Like Pacific salmon (Oncorhynchus spp.),nonnative American shad (Alosa sapidissima) hold the potential to convey large quantities of nutrients between the Pacific Ocean and freshwater spawning areas in the Columbia River Basin (CRB). American shad are now the most numerous anadromous fish in the CRB, yet the magnitude of the resulting nutrient flux owing to the shift from salmon to shad is unknown. Nutrient flux models revealed that American shad conveyed over 15000 kg of nitrogen (N) and 3000 kg of phosphorus (P) annually to John Day Reservoir, or the largest mainstem reservoir in the lower Columbia River. Shad were net importers of N,with juveniles and postspawners exporting just 31% of the N imported by adults. Shad were generally net importers of P, with juveniles and postspawners exporting 46% of the P imported by adults on average. American shad contribute
Source: usgs.gov