Research Document - 2016/033

Modelling the effects of chemical and physical drivers on fisheries productivity metrics across rivers of varying hydrological regimes: lessons learned from NSERC HydroNet 2009-2015

By D. Boisclair, M. Lapointe, A. Saint-Hilaire, J.B. Rasmussen, C. Senay, G. Lanthier, G. Bourque, G. Guénard, C.J. Macnaughton and S. Harvey-Lavoie

Abstract

Natural Sciences and Engineering Research Council (NSERC) HydroNet is a national research network whose overall objective is to provide government and industry with the knowledge and tools that will improve the capacity of scientists and managers to assess and minimize the effects of hydropower installations and operations on aquatic ecosystems. This project was divided in three components that focused on the existence of significant among-river variations of fisheries productivity metrics, the development of relationships between fisheries productivity metrics and environmental conditions, and the identification of promising new metrics of fisheries productivity. We achieved our objective by estimating fisheries productivity metrics (density [number of fish ∙m-2) and biomass [g∙m-2] by fish species and size-classes; species richness), nutrient concentrations (total phosphorus, nitrates, nitrites), meso-habitat variables (depth, velocity, substrate composition, macrophyte cover, woody debris, etc), hydrological indices, and thermal indices in 15 unregulated rivers and 13 rivers regulated for hydropower production distributed from Alberta to New Brunswick, Canada. Relationships between fisheries productivity metrics and environmental conditions were assessed with different fisheries productivity metric (e.g. production, catch, recruitment, density, biomass, growth, survival, species richness), organismal scales (e.g. total fish community, guilds, species associations, phylogenetic group, species, life-stages [combinations of species and size-classes]), and spatial scales (e.g. complete river, river segment, meso-habitat, micro-habitat). The explanatory and predictive capacity of fish-environment relationships respond directly to the need of both the proponents and the regulators to:

1. predict the potential effect of a project on metrics of fisheries productivity;
2. assess the need for, or the magnitude of, mitigation measures;
3. identify and measure the relative efficiency of different mitigation strategies;
4. estimate the existence or the magnitude of residual effects on metrics of fisheries productivity, and;
5. quantify the need for, or the magnitude of, offsetting.

However, it may be inappropriate to apply the relationships between fisheries productivity metrics and environmental conditions unveiled in this study to rivers, fish communities, or environmental conditions that are outside the range used to develop these relationships. Once these limits are respected, the relationships between fisheries productivity metrics and environmental conditions could be used to predict future river fisheries productivity metrics under a new set of environmental conditions. Knowledge and tools developed by the present project may be useful to inform the decision-making process regarding the development or operation of hydropower facilities, and, if authorities recognize the knowledge and tools developed by the present study, augment the clarity, the consistency, and the certainty of the decision-making process.

Complete document (PDF, 1,862 KB)

Accessibility Notice

This document is available in PDF format. If the document is not accessible to you, please contact the Secretariat to obtain another appropriate format, such as regular print, large print, Braille or audio version.