NWT RESEARCH DATABASE

Regions: Dehcho Region

Tags: mining, aquatic ecosystems, environmental baseline, fisheries assessment

Objective(s): To collect baseline aquatic data in advance of the development of the Prairie Creek Mine.

Project Description: To collect baseline aquatic data in advance of the development of the Prairie Creek Mine. The study will be part of the Aquatic Effects Monitoring Program (AEMP) and will satisfy the requirements of the federal Environmental Effects Monitoring (EEM). The description below is a summary of the planned methodology. Most work will be carried out on Prairie Creek; however, sampling will also be conducted on a number of nearby tributaries to the Nahanni River. Components of the study will consist of the following: An assessment of fish health. One hundred slimy sculpin will be collected from each sampling location using electrofishing then later released. Length/weight and external condition will be recorded for these fish. Catch per unit effort will also be documented for each location. An assessment of juvenile bull trout occupancy and density. The bull trout occupancy and density study will involve electrofishing each of the four creeks twice in three days (leaving one day in between for fish to recolonize). Ten to 15 sub-sites will be electrofished at each creek. Fishing will target juveniles and young of the year. The purpose will be to assess whether or not there is any change in the fish use of spawning/rearing locations as a result of mining. Fish length and weight would be measured on each fish caught. Substrate and temperature data (from DFO temperature loggers) would be recorded for each sub-site. An assessment of mercury and selenium concentrations in Arctic grayling. Arctic grayling (30 fish) will be caught near the confluence with the Nahanni River by angling. This portion of Prairie Creek has been used on occasion by aboriginal people for Arctic grayling fishing. Caught grayling will be weighted, measured, and the following will be collected from each fish: a muscle tissue plug using a biopsy needle (for metals analysis), a caudal fin clipping (for metals analysis), a pelvic fin clipping (for aging) and scales (for aging). Collected muscle tissue samples will be stored on ice and submitted for metals analysis (including mercury). An assessment of benthic invertebrate communities. Benthic invertebrate samples will be collected using a D-shaped kicknet following Canadian Aquatic Biomonitoring Network (CABIN) protocols. In order to satisfy EEM requirements, five sub-samples will be collected from the reach immediately upstream of the mine, as well as the downstream nearfield and downstream farfield reaches. In addition to the exposure (downstream locations), a few of the reference stations sampled will be re-sampled. An assessment of algal biomass and diversity (chlorophyll-a). The procedure followed for algal analysis follows the methodology used in previous years. Using a template, scrapings will be collected from nine cobbles rocks collected in each of the sampling reaches. For each site, three composted samples will be submitted for chlorophyll-a analysis and a single sample will be submitted for taxonomic identification. Copies of all report will be sent to both the communities of Nahanni Butte and Fort Simpson. The fieldwork for this study will be conducted from July 20 2014 to August 15, 2014.