Longitudinal genetic analysis for Pacific abalone growth-related traits in sea-based culture system

Abstract

Pedigreed family-based selective breeding is an appealing approach in genetic improvement of aquaculture species as the benefits can be cumulative and permanent. To determine the longitudinal growth characteristics of Pacific abalone (Haliotis discus hannai), shell colour rings were manipulated by feeding alternative algae, and shell length (SL) identification was performed at different ages. Eight SL records were obtained from 3147 individuals in 192 full-sib families at 6, 7, 9, 13, 18, 24, 28, and 32 months after hatching. To estimate the additive genetic and environmental variance components, longitudinal genetic analysis of repeated SL measurements was conducted using multivariate, auto-regressive, antedependence and random regression models with restricted maximum likelihood method. The results showed that the multivariate model with common full-sib family variance and residual heterogeneity of variance was the best model for the given dataset. Heritability estimates showed a decreasing trend with age, which is similar to the results obtained from the quadratic polynomial random regression model, and ranged from 0.629 at 9 months to 0.259 at 32 months. The separate rearing and tagging of single abalone at 6 months may have led to significant common environment family bias and overestimation of heritability. The antedependence model did not achieve a better fit for the obtained dataset. Estimates of genetic correlation between contiguous ages were high, ranging from 0.622 between 6 and 32 months to 0.987 between 28 and 32 months. The results demonstrated that genetic gain can be obtained in selection for Pacific abalone growth and outlined information regarding the age at which selection should be performed. This study can provide data and guidelines to a Pacific abalone selection program for growth related-traits.