1a.Objectives (from AD-416)
Determine steroid levels in reproductive catfish to determine early signs of reproductive success. Evaluate the use of ultrasound estimation of ovary size, level of plasma steroids, group/family of origin, and body weight as predictors of incidence and timing of pond spawning of 2 and 3 year old channel catfish. Evaluate use of ultrasound imaging to sort female channel catfish broodfish on commercial farms into two groups based on estimated ovary size (large vs. small ovaries), and compare steroid levels and incidence and time of spawning of these two groups. Determine the influence of chemical, biological and environmental factors on channel catfish respiration, growth and production, and develop and test practical management methods to minimize limits on production. Induce early maturation in channel catfish.
1b.Approach (from AD-416)
Catfish blood will be analyzed for steroid levels using HPLC/MS. Ultrasound images of female channel catfish ovaries and plasma steroid hormone levels of male and female channel catfish will be collected prior to the spawning season. Fish will be allowed to mate at random in spawning ponds and parentage of spawns will be determined via molecular markers. Statistical analysis will be conducted to determine if ultrasound imaging or steroid hormone levels are predictive of spawning time and incidence. Female channel catfish will be sorted based on ultrasound image predicted ovary size on commercial catfish farms to determine if ultrasound image of ovary size can be used to predict spawning success of females on commercial catfish farms. Ten standard hatchery troughs will be operated during the 2008 spawning season. Spawns will be weighed and sampled prior to being placed in the incubator, and the number of sac fry produced from each trough will be determined, allowing for a calculation of hatch rate. A similar number of troughs will be operated and sampled using the traditional method. Water flow rates, dissolved oxygen concentrations, and water temperature will be monitored. Fish will be exposed to different environmental temperature regimes.
This project is in its initial phase and data collection has begun to evaluate factors affecting maturation, spawning, and hatching success of channel catfish.