Influence of Physicochemical Characteristics on Annual Growth Increments of Four Fishes from the Lower Mississippi River

Abstract

Abstract We examined relationships between lower Mississippi River physicochemistry and growth of young (≤age 2) blue catfish Ictalurus furcatus, channel catfish I. punctatus, freshwater drum Aplodinotus grunniens, and gizzard shad Dorosoma cepedianum collected from dike fields (river kilometers 669.0–883.2 upstream from the mouth) in September and October 1987–1990. Growth increments of the four fishes were determined from cross sections of otoliths (freshwater drum and gizzard shad) or spines (blue and channel catfishes), and we used regression analysis to assess the effects of annual variability in 15 physicochemical variables on growth. We hypothesized that growth of these fishes would be positively related to the extent and duration of the annual flood pulse, as it is in tropical floodplain systems. However, growth increments of age-0 blue catfish, channel catfish, and gizzard shad were related only to length of the growing season. Further, positive relationships between growth and total organic carb...