Growth, density, and biomass production of Atlantic croaker (Micropogonias undulatus), spot (Leiostomus xanthurus ), white shrimp (Litopenaeus setiferus), brown shrimp (Farfantepenaeus aztecus), and blue crabs (Callinectes sapidus) in the Weeks Bay Nation

I collected juvenile and sub-adult Micropogonias undulatus, Leiostomus xanthurus, Litopenaeus setiferus, Farfantepenaeus aztecus, and Callinectes sapidus with a 4.9m otter trawl in Weeks Bay, Alabama during May 1996 through December 1997 to investigate species-specific temporal and spatial trends in both density and daily biomass production. Quantitative descriptions of population dynamics and an evaluation of the potential for these species to export nutrients from Weeks Bay was needed as this project was part of a larger project to develop a nutrient budget for Weeks Bay. Statistically significant temporal (across months) and spatial (across sites) trends in density and daily production rates were found. Hydrographic (temperature, salinity, dissolved oxygen, and percent oxygen saturation) and biogeochemical (nitrate, nitrite, ammonium, and phosphate concentrations) variables were measured along with chlorophyll-α concentrations, phytoplankton productivity, and zooplankton densities in an attempt to relate these variables to observed temporal and spatial trends in fish density and daily production rates. Variability among these factors, inherent in estuarine systems, precluded any statistically significant relationships among the variables of interest. On a temporal scale relatively higher observed densities and daily production rates occurred during spring once young-of-the-year cohorts recruited to Weeks Bay and increases in biomass offset losses due to mortality and/or emigration. Spatially, higher observed densities and daily production rates were observed at the mid- and upper-bay sites where habitat was similar. Lower densities and daily production rates were observed at the lower-bay and the lower-river sites where habitat was much different. The estimated fraction of primary production that was assimilated by the demersal fish and crustacean community was less than 1%. Differences in relative cohort sizes, trophic position, primary production of Weeks Bay compared to that observed by Deegan (1993) for gulf menhaden in Fourleague Bay, Louisiana likely contributed to differences in potential export of these species.