Freshwater ecosystems and the fisheries they support are increasingly threatened by human activities. To aid in their management and protection, we outline nine key principles for supporting healthy and productive ecosystems based on the best available science, including laws of physics and chemistry apply to ecology; population dynamics are regulated by reproduction, mortality, and growth; habitat quantity and quality are prerequisites of fish productivity; connectivity among habitats is essential for movements of fishes and their resources; freshwater species and their habitats are tightly linked to surrounding watersheds; biodiversity can enhance ecosystem resiliency and productivity; global processes affect local populations; anthropogenic stressors have cumulative effects; and evolutionary processes can be important. Based on these principles, we provide general recommendations for managing and protecting freshwater ecosystems and the fisheries they support, with examples of successful implementation for each strategy. Key management strategies include engage and consult with stakeholders; ensure that agencies have sufficient capacity, legislation, and authority to implement policies and management plans; define metrics by which fisheries resources and management success or failure will be measured; identify and account for threats to ecosystem productivity; adopt the precautionary approach to management; embrace adaptive management; implement ecosystem-based management; account for all ecosystem services provided by aquatic ecosystems; protect and restore habitat as the foundation for fisheries; and protect biodiversity. Ecosystems are complex with many intertwined components and ignoring linkages and processes significantly reduces the probability of management success. These principles must be considered when identifying management options and developing policies aiming to protect productive freshwater ecosystems and sustainable fisheries.

Habitat temperature is a major determinant of performance and activity in fish. We summarize published studies of 173 North American freshwater fish species to examine the interrelationships among thermal response metrics associated with three types of individual performance: growth (optimal growth temperature (OGT), final temperature preferendum (FTP)), survival (upper incipient lethal temperature (UILT), critical thermal maximum (CTMax)), and reproduction (optimum spawning temperature (OS), optimum egg development temperature (OE)). We found that all metrics were highly correlated, especially those associated with a specific performance type. Differences in thermal metrics were also significantly linked to traditional thermal guild classifications, spawning season, and strategy. We found an overall decline in correlation strength when we used phylogenetically independent contrasts to control for the effect of phylogeny. This decline was much greater for growth and survival metrics than for reproduction. This suggests that the role of evolutionary history in determining thermal sensitivity at the species level varies greatly across the range of performance types that can be used to characterize the behaviour of an individual.

No net loss of productive capacity (PC) of fish habitat has been the central concept guiding Canadian fish habitat management policy since 1986. The purpose of this paper is to describe the concept of PC, to review the history and application of the fish habitat management policy in Canada, and to provide a critical review of the range of potential approaches to estimating PC. The approaches were grouped by their central focus: habitat, individual, population, and community–ecosystem. A set of case studies is used to illustrate the use of some approaches drawn from freshwater and marine contexts. Ten components to assessing no net loss of PC were developed and used in the review of approaches for evaluating potential limitations. The review also highlighted the likely future direction of method development, with increasing emphasis on dynamic models integrating population responses to habitat supply characteristics. More work needs to be done to turn research-based metrics of PC into practical operational management assessment tools and to better quantify the link between habitat structure and function and fisheries productivity. The evolving approaches to measure PC reinforce the ties that fish habitat management has to the emerging practices in ecosystem-based management.

Changes in resource development and expansions of urban centres suggest that the intensity and types of anthropogenic stressors affecting Canada’s watersheds are changing. Chu et al. (2003) integrated indices of freshwater fish biodiversity, environmental conditions, and anthropogenic stress to identify priority watersheds for conservation and management. Here, we update those indices using recent climate and census data to assess changes through time. We also applied different conservation and management scenarios to evaluate the robustness of our prioritization approach. Between time periods, the environmental and stress indices expanded northward because of warmer temperatures at higher latitudes and more intense anthropogenic stress in the northern regions of the provinces. Conservation priorities increased in northern British Columbia, Alberta, and Ontario but decreased in southern British Columbia, Saskatchewan, and south-central Quebec. Under multiple scenarios, conservation priorities were consistently highest in British Columbia, the Maritimes, southern Ontario, and southern Quebec. Future research to refine this assessment should focus on developing a nationwide georeferenced assessment of freshwater fisheries stress, quantifying spatial changes in the stressors, and evaluating the sensitivity of each index to the weighting of the individual variables. This work highlights the necessity for conservation and management strategies in Canada to keep pace with changing patterns in climate and human activities.