Good and bad years in the Gulf: tracking age-structure for gag grouper and red snapper

Gary R. Fitzhugh, William A. Fable, and Linda A. Lombardi
National Marine Fisheries Service, Southeast Fisheries Science Center, 3500 Delwood Beach Road, Panama City, FL, 32408; 850/234-6541 FAX: 850/235-3559; fitzhugh@bio.fsu.edu

Allyn G. Johnson
3728 Florida Avenue, Panama City, FL, 32405

As management interest and otolith sample availability for reef fish has increased during the decade, we looked back through archived otolith samples to construct and compare annual age frequencies for gag and red snapper since 1991. Samples were largely obtained from recreational "for hire" and commercial hook and line fishing sectors. These samples of over 7000 aged red snapper ranged from age-1 to 39 and 2500 gag grouper ranged from age-1 to 23. Although some annual sample sizes were relatively small (a few hundred fish), consistent trends were observed revealing patterns of gear selectivity and year-class strength. Gag in particular showed a series of strong year classes. The 1983, 1989, 1993 and 1994 cohorts reached ³30% of an annual sample age structure and could be "tracked" across several years. Although red snapper are longer-lived, dominant year-classes were not as readily evident from the aged samples. An increased sampling effort in 1998 allowed a comparison of red snapper age structure by fishing gear. It was apparent that all hook and line fisheries for red snapper, whether commercial or recreational, were harvesting similar ages; predominantly age-3 and age-4. The age proportions of hook and line caught fish also appeared to be very low beyond age 8-9, dropping to less than 1% of the ages within each fishing sector. An inference from the archived data is that this pattern has persisted through the 1990s. However, long-line gear, representing a small component of the commercial fishery, was harvesting older individuals with fish reaching age 18 before the proportion of age was less than 1%.