This study was initiated to assess the biological, ecological and sociological aspects of the blue crab, Callinectes sapidus, fishery associated with the Pascagoula River Estuary in southern Mississippi. Household surveys were conducted in the cities of Moss Point and Pascagoula, Mississippi, September 2010 to September 2011, to identify, describe and classify subsistence fishing activities associated with the estuary. A stock assessment of blue crab was conducted to determine how biological and environmental variability affect the people engaged in this subsistence fishery. The study revealed two types of subsistence fishing occurring in the Moss Point/Pascagoula area. The first type involves fishing as a livelihood strategy based on economic dependence, and the second type involves fishing as a lifestyle choice based on economic independence. Both are based on customary and traditional patterns of local resource use and consumption and maintained by reciprocal kinship-based social networks. The blue crab fishery in the Pascagoula River Estuary was highly variable and exhibited strong seasonal and spatial patterns in distribution and abundance. Subsistence fishers in the region have developed strategies to cope with this biological and environmental variability. These region-specific strategies include but are not limited to: fishing using multiple gears simultaneously (rod and reel and crab nets), freezing fish, relying on other natural resources including agriculture and wildlife, and generalized reciprocity.

Assessment of water quality within the Escatawpa River system was accomplished utilizing the Better Assessment Science Integrating Point and Nonpoint Sources (BASINS 2.0) to develop the watershed model, and the CE-QUAL-W2 software to develop the estuary model. The watershed model was utilized to quantify both hydrodynamic and water quality (fecal coliforms) characteristics of the watershed for a simulation period spanning from 1990 through 1999. Herein, calibration and application results are presented for watershed and estuary simulations made in an uncoupled manner. The models were developed such that loose coupling of watershed and estuary models can be accomplished as a subsequent phase of this ongoing project. CE-QUAL-W2 model calibration was performed utilizing a set of site specific data acquired on the Escatawpa Estuary System during an intensive survey period of September 10-15, 1997. Dissolved oxygen levels in the system were closely examined, with regards to the impacts from point source discharges.

This thesis focuses on the simulation of astronomic tides of the Pascagoula River. The work is comprised of five steps: 1) Production of a digital elevation model describing the entire Pascagoula River system; 2) Development of an inlet-based, unstructured mesh for inbank flow to better understand the basis of the hydrodynamics within the Pascagoula riverine system. In order to assist in the mesh development, a toolbox was constructed to implement one-dimensional river cross sections into the two-dimensional model; 3) Implementation of a sensitivity analysis of the Pascagoula River two inlet system to examine the inlet effects on tidal propagation; 4) Improvement of the inlet-based model by performing a preliminary assessment of a spatially varied bottom friction; 5) Implementation of an advection analysis to reveal its influence on the flow velocity and water elevation within the domain. The hydrodynamic model employed for calculating tides is ADCIRC-2DDI (ADvanced CIRCulation Model for Shelves, Coasts and Estuaries, Two-Dimensional Depth Integrated). This finite element based model solves the shallow water equations in their full nonlinear form. Boundary conditions including water surface elevation at the off-shore boundary and tidal potential terms allow the full simulation of astronomic tides. The improved astronomic tide model showed strong agreement with the historical data at seven water level monitoring gauge stations. The main conclusions of this research are: 1) The western inlet of the Pascagoula River is more dominant than the eastern inlet; however, it is necessary to include both inlets in the model. 2) Although advection plays a significant role in velocity simulation, water elevations are insensitive to advection. 3) The astronomic model is sensitive to bottom friction (both global and spatial variations); therefore, a spatially varied bottom friction coefficient is suggested. As a result of this successful effort to produce an astronomic tide model of the Pascagoula River, a comprehensive storm surge model can be developed. With the addition of inundation areas the surge model can be expected to accurately predict storm tides generated by hurricanes along the Gulf Coast.