Here we review the best available science to describe nine key ecological principles governing the functioning of freshwater ecosystems and the fisheries they support. To develop each of these principles, existing literature was broadly reviewed, and a mix of classic papers, more recent reviews, and empirical studies related to each principle was cited. These principles must be accounted for to protect sustainable and productive fisheries and healthy aquatic ecosystems. Adherence to these principles is essential to the success of national and regional fisheries management plans, aquatic biodiversity protection plans, and associated policies, laws, and governance structures, along with monitoring programs. These principles are founded on our understanding of fish ecology, fisheries science, aquatic ecology, limnology, landscape ecology, evolutionary biology, conservation science, and watershed hydrology. Additionally, we discuss key components of successful fisheries management plans based on the history (including successes and failures) of freshwater fisheries management in Canada and beyond. The principles outlined here are generalized, though they are particularly relevant to
both north temperate regions and those that are vast and diverse in terms of peoples, physiography, and ecology.