Three-way cross hybrid abalone exhibit heterosis in growth performance, thermal tolerance, and hypoxia tolerance

Abstract

Abalone is an economically important aquaculture resource worldwide, with high commercial value. Abalone productivity, stress resistance, and profitability have been improved by interspecific and intraspecific hybridization. In this study, a systematic comparative assessment of heterosis for survival, growth, thermal tolerance, and hypoxia tolerance in Haliotis gigantea (SS), H. discus hannai (DD), H. discus hannai♀ × H. fulgens♂ (DF), and three-way cross hybrids SS♀ × DF♂ and DF♀ × SS♂ was conducted. Two three-way cross hybrids, SS × DF and DF × SS, showed positive mid-parent heterosis in the growth rates of shell length and total wet weight in different months. The proportion of large individuals with higher total wet weight or shell length in DF × SS and SS × DF was higher than in other abalone species. The thermal and hypoxia tolerance of these abalone were assessed using Arrhenius break temperatures (ABT) and the breakpoint of dissolved oxygen (BPDO) of cardiac performance, respectively. The mid-parental heterosis values of ABT in SS × DF and DF × SS were 2.29% and 1.38%, respectively, while the BPDO values in SS × DF and DF × SS were − 11.48% and − 11.96%, respectively, confirming heterosis for thermal and hypoxia tolerance in these three-way cross hybrids. Overall, this is the first three-way interspecific cross of abalone, and the improvement of commercial traits can be achieved through a combination of selection and further hybridization among purebred and hybrid abalone.