Movement Patterns and Habitat use for Fishery Species of Varying Life History Strategies
Gibson, Kesley Jae
Gibson, Kesley Jae
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Population level responses of organisms to a variety of factors including environmental change and fishing pressure can be influenced by habitat use and availability. Changes in habitat use over the life span of individual fishes is critical information for managers to conserve populations for the future. Thus, the goal of this dissertation research was to explore movement and habitat use by economically important species with different life history strategies in the Gulf of Mexico (GOM) across a variety of habitat types and spatial scales. These species were chosen to examine differences and commonalities to make predictions about habitat use and movement patterns for management. In Chapter 2, I tracked Red Snapper, which are structure-dependent, using a VEMCO© Positioning System (VPS) around a nearshore reef comprised of three types of reefing materials. Habitat use patterns changed seasonally, but generally Red Snapper did not select one reefing material over another, suggesting fish were influenced more by the presence of structure than material type. Cost comparison of reefing material suggested reefing the most effective and least expensive material covering the largest area may be the best policy in designing future artificial reefs. In Chapter 3, I opportunistically monitored Red Snapper movement at a nearshore artificial reef using a previously deployed VPS array to examine how a hurricane influenced habitat use. Red Snapper had a variety of responses with fish both remaining on and emigrating from site during the hurricane; however, differences in habitat use patterns were observed between pre- and post-hurricane. In Chapter 4, I tracked highly migratory Shortfin Mako sharks using satellite telemetry to determine their movement patterns in the northwestern GOM. Mako sharks exhibited impressive sex-specific movements over large spatial scales, demonstrating the need for more cooperative international management. They also used more of the northwestern GOM than reported in previous movement studies. In Chapter 5, I expanded on a large shark tagging effort of >5,400 sharks as a massive citizen science effort to examine a variety of demographic parameters for shark population dynamics. My goal was to evaluate the accuracy of shark species identifications made by recreational anglers. These activities represent an enormous bout of effort and potentially valuable science regarding habitat use for incorporation into my broader studies. However, validation of citizen collected data was essential. The overall high accuracy in species identification in this study suggests involving recreational anglers as citizen scientists can contribute meaningful scientific data. Specifically, this study showed that these data are a viable option in monitoring nearshore habitats that are largely neglected in traditional surveys, which can potentially be incorporated into future stock assessments. Understanding habitat use is a critical factor in the conservation of species, and more studies are needed to refine our understanding of these habitat types contribute to the conservation of economically important fishery stocks. The findings of this dissertation contribute to our knowledge of habitat use and seasonal movements of economically important species in the GOM, many of which are declining.