Heritability of growth traits and correlation with hepatic gene expression among hybrid striped bass exhibiting extremes in performance

Abstract Hybrid striped bass is a major aquaculture species in the United States. Artificial breeding of this species can introduce large variation in growth during production to market size. To assess the genetic and nutrigenomic basis behind growth variability in these hybrids, fingerlings (n = 5072) from 47 families were size-matched and communally grown in earthen ponds for 115 days. Families were then ranked by weight gain and individuals from the three fastest growing (mean 240.8 ± 9.75 g; 242.0 ± 11.52 mm) and three slowest growing families (mean 153.5 ± 52.38 g; 223.3 ± 21.31 mm) were collected for liver RNA sequencing. As expected, growth characteristics in hybrid striped bass are highly heritable (p < 0.0001). Through differential gene expression analysis we identified 86 genes that were responsive between groups including 40 up-regulated (1.89˂fold-change < 7.66) and 46 down-regulated (−1.71 > fold-change ˃−4.59) genes in the largest fish. This included two somatic growth-related genes, growth factor receptor gene and a gene encoding an insulin-like growth factor binding protein, that may directly explain some of the genetic variation between families. Several additional genes involved in metabolic pathways such as glycolysis/gluconeogenesis and lipid biosynthesis were also revealed. The candidate gene list may also provide some evidence that both physiological and behavioral factors may be influencing growth differences in communally reared fish.