White Crappie Tank Culture and Out-of-Season Spawning

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 degrees C, 8 h light), photoperiod and temperature were increased to spring (22 degrees C, 16 h light) conditions over 3 weeks (1 degrees C and 30min increase every 2 d) and 6 weeks (1 degrees 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.