Spatial Patterns of Estuarine Habitat Type Use and Temporal Patterns in Abundance of Juvenile Permit, Trachinotus falcatus, in Charlotte Harbor, Florida

Abstract

The life history of many marine fishes is a 2-phase cycle: juveniles and adults make up a demersal phase, whereas larvae are planktonic. Determining ontogenetic patterns of habitat type use of the demersal phase has important management and habitat conservation implications for species that use coastal habitat types as juve- niles. Juvenile permit, Trachinotus falcatus, are presumed to be limited to beaches exposed to open ocean, but few studies have addressed juvenile permit use of estuarine habitat types. Ten years of fisheries-independent monitor- ing data from a subtropical estuary were analyzed to determine habitat type use patterns and seasonality of juvenile permit. Shallow (< 2 m) habitat types in Charlotte Harbor, Florida, were sampled with 21 m and 183 m seines from 1991 through 2000. Juvenile permit were most abundant along sandy beaches in the lower estuary and were in den- sities similar to or higher than along exposed coastal beaches reported in other studies. Size of captured permit ranged from 15 to 360 mm standard length. Small juveniles (< 100 mm) were present almost exclusively from June to December. Both small and large (≥ 100 mm) juveniles were most abundant over shallow bottom adjacent to unvegetated beach shorelines. These findings indicate that post-settlement permit recruit seasonally to specific estu- arine habitat types. Then, as they grow, they shift to other habitat types, before migrating out of the estuary. Since identification of the suite of juvenile habitat types is prerequisite to determining their nursery value, and many estu- arine habitat types are under anthropogenic stress, research on the relative importance of estuarine nurseries for juvenile permit is warranted.