Age and growth of sheepshead, Archosargus probatocephalus (Pisces: Sparidae), from the northwest coast of Florida

Age and growth is described for sheepshead (Archosargus probatocephalus) from the northwest coast of Florida. Fish (n = 511) were collected from Cedar Key to Keaton Beach, Florida, from March 1997 to November 1998. The majority of fish were subspecies A. p. probatocephalus (84%), 11% were A. p. oviceps, and 5% could not be designated. Fish were aged using sectioned sagittal otoliths. Maximum ages were 12 and 14 yrs for females and males, respectively. Marginal-increment analysis and chemical marking validated the formation of only one annulus per year. Annulus deposition occurred during March and April, and was complete by May. Patterns of growth in both length-at-age and weight-at-age were not different either between the sexes or between subspecies. Sheepshead were smaller at any given age compared to fish from South Carolina, but were generally larger than sheepshead used in coast-wide estimates for Florida. Fish from Louisiana were of similar overall size compared to sheepshead from both the northwest coast of Florida and coast-wide Florida. The use of regionally-explicit models of growth may be appropriate for sheepshead because of growth differences among populations in the southeastern United States. These differences in growth may result from several factors, including differences in mortality rates, environmental conditions, or genetic variation.