Effects of estuarine environmental conditions on population dynamics of young-of-the-year gulf menhaden

Abstract

Environmental factors, primarily river discharge and winter temperatures, are strongly correlated with growth and survival of young-of-the-year gulf menhaden Brevoortia patronus in Fourleague Bay, Louisiana, USA. Gulf menhaden were found in highest abundance from February to November. They first use marsh creeks and then in early summer they migrate out into deeper open bay areas where they remain until late summer or fall. This migration pattern coincides with the productivity peaks in marsh and open bay areas. Instantaneous growth coefficients were slightly different between years (1982 = 0.005, 1983 = 0.004). Mortality rates were different between year-classes (1982 year-class = 0.007; 1983 year-class = 0.018), but not between habitats within a year-class. In periods of high river discharge and cooler spring temperatures, fish apparently grew more slowly and mortality rates were higher. This is consistent with other studies that correlated catch of adult gulf menhaden with environmental factors during their juvenile estuarine stay.