Genotype-Environment Interactions For Growth, Survival, Sexual Dimorphism and Seinability For Different Genetic Types of Channel Catfish (Ictalurus punctatus) ♀ X Blue Catfish (I. furcatus) ♂ Cultured In Three Environments
Type of Degreethesis
Fisheries and Allied Aquacultures
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For this study, eight genetic types of channel catfish (Ictarulus punctatus) female x blue catfish (I. furcatus) male hybrids were reared in three environments: a low density pond, a high density pond and an in-pond raceway for a period of five months and were fed to satiation. MR X DB, KS X DB, KR X RG and KS X RG ranked in the top group in all three environments for adjusted body weight (P<0.05). 103KS X RG ranked in the top group for the pond environments, but had the lowest adjusted body weight in the in-pond raceway. Genotype X environment, sex X environment and genotype X sex X environment interactions were observed (P<0.05). Fish in the low density pond and the in-pond raceway were of similar size, yet the sexual dimorphism was different in these two environments. There were genotype- environment interactions observed for survival (P<0.05). 103 KS X RG had higher survival rates than the other genetic types in the low density environment and in-pond raceway while KR X RG had the highest value for the high density pond with a survival of 88.7%. MS X RG and MR X DB performed poorly for survival in all the environments. No genetic differences were observed among the 8 genetic types within each environment for seinability (P>0.05). However, when sires were pooled, hybrids from D&B males were easier to catch than those from RG males in the in-pond raceway only. Significant genotype-environment interactions existed, therefore suggesting that multiple breeding programs are needed for the multiple culture systems to genetically design hybrids specific for each one. However there was a high probability that selecting the top performer in one environment would result in selecting a genetic type that would perform well in other environments. The results obtained also suggest that in many cases general combining ability exists in channel catfish dams and selection for general combining ability for growth in channel catfish can increase hybrid catfish performance in multiple environments.