Extensive crappie, Pomoxis spp., culture has been practiced for decades, however, knowledge of crappie aquaculture methods is limited. The following review synthesizes existing research on crappie aquaculture and identifies knowledge gaps where further research is needed. Topics such as life history, tank culture, feeding, reproduction and spawning, larval rearing, transport and harvest, triploidy, hybridization, and out-of-season spawning were reviewed. The outcome is a better understanding of hindrances preventing crappie aquaculture development in the past, particularly tank culture and induced spawning techniques, and specific research objectives with potential to enhance recreational and commercial production.

Crappie, Pomoxis spp., are popular game fish throughout North America and are produced by public and private hatcheries. However, production is limited by a lack of information on tank culture and induced spawning methods. Development of techniques for storage of sperm and in vitro fertilization would increase flexibility in spawning. Therefore, techniques for sperm cryopreservation were examined in white crappie, Pomoxis annularis. Sperm from adult wild white crappie were used to evaluate sperm extender, cryoprotectant agent and concentration, and cooling technique based on post‐thaw sperm motility. Percent egg fertilization was also compared between sperm stored in the two best cryopreservation protocols and two different osmotic activator solutions. Sperm were cryopreserved using treatment combinations of two extenders (350 mOsmol/kg Hanks' balanced salt solution [HBSS] and 350 mOsmol/kg Ca2+free HBSS) and two cryoprotectants (dimethyl sulfoxide [DMSO] and methanol) at concentrations of 5, 10, and 15% that were cooled at four different rates: 5, 10, 20, and 40 C/min. Post‐thaw sperm motility and fertilization rates indicated white crappie sperm can be cryopreserved using either extender, cryoprotectants of either 5% DMSO or 10% methanol, and cooling at 40 C/min. A follow‐up experiment demonstrated sperm in suspensions on ice retained viability after overnight transport.

While extensive crappie culture has been practiced for decades, limited knowledge of crappie aquaculture methods has hampered the production potential of White Crappie Pomoxis annularis to a small time frame during the natural spawning season, which occurs only once annually. Out‐of‐season spawning of White Crappie could greatly enhance annual production potential. Therefore, White Crappie out‐of‐season spawning experiments were conducted from November to February in recirculating tank systems. After 2 weeks of simulated winter (10°C, 8 h light), photoperiod and temperature were increased to spring (22°C, 16 h light) conditions over 3 weeks (1°C and 30 min increase every 2 d) and 6 weeks (1°C and 30 min increase every 4 d). Fish were injected with gonadotropin‐releasing hormone analog (GnRHa; 100% priming dose and 100% resolving dose, 24 and 48 h later) and strip‐spawned upon ovulation. The 3‐week treatment (11 females : 10 males) induced 1 female to spawn with 11% fertilization rate. The 6‐week treatment (12 females : 10 males) induced 2 females to spawn with fertilization rates of 31.5% and 79.2%. Gonads of unspawned females were sampled at 96 h after the resolving dose to assess reproductive maturity. Gonadosomatic index (GSI) and egg diameter (ED) from unspawned females (3‐week GSI [mean ± SE] = 0.02 ± 0.01, ED = 0.71 ± 0.22; 6‐week GSI = 0.03 ± 0.02, ED = 0.72 ± 0.10) were compared with wild females sampled during December (winter; GSI = 0.02 ± 0.01; ED = 0.53 ± 0.07) and April (spring; GSI = 0.04 ± 0.01; ED = 0.90 ± 0.12). No difference between 6‐week GSI and spring GSI was detected; however, ED was smaller for 3‐ and 6‐week treatments when compared with spring ED. Therefore, out‐of‐season spawning of White Crappies, using recirculating tank systems and hormone‐induced spawning, is possible, but a longer seasonal shift regime is needed to enhance spawning success.

Pectoral fin healing in fin spines and rays were examined in juvenile Atlantic sturgeon Acipenser oxyrinchus oxyrinchus following three different sampling techniques (n = 8-9 fish per treatment): entire leading fin spine removed, a 1-2 cm portion removed near the point of articulation, or a 1-2 cm portion removed from a secondary fin ray. Also, to determine whether antibiotic treatment influences healing, an additional group of fish (n = 8) was not given an injection of an oxytetracycline (OTC)-based antibiotic following removal of the entire leading fin spine. Following fin sampling, fish from different treatments were mixed equally between three large (4,000 I) recirculating systems and fin-ray healing and mortality were monitored over a 12 month period. To assess healing, blood samples were collected at 4 months to measure immune system responses, radiographs were taken at 4, 8 and 12 months to assess the degree of calcification in regions of damaged fins and fins were analyzed histologically at 12 months. Fish grew from a mean weight of 1.8 to 3.2 kg during the experiment and survival was near 100% in all treatments, with only one fish dying of unknown causes. Leukocyte counts, an indication of health status and survival were similar among treatments and in groups with or without antibiotic injection. Radiographs revealed mineralization took longer in fish with the entire leading fin spine removed and was the slowest near the point of articulation, presumably due to the greater structural support for the pectoral fin at this location. Histological sampling indicated spines and rays had similar healing patterns. Following injury, an orderly matrix of collagen bundles and many evenly spaced scleroblasts were present, transitioning to Sharpey fibres, with concentric layers forming lamellar bone. Healing and mineralization were characterized as periosteal osteogenesis and included embedded osteocytes surrounded by an osteoid seam. Chondroid formation was apparent in a few fractures not associated with treatments. The duration of time for external wound healing and internal mineralization of spines and rays depended on the fin treatment, with the slowest healing observed in fish with the most tissue removed, the entire leading fin spine.

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