1R & D Division, Marua Suisan Co., Ltd. Kamijima, Ehime 794-2410, 2South Ehime Fisheries Research Center, Tarumi Branch, Ehime University, Matsuyama, Ehime 790-8566, Japan
Artificially raised red sea breams with abnormal body shapes were morphologically characterized, and genetic investigations were conducted using microsatellite DNA markers. Normal and deformed individuals were collected at 68 days post-hatch. Deformed individuals were truncated because their dorsal regions were swelled and had scoliosis. A complex spinal column deformity consisting of a consecutive repetition of lordosis, kyphosis, and scoliosis from the head to the caudal fin was described by soft X-ray analysis. Four microsatellite markers, Pma-2*, -3*, -4*, and -5*, were used for parentage analysis, and two dams and sires generated significant numbers of deformed individuals. Genetic investigations were also conducted and genotype frequency revealed that 90% of deformed individuals had an allele-113 on Pma-4*, even though 60% of normal individuals also had the allele. Our results suggest that genetic factors may be one of the causes of the deformed individuals identified as juveniles of a hatchery population of red sea bream.