(1999) histologically examined individual abalone from mass mortalities that occurred in different hatcheries during this period from 1988 to 1996, and they reported that most of mass mortalities were attributable to abalone amyotrophia. The characteristic relation between the occurrence of abalone amyotrophia and ambient water temperature has been reported as follows: the progress of abalone amyotrophia occurs when the water temperature rises to 18[degrees]C or higher and is suppressed at more than 23[degrees]C (Nakatsugawa 1990, Okada et al.
As a result, the change of the percentage composition of the six families from May to August suggests that the survival of the 2 selected families (family #1 and #2) were significantly better than that of the other 4 families (family #3, #4, #5, and #6) after the occurrence of mass mortality caused by abalone amyotrophia. Juvenile individuals of the six families were reared in the same tank, thus minimizing environmental effects immediately after hatching; therefore their survival performances among families are considered to have been strongly influenced by heritability.
The two selected families were produced from the families that had higher survival rates than the other families after an occurrence of mass mortality caused by abalone amyotrophia, and in this experiment their offspring bad survived higher rates than the other families examined.
The results of this experiment strongly suggested that resistances to abalone amyotrophia is due to genetic effects.
Mamoru Nishimura, Mie Prefectural Fisheries Experimental Station for the donation of the candidate abalone resistant to abalone amyotrophia and Mr.
Mass mortalities of juvenile abalone, Haliotis spp., caused by amyotrophia. Fish Pathology 34:7-14.