The pearling industry is economically important to northern Australia but has recently been plagued by mass-mortality events from an unknown disease agent, along with financial impacts from global downturns. There has been active research into the potential for selective breeding to increase the survival and overall profitability of the industry; however, efforts have been primarily focused on estimating genetic parameters and developing the knowledge and genomic tools useful for a genetic improvement program, rather than into definition of breeding objectives and indexes. Considering the effect of the environment, market traits, profitability and the current genetic knowledge on a silver-lip pearl oyster cohort, we developed a breeding objective and associated index that permits the selection of candidates based on commercial traits (see process in Figure 1).
The breeding goal is defined by the final product to be commercialised (e.g. larger pearls of gem quality). Since all pearls are produced from seeding a nucleus into an oyster, the size of a pearl is influenced not only by the size of the oyster, but also by the size of the nucleus seeded. Thus, selecting for large oysters at seeding time will influence pearl size. One way to achieve this is to focus on genetic improvement of growth and survival of oysters themselves. With a well-defined breeding goal, important traits can be determined via selection index theory. Using morphometric traits and the size of nucleus seeded, we developed a breeding index with an accuracy of 0.43 for individuals based on their own performance and where adding information from their relatives can increase the accuracy to 0.8.
The Australian pearling industry could benefit greatly from the implementation of advanced genetic breeding programs for silver-lip pearl oysters focusing on shell growth and survival as well as pearl quality