Can Greenlip (Haliotis laevigata) Abalone Breeding Programs Tolerate Fluctuations in Reproductive Performance?

Abstract

Fluctuations in reproductive performance (i.e., spawning success, hatching rate, larval survival) are a common occurrence in abalone breeding programs, in particular during the early stages of their development. Such fluctuations affect the numbers of families available for progeny testing and selection, and can have consequences for genetic gains and inbreeding. We used stochastic computer simulations to understand how genetic gains and levels of inbreeding are affected when greenlip (Haliotis laevigata) breeding programs encounter varying severity and frequency of reproductive failure. We simulated breeding programs for greenlip abalone with both conservative and aggressive selection approaches over 35 y (10 generations). Without reproductive failure, genetic improvements of 36%-55% could be achieved after 10 y of selection in a single trait in a commercial abalone breeding program with a conservative selection approach, and gains of twice that could be achieved with a selection approach that allowed high rates of inbreeding. A conservative selection approach would be sustainable even at high rates of reproductive failure, whereas a more aggressive approach would lead to nearly twice the recommended level of inbreeding. It was concluded that breeding programs for greenlip abalone may be buffered against unexpected fluctuations in reproductive performance if the selection approach is chosen strategically.

An Assessment of Hatchery Cohort Growth Rates of South African Abalone, Haliotis midae, Across Four Commercial Environments

“…However, differential broodstock contributions to the seed at any given spawning event may lead to genetic differences among the cohorts (Slabbert et al ; Rhode et al ), which may translate into differential phenotypic performances. Dominik et al () highlighted that such fluctuations in reproductive performance among broodstock may pose challenges for the implementation of a selective breeding program in abalone, but could be negated through careful management. While the objective of cohort (strain) evaluation trials is to identify the best “strains” for starting a breeding program or to quantify the amount of genetic variation between “strains,” the current design precludes this due to risks of overestimating significance levels due to confounding factors including fluctuations in reproductive performance, hatchery effects, and hatchery cohorts.…”