ARS | Publication request: IDENTIFICATION OF A CALCIUM-CRITICAL PERIOD DURING CHANNEL CATFISH EMBRYO DEVELOPMENT

Submitted to: Journal of the World Aquaculture Society
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: February 24, 2004
Publication Date: June 1, 2004
Citation: Small, B.C., Wolters, W.R., Bates, T.D. 2004. Identification of a calcium-critical period during channel catfish embryo development. Journal of the World Aquaculture Society 34:313-317.

Interpretive Summary: The aquifer used for channel catfish hatcheries in much of the Mississippi delta has a calcium hardness of less than 10 mg/L. Water hardness levels less than 10 mg/L are known to reduce survival and growth of newly hatched catfish; however, the effect of low-calcium hardness on embryo survival and hatching success was previously unclear. This study examined the effect of low-calcium hardness concentrations on channel catfish embryo development and survival during sequential 24-hour periods up to hatch. Embryo survival was 72% lower from eggs incubated in low-calcium water during the first 24 hours compared to eggs incubated in high calcium water. This effect was only observed during the first 24 hours of embryo development. This research supports a need for calcium supplementation in hatchery water, and provides valuable information for managing an optimal hatchery environment for maximizing channel catfish production.

Technical Abstract: Research was conducted to determine the effect of removing supplemental calcium during 24-h developmental periods on channel catfish, Ictalurus punctatus, embryo survival. Low water calcium-hardness (< 10 mg/L as CaCO3) was found to have a dramatic negative effect (P < 0.05) on embryo survival during the first 24 h post-fertilization. Fertilized eggs incubated in water containing less than 10 mg/L calcium-hardness during the first 24-h post-fertilization had 72% lower survival compared to controls incubated in water containing 95 mg/L calcium-hardness. Incubation in low-calcium water during all other 24-h developmental periods did not cause a significant (P> 0.05) reduction in hatching success. These observations further support that the first 24 h post-fertilization, prior to embryonic axis formation, is a critical period for channel catfish embryo development and survival.