Effect of saddleback syndrome and vertebral deformity on the body shape and size in hatchery-reared juvenile red spotted grouper, Epinephelus akaara (Perciformes: Serranidae): a geometric morphometric approach

Abstract

This study examined how saddleback syndrome (SBS) and vertebral deformity affect the body shape and size of juvenile stage red spotted grouper, Epinephelus akaara, using the landmark-based geometric morphometrics method. According to the criterion of skeletal conditions, three groups, i.e. vertebral deformity, SBS, and normal groups, were identified. The results revealed significant differences in body shape among the three groups, in which the vertebral-deformed group had the deepest mid-body, the broadest anterior part, and a shortened caudal peduncle, while the SBS group showed the shallowest mid-body and the narrowest anterior part. The normal group had a body shape intermediate between the vertebral and SBS groups. A comparison of body size among the three groups revealed significant differences in centroid size, with the vertebral-deformed and SBS groups showing smallest and largest centroid size, respectively. This study illuminates that not all skeletal deformities lead to smaller body size. We suggest that rearing conditions might have caused the deformities reported herein.