Genetic architecture of early life history traits for channel catfish, Ictalurus punctatus female X blue catfish, I. furcatus male hybrid production

Authors: MYERS, JAELEN - Auburn University; Chatakondi, Nagaraj; DUNHAM, REX - Auburn University; BUTTS, IAN A - Auburn University

Submitted to: Aquaculture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/28/2019
Publication Date: 10/31/2019
Citation: Myers, J.N., Chatakondi, N.G., Dunham, R.A., Butts, I.E. 2019. Genetic architecture of early life history traits for channel catfish, Ictalurus punctatus female X blue catfish, I. furcatus male hybrid production. Aquaculture. 514:734436.

Interpretive Summary: Hybridization of channel catfish with blue catfish had improved the production efficiency of catfish production and is widely adopted in the US farm-raised catfish industry. Hybrid catfish fry production has been inconsistent and variable in hatcheries. Effects of environment and parental species and their interactions during embryonic development to know that variations in survival and development. A full-factorial mating design with 4 channel catfish females with 5 blue catfish males to produce 20 unique hybrid catfish families were incubated in two incubation temperatures. Variations in performance traits of hybrid catfish embryo were portioned to parental, maternal, and their interactions within two incubation temperatures. Embryonic survival ranged from 45-93% by 120 degree-hours post fertilization (critical period) and maternal effects were responsible for 51% of the variation. Incubation temperature significantly impacted hatching success of hybrid catfish eggs. Deformities and larval morphology were also monitored during the critical period. This study demonstrated environmental and parental effects during embryonic development of hybrid catfish. Optimal egg quality and incubation temperature are most important factors during the critical period of hybrid catfish development, that invariably contribute for successful hybrid catfish fry production in hatcheries.

Technical Abstract: Hybrid catfish, the progeny of channel catfish, Ictalurus punctatus females ' blue catfish, I. furcatus males, are in high demand by the aquaculture industry due to their superiority for pond and raceway culture. Unfortunately, fry production can be a limiting factor due to a lack of natural hybridization between the two species and the necessity to sacrifice males for artificial fertilization. In this study, we used a quantitative genetic breeding design to assess genetic, environmental, and gene by environmental interactions to detail the genetic architecture of fitness in the hatchery during the “critical” early life history (ELH) stages. Males and females were crossed using a full-factorial design, creating 20 unique families. Offspring from each family were split into 2 temperature-controlled environments, based on conditions that mimic early (26.6 oC) and late (32.2 oC) seasonal temperatures. Embryonic survival, hatch success, as well as larval morphology and deformities were quantified at hatch, mid-yolk sac transition, and swim-up stages of early development. Variation in early performance traits (calculated as variance components, VC) were partitioned to maternal and paternal effects as well as parental x environmental interactions, analyzed across and within temperatures. Embryonic survival ranged from 45-93% by 120 degree-hours post-fertilization and was not impacted by temperature until hatch. Maternal effects were responsible for large amounts of variation (VC = 51.0%) for embryonic survival, and paternal effects also became apparent during later stages but in smaller quantities (VC = ~7%). Temperature significantly impacted hatch success, in which hatch decreased at 32.2 oC (from 40% to 32%). Maternal effects were highly significant (VC = 65%), and there were also significant paternal effects (VC = 12%) for hatch, where it varied widely between families (14-71%). Deformity rate increased from 3.6% at 26.6 °C to 6.0% at 32.2 oC, but variation was driven more by maternal effects than temperature. For larval morphology, fry reared at 32.2 oC had smaller body sizes at each developmental stage. Maternal variation across morphology traits ranged widely from 9-80% and were highest for maternal yolk, and paternal effects/interactions ranged from to 0-29%. Parental by environmental interactions were also observed for morphology traits, such that values for VCs differed within each temperature. From our results, we conclude that temperatures at the start of the spawning season are better for embryo/fry development. This information showed the importance of environmental effects, parentage, and their associated interactions, which by isolating indicators of male/female quality, can be used to improve broodstock selection. Results can also be applied to improve incubation conditions for long-term sustainable development of hybrid catfish during the crucial ELH stages.