of existing land, equipment and using alternative pond designs. If existing farms are able to use existing capital equipment for redclaw farming then opportunity costs (value of next most profitable use) rather than new values need to be incorporated. Capital costs for items such as sheds, vehicles, electricity connection and workshop equipment would also need to be adjusted. Payback periods of between eight and twelve years are necessary using the model redclaw farms. The longer payback period applies for farms requiring pond lining. The costs of producing redclaw for the model farms were $9.30/kg and $7.87/kg with and without pond lining respectively. Included in these costs was an allowance for family labour and depreciation. At present the average price received is about $10.00/kg. After allowing for growing and overhead costs there are low margins for both model farms. A competitive advantage exists for farms that can produce redclaw without lining ponds compared to those that need pond lining. Variable costs for both model farms represented about $0.62/kg. Overhead costs were $7.87/kg for farms without pond liners and $8.68/kg for farms with pond liners.


Economies of size are significant due to the large overheads involved. As total pond areas increase the overhead costs per kilogram decrease. By expanding the operation to six hectares reduces total production costs to $8.44/kg and $7.00/kg, representing savings of $0.24/kg and $0.87/kg with and without pond liners respectively. Negative returns to capital and management result if pond areas are less than 3.6 hectares for farms required to line ponds compared to 2.6 hectares for remaining farms. The model farms were unprofitable with reductions in farm-gate prices below $9.40/kg or $7.90/kg with and without pond lining respectively. There exists a competitive advantage of about $1.50/kg for farms with ponds located on clay based soils that do not require pond lining compared to those that require lining. Based on the 53x750m2 model pond farm with pond liners it is estimated that an improvement in yield by 10% would double the return to management. For remaining farms the return to management would improve by 50%. Farms that require pond lining require a yield improvement of about 15% to obtain similar levels of returns to management as remaining farms.

Introduction Since the redclaw industry is at such an infant stage with few growers it is difficult to derive a typical redclaw farm. Significant variations exist between farms with each farm having unique soils, location, management and size. For this reason the following analysis uses parameters, that according to several growers in the Far North Queensland, are considered to be conservative and representative. Three existing growers were consulted by DPI&F&F to help develop the following economic analysis. All these grower's farms are located on the Queensland coast south of Innisfail. Soils and water costs for the farms consulted are significantly different from potential farms in the Mareeba-Dimbulah region. Farms on the coastal region south of Innisfail have clay based soils and access to either creek or bore water. The Mareeba-Dimbulah region has generally sandy soils with access to irrigation channel supply. Such differences meant altering the capital and operating costs. Pond lining would be necessary if the farm ponds are located on sandy soils to prevent excessive seepage. The capital cost of pond lining is high and places farms with sandy soils in the Mareeba-Dimbulah district at a competitive disadvantage to those on clay soils. Methods used to line ponds may vary depending on the pond site. In the analysis that follows two scenarios are presented; a farm with pond lining and a farm without pond lining. Both farms are 4 hectares in pond area (8 ha total farm area required) considered to be sufficient to support a family-based operation by existing growers on the north coast.

Results The results of the analysis are presented as follows:

REDCLAW CRAYFISH AQUACULTURE 41 • Cost of production and profitability for 53x750m2 pond model redclaw farms with

and without pond lining. • Sensitivity analysis to show what effect changes in prices received and yields

have on profitability for the 53x750m2 pond model farms. • Cost of production and profitability for varying pond areas for farms with and

without pond lining. Costs of production and profitability Costs presented in the analysis can be broken down into variable and overhead costs, each are defined as follows: Variable costs. Variable costs consist of the following: • Feed • Dolomite • Fertiliser The following estimates are based on actual costs incurred by existing redclaw farms on the coast with the exception for water charges which are adjusted for the Mareeba-Dimbulah region. Feed. The different feed conversion ratios and the variety of feeds available make this estimate difficult to calculate. Feed costs may vary between $400/t and $800/t. For the purpose of this analysis $430/t was used based on recommendations by DPI&F technical officers. Table 5 summarises the feed cost calculation for the model farm in a steady-state situation which is achieved by the end of year 3. Dolomite and fertiliser. Fertiliser used in the ponds will assist in the development of a rich microbial flora and fauna, adjusts the pH level and water hardness. The rate of application, particularly for newly constructed ponds, is dependent on local conditions. The rate used in this analysis is $200/ha dolomite and $100/ha fertiliser (DAP, hay, liquid fertiliser) each year.

Table 5. Estimated feed costs for a model redclaw farm with 53 x 750m2 ponds.

Item Production of redclaw (t/ha/yr)* 2.109 Total production of redclaw (t/yr) 8.44 Feed conversion ratio (feed required:animal sold)

1.3:1

Feed consumed (t/yr) 10.97 Cost of feed @ $430/t ($/yr) $4,717

*Calculated for total pond area (equivalent to 2.5t/ha growout pond) Overhead costs. Overhead costs consist of the following (see Figure 8):


• Allowance for owner's unpaid labour • Hired labour • Administration • Fuel and oil • Electricity • Water charges • Repairs and maintenance • Depreciation • Interest on capital invested Allowance for owner's unpaid labour. This allowance is a reward to the owner for the labour and management of the farm. The figure of $25,000 is used. Hired labour. Permanent casual and permanent hired labour is required for various farm sizes. Table 6 below shows the hired labour allocations assumed for various farm size groupings. An additional amount of labour was allocated for the initial construction of the farm.

Table 6. Allocation and costs of hired labour for redclaw farms of varying size.

Type of hired labour Range of total pond area (ha)

Allowance ($)

None required Permanent casual Permanent casual Permanent

< 3.1 3.1 - 4.0 4.1-6.0

>6.0

- 4,000

15,000 25,000

Administration costs. Included in administration costs are rates, bank fees, accountancy fees, telephone and licences. An estimate of $4,700 is used. Fuel and oil. Fuel and oil are used to operate the farm tractor and utility. This estimate will vary on management style, size of machinery and price of fuel. This analysis assumes the price of diesel is 65 cents/litre and that 321 litres are used per month. The overall cost of fuel per year is estimated to be $2,504. Electricity. Electricity is used for operating pumps, driving the aeration units in the ponds plus lighting and workshop equipment. An annual rate of $5,600 is used (based on $1,400/ha). Water charges. Water is assumed to be supplied from the irrigation channel and is pumped to the farm. The cost of water supply is based on 20 ML/ha being used each year at a cost of $30/ML. This amounts to a cost of $2,400/yr. Repairs and maintenance. The cost of repairs and maintenance to farm machinery, earthworks and buildings was based on farmer estimates. A value of $3,000 is used.

REDCLAW CRAYFISH AQUACULTURE 43 Depreciation and interest. Based on the discounted cash flow used in this analysis an annual depreciation and interest cost was calculated from the replacement value of farm assets. The depreciation and interest cost represents an annuity or payment of equal instalments for capital in 1994 dollars. Table 7 lists the major capital costs for establishing a redclaw farm. The total cost of establishment for year 0 is shown at the bottom of the table. The analysis assumes that all capital items need to be purchased at the start of the project. If existing farms can use equipment already owned for redclaw farming then opportunity costs rather than new values need to be incorporated. These opportunity costs represent the values of the items based on their next most profitable alternative.

Table 7. Total capital costs for a model redclaw farm with 53 x 750m2 ponds.

Capital item New value ($)

Scrap value (%)

Years of purchase

Earthworks1 (ponds and channels) Pond lining2 Land3 Roads (access roads) Shed (20ftx20ft) Pond fencing (zincalume) Piping (incl. trenches and fittings) Bird netting (incl. posts) Electricity (3 phase) Holding tank (incl. plumbing) Habitat Blower/air lift pumps Pond inlet filter Bait trap Scales Bins/flow traps Meters (pH,O2 etc.) Workshop equipment Tractor and slasher Utility 4x4 Bearing females/juveniles4

80,000 158,933

8,000 3,000 8,000

12,020 8,000

11,000 8,000 3,333 5,333 3,600

400 417 500

1,000 2,100 1,000

10,000 20,000 31,375

- 20

100 -

30 10 - -

100 10 -

10 10 -

20 20 10 10 20 40 -

0 0 0 0 0 0 0 0,10 0 0 0,10 0,10 0,2,4,6,8,10,12,14,16,18 0 0,5,10,15 0,5,10,15 0,5,10,15 0,5,10,15 0 0,5,10,15 0

Total including pond liners Total excluding pond liners

376,012217,078

1 Based on a contract rate of $1,500 per 750m2 pond to depth of 1 m. 2 Pond lining for the model farm is based on one layer of PVC lining with sand, located on the farm, used as an underlay and covering above the liner. To line the 750m2 pond to a depth of 1 metre costs about $3,000. This cost includes liner, labour and sump construction. 3 Based on 8 hectares to yield 4 hectares of ponds. This makes provision for pond walls, drains, access roads and buildings. The value of $1,000/ha is the opportunity cost (value) of the next most profitable alternative. 4 Bearing females and juveniles represent the initial stocking of the ponds. See the Appendix for stocking details.

Depreciation and interest are estimated to be $34,697 and $18,214 for farms with and without pond lining, respectively. Discounted cash flow analysis is used to determine the annual cost of production and profitability of redclaw farming. A characteristic of redclaw farming is that the costs


and returns they give rise to are spread out over time. People are not indifferent with respect to the timing of costs and benefits -usually they prefer to receive benefits as early as possible and to pay for costs as late as possible. It is therefore important that the valuation of costs and benefits takes explicit account of the time at which they occur. Discounted cash flow analysis reduces a time stream of costs or benefits to an equivalent amount of today's dollars. That single amount is known as the present vale of the future stream of costs and benefits. The present value is calculated using the method of compound interest and the rate by which the present value is computed is known as the discount rate. Thus the discount rate is in effect an `exchange rate' between values today and values in the future. In the following analysis a project life of 20 years is used with a discount rate of 6% (real rate) to calculate the net present value (NPV). The NPV of a project is the difference between the present value of the benefits and the present value of the costs. A project creating a positive NPV is generally considered acceptable. Tables 8 and 9 illustrate the discounted cash flows for the model redclaw farms with and without pond liners. Table 10 summarises all the costs on a per farm and per kilogram basis for farms with and without pond liners.

45

Table 8. Discounted cash flow for model redclaw farm with 53 x 750m2 ponds with pond liners. Farm size (ha)...............4.00 No. of ponds................. 53 Real discount rate.......... 6%

Project benefits

Year Percentage steady state (%)

Yield (t/ha/yr) total area

Revenue from crop

TOTAL PROJECT BENEFITS ($/yr)

FEED ($)

LIME ($)

ELECT. ($)

FERT. ($)

REPAIRS & MAINT. ($)

WATER CHARGES ($)

FAMILY LABOUR ($)

HIRED LABOUR ($)

ADMIN. COSTS ($)

FUEL & OIL ($)

TOTAL OPERATING COSTS ($)

TOTAL CAPITAL COSTS ($)

ANNUAL CASH FLOW ($)

ACCUMUL. CASH FLOW ($)

0 0.00% 0.000 0 0 0 0 0 0 0 0 12500 2000 0 0 14500 376012 -390512 -390512 1 45.00% 0.949 37969 37969 4717 800 5600 400 3000 2400 25000 4000 4700 2504 53120 0 -15152 -405663 2 90.00% 1.898 75938 75938 4717 800 5600 400 3000 2400 25000 4000 4700 2504 53120 360 22457 -383206 3 100.00% 2.109 84375 84375 4717 800 5600 400 3000 2400 25000 4000 4700 2504 53120 0 31255 -351952 4 104.00% 2.194 87750 87750 4717 800 5600 400 3000 2400 25000 4000 4700 2504 53120 777 33853 -318099 5 108.00% 2.278 91125 91125 4717 800 5600 400 3000 2400 25000 4000 4700 2504 53120 15990 22015 -296084 6 112.00% 2.363 94500 94500 4717 800 5600 400 3000 2400 25000 4000 4700 2504 53120 360 41020 -255064 7 116.00% 2.447 97875 97875 4717 800 5600 400 3000 2400 25000 4000 4700 2504 53120 0 44755 -210310 8 120.00% 2.531 101250 101250 4717 800 5600 400 3000 2400 25000 4000 4700 2504 53120 777 47353 -162957 9 124.00% 2.616 104625 104625 4717 800 5600 400 3000 2400 25000 4000 4700 2504 53120 0 51505 -111452

10 128.00% 2.700 108000 108000 4717 800 5600 400 3000 2400 25000 4000 4700 2504 53120 35923 18956 -92496 11 129.45% 2.731 109223 109223 4717 800 5600 400 3000 2400 25000 4000 4700 2504 53120 417 55686 -36809 12 130.90% 2.761 110447 110447 4717 800 5600 400 3000 2400 25000 4000 4700 2504 53120 360 56967 20157 13 132.35% 2.792 111670 111670 4717 800 5600 400 3000 2400 25000 4000 4700 2504 53120 0 58550 78707 14 133.80% 2.822 112894 112894 4717 800 5600 400 3000 2400 25000 4000 4700 2504 53120 777 58997 137704 15 135.25% 2.853 114117 114117 4717 800 5600 400 3000 2400 25000 4000 4700 2504 53120 15990 45007 182711 16 136.70% 2.884 115341 115341 4717 800 5600 400 3000 2400 25000 4000 4700 2504 53120 360 61860 244571 17 138.15% 2.914 116564 116564 4717 800 5600 400 3000 2400 25000 4000 4700 2504 53120 417 63027 307598 18 139.60% 2.945 117788 117788 4717 800 5600 400 3000 2400 25000 4000 4700 2504 53120 360 64307 371905 19 141.05% 2.975 119011 119011 4717 800 5600 400 3000 2400 25000 4000 4700 2504 53120 0 65891 437796 20 142.50% 3.006 120234 120234 4717 800 5600 400 3000 2400 25000 4000 4700 2504 53120 -58732 129846 567642

Total(PV) 109.84 1098431 1098431 54099 9176 64232 4588 34410 27528 299248 47880 53909 28718 623786 379973 IRR(%)= 7.70% Farm av/yr 9.58 95776 95766 4717 800 5600 400 3000 2400 26090 4174 4700 2504 54385 34697 TOTAL COSTS/YR= 89082 Av/pond/yr 0.180 1796 1796 88 15 105 8 56 45 489 78 88 47 1020 651 TOTAL COSTS/HA= 22270 Av/kg 10 10 .49 0.08 0.58 0.04 0.31 0.25 2.72 0.44 0.49 0.26 5.68 3.67 TOTAL COSTS/KG= 9.30

SUMMARY TABLE (all NPV format) $/farm/yr $/kg Total project benefits 95,766 10.00 less variable costs 5,917 0.62 equal gross margin 89,850 9.38 less overhead costs 83,165 8.68 equals Return to management 6,685 0.70 Internal rate of return 7.70%

46

Table 9. Discounted cash flow for model redclaw farm with 53 x 750m2 ponds without pond liners. Farm size (ha)...............4.00 No. of ponds................. 53 Real discount rate.......... 6%

Project benefits

Year Percentage steady state (%)

Yield (t/ha/yr) total area

Revenue from crop

TOTAL PROJECT BENEFITS ($/yr)

FEED ($)

LIME ($)

ELECT. ($)

FERT. ($)

REPAIRS & MAINT. ($)

WATER CHARGES ($)

FAMILY LABOUR ($)

HIRED LABOUR ($)

ADMIN. COSTS ($)

FUEL & OIL ($)

TOTAL OPERATING COSTS ($)

TOTAL CAPITAL COSTS ($)

ANNUAL CASH FLOW ($)

ACCUMUL. CASH FLOW ($)

0 0.00% 0.000 0 0 0 0 0 0 0 0 12500 2000 0 0 14500 217078 -231578 -231578 1 45.00% 0.949 37969 37969 4717 800 5600 400 3000 2400 25000 4000 4700 2504 53120 0 -15152 -246730 2 90.00% 1.898 75938 75938 4717 800 5600 400 3000 2400 25000 4000 4700 2504 53120 360 22457 -224273 3 100.00% 2.109 84375 84375 4717 800 5600 400 3000 2400 25000 4000 4700 2504 53120 0 31255 -193018 4 104.00% 2.194 87750 87750 4717 800 5600 400 3000 2400 25000 4000 4700 2504 53120 777 33853 -159165 5 108.00% 2.278 91125 91125 4717 800 5600 400 3000 2400 25000 4000 4700 2504 53120 15990 22015 -137151 6 112.00% 2.363 94500 94500 4717 800 5600 400 3000 2400 25000 4000 4700 2504 53120 360 41020 -96131 7 116.00% 2.447 97875 97875 4717 800 5600 400 3000 2400 25000 4000 4700 2504 53120 0 44755 -51376 8 120.00% 2.531 101250 101250 4717 800 5600 400 3000 2400 25000 4000 4700 2504 53120 777 47353 -4023 9 124.00% 2.616 104625 104625 4717 800 5600 400 3000 2400 25000 4000 4700 2504 53120 0 51505 47481

10 128.00% 2.700 108000 108000 4717 800 5600 400 3000 2400 25000 4000 4700 2504 53120 35923 18956 66438 11 129.45% 2.731 109223 109223 4717 800 5600 400 3000 2400 25000 4000 4700 2504 53120 417 55686 122124 12 130.90% 2.761 110447 110447 4717 800 5600 400 3000 2400 25000 4000 4700 2504 53120 360 56967 179091 13 132.35% 2.792 111670 111670 4717 800 5600 400 3000 2400 25000 4000 4700 2504 53120 0 58550 237640 14 133.80% 2.822 112894 112894 4717 800 5600 400 3000 2400 25000 4000 4700 2504 53120 777 58997 296637 15 135.25% 2.853 114117 114117 4717 800 5600 400 3000 2400 25000 4000 4700 2504 53120 15990 45007 341644 16 136.70% 2.884 115341 115341 4717 800 5600 400 3000 2400 25000 4000 4700 2504 53120 360 61860 403504 17 138.15% 2.914 116564 116564 4717 800 5600 400 3000 2400 25000 4000 4700 2504 53120 417 63027 466531 18 139.60% 2.945 117788 117788 4717 800 5600 400 3000 2400 25000 4000 4700 2504 53120 360 64307 530838 19 141.05% 2.975 119011 119011 4717 800 5600 400 3000 2400 25000 4000 4700 2504 53120 0 65891 596729 20 142.50% 3.006 120234 120234 4717 800 5600 400 3000 2400 25000 4000 4700 2504 53120 -58732 125846 722575

Total(PV) 109.84 1098431 1098431 54099 9176 64232 4588 34410 27528 299248 47880 53909 28718 623786 240287 IRR(%)= 13.24 Farm av/yr 9.58 95776 95766 4717 800 5600 400 3000 2400 26090 4174 4700 2504 54385 20949 TOTAL COSTS/YR= 75334 Av/pond/yr 0.180 1796 1796 88 15 105 8 56 45 489 78 88 47 1020 393 TOTAL COSTS/HA= 18833 Av/kg 10 10 .49 0.08 0.58 0.04 0.31 0.25 2.72 0.44 0.49 0.26 5.68 2.19 TOTAL COSTS/KG= 7.87

SUMMARY TABLE (all NPV format) $/farm/yr $/kg Total project benefits 95,766 10.00 less variable costs 5,917 0.62 equal gross margin 89,850 9.38 less overhead costs 69,417 7.25 equals Return to management 20,432 2.13 Internal Rate of Return 13.24%


Table 10. Summary of economic analysis for a model redclaw farm with 53 x 750m2 ponds, using a farm-gate price of $10.00/kg.

Item With pond lining Without pond lining

1. Physical description Number of ponds 53 53 Number of growout ponds 45 45 Area/pond (m2) 750 750 Total pond area (ha) 4.0 4.0 Total farm area (ha) 8.0 8.0 Production/growout pond (t/ha) 2.5 2.5 Total production of redclaw (t/yr)

8.44 8.44

Feed conversion ratio 1.3:1 1.3:1 Feed consumed (t/yr) 10.97 10.97 Capital costs of establishment ($)

390,512 217,078

2. Financial description (NPV format) ($/farm/yr) ($/kg) ($/farm/yr) ($/kg) (a) Gross income 95,766 10.00 95,766 10.00 (b) Variable costs Feed 4,717 0.49 4,717 0.49 Dolomite 800 0.08 800 0.08 Fertiliser 400 0.04 400 0.04 Subtotal (b) 5,917 0.62 5,917 0.62 (c) Overhead costs Repairs & maintenance 3,000 0.31 3,000 0.31 Fuel & oil 2,504 0.26 2,504 0.26 Electricity 5,600 0.58 5,600 0.58 Hired labour 4,174 0.44 4,174 0.44 Depreciation plus interest* 34,697 3.62 20,949 2.19 Allowance for owner's labour 26,090 2.72 26,090 2.72 Water charges 2,400 0.25 2,400 0.25 Administration costs 4,700 0.49 4,700 0.49 Subtotal (c) 83,165 8.68 69,417 7.25 Total costs (b+c) 89,082 9.30 75,334 7.87 (d) Return to management [a-(b+c)]

6,685 0.70 20,432 2.13

*Assuming a real rate of interest of 6%

Figure 8 shows the accumulative cash flows for the two scenarios. Where the line crosses the horizontal axis represents the time required to achieve a positive accumulative cash flow (payback period). The payback period is the time required to recover the initial project outlay. A payback period of between twelve and eight years are required for the model farms with and without pond liners, respectively.

REDCLAW CRAYFISH AQUACULTURE

48

It was assumed that steady-state production was not achieved until the end of the third year and that yields from then onwards are increased gradually over time. Such improvements are included in the analysis because a conservative yield is assumed at the start of the analysis and yields are expected to improve as more research, experience and information becomes available to farm operators. The yield achieved at year 20 would place the growers in far north Queensland with comparable yields achieved by southern Queensland redclaw farms. Price is expected to remain constant for the twenty years. According to existing growers, more growers coming into the industry would create little competition and the extra demand created from a more widely accepted product is expected to keep prices at the same level.

Sensitivity analysis Variation in redclaw farm-gate price Table 11 and Figure 10 in the Appendix show the effect that farm-gate price has on the return to management for the model redclaw farms. A margin of about $1.50/kg exists between the two model redclaw farms. The farm without pond liners has a significant competitive advantage. Prices could reduce to $7.90/kg and the farm without pond liners would still obtain a positive return to management whereas $9.40 is required for farms with pond liners.

Table 11. Variations in farm-gate price on return to management for a model redclaw farm with 53 x 750m2 ponds.

Return to management ($) Farm-gate price ($/kg)

With pond liners

Without pond liners

16 15 14 13 12 11 10 9 8 7

64,144 54,568 44,991 35,414 25,838 16,261 6,685 -2,892 -12,469 -22,045

77,892 68,315 58,739 49,162 39,586 30,009 20,432 10,856 1,279 -8,297

49 REDCLAW CRAYFISH AQUACULTURE Variation in redclaw yield Table 12 shows the effect that yield has on the return to management for the model redclaw farms. A conservative yield of 2.5t/ha growout pond is used as the control (achieved in year 3).

Table 12. Variations in redclaw yields on return to management for a model redclaw farm with 53 x 750m2 ponds.

Return to management ($) Increase in yield (%) Yield (t/ha growout

pond) With pond liners

Without pond liners

Control 10% 15% 20% 25% 30% 40% 50%

2.5 2.75 2.875 3 3.125 3.25 3.5 3.75

6,685 15,790 20,342 24,895 29,447 33,999 43,104 52,209

20,432 29,537 34,090 38,642 43,195 47,747 56,852 65,957

A 10% improvement in yield would double the return to management for the model redclaw farm with pond liners. The same yield improvement increases the return to management about 50% for the model redclaw farm without pond liners. Another interpretation could be that a yield improvement of 15% is needed above the control level for the farm with pond lining so that the returns from the two scenarios are similar. Cost of production and profitability for varying pond areas Economies of size are believed to be significant in redclaw farming. To test this effect various pond areas were incorporated into the two redclaw farm models. Table 13 and Figure 11 shows how changing pond area causes significant economies of size. Hired labour inputs vary between pond area (see Table 6) and for this reason the reduction in costs of production per kilogram is not continuous as size increases. i.e. The transition between areas 4 to 4.5 ha and 6.0 to 6.5 ha results in higher costs of production per kilogram due to higher labour thresholds. Costs of production reduce from $13.78/kg to $8.46/kg shifting from a 2 ha pond area to 7 ha pond area for the model redclaw farm with pond liners. It appears that it is unprofitable to farm redclaw with a pond area less than 3.6 hectares for this model farm. When pond lining is excluded the total costs reduce from $12.31/kg to $7.01/kg for 2 ha and 7 ha pond areas respectively. This model farm becomes unprofitable at pond areas less than 2.6 hectares.


50

Table 13. Cost of production and return to management for redclaw aquaculture with various total pond area.

With pond liners Without pond liners Total pond area (ha)

Cost of production ($/kg)

Return to management ($)

Cost of production ($/kg)

Return to management ($)

2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0 6.5 7.0

13.78 11.69 10.63 10.09 9.30 9.87 9.24 8.86 8.44 8.73 8.46

-17,704 -10,082 -4,401 -767 6,685 1,400 9,021 14,742 22,204 19,831 25,557

12.31 10.25 9.16 8.64 7.87 8.41 7.80 7.41 7.00 7.29 7.01

-10,830 -1,490 5,910 11,262 20,432 16,866 26,206 33,645 42,825 42,171 49,615

Provision of Initial Stock The ways and therefore the costs of initial stocking of the ponds can vary greatly across farms. Each method will have different affects on redclaw yields for the first 3 to 5 years before steady state production levels are reached. For this analysis the cost of stocking the ponds in the first year is based on a proportion of bearing females, juveniles and advanced juveniles being purchased. This represents one way of stocking the redclaw farm with 6-12 months before the first harvest and up to 3 years before steady-state production levels are achieved. Table 14 provides a description of the pond allocation and costs for the 53 pond model.


Table 14. Cost and pond allocation for stocking a model redclaw farm with 53 x 750m2 ponds.

Stock purchased

No.of ponds

Brooding rate (j/fem)

Stocking rate for new juveniles (no./m2)

Stocking rate (no./m2)

No. per pond

Price per unit ($)

Total cost per pond ($)

Total cost per farm ($)

Bearing females

28 75 10 n/a 100 2.50 250 7,000

Juveniles 10 n/a n/a 10 7500 0.25 1,875 18,750 Advanced juveniles

5 n/a n/a 5 3750 0.30 1,125 5,625

Total 43 31,375

Figure 8. Accumulative cash flow over time for a model redclaw farm with 53 x 750m2 ponds.

0 5 10 15 20

0

500

1,000

0

-500

Accumulative cash flow ($'000)

Year


52

Figure 9. Percentage breakdown on overheads for model redclaw farm with 53 x 750m2 ponds.

Figure 10. Price and return to capital and management for a model redclaw farm with 53 x 750m2 ponds.

7 8 9 10 11 12 13 14 15 16

0

20

40

60

80

0

-20

-40

Return to Capital & Management ($'000)

Farm-gate Price ($/kg)

53 REDCLAW CRAYFISH AQUACULTURE Figure 11. Total pond area versus return to capital and management for a model redclaw farm with 53 x 750m2 ponds.

2 3 4 5 6 7 8

0

20

40

0

-20

Return to Capital & Management ($'000)

Total Pond area (ha)


54

INDUSTRY OVERVIEW (1994) by Greg Love Regional Activity The redclaw aquaculture industry throughout the State is expanding very slowly. This, I believe is due to a number of factors. Firstly, lack of a business plan available for new farmers prevents many from making a start, primarily because their accountant or bank manager cannot make an informed decision. The economic analysis included with these notes will go a long way towards alleviating this problem. There are also too many unknowns (variables) and a lack of set farm procedures. This is a little daunting for some. I believe that the industry will expand when farming techniques are improved and become more consistent. Again, access to the information contained in the seminar notes will be of great benefit. Production Total production for the State for 1992/93 was 40 tonnes as per the annual farmer survey. Actual production was probably considerably higher, somewhere in the area of 70 to 80 tonnes. At an average farm-gate price of $14.50 per kg, the value of the industry is in the order of one million dollars. However, given that there are at least 35 farmers producing, none of us are becoming millionaires. Demand for Juveniles to China At present there is a very strong demand for juveniles to China. Prices are reasonable but numbers required are large. Inspection costs to get them out of the country are taking the cream off this market. This needs to be addressed. ACM ACM (Australian Crayfish Marketing) a company owned by farmers was set up to aid the marketing of redclaw - large crayfish, juveniles and associated technology. ACM is working towards a compilation of a Business Plan. ACM can't do a lot until production increases over and above that required for the Domestic Market. ACM has made a lot of overseas contacts recently. Shares are still available at the original price for farmers wishing to buy into the company. Markets At the moment, almost all product is sold on the domestic market but I feel this can be expanded greatly with better marketing and packaging techniques. Direct contact with chefs, better purging and holding facilities would be advantageous.

55 REDCLAW CRAYFISH AQUACULTURE DPI&F Service Information available from the DPI&F is adequate for beginning farmers and is improving with time and research. There are many different farming techniques, climates and situations and therefore it is difficult at this stage to develop cut & dried procedures, even though the base of information is solid and accurate, it may sometimes have to be adapted to your own particular situation. Industry expansion will be greatly aided by development of better food and a suitable cheap habitat. Other Issues It would also be an advantage to be able to accurately determine the age of a crayfish. This would help in the selective breeding process on most farms. It's this attention to breeding that I believe has set farm bred stock well ahead of wild caught animals for aquaculture purposes. One of the good points for the industry is the operation of strong Crayfish Farmers Associations. These Associations help farmers through dissemination of information. They also help to overcome problems by allowing farmers to pre-empt problems through discussion. This was brought home to me at a recent North Queensland Aquaculture Consultative Committee (NQACC) meeting where barramundi Farmers are facing severe marketing problems through excess barramundi for this size of demand from the southern markets. They are now trying to start a Barramundi Farmers Association. The prawn farmers have an Association and are having no problems marketing large amounts of products at excellent prices. Our problem is not enough product. In finishing, I will say that there are bright prospects in this industry. However, I think that with each answer there seems to be more questions. These will be solved more readily if we are able to maintain a close working relationship between farmers, enabling us to pool results and resources.


56

REDCLAW MARKETING by Maurice Downing

Introduction Commercial farming of redclaw crayfish is a relatively new industry and is faced with a number of challenges such as small production volumes and a low level of consumer awareness. Made up of 35 members, each with a $500 shareholding, Australian Crayfish Farming (ACM) was formed in 1992 to address these and other relevant issues. ACM accounts for 98 per cent of redclaw production ACM and gives growers a vehicle by which they can achieve more by collaborating than by acting individually. While ACM has concentrated on developing export markets, in the short term it also has a significant future role to play in co-ordinating the domestic marketing of redclaw. In the middle of 1993 ACM undertook a market visit to Asian countries. Data gathered during this trip is being used as the basis for a business plan that is currently in its final stages. This paper has drawn on this information plus existing literature and interviews with wholesalers and restaurants to provide potential new farmers with an overview of the marketing environment facing redclaw crayfish.

Overseas Markets Europe Freshwater crayfish enjoy a higher level of consumer acceptance in Europe than anywhere else. Total consumption is approximately 10,000 tonnes per year. France and Sweden are the largest markets, each accounting for between 3000 and 4000 tonnes annually. The next largest are Belgium and Germany with 200 tonnes each. Prior to the mid 1980's Turkey was the major supplier of freshwater crayfish to European markets. However, when the crayfish plague devastated this source a shortfall of between 3000 and 5000 tonnes was created. The major player in meeting this demand is North America. Freshwater crayfish attract an import duty of between 15 and 18 percent on entering most European countries which tends to make them an expensive item. In addition to import duty some European countries will only allow entry to frozen or cooked product due to their concerns regarding disease. Asia

57 REDCLAW CRAYFISH AQUACULTURE Information from the market visit to Asia by Australian Crayfish Marketing (ACM) reveals that China is undertaking major expansion in the production of redclaw. A number of large farms are being established, some with up to 2500 hectares of ponds. While this has remarkable production potential and may initially be seen as a threat to the Australian redclaw industry it may also be of assistance in that it will help raise the level of awareness of redclaw in the marketplace. This may then open the way for niche marketing by Australia producers because large volume suppliers traditionally miss smaller market segments that may have particular needs different from the majority of consumers. For example, those who place a higher value on food products produced in clean environments. It is important that we try to identify these niche markets as the Chinese are expected to have significantly lower costs of production. They are already producing North American species of freshwater crayfish and they can land the peeled tails in the USA more cheaply that the American industry can produce their live animals. In Hong Kong samples of redclaw were given to five star hotels and were judged to be satisfactory. The Maine lobster coming in from the USA looms as the major competitor for redclaw in this market. At around 400 grams it is significantly smaller than traditional crayfish of 800 to 1000 grams. Most likely order size for redclaw was expected to be 200 kilos per week.. The hotels insisted on dealing via an importer/wholesaler as they were not interested in dealing with single product suppliers, a similar situation to that in most markets. In Japan animals of 120g or larger were the preferred size although there was a strong preference for seafood rather than freshwater crustaceans. By regulation only farmed animals can be exported from Australia. ACM has reported that since returning from the trip it has had to reject five orders for weekly shipments of 1 tonne because of the limited output of the industry. While prices quoted during the trip were $17 per kilo it was also mentioned that the Australian industry should work towards producing the product for around $6 per kilo (farm gate) to be competitive in the long term.. USA A 1991 report compiled by the Australian Bureau of Agricultural Economics (ABARE) reported that the USA's production of freshwater crawfish was 50 000 tonnes, mainly from Louisiana. The vast majority of this output was consumed domestically. However, this figure had risen to 140 000 in 1993 according to information gained during ACM's recent overseas marketing trip. As mentioned earlier a portion of this production is exported to Europe to meet the significant shortfall in this market caused by the crayfish plague. With this volume of production crawfish in the USA are able to be graded by size:


58

Size (cms) Name 6 hotel 7.5 whale 8.75 big daddy In Australia redclaw have only one common grade of 50 - 80 grams and are significantly larger than their North American competitors. When production volumes increase it may be possible to also develop various grade sizes. By doing so you are able to offer customers a wider product range so that they are able to choose a product that better meets their specific requirements.

Domestic Market Three species of freshwater crayfish are commercially farmed in Australia. Detailed below are the estimated production and value for each species for 1991. Crayfish tonnes $’000 $/kg Marron Redclaw Yabbie

10 46 97

226 690 1253

22.6 15 12.9

Total 153 2168 In the catering industry redclaw also competes with saltwater prawns, scampi, and the various species of saltwater crayfish. Size is a major determinant of the prices received. Marron, at an average of 200g, attracts the highest price followed by redclaw and the yabbie. For the current year production of redclaw is expected to be 60 tonnes according to industry sources. Approximately 70 percent is consumed domestically with the balance being exported, mainly to Europe.

Product Issues All redclaw sold fall into the one size category of 50-80g, unlike the situation in the USA as mentioned earlier where there are three grades each with its individual brand name. This is primarily due to the small industry size. Once larger volumes are achieved product can be graded accordingly which opens the way for a broader product range to be offered to customers thereby increasing the industry's ability to satisfy their individual requirements. Animals in the size range of 50 - 80g are preferred by restaurants as any larger specimen would not enable them to put 3 or 4 on a plate. Being a freshwater animal redclaw were reported as tending to have a more subtle taste than seafood.

59 REDCLAW CRAYFISH AQUACULTURE Practically all redclaw are sold live. As a result packaging requirements are minimal. However, product is allowed to be sold in a chilled or frozen state but no other processing is currently permitted. Two major prerequisites for successful marketing are consistent quality and supply. For a relatively new product like redclaw it is imperative that only a consistently high quality product is sold. Quality within the industry is determined by : • Thickness of the shell • Degree of vigour • Being free of parasites and discolouring Thin shelled animals are preferred by the market, as are healthy animals with strong vigour. Animals should be clean and free of parasites and/or stains. Should a consumer be confronted by a substandard product the industry risks losing future sales. This is vitally important for a new product such as redclaw because, as with anything new, people are often hesitant to try it. If they enjoy it they are likely to have it again which leads to increased sales and market growth. If they do not enjoy it the first time they are unlikely to ever order it again , an opportunity lost. Restaurants primarily present redclaw as an entree with two portions per plate. When ordered as a main course the diner will typically receive a serving of four. Once formulated, restaurant menus are set for six months at a time. For this reason consistent supply is of prime importance to wholesalers and restaurants. Chefs are reluctant to use an unreliable product that may embarrass them and possibly disappoint a customer which will result in lost sales. Distribution There are three major elements in the distribution chain for redclaw; farmer to wholesaler to restaurant. Product is typically handled in 10 kilo lots. Given the animal's ability to survive out of water freezer vans are not required for short distance deliveries. No product is sold at the retail level although one wholesaler reported that they used to sell them at their own shop for between $17 - $18 per kilo. However, the public considered this a little too expensive, largely because they did not have a clear value concept for the animal. Marketing licences issued to farmers dictate that product can only be sold to "licensed seafood marketers holding either a Processor Class A licence or a Commercial Buyer Class A licence". Farmers can sell product themselves if they have the appropriate licence. While selling direct to restaurants may result in slightly higher returns the practice can have a limiting effect on market growth. Effective and conscientious wholesalers can play a major role in increasing the market penetration of a product, a feature that


60

is especially helpful to fledgling industries struggling to develop markets. Wholesalers have the ability to cross-sell a new product while servicing a customer from there existing product range.

Pricing & Its Implications According to the most recent industry survey the average farm gate price for redclaw is $14.50 per kilo, including both domestic and export sales. Unlike other seafood products the price of redclaw is predominantly stable on domestic markets. Wholesalers are currently paying $13 per kilo and selling them to restaurants and hotels at between $15.60 and $16.50 per kilo. Although illegal, wild caught redclaw can be bought for $8 per kilo. Wholesalers typically need to achieve margins of at least 20 per cent to remain viable. Restaurant are reported to need margins on around 400 per cent on the cost of inputs to cover preparation and other overheads. Because of the price paid for redclaw restaurateurs had to charge prices similar to lobster and mudcrab. Essentially it is positioned as a "fine dining item". However, diners did not place the same value on redclaw as they did for the other items with the result that sales were restricted. It was considered that a slight reduction in price would enable redclaw to be used in buffets that would induce more people to try them which in turn helps to establish consumer acceptance and consequently build market demand. Wholesalers and chefs have tended to position redclaw lower than lobster but higher than prawns. Interviewees also felt that the more relevant competitors for redclaw were scampi and small champagne lobsters of 250-300 g. Some consumers were reported as thinking redclaw were baby lobster.

Promotion To date very little promotion of redclaw is done, characteristic of most fledgling industries. However, before truly effective promotion can be undertaken something that is different or unique about the product must be identified.. This attribute then becomes the central theme of all promotional activities. In short you must give the customer a reason for buying your product; you must attempt to "stand out from the crowd".

Summary Redclaw is a relatively new product and it is worthwhile to put this in perspective. In marketing terms redclaw is at the early stages of its product life cycle. The following characteristics are typical of such a situation: 1. Small production volume 2. Single product or limited product range

61 REDCLAW CRAYFISH AQUACULTURE 3. Low level of customer awareness 4. Struggling to establish a clear identity among competing products 5. Relatively few customers. Popular opinion suggests the most critical issue facing the redclaw industry at this stage is a lack of supply and therefore the inability to put significant volume onto the market. However, I believe there is an equally critical, albeit more subtle, issue that also needs attention People had a difficult time deciding exactly where redclaw fitted compared to other available products i.e. where it is positioned in the marketplace. Some said it was closer to lobster, others said it was unique and did not have a close substitute and herein lies the challenge. While it is agreed that the Australian industry needs to boost production a lot of thought also needs to be given to where redclaw is to be positioned in the minds of consumers. Ultimately it is the consumer who decides how much value a product represents for them and, therefore, how much they will pay for it relative to possible substitutes such as prawns, lobster or Moreton bay bugs. If this issue is not addressed then when the industry finally arrives at their desired destination in volume terms the customers wont be there to meet them. Should this happen the industry may find itself in the position of having to discount prices to attract customers. Rather, the industry must endeavour to ensure that the customer has the same value concept of redclaw as it does, that it is something they prize and are willing to pay a premium for.

Date post:	27-Nov-2014
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Redclaw Crayfish Aquaculture

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