White Crappie Tank Culture and Out‐of‐Season Spawning

Abstract

AbstractWhile 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.