Skin lesions and physical deformities of coastal and offshore common bottlenose dolphins (Tursiops truncatus) in Santa Monica Bay and adjacent areas, California.

Skin lesions and physical deformities on coastal and offshore bottlenose dolphins (Tursiops truncatus) were assessed during a photo-identification study conducted between 1997 and 2007 in Santa Monica Bay and adjacent areas in California. During 425 boat surveys, 647 individuals were identified based on marks on their dorsal fins. Of 637 individuals examined for skin lesions and deformities, 79.0% exhibited at least one type of lesion. Offshore animals showed more lesions than coastal animals (offshore: 87.8%, n=209; coastal: 73.4%, n=270). Only one individual showed a physical deformity. Results show that skin lesions affect a large portion of the coastal and offshore dolphin populations in the study area. When considering that lesions and physical deformities can be a sign of disease and may be related to anthropogenic factors, their high presence on dolphins must be a cause of concern.