Intraspecies and interspecies hybrids in Haliotis: natural and experimental evidence and its impact on abalone aquaculture

Abalone is a highly valued seafood in many parts of the world. Depending on size and species, it can fetch between US$15 and US$30 per kg in some markets. Because of its high value, abalone is cultured in several countries, including China, Australia, Japan, Chile, South Africa, Canada, Mexico, the USA and many other Asian countries, such as Thailand, the Philippines and Korea. Hybridization is widely used to improve specific traits in animal and agricultural stocks by using a new genetic conformation in the offspring. In general, hybridization offers several benefits in aquaculture conditions, such as improvements in growth rate, survival, food conversion and stress resistance (to temperature and disease). Under commercial conditions, hybrids make it possible to diversify the industry and to offer new products and gain new markets. This review examines evidence of wild and experimental hybridization among abalone species from several biogeographical areas worldwide, and provides information on the phenotype characteristics of artificially produced hybrid abalone. Genetic and phenotypic approaches were analysed to determine whether there is a relationship between the genetic variability and positive heterosis in hybrid crosses. In this review, we also reported embryonic and larval development of hybrid and genetic studies derived from gene expression analysis of thermal tolerance. Furthermore, alloenzyme, cytogenetic and molecular DNA markers were reviewed to certify the hybrid status in Haliotis. This review will also discuss the impact of intra and interspecies hybrids on abalone aquaculture worldwide.