Reproductive Phenology of Fishes of the Middle Rio Grande, New Mexico

Fish species often exhibit differences in reproductive timing within a community.  In arid-land river systems where resource availability is temporally variable, differences in timing can differentially affect reproductive success among species.  Consequently, reproductive timing can be an important determinant of adult fish community composition.  In this study, we ask two questions related to reproductive timing:  (1) Is phenology consistent across years?  (2) To what extent do environmental conditions (photoperiod, temperature, discharge) correlate with reproduction across species?  We collected larval fishes over three years (2008-2010) in the middle Rio Grande, New Mexico, to determine species-specific spawning periodicity and address these questions.  Spawning periodicity data were compared with environmental variables to test whether species differed in the suite of environmental conditions under which spawning occurs.  We find that, while rank order of spawning is generally similar across years, the absolute timing of spawning varies in relation to interannual-variation in environmental conditions.  These data have important implications for determining likely responses of fishes to environmental disturbance (e.g., global climate change).  Knowledge of how fishes time reproduction, coupled with adaptive management practices, may assist restoration efforts of native fish communities in altered and regulated rivers.