Comparison of Ictalurid Hybrid Crosses (Ictalurus punctatus x Ictalurus furcatus) in Floating In-Pond Raceway Systems
Type of DegreeMaster's Thesis
Fisheries and Allied Aquacultures
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With the US catfish industry facing higher feed costs and stiff international competition, producers are beginning to adopt intensive alternatives to traditional pond culture. Among these are split pond systems and in-pond raceways which offer the ability to produce higher fish biomasses in more stable environmental conditions. The selective pressures of intensive systems necessitate, however, increased attention to identification of genetic strains and crosses of catfish best suited for survival and growth in this dense, competitive environment. Hybrid catfish (Ictalurus punctatus ♀ x Ictalurus furcatus ♂) have demonstrated aggressive feeding behavior and disease resistance characteristics which recommend them for use in intensive systems. However, considerable variability exists in performance among hybrid crosses due to their differing domestication histories and selection strategies carried out on their parental lines. Therefore, here I examined the performance of three hybrid catfish crosses when raised from fry to stocker size fish in intensive systems. Eight hybrid catfish crosses were originally stocked as fry into recirculating aquaculture tanks (RAS) and raised to 6-inch fingerlings. Due to disease susceptibility and/or poor growth observed in five of the crosses, only three hybrid crosses, JSS x D&B, JS x D&B, and KSS x D&B, were then carried forward for the main part of the study. For this study, floating in-pond raceways (FIPRS) were designed and built to improve upon traditional pond culture by offering reduced manpower, higher stocking densities, ease of feeding, grading and complete harvest, and precise disease treatment. The three hybrid crosses were stocked into 12 FIPRS with 4 replicate cells/cross. Fingerlings were grown to stocker size fish and production factors were compared including growth, weight gain, feed conversion ratio (FCR), and survival. Length weight regressions were constructed for each of the three crosses for size and weight comparisons and to examine uniformity of growth. From these comparisons, it was determined that there were no significant differences among production per cell, FCR, or survival among the three tested crosses. FCR values averaged 1.4 among the three crosses and survival averaged 92%. Our results indicated that a) D&B blue crosses may produce a more robust hybrid catfish for intensive production, although these results need additional replication and b) early selection for superior performance in intensive systems during the fry to fingerling stage may help to ensure even, predictable production in later stages of grow-out. . Although these experiments were run at a research scale, enterprise budgets (both actual and scenarios at production scale) were developed for each of the three hybrid crosses to analyze the economic feasibility of FIPRS production using selected genetic lines. From these budgets it was determined that a majority of the production cost for these systems come from electricity cost and feed. Due to higher electrical costs, producers would need to carefully match up blower usage with biomass needs, avoid overwintering, and maximize stocking density in order to ensure profitable production.