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

Abstract In late summer 1979, 948 leopard sharks Triakis semifasciata were tagged and released into San Francisco Bay 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 years to determine how often the calcified bands are formed. As of 31 December 1982, 25 vertebral samples were recovered and examined. Although OTC deposition was variable, an intense fluorescent mark was evident in 12 individuals. The results confirm that one opaque (highly calcified) zone and one translucent zone are deposited per year, and that 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 September. Received July 22, 1983 Accepted March 18, 1984