Professor Harvey is interested in several aspects of the biology of freshwater fishes. Population dynamics studies include recruitment of age classes, growth, age at maturity and natural mortality, in relation to population density and food supply. Research projects with graduate students include analysis of physical and chemical variables in determining fish community structure, DNA fingerprinting of fish populations, the bioenergetics of the white sucker, and the effect of climate change on fish populations. Crayfish studies include movement, substrate preference, population size and composition.