Advancing the production efficiency and profitability of aquaculture is dependent upon the ability to utilize a diverse array of genetic resources. The ultimate goals of aquaculture genomics, genetics and breeding research are to enhance aquaculture production efficiency, sustainability, product quality, and profitability in support of the commercial sector and for the benefit of consumers. In order to achieve these goals, it is important to understand the genomic structure and organization of aquaculture species, and their genomic and phenomic variations, as well as the genetic basis of traits and their interrelationships. In addition, it is also important to understand the mechanisms of regulation and evolutionary conservation at the levels of genome, transcriptome, proteome, epigenome, and systems biology. With genomic information and information between the genomes and phenomes, technologies for marker/causal mutation-assisted selection, genome selection, and genome editing can be developed for applications in aquaculture. A set of genomic tools and resources must be made available including reference genome sequences and their annotations (including coding and non-coding regulatory elements), genome-wide polymorphic markers, efficient genotyping platforms, high-density and high-resolution linkage maps, and transcriptome resources including non-coding transcripts. Genomic and genetic control of important performance and production traits, such as disease resistance, feed conversion efficiency, growth rate, processing yield, behaviour, reproductive characteristics, and tolerance to environmental stressors like low dissolved oxygen, high or low water temperature and salinity, must be understood. QTL need to be identified, validated across strains, lines and populations, and their mechanisms of control understood. Causal gene(s) need to be identified. Genetic and epigenetic regulation of important aquaculture traits need to be determined, and technologies for marker-assisted selection, causal gene/mutation-assisted selection, genome selection, and genome editing using CRISPR and other technologies must be developed, demonstrated with applicability, and application to aquaculture industries.Major progress has been made in aquaculture genomics for dozens of fish and shellfish species including the development of genetic linkage maps, physical maps, microarrays, single nucleotide polymorphism (SNP) arrays, transcriptome databases and various stages of genome reference sequences. This paper provides a general review of the current status, challenges and future research needs of aquaculture genomics, genetics, and breeding, with a focus on major aquaculture species in the United States: catfish, rainbow trout, Atlantic salmon, tilapia, striped bass, oysters, and shrimp. While the overall research priorities and the practical goals are similar across various aquaculture species, the current status in each species should dictate the next priority areas within the species. This paper is an output of the USDA Workshop fo...
Four treatment groups that received repeating cycles of fixed feed deprivation for either 0, 1, 2, or 3 d (control, treatment 1, treatment 2, and treatment 3, respectively), followed by periods of refeeding with a 36% protein commercial catfish feed once daily as long as the active phase of compensatory growth (CG) persisted, were assessed in flow‐through aquaria. No‐feed periods elicited the CG state and were immediately followed by days of ad libatum refeeding. At the end of 10 wk, average growth rate (AGR) of fish was higher (P < 0.05) than the control by 40%, 180%, and 191% for treatment 1, treatment 2, and treatment 3, respectively. The average weight of fish in treatment 3 was heavier (P < 0.05) than the average control group at the end of the study period. Mean daily feed consumption was 3.91%, 5.03%, 5.36%, and 5.98% for control, treatment 1, treatment 2, and treatment 3, respectively. Mean feed consumption per fish per day was 24%, 71.3%, and 70.7% higher than the control in treatment 1, treatment 2, and treatment 3, respectively. Restricted feeding is one of the effective methods to contain ESC‐related losses in commercial channel catfish fingerling operations. The mean cumulative survival of treatment groups registered higher (P < 0.05) survival to Edwardsiella ictaluri infection compared to the daily fed control fish. Results from this study show that compensatory growth response triggered by periodic non‐feeding days can improve growth rate, feed consumption, and improved survival to ESC infections in channel catfish fingerlings.
This study examined the influence of strain of sire on hybrid catfish embryo production and performance of fingerlings under commercial conditions. Four hundred 4‐year‐old female Gold Kist strain Channel Catfish Ictalurus punctatus were induced to spawn in eight spawning trials. The stripped eggs were fertilized with the sperm of either D&B or Rio Grande Blue Catfish I. furcatus to produce D&B or Rio Grande hybrid catfish embryos. Testes weight (g/kg body weight [BW]) was higher in Rio Grande (1.98 ± 0.28 g/kg BW) than in D&B (1.02 ± 0.12 g/kg BW) Blue Catfish males. Hatching parameters between Rio Grande and D&B hybrids did not differ. Approximately 100,000 hybrid catfish fry produced from each spawning trial were stocked in an individual 0.4‐ha pond to raise fingerlings. Four ponds of D&B and four ponds of Rio Grande hybrids were stocked in eight ponds of identical conditions at the same time. The mean individual BW of D&B hybrid fingerlings (38.5 g) was higher than that of Rio Grande hybrid fingerlings (32.5 g) at 9 months of age. Mean survival (99.3%), production (8,875 kg/ha), and feed conversion (1.14) of D&B hybrid catfish fingerlings were superior to Rio Grande hybrid catfish fingerling survival (92.1%), production (7,664 kg/ha), and feed conversion (1.23), the catfish being raised in replicated earthen ponds under farm conditions. While the D&B strain of sire improved the performance of hybrid catfish fingerlings, it had minimal influence on hybrid catfish fry production.
Two experiments were conducted to evaluate the effects of stocking density and feeding frequency on the growth, net yield, and feed conversion of hybrid catfish (female channel catfish Ictalurus punctatus × male blue catfish I. furcatus). In experiment 1, hybrid catfish fingerlings with a mean initial weight of 65 g were stocked into ten 0.4‐ha earthen ponds at a density of 12,355 fish/ha. In experiment 2, hybrid catfish fingerlings with the same mean initial weight as in experiment 1 were stocked into twenty 0.4‐ha earthen ponds at densities of 18,532 and 24,710 fish/ha, respectively. Fish were fed once or twice daily to apparent satiation. In experiment 1, all fish were harvested in early September. In experiment 2, market‐size fish (target size, ≥0.794 kg/fish) were selectively harvested in late September by means of an in‐pond mechanical fish grader with the bar spacing set to 5.4 cm. All remaining fish were harvested in mid‐June the next year. In both experiments, fish fed twice daily were given more feed, but there were no significant differences in weight gain per fish and net yield between fish fed once daily and those fed twice daily. Fish fed twice daily had a significantly higher feed conversion ratio. In experiment 2, a stocking density of 18,532 fish/ha resulted in higher weight gain and lower net yield than a stocking density of 24,710 fish/ha. Based on the results from this study, it appears to be efficient to stock hybrids at a density of 12,355 fish/ha, feed them once daily over a growing season, and “clean” harvest them at the end of the season. However, a multiple‐batch system may also be used to grow hybrids at densities of 18,532–24,710 fish/ha by means of a catfish grading system to remove market‐size fish.
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