SRAC Publication No. 244

VI April 1997 PR

Australian Red Claw

Michael P. Masser and David B. Rouse*

When it was discovered that and have quite distinct natural ditions. It survives water tempera- freshwater crayfish from the land histories (Figure 1). tures between 55 and 85oF but “down under” grew to over a appears to grow best between 70 Marron grow to be the largest and o pound, aquaculturists in the attracted considerable interest in and 75 F. In its natural habitat, United States got excited. the U.S. during the 1980s. marron live in cool streams and Dubbed “freshwater lobsters,” Research with marron has not rivers of southwest Australia. these Australian crayfish have been encouraging, however. Summer water temperatures in received a great deal of media Research has shown that this most of the southeast U.S. remain attention. Today Australian cray- species grows relatively slowly (1 at or above 85oF for two or more fish are reportedly farmed not to 2 ounces per year even though months each summer and may for only in Australia but in New they may obtain a size of several short periods exceed 90oF. Zealand, Southeast Asia, Africa, pounds) and tolerates a very nar- Marron are also sensitive to han- Central and South America, and row range of environmental con- dling and water quality changes. the United States. Very little about the culture of Australian crayfish was known before 1975 when the selling of farm raised crayfish was first legalized in Australia. Once cray- fish farming began, aquaculture enthusiasts in Australia began investigating several different species of crayfish for their culture potential. There are more than 100 species of Australian crayfish, but only three species are presently being cul- tured. These are the “marron” ( tenuimanus), the “yabbie” (Cherax albidus-destructor), and the “red claw” (Cherax quadricarina- tus). These three species are native to different regions of Australia

*Extension Fisheries Specialist, and Professor, Alabama Cooperative Extension System, Auburn University, AL. Figure 1. Natural distributions of cultured species of Australian crayfish.

1 Low levels of salt (100 to 300 This publication summarizes When burrowing does occur, it is ppm) and moderate levels of available information on the life usually in the deeper portions of alkalinity and hardness (50 to 100 history, environmental require- the pond and does not damage ppm) were found to be necessary ments, techniques for spawning, dams or levees. for successful growth/molting hatching and production, and Another major difference between and survival. Other problems diseases of red claw based on red claw and native crayfish is the with marron are that they are dif- research in both Australia and the water temperature requirement. ficult to breed in captivity, do not United States. A brief discussion is Native crayfish are from a temper- reproduce until two or three years included on potential markets for ate climate and generally tolerate of age, and are territorial. red claw. a wide range of temperatures. Considering these factors, marron They are more active and grow appears to be a species with limit- General life history during the cooler months and ed potential in the Southeast. and environmental usually spend hot summer Yabbie, another cultured species, considerations months in burrows underground. are native to the southeastern Red claw are native to the tropical Red claw are similar to native region of Australia. Yabbie are the region of northern Australia. American crayfish in their general smallest of the cultured Therefore, red claw grow best in anatomy, reproduction, and feed- Australian species, growing rela- relatively warm water (75 to 85oF) 1 ing habits. However, there are tively slowly (1 /2 to 2 ounces and will not tolerate cold temper- some important differences. These per year) and only attaining a size atures. Water temperatures below 1 1 include: of /4 to /2 pound. Yabbie are 70oF significantly reduce growth able to tolerate a wide range of 1. larger potential size, rates. Water temperatures below environmental conditions. The 50oF are lethal and will limit red main problem with yabbie is their 2. higher percentage of dress-out (meat), claw production in outdoor ponds extensive burrowing habit. While to a 5- to 7-month growing season burrowing is an important trait 3. multiple annual spawning and in the Southeast. Much of the for crayfish that must survive higher fecundity (fertility), hatchery and juvenile production extended dry periods, this trait 4. nonburrowing and nonagres- will need to be done indoors dur- creates problems in ponds. Yabbie sive behavior, and ing the cooler months. have been known to cause ponds to leak or even drain by burrow- 5. growth at temperatures ranging Red claw and native crayfish are o ing through the dam (as have from 70 to 90 F. both omnivorous detritivores, native crayfish). Because of their Red claw can reach a weight of 2 meaning that they prefer to eat burrowing habits and the fact that to 4 ounces (50 to 100+ grams) in decaying plant or matter. they do not grow much larger a seven-month growing season In their native habitat their diets than native American crayfish, while native crayfish normally consist mostly of decaying plant yabbie have received little atten- grow to about 1 to 1 1/2 ounces material. Under culture conditions tion from aquaculturists in the (20 to 35 grams) during a growing both species have been found to U.S. season. Furthermore, about 30 readily accept a wide variety of foods including formulated diets. Red claw, the third species, are percent of the total body weight native to remote areas of tropical of the red claw is edible tail meat Red claw, like native crayfish, northern Australia and hold the compared to 15 to 20 percent for seem to tolerate a wide range of most promise for southeastern native crayfish. water quality conditions includ- producers. Red claw have been Both red claw and native crayfish ing: dissolved oxygen (>1 ppm), cultured in Australia since 1985. reach sexual maturity at less than hardness and alkalinity (20 to 300 Research on red claw began in the one year of age. However, native ppm), and pH (6.5 to 9). Adult red U.S. about 1989, and has shown crayfish are considered seasonal claw have been shown to tolerate positive results: spawners. Day length and tem- dissolved oxygen to as low as 1.0 ■ perature changes are necessary to ppm but young are more sensitive Red claw tolerate higher tem- to low dissolved oxygen. Red peratures and relatively low promote fall and spring mating activity. Red claw are multiple claw have been known to tolerate dissolved oxygen concentra- unionized ammonia concentra- tions. spawners capable of spawning several times (3 to 5 times) each tions up to 1.0 ppm and nitrite as ■ They tolerate crowded culture year as long as water tempera- high as 0.5 ppm for short periods conditions and are considered tures remain above 75oF. without noticeable adverse effects. a nonburrowing crayfish. Red claw do not excavate deep An important behavioral trait, ■ Red claw can grow to 2 to 4 burrows like native crayfish. Red from a culture standpoint, is that ounces during the five to seven claw will occasionally dig shallow red claw are relatively gregarious warmest months in the depressions or short burrows. and tolerate crowded conditions Southeast. to an unprecedented degree for a

2 large-clawed . Even at Reproduction and In a hatchery red claw can spawn densities greater than 50 per hatchery techniques almost continuously throughout square yard, adults show limited the year if conditions are suitable. cannibalism. This trait may reflect Red claw generally reach sexual Individual females do not spawn an adaptation to the environmen- maturity by the age of 6 to 12 when going through a growth tal conditions this species experi- months at which time they range phase (i.e.,molting). Each female ences in tropical Australia, where from 2 to 3 ounces in weight. will produce 100 to 1,000 eggs per pronounced wet and dry seasons Mature male red claw develop a spawn depending on her size and cause them to congregate at rela- distinctive red or orange patch on general health. The first spawn of tively high densities in water the outside margin of the claws. young females usually has fewer holes during the dry season. Individuals of this same size with- eggs than latter spawns. Newly Under these conditions nonag- out the reddish claw patch are spawned eggs average 10 eggs per gressiveness is a critical adapta- usually females. The sexes are gram of female. About 30 percent tion to survival and repopulation. best identified, however, by exam- of the eggs are lost during incuba- Once the rainy season begins they ination of the genital openings on tion, resulting in an average of 7 disperse by migrating into newly the underside of the cephalotho- eggs (that hatch) per gram of flooded areas. Juveniles are more rax at the base of the walking legs female. For example, a female aggressive and display a degree of (Figure 2). Females have a pair of weighing 3 ounces (85 grams) cannibalistic behavior. genital pores at the base of the would produce about 600 eggs. third pair (counting from the Figure 3 can be used to estimate head) of walking legs. Males have the number of eggs a female of a a pair of small genital papillae given size will produce. (small projections) at the base of the fifth pair of walking legs.

Abdomen Cephalothorax

Antennae

Male Swimmerets Walking Leg Female

Reddish Patch

Genital Pore Genital Papilla

Figure 2. External anatomy of male and female red claw.

3 imately 70 adult occurred at water temperatures of females and 25 adult 82oF and 14 hours of light. males (considering Light intensity should be low (just spawning and sur- enough light for hatchery person- vival rates). nel to work). Dark colored tanks The key points to suc- with partial covers can reduce cessful maintenance stress associated with intense light and reproduction of and movement around the tanks. broodstock in indoor Also tanks with smooth surfaces, holding systems like fiberglass or stainless steel, include: minimize damage to the exoskele- 1. select healthy ton of the crayfish. Damage or mature adults, abrasions of the exoskeleton can lead to disease problems. 2. maintain warm temperatures Broodstock should be stocked into (preferably 75 to holding tanks at 1 to 3 Figure 3. Relationship of female red claw body weight to 85oF), per square foot of bottom area. number of eggs produced. Males should be of similar size 3. maintain good (within an ounce of each other in water quality, Natural reproduction will occur in weight), or spawning can be sup- ponds if the animals are mature 4. provide proper nutrition, and pressed by nearly 50 percent. The and the water temperature is 5. isolate berried females to hatch- ratio of females to males in each above 70oF. Most Australian pro- ing tanks. tank should be between 1 to 3 ducers simply collect juveniles females for each male. Good Broodstock should be selected from ponds stocked with mature spawning success has occurred based on size, vigor, and general red claw. Juveniles seek shelter in using tanks with water depths of health. It is important to select suspended substrate like burlap, 1 to 3 feet. Small rectangular tanks large, healthy animals. Before shade cloth, onion bag mesh, or of 15 to 20 square feet, as well as introducing broodstock into the window screen mesh hung verti- large circular tanks of 15 feet in hatchery it may be a good practice cally from the surface to the bot- diameter have been used success- to treat them with a salt or forma- tom of the pond from floats. These fully. Shallow rectangular tanks lin dip to eliminate potential collectors are periodically checked (8 to 10 feet long by 2 to 3 feet external pathogens. Specific stud- and juveniles carefully removed wide) with water 12 to 18 inches ies on prophylactic treatments for from the mesh. This method deep are commonly used. red claw have not been conducted results in low returns/survival, but recommended fish treatments Red claw are excellent climbers only 5 to 10 percent. Juvenile (e.g., a prolonged bath of 1,000 to and escape from tanks if the water growth and survival are limited 2,000 ppm salt or 15 to 25 ppm level is near the tank top or if because of lack of access to ade- formalin) have been used experi- equipment such as air line tubing quate food and to cannibalism mentally. These treatments did not or heater cords extends over the which occurs among the juveniles. seem to harm the red claw and sides of the tank. To reduce Production of red claw outdoors have appeared to be effective at escapes, equipment should be sus- in the southeastern U.S. is limited preventing introduction of para- pended from overhead so that it to five to seven of the warmest sites. At present, there are no does not touch the sides of the months. Therefore, outdoor approved therapeutics for red tank. spawning is not practical. The use claw. Research has shown that red claw of indoor hatcheries to spawn Good water quality must be main- are most active in the evening adults and rear juveniles during tained in the holding tanks by between 6 p.m. and midnight the winter months is the most using either a flow-through sys- (Figure 4). This should be the best practical and economical method tem utilizing warm water (e.g., time for daily feeding since the in the U.S. Mature adults moved geothermal) or a heated, recircu- animals are actively foraging dur- into hatcheries during late fall can lating system with particulate and ing this period. be spawned during the winter. biological filtration. Water tem- Broodstock nutrition is extremely Young from these spawns can be perature in the system should be important. Broodstock should be reared indoors using natural and maintained between 75 and 85oF. fed a complete diet (with vitamin formulated feeds, then stocked Warmer water temperatures (80oF) and mineral supplements). into grow-out ponds the following and a longer photoperiod (12 to 14 Sinking crayfish or shrimp feed spring. Stocking a one acre grow- hours of light) in the hatchery will (at least 28 percent protein) fed at out pond, at 10,000 to 12,000 juve- increase spawning rates. Research 3 percent of body weight per day niles per acre, will require approx- has shown that peak spawning is recommended. Some hatchery

4 hours the female usually releases Hatching eggs from the pore on the base of the third pair of walking legs. Red claw eggs go through several These eggs are fertilized by the identifiable stages during devel- spermatophore as they are opment (Figure 6). The length of released. development varies depending on water temperature. The stages are Female red claw, like native cray- identified by color changes and fish, attach the eggs to the swim- appearance of body structures in merets under their tail or the developing embryo. The abdomen. The eggs remain sequence of development stages attached through the incubation and approximate timing at 82oF is: period (Figure 5). The incubation period may last 4 to 6 weeks stage 1 - light cream color (day depending on water temperature. 1-3), At 82oF the incubation period stage 2 - dark brown (day 12- averages 30 days. Individual eggs 14) are oval and about 1/10 of an inch stage 3 - eye spots (day 20-23) in diameter. Females carrying eggs are called “berried” females. stage 4 - hatched, orange-red in Berried females are easily recog- color (day 28-35) Figure 4. Typical hatchery tanks used nized because they tightly curl stage 5 - released (day 35-40). in red claw production. their abdomen under the body for the first 10 to 14 days after Hatching can occur within 30 days at 82oF but may take as operators like to supplement for- spawning. They are also less o active during this period. Berried many as 45 days at 75 F. Females mulated diets with fresh foods. in hatching tanks should be These supplements have included females should be moved to sepa- rate spawning tanks so that the grouped according to similar egg frozen mixed vegetables, bird development and should not be seeds, and chopped beef heart or young hatchlings do not have to be captured from the broodstock disturbed during early stages of liver. Care should be taken not to egg development. Young remain overfeed, especially with fresh tanks. Broodstock tanks should be checked for berried females at attached to the females’ swim- food, because it may adversely merets for about 7 to 10 days after affect water quality. three to four week intervals. Berried females must be carefully hatching, becoming independent During mating the male red claw netted and transferred to hatching of the mother over a period of will attach a spermatophore (sack tanks (to prevent egg loss). Keep several days. This post-hatch peri- containing sperm) to the under- the berried females with their od appears to be important to the side of the female between the abdomen curled around the eggs survival of the young. Therefore, third and fifth pair of legs. The during transfer to prevent eggs females should be removed from spermatophore is white and about from being dislodged by tail the hatching tanks only after the 1/3 inch in diameter. Within 24 movements. young are no longer observed

a.m. a.m. p.m. p.m. p.m. p.m. a.m. a.m. Figure 6. Eggs remain attached to the swimmerets through Time the incubation period. Figure 5. Daily activity level of red claw crayfish.

5 clinging under her tail. One word Nutrition is also an important Survival of juveniles in the hatch- of caution: females have been aspect in juvenile production. ery should average 50 to 70 per- observed cannibalizing their Newly hatched red claw occupy a cent. Once the juveniles reach young if crowded into small very small territory (a few square about 1 to 2 inches in length and hatchery tanks or aquaria. inches). Therefore, feed must be weigh approximately 1/28 of an distributed throughout the tank The keys to good juvenile sur- ounce (1 gram) they can be so that juveniles will have access vival in the hatchery are stocking stocked into grow-out or produc- to it both on the bottom and with- density, size uniformity, cover, tion ponds if pond water temper- in the mesh. Several diets have o nutrition, and water quality. atures are above 68 F. been used to rear juveniles in the Stocking density of juvenile red hatchery. At the present time, the claw should not exceed 25 per Pond production best recommendation is to feed a square foot of nursery tank bot- high protein (>33 percent) com- Red claw are probably best pro- tom. At this density 50 to 75 per- mercial shrimp diet. Juveniles duced in traditional fish produc- cent survival should be expected. should be fed at 40 percent of esti- tion ponds 3 to 4 feet deep with Again, juvenile numbers can be mated biomass per day, with the sloping bottoms and a drainage estimated from the females’ size feed being fed over three to five system. Ponds ranging from 1/4 (see Figure 3). Many producers feedings a day. Improved survival to 2 acres have been used in red prefer shallow (6 to 12 inches and growth have been obtained claw production, but ponds of 1 deep) tanks for this phase. by feeding brine shrimp (Artemia) acre or less are recommended for Handling the newly hatched juve- during the first week. Newly ease of management and harvest- niles during the first few weeks hatched brine shrimp nauplii are ing. should be avoided as they are best but frozen adult brine shrimp easily injured. Research suggests the following have been used. Brine shrimp can production strategy: Research has shown that formu- be substituted for one of the daily 1. Stock juveniles of 1 gram or lated feeds and adequate sub- feedings of formulated diet. Care larger in the spring when water strate in juvenile rearing tanks should be taken to ensure young temperatures stay above 68oF; increase overall growth and sur- crayfish have all they can eat vival. Juveniles 2 inches or longer without overfeeding. Overfeeding 2. Stock at a density of 10,000 to (>1 gram) will have a much high- can quickly cause deterioration of 12,000 per surface acre of pond; er survival rate when stocked into water quality. Excess food should 3. Feed hay at 500 pounds per ponds. Indoor hatcheries can be removed from tanks by acre per month and supple- improve the quantity and quality siphoning daily. Feeding behavior ment with a commercial diet at of juveniles available for stocking and water quality should be 3 percent of estimated biomass: and could make larger juveniles closely monitored. available for differential stocking. 4. Partial harvest using traps start- Maintaining good water quality is ing 3 to 4 months after the Older (i.e., larger) juveniles tend always important, especially with young crayfish were stocked; to cannibalize smaller ones, hence young crayfish (Table 1). Care the need to group females togeth- 5. Drain harvest when water tem- should be taken to ensure that old o er in the hatching tanks that have feed and wastes do not accumu- peratures drop below 60 F. a similar egg stage or larval late and that proper aeration, fil- To reduce the chance of disease development. Juvenile red claw tration, and circulation are main- and competition, native crayfish growth rates will vary. After four tained. should be eliminated from ponds weeks a few individuals may be five times larger than others in the tank. Overall survival can be Table 1. Water quality for hatchery production of red claw. improved by grading or remov- ing the larger juveniles. Netting Parameter Recommended Range or screening should be added to Temperature 80 to 85oF juvenile tanks, providing hiding Dissolved Oxygen 5.0 ppm (mg/L) or above places to reduce cannibalism. Any habitat that provides a large sur- Total Ammonia 0.5 ppm (mg/L) or less face area, adequate water flow, Nitrite 0.3 ppm (mg/L) or less and access to the bottom for feed- pH between 7.5 and 8.0 ing should improve survival. Alkalinity above 100 ppm (mg/L) Some substrates which have been used effectively are fiberglass Total Hardness above 50 ppm (mg/L) window screen, shade cloth, and Chloride 50 ppm (mg/L) or above mesh bags in which onions and citrus fruits are packaged.

6 in which red claw will be stocked. Harvesting One flow-trap design is the box-n- Fill the ponds with well water if ramp trap. The box-n-ramp trap possible to eliminate introduction Red claw can be harvested by consists of an impervious box of other species and their diseases. using baited crayfish traps, flow- (e.g., plastic trash can or metal Ponds should be filled only a few traps, and by draining the pond. drum) into which water is weeks before stocking to prevent Crayfish traps used to catch pumped and a ramp which carries the establishment of predaceous native crayfish can be used for red the out-flow water to the pond 3 aquatic insects. Ponds should be claw. These traps are made of /4- bottom (Figure 7). The crayfish limed if hardness is below 20 ppm inch plastic coated chicken wire move up the ramp against the and fertilized to establish a plank- mesh (Figure 7). Both stand-up flow and are trapped when they ton bloom. Survival improves sig- and pyramid traps have been fall into the box. Adding fiber- nificantly if a 1 gram (28 to the used effectively. Baits include for- glass screen, vexar, or some other ounce) or larger juvenile is mulated commercial crawfish rough texture to the surface of the stocked rather than newly- baits and fish feed contained in ramp will help the crayfish climb hatched juveniles. Stocking densi- small mesh bags. Final harvesting into the trap. Flow-traps must be ties of 0.25 to 0.3 per square foot is done by partially draining the checked often (every few hours) 1 of pond surface area (10,000 to pond (to /4 of original size) and as they can fill with crayfish, caus- 12,000 per acre) appear to give the setting up a flow-trap. ing those in the bottom of the trap best overall survival and produc- Flow-traps are traps through to suffocate. tion of larger crayfish. Dried hay which water moves or flows. Red should be spread around the claw are strongly attracted to Diseases edges of the pond monthly at a moving water, possibly an adap- rate of about 500 pounds per acre tive response to spring floods in Red claw are probably susceptible per month, divided into two or their natural environment. to most diseases that affect native three applications. Commercial Research suggests that flow-traps crayfish. In addition, red claw are crayfish, shrimp, or fish feeds are very successful at capturing susceptible to the “crawfish should be used in addition to the crayfish. Pumping rates in flow- plague” which is a fungal hay during the last half of the cul- traps should not exceed 8 gallons pathogen. Native North American ture period. Total commercial feed per minute, and water from crayfish carry the plague but are input should be fed at 3 percent of another pond or a well appears to usually not adversely affected by estimated total crayfish weight work better than water from the it. The fungus was not known to per day but not to exceed 35 same pond. be a problem until North pounds per pond surface acre per American crayfish were intro- day. duced to Europe over 100 years Water quality must be maintained if red claw are to survive and grow. Aeration should be used to maintain dissolved oxygen above 3 ppm. Remember that these ani- mals live on the pond bottom; therefore, oxygen should be checked near the pond bottom and not at the surface. Ammonia and nitrite concentrations should be determined twice weekly toward the end of the growing season, but are not usually a prob- lem at recommended feeding rates. If water quality declines, stop feeding and flush with clean water, if possible. Red claw may attempt to migrate from the pond if water quality is poor. Proper management should lead to the production of 1,000 to 1,500 pounds per acre after six months. Individual red claw should weigh about 2.5 ounces or six to the pound, although some individuals Figure 7. Commercial flow-trap design. will weigh more than 1/4 pound.

7 ago. European crayfish had no research was started at Auburn whole animals without any need resistance or immunity to the University to look at possible for processing. One disadvantage North American pathogen and interactions of red claw with will be the development of a year- many natural populations were native red swamp crawfish, the round supply since production devastated. Research has shown predominately cultured species in cycles will be limited by cold that the red claw are susceptible the U.S. Both species survived, weather from U.S. production. to this fungus. The fungus grows grew, and reproduced in these o Most juvenile red claw currently best at temperatures below 65 F interaction studies without any produced in the Southeast are and does not appear to be active obvious negative impacts through o being sold to the ornamental or or pathogenic above 70 F. Since a summer culture period. How- aquarium market. The color (light red claw need temperatures above ever, the red claw did not survive o blue) and uniqueness of the red 70 F for good growth, careful the winter. From these studies it claw have demanded high prices attention to stocking and harvest- would appear that if red claw from aquarium enthusiasts. ing temperatures may reduce were to escape there would be no Again, even this market has potential problems. There are no impact on native red swamp cray- to be developed by individual known methods of prevention fish populations and the red claw producers. and treatment of the plague. could not become established in natural waters. Financial considerations Legal and environmental constraints Marketing Red claw farming, like any type of agricultural enterprise, is a risky Most states have restrictions on No one knows what price red venture. Red claw farming is even the introduction of exotic species. claw crayfish will bring in the U.S. more risky since little is known Before purchasing red claw or any A market for red claw will have to about full scale commercial pro- other non-native species, state be developed. If red claw have to duction problems, diseases, and conservation departments should compete in the native crayfish potential markets. be contacted. There are no federal market their production will not be economically feasible. Because Failures (to some degree) are still laws which prevent the introduc- the rule and not the exception in tion of invertebrates such as of its size (4 to 6 per pound), how- ever, it should fall into a totally aquaculture when it involves new Australian crayfish, fresh water species. All commercial ventures shrimp, etc. Permits for the new market niche and not com- pete with native crayfish or large should be preceded by appropri- importation or stocking of exotic ate pilot scale operations. It is pru- crayfish are presently in effect in lobsters. Contacts with marketing specialists indicate that red claw dent that beginning producers be some states (e.g., Louisiana and conservative. Start slowly, mini- Kentucky). should have high appeal and command a high price when sold mize capital investment, keep It is important that studies be con- as “small lobsters.” Until large overhead low, and develop mar- ducted before any new species is numbers are available, however, kets (i.e., start small and learn as introduced to ensure that there all marketing potential is specula- you go). will not be negative impacts on tive. One advantage of red claw our environment. In 1990, will be the ability to market live,

The work reported in this publication was supported in part by the Southern Regional Aquaculture Center through Grant No. 94-38500-0045 from the United States Department of Agriculture, Cooperative States Research, Education, and Extension Service.

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