The microbiome on the external surfaces of marine animals plays a crucial role in immunity against environmental pathogens, but the viral component of marine vertebrate epidermal communities is still a mystery. The epidermis of sharks is a unique viral ecosystem characterized by a substrate of mucus-producing skin covered by placoid scales (dermal denticles) which heals quickly from epidermal injury with low rates of infection. The size, shape, and distribution of dermal denticles and the quantity and chemical composition of the mucus vary among shark species, which establishes a selective habitat that supports a species-specific microbiome distinct from the water column. To investigate the community dynamics of this novel viral ecosystem, we sampled the epidermis of four shark species from the southwest pacific with a two-way blunt recapture syringe and used flow cytometry to enumerate the microbiome and virome. Shark microbiomes demonstrated 10- to 100-fold variability in virus-like particle (VLP) and bacterial abundance among individuals, with no significant differences in virus-to-microbe ratios (VMR) among species. VMR often ranged from 1:1 to 10:1 among healthy individuals within a species, but on wounded sharks, VLP abundance spiked and shifted the VMR as high as 100:1. VLP abundance and VMR were significantly higher on wounds compared to healthy epidermis on the same individual and on other individuals of the same species. Therefore, we propose a phage-mediated immune response to epidermal injury in sharks.