Date of this Version
The Prairie Naturalist 40(1/2): March/June 2008, pp 23-36
Reproductive timing of common carp (Cyprinus carpio) was examined in the Red River of the North and compared with environmental factors that might have triggered spawning during 1999 and 2000. We estimated spawn dates for individual common carp larvae collected in the drift by back-calculating from datc of capture and by accounting for developmental stage at capture and water temperature during the period of egg incubation. Reproductive timing was compared with discharge and water temperature to determine which of these likely might be a synchronizing cue for spawning of common carp in the Red River basin. In both years of the study, water temperature regimes were similar in comparison with time of year; however, discharge hydrographs differed substantially, which provided an opportunity to test our hypothesis that within a window of suitable temperature (and photoperiod), spawning in common carp is triggered by an increase or peak in discharge. The discharge hydrograph during 1999 was typical for the Red River, with peaks in April from snowmelt and precipitation. In atypical 2000 no early spring peak occurred due to a lack of snow cover and spring precipitation, but heavy precipitation produced a peak in discharge much later than normal during the third week of June throughout most of the study area. In both years successful common carp spawning occurred after the first peak in discharge following the attainment of a minimum spawning temperature. These results supported our hypothesis suggesting that a discharge related environmental factor might act as the synchronizing cue for spawning in common carp in some lotic habitats.