Port Bay, An Evaluation of the Marine Habitat

Trawl samples taken at weekly intervals from December 1970 through November 1971 in Port Bay, a tertiary bay of the Aransas Bay system, produced 38 species of fin fish and 9 species of crustacea. A nine-month period of below normal rainfall from November 1970 through July 1971 influenced white shrimp, Penaeus setiferus, and blue crab, Callinectes sapidus, populations by raising salinities above optimum ranges during juvenile migration periods. In September 1971, rainfall associated with tropical storm "Fern" dropped salinities from above 30.0 to 0.0 ppt. Eight hundred ninety six hydrographic samples collected during the survey were correlated with population densities to establish the salinity influence on individual species. The parameters determined for each sample were salinity, temperature, turbidity, pH, dissolved oxygen, calcium, total hardness and magnesium.