Effects of environmental sodium chloride on percent hatch, yolk utilization, and survival of channel catfish fry

Abstract

Only limited research has addressed the effect of salinity on hatching of channel catfish Ictalurus punctatus eggs, and no studies have evaluated the effect of salinity on fry development and survival. This study was undertaken to determine the effect of environmental sodium chloride (0, 1, 2, and 4 g/L NaCl) on percent hatch, yolk utilization, and survival of channel catfish fry. Experiments were conducted in recirculating systems using seven egg masses (1-2 d old). Each egg mass was divided into smaller portions which remained undissociated or were dissociated with sodium sulfite (NaSO3). Eggs were incubated until hatching. Wet and dry weights were obtained for sac-fry at 1 and 5 d post-hatch to determine wet weight gain and dry weight loss, and fry were sampled 7 d after initiation of exogenous feeding to determine survival. Percent hatch, yolk utilization, and survival of fry hatched from undissociated eggs were greatest at 1 g/L NaCl. In addition, treatment of eggs with NaSO3 significantly reduced percent hatch at all NaCl levels. Although our results indicate that addition of NaCl to hatchery water supplies can increase production of channel catfish fry, additional research is needed before this practice can be recommended on a commercial basis.