LAUSR

Abstract Abalones are especially susceptible to environmental lighting conditions. This factor greatly affects crucial biological process such as feeding rates, energy balance, physiological stress status, and consequently, growth and survival of farmed abalone. Most of these effects have been studied in the economically valuable abalone Haliotis discus hannai. The use of specific photoperiods, and/or light qualities and intensities, have been proposed as managing strategies to increase its production; however, for extensive off-shore or in intensive land-based farming systems, lighting conditions are not likely to be easily managed. Despite the great importance of the biological responses to the light/dark stimuli for abalone farming production, to the best of our knowledge the genetic control upon the variation associated behavioral traits have not been studied. Therefore, the aim of this study was to estimate the heritable variation and potential responses to selection for the phototaxis [i.e., displacement towards (positive) or against (negative) the light source] and locomotion behaviors associated to the intensity of the response (i.e., crawling speed and displacement distance) to the light/dark stimuli in juvenile H. discus hannai. Genetic and phenotypic correlations between these traits were also estimated. Results showed moderate but significant heritable variations for phototaxis (h2 = 0.15) and locomotion responses (h2 = 0.18–0.37); and significant positive genetic correlations among them. Expected gain responses to selection per generation (with a selection intensity of 2.06, i.e., selecting 5% of the individuals from a population) were moderate for phototaxis variation (16%) and high for locomotion responses variation (33–67 or 36–73%, depending on the model used for the estimations). As a consequence, the potential for reducing (or incrementing, depending on the breeding goal) the reactivity or the sensibility to the light stimulus by selective breeding is good, and can be an attractive way of indirectly improving growth, survival and general welfare of farmed H. discus hannai.