Spatial Ecology of Adult Spotted Seatrout, Cynoscion nebulosus, in Louisiana Coastal Waters

• Main Author: Callihan, Jody Lynn
• Other Authors: Cowan, James H. Jr.
• Format: Others
• Language: en
• Published: LSU 2011
• Subjects: Oceanography & Coastal Sciences
• Online Access: http://etd.lsu.edu/docs/available/etd-08072011-084238/

Spotted seatrout, Cynoscion nebulosus, are common in estuaries and coastal waters of the south Atlantic and Gulf of Mexico and are of considerable recreational and economic importance. Still, the spatial ecology of this species is under-studied and poorly resolved, especially in Louisiana waters. To address this important knowledge gap, I examined the movements, distribution, and habitat use of adult spotted seatrout in coastal Louisiana primarily using high-resolution acoustic telemetry and secondarily, conventional tagging (mark-recapture) data. At the largest spatial scale investigated, I found that adults exhibited a high degree of estuarine fidelity and rarely undertook large-scale movements in excess of 50 km. At smaller (intra-estuarine) spatial scales, abiotic factors had a strong effect on fish distribution. Specifically, fish primarily utilized deeper channel habitats during severe weather events (cold storms and tropical fronts) and females avoided olighaline waters (0.5-5 psu). Adult spotted seatrout also showed clear habitat preferences, whereby oyster reefs and mud-bottom habitats of the estuary proper were used to a greater extent than channel and marsh regions. Seasonal and size trends in habitat use were also evident, as larger fish (> 400 mm TL) showed a high affinity for structured (reef) habitats and across size classes, artificial reefs were utilized most during spring and summer. My results have direct bearing on the assessment and management of this important species and support the current initiative of an ecosystems-approach to management by informing spatial management options. Finally, the results of my methods validation work on the effects of tagging on spotted seatrout and performance dynamics of telemetry equipment have important implications for future studies. Given the high transmitter retention and survival of telemetered spotted seatrout in my holding experiments, biotelemetry should be a feasible approach for future studies on the movement and behavior of this species. Still, in designing receiver arrays to study fish movements (of any species), it will be necessary to consider the high variability in receiver detection ranges as revealed by my extensive range testing efforts.