36 JUNE 2025 • WORLD AQUACULTURE • WWW.WAS.ORG (Lutz and Wolters 1989). They contained approximately 15 cm of river silt in which forages were planted or transplanted (Figure 2). As forages were growing, adult F. lancifer from a captive population were checked every 3-5 days during the spawning season (late January through March). Ovigerous females were transferred to pools designated for egg incubation and subsequent maintenance of hatchlings. All captive females (53 in total) laid eggs, with high levels of fertilization and hatching (approaching 100 percent). Hatchling crayfish were held in mesocosms at densities of approximately 260 – 285 m-2 prior to stocking (Figure 3). Four forage crops were evaluated to support F. lancifer culture, including wheat (Triticum spp.), maidencane (Panicum hemitomon), mixed natural volunteer vegetation (Sagittaria latifolia, S. lancifolia, Leersia hexandria, Echinochloa sp. and other terrestrial grasses), and rice (Oryza sativa var. Bengal). Wheat was identified as a promising option to provide a cool-season forage stand available for early stocking, although its persistence once flooded was anticipated to be less than optimal. Maidencane and mixed natural vegetation were examined as potential low-cost native forages. Maidencane was considered an especially promising forage due to its high total digestible nitrogen and protein levels during the summer growing season, and for its tolerance of flooding. Rice was utilized to provide a common reference forage for comparison with previous mesocom-based research with P. clarkii, and to gain insights into how F. lancifer culture might be incorporated into traditional monocropping or rotational strategies used for crawfish production in Louisiana. Filtered pond water was added to forage trial mesocosms to a depth of 40 cm two days prior to stocking (Figure 4). The freeboard maintained on internal pool walls prevented wind mixing that would typically occur in commercial ponds, so mesocosms were supplied with aeration using a regenerative blower and airstones to maintain acceptable oxygen levels (> 3 mL-1) throughout the trial. Tanks were covered securely with plastic netting to discourage predation by birds, frogs and other animals. A range of stocking densities typically encountered in procambarid aquaculture were used to allow for meaningful comparisons with prior studies focusing on P. clarkii. Crayfish in wheat forage treatments were stocked as approximately 30 - 40 day old juveniles (26.2 + 3.4 mm total length). Mixed vegetation, maidencane and early rice treatments were stocked when juveniles were approximately 60 - 70 days old (32.5 + 4.1 mm total length, Figure 5), and late rice stocking utilized juveniles of 90 – 100 days in age (36.2 + 5.5 mm total length) (Table 1). Beginning 75 days post-stocking for the earliest (wheat) treatments, crayfish in all mesocosms were sampled to evaluate growth in length (mm) within each treatment. Sampling with unbaited traps was carried out approximately once weekly, initially with 6 mm-mesh 2-funnel minnow traps and later with traditional, 16 mm-mesh commercial ‘pyramid’ traps (Shirley and Lutz 2009). All animals >80 mm total length were considered ‘harvested’ and measured but not returned to the mesocosms (Figure 6). Sampling continued until 223 days post-stocking at which time all sampled FIGURE 4. Early-season rice appeared to support good growth even at higher stocking densities. FIGURE 6. Market demand and high prices during the fall could make F. lancifer profitable under some scenarios. FIGURE 5. Juvenile F. lancifer tolerated prolonged periods at high densities prior to stocking.
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