Author
 |
Small, Brian |
|
Submitted to: Larval Fish Conference
Publication Type: Abstract Only Publication Acceptance Date: 4/4/2003 Publication Date: 8/20/2003 Citation: Small, B.C. 2003. A critical period in channel catfish, ictalurus punctatus, embryo development. 27th Annual Larval Fish Conference, Santa Cruz, CA. p. 95. Interpretive Summary: Technical Abstract: Channel catfish, Ictalurus punctatus, embryo survival varies greatly in both commercial and research hatcheries. On average, approximately 60-70% of catfish embryos survive to hatch; however, hatching rates can vary from 0-100% among individual spawns. Research was conducted to document normal embryo development, and determine the effects of temperature, calcium hardness, and handling stress on embryo survival. At a temperature of 28oC, the embryonic period of channel catfish lasts an average of 5 days. As expected, the period of embryonic development increases as temperature decreases, and embryo survival decreases beyond the optimal temperature range, which was determined to be 26-28oC. Embryo survival was found to be greatest (P < 0.05) when temperature acclimation occurred following formation of the embryonic axis, approximately 24 h post-fertilization. Low water calcium-hardness (< 10 ppm as CaCO3) was also 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 ppm calcium-hardness during the first 24 hours post-fertilization had 72% lower survival compared to controls. Incubation in low calcium water during all other 24 h developmental periods resulted in a 24% reduction in survival. In conducting these studies, it was also observed that the collection and removal of catfish egg masses from ponds negatively impacted embryo survival when transported during the first 24 h post-fertilization. On average, survival to hatch decreased 10% compared to survival from egg masses left in the ponds until after the development of the embryonic axis. Our observations suggest that the first 24 h post-fertilization, prior to embryonic axis formation, is a critical period for channel catfish embryo survival. Changes in hatchery management practices to avoid environmental and physical stressors during this developmental period could have a significant impact on channel catfish embryo survival and hatching success. |
