EFFECTS OF ENVIRONMENTAL SODIUM-CHLORIDE ON PERCENT HATCH, YOLK UTILIZATION, AND SURVIVAL OF CHANNEL CATFISH FRY

Only limited research has addressed the effect of salinity on hatching of channel catfish Ictalurus punctatus eggs, and no studies have eval uated the effect of salinity on fry development and survival. This stu dy was undertaken to determine the effect of environmental sodium chlo ride (0, 1, 2, and 4 g/L NaCl) on percent hatch, yolk utilization, and survival of channel catfish fry. Experiments were conducted in recirc ulating systems using seven egg masses (1-2 d old). Each egg mass was divided into smaller portions which remained undissociated or were dis sociated with sodium sulfite (NaSO3,). Eggs were incubated until hatch ing. Wet and dry weights were obtained for sac-fry at 1 and 5 d post-h atch to determine wet weight gain and dry weight loss, and fry were sa mpled 7 d after initiation of exogenous feeding to determine survival. Percent hatch, yolk utilization, and survival of fry hatched from und issociated eggs were greatest at 1 g/L NaCl. In addition, treatment of eggs with NaSO3, significantly reduced percent hatch at all NaCl leve ls. Although our results indicate that addition of NaCl to hatchery wa ter supplies can increase production of channel catfish fry, additiona l research is needed before this practice can be recommended on a comm ercial basis.