If the produced juveniles are supplied for culture in farms, breeding of disease
resistance in brood stocks is an important subject for the study. However, for the seed to
be released into the sea, it is difficult to determine the target diseases against which the
released juveniles should be resistant, because we do not have enough information on
the disease and parasite in the natural waters. For the time being, brood stocks should be
obtained in the sea where released fish will grow, because adult fish captured in that
area might have survived infections prevailing in that area owing to their innate
resistance.