Heritability of the categorical trait 'number of spawns' in Pacific white female shrimp Penaeus (Litopenaeus) vannamei

We estimated the heritability for the number of spawns during a reproductive period of 30 days in female Pacific white shrimp, Penaeus (Litopenaeus) vannamei. The estimate was based on Bayesian statistical methods, with data collected on full-sibs and mothers and daughters during two generations (years). Heritability was estimated in a threshold model for categorical data, including the fixed effects of year and sets within years. All ablated females provided information regardless of whether they spawned or not. Phenotypes were reordered for each of 5 categories: 0, 1, 2, 3, and 4 or more spawns. Heritability of spawn numbers was 0.20, with a 95% confidence interval of 0.06-0.43, indicating that this trait can be improved by selective breeding.