Timing of Vertebral-Band Deposition in Tetracycline-Injected Leopard Sharks

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Abstract
In late summer 1979, 948 leopard sharks T. semifasciata were tagged and released into San Francisco Bay [USA] after being injected with the bone-labeling reagent oxytetracycline (OTC). The fluorescent time mark was compared to new growth zones in the vertebral centra of tagged fish recovered over 3 yr to determine how often the calcified bands are formed. As of 31 Dec. 1982, 25 vertebral samples were recovered and examined. Although OTC deposition was variable, an intense fluorescent mark was evident in 12 individuals. One opaque (highly calcified) zone and 1 translucent zone are deposited per year, and these zones can be used reliably in aging this species within the size group examined. The progression of band formation indicates that opaque zones probably form sometime between May and Sept.