56 March 2012 Evaluation of various hatchery-nursery procedures to maximize survival and growth of juvenile Australian redclaw crayfish (Cherax quadricarinatus) Antonio Garza de Yta1, Lidia G. Fournue Guerrer2, Joly Ghanawi3, I. Patrick Saoud4* and David B. Rouse5 Red claw, Cherax quadricarinatus (von Martens 1868), is a freshwater crayfish native to northern Australia and the Southeast of Papua, New Guinea (Jones 1990, Holthuis 1986). Over the past two decades, commercial interest in the species has led to introductions into countries in Southern Asia, North and South America and Africa (Lawrence and Jones 2002). Because it is an omnivore, in tropical conditions can have multiple annual spawns (3-5 times), has a relatively rapid growth rate, tolerates a wide range of water quality parameters such as low oxygen concentrations (> 1 ppm), hardness and alkalinity (20 to 300 ppm), and pH (6.5 to 9) (Masser and Rouse 1997, Sammy 1988, Lawrence and Jones, 2002), the species is considered a very good aquaculture organism. Red claw crayfish are presently cultured semi-intensively in earthen ponds and intensively in large tanks quite successfully in both tropical and sub-tropical regions (Lawrence and Morrisy 2000, Lawrence and Jones 2002). Over the last few decades, there has been an increasing interest in the development of hatchery and nursery protocols for intensive production of juvenile freshwater crayfish (Verhoef and Austin 1999, Manor et al. 2002). Various hatcherynursery protocols were described by Jones (1995a), Masser and Rouse (1997) and Parnes and Sagi (2002) but no unified set of procedures has been tested or described. Development of hatchery techniques have been investigated for other crayfish, such as red swamp crawfish Procambarus clarkii in the United States (Trimble and Gaudé III 1988), the royal crayfish Astacus astacus in Northern Europe (Huner and Lindqvist 1987), the white-clawed crayfish Austropotamobius pallipes and the introduced signal crayfish Pacifastacus leniusculus in Spain (Celada et al. 1989, Perez et al. 1999, Gonzalez et al. 2008). However, as the redclaw aquaculture industry develops, demand for quality juveniles is increasing rapidly. The need for proven rearing protocols that optimize the quantity and quality of juveniles is a must if the industry wants to maintain its present rate of growth. To achieve this, understanding the biology and behavior of the species under culture conditions is imperative. AGY Redclaw Hatchery and Farm of Megar S.A. de C.V. Intensive redclaw production is hindered by two main factors: The benthic nature of the species and cannibalism during early juvenile stages (Jones 1995b, Parnes and Sagi 2002). Although juveniles are less benthic than adults (Jones 1995b), juvenile C. quadricarinatus still spend most of the time on bottom, leaving the water column virtually empty. Hatchery operators working with Macrobrachium rosenbergii have increased production by supplying adequate substrate and increasing the water volume while keeping the same surface area (Tidwell et al. 1999, D’Abramo et al. 2000). During early juvenile stages, redclaw crayfish are subject to cannibalism of newly molted individuals, and larger individuals on smaller individuals. The fact that juveniles molt frequently and that competition for resources leads to size hierarchy among individuals only exacerbates the situation. Consequently, precise predictions of juvenile production in hatchery-nursery systems are not possible because of poor survivals (5 to 10 percent) and size variability among congeneric juveniles (Jones 1995a). Although enough production
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