Temperature Selection by Striped Bass in a Gulf of Mexico Coastal River System

Behavior of adult striped bass Morone saxatilis in the Flint River‐Lake Seminole portion of the Apalachicola River system was evaluated to determine if temperature preferences differed from those of striped bass from Atlantic coast stocks. Previous research has shown that striped bass native to this Gulf of Mexico river system had higher condition factors, greater longevity, and less weight loss in summer than did introduced Atlantic fish, presumably because the native fish were better adapted to the higher temperatures prevalent in waters of the Gulf region. Radiotelemetry was used to monitor fish distribution and temperature selection from March 1984 to November 1985. Seasonal distribution patterns and influences of water temperature on striped bass behavior were similar to those reported elsewhere for Atlantic striped bass. The fish ranged widely and occurred throughout the 166‐km‐long study area during fall, winter, and spring. During summer, however, they inhabited spring‐fed areas almost exclusively. The fish moved into these sites during May, when surrounding waters averaged 24.3°C, and remained there through late October or early November, when ambient water temperatures declined to an average of 20.1°C. Temperatures selected by the fish averaged 21.6°C during both summers. When the data were separated into subsets of native Gulf and introduced Atlantic striped bass by the use of previously reported meristic characteristics, there were no differences between groups for average temperatures selected during summer or for temperatures at which the fish moved into or out of springs. The results indicate that preferred temperatures of striped bass in the Apalachicola River are not higher than those of other stocks.