Research Document 2017/018
Determining regional benchmarks of fish productivity using existing electrofishing data from rivers: proof of concept
By Randall, R.G., Bradford, M.J., de Kerckhove, D.T., and van der Lee, A.
Abstract
Electrofishing data from streams and rivers in Newfoundland, the Maritime Provinces, Ontario, Alberta and British Columbia showed regional differences in fish productivity. The existing electrofishing data were originally collected by different agencies for various reasons, including the determination of stock status of harvested species, the investigation of fish habitat associations, and the investigation of the status and life history characteristics of Endangered fish species. Despite being targeted for specific species, electrofishing catches of all cohabiting species at the sites were recorded, providing estimates of total density (fish m-2) and biomass (g m-2) of the fish community. The datasets varied in duration and spatial extent from ‘snapshots’ (< 5 years and a small number of sites) to time series (> 10 years and spatially extensive). For each site, a Habitat Productivity Index (HPI) was also estimated as an index of production.
The average fish biomass density and HPI varied among the regions from about 2.5 to 22 g m-2, and were roughly similar to literature values from a small subset for these areas. The regional averages however are tentative, and require further confirmation. The lowest biomass and HPI estimates were from insular Newfoundland, where water fertility and species richness (SR) were low. In contrast, fish biomass and HPI values in the relatively warm fluvial waters of southern Ontario (Toronto region) were high. Average biomass densities among regions were significantly and positively related to average long-term air temperature, for both the fish community biomass and for the biomass of individual species of Salmonidae. The salmonid biomass-temperature relationship was likely not linear (i.e., dome-shaped). Body size-density relationships were variable among the data sets, but generally showed an inverse relationship between body size and density consistent with the science literature. Together, fish density, body size and temperature were key metrics of region-dependent fish productivity.
Estimates of region-dependent fish productivity were proof of concept and demonstrated the feasibility of using existing electrofishing data to determine spatial differences in productivity in the rivers and streams of Canada. Also, differences in productivity are likely predictable from readily-available landscape drivers such as air temperature and location. Existing fishing areas or zones are a possible spatial unit for aggregating the data. Limitations of using existing electrofishing data included uncertainty of fish capture probability and unknown status of resident and migratory species in terms of carrying capacity.
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.
- Date modified: