Utilization of two river basins by common snook, Centropomus undecimalis in Tampa Bay, Florida

*Winner, Brent L., Robert H. McMichael, Jr., and Julie M. Fine
Florida Marine Research Institute, 100 8th Ave. SE, St. Petersburg, FL 33701, Ph: (727) 896-8626, Fax: (727) 823-0166, Brent.Winner@DEP.State.FL.US

The common snook, Centropomus undecimalis, is one of the most sought-after gamefish in the inshore waters of southern Florida. Snook are euryhaline and may be found in a wide variety of habitats, including rivers, estuaries, coastal beaches, and nearshore reefs. The objective of this study was to describe abundance, spatial and temporal distribution, and habitat preference of snook along shoreline habitats in two river basins in Tampa Bay, Florida. Stratified random (SRS) and fixed station sampling was conducted with a 21.3-m (3.1-mm mesh) center-bag seine in the Alafia and Little Manatee rivers between January 1989 and December 1998. Additional fixed station sampling was conducted with a 183-m (38-mm stretch mesh) haul seine in the Alafia River between December 1992 and August 1996 to collect larger sub-adult and adult snook (<200 mm SL). A total of 4,266 snook, ranging from 8 to 875 mm standard length, were collected in 2,956 seine collections. Snook catch per unit effort (CPUE) with the 21.3-m seine was higher in the Little Manatee River (Fixed: 2.99 fish/haul; SRS: 0.73 fish/haul) than in the Alafia River (Fixed: 0.70 fish/haul; SRS: 0.28 fish/haul). Snook length-frequencies differed between rivers. Although initial recruits (< 30 mm) were found in both rivers, fewer recruits and more sub-adult and adult snook (> 200 mm) were collected in the Alafia River than in the Little Manatee River. Snook were present in both rivers year-round, with peak abundance from August through December, coinciding with recruitment of YOY snook. Young-of-the-year snook (< 50 mm) were present during all months of the year in the Little Manatee River and during all months but May and June in the Alafia River, suggesting a protracted spawning period for snook in Tampa Bay. Most of the snook were collected from shorelines containing some type of overhanging vegetation (e.g., mangroves), which can provide both shade and protection.