Habitat- and sex-specific life history patterns of yellow tang Zebrasoma flavescens in Hawaii, USA

Yellow tang Zebrasoma flavescens is the primary coral reef fish species taken in Hawaii for the aquarium trade. As part of an extensive adaptive management effort that included a network of marine protected areas that prohibited commercial aquarium fishing, an emphasis was placed on obtaining habitat- and sex-specific life history information for this valuable species. Using otolith and capture-mark-recapture methods we examined sexual differences in ontogenetic patterns of habitat use, growth rate, size dimorphism and longevity. Age validation using tetracycline to mark otoliths provided evidence that a single annulus formed each year. Yellow tang are a long-lived species (the oldest individual collected was 41 yr old) and display an asymptotic growth pattern typical of the family Acanthuridae. Median size and age at the transition between deeper coral-rich and shallow turf-dominated habitat use were about 20 mm longer and about 2 yr older for males than females and coincided with an increase in reproductive output. The sexual difference in size at habitat transition, combined with sexual size dimorphism (mean asymptotic maximum length - male: 179 mm; female 156 mm) results in differences in the size distributions of both sexes in the 2 habitats. Sexual size dimorphism resulted from a higher growth rate for males through the juvenile period.