The identification of genetic resistance to amyotrophia in Japaneseabalone, Haliotis discus discus

摘要

This experiment was designed to evaluate the genetic resistance to amyotrophia of Japanese abalone (Haliotis discus discus) under a mixed rearing environment. Two selected families that had previously shown resistance to abalone amyotrophia as candidates, two nonselected families as controls that had previously not shown resistance, and two hybrid families were used. Individuals from these families were fertilized and mixed immediately after hatching, and then they were raised in a mixed rearing tank at an abalone hatchery during the period of frequent spontaneous occurrences of abalone amyotrophia. Furthermore, we have isolated seven new microsatellite DNA loci for identifying families, and so the six offspring families in the mixed rearing tank could be discriminated unambiguously. The survival ratio of the two selected families was 87% and 93% after the occurrence of mass-mortality caused by abalone amyotrophia, whereas that of the four other families ranged from 0% to 37%. Survival performance among the offspring families was significantly different under the mixed rearing environment. This result suggests strongly that resistance to abalone amyotrophia of juveniles is related to the genetic characters of the spawners. Therefore, this experiment shows that resistance to the disease is a heritable trait, because the two selected families produced offspring with a high survival ratio after the occurrence of abalone amyotrophia.