NWT RESEARCH DATABASE

Tags: physical sciences, contaminants, water quality, environmental monitoring, mining impacts, fish, environmental impact assessment

Objective(s): To evaluate fish health, energy use, energy storage, and age distribution within the exposure and reference area populations.

Project Description: The objectives are to evaluate if there are differences in biological parameters among study sites and between years at the Tungsten Mine site; as well as to determine whether observed differences from the most recent (2015) Environmental Effects Monitoring study are still present and whether any differences are the result of mining practices. The study objectives are to evaluate fish health, energy use, energy storage, and age distribution within the exposure and reference area populations. The following components will be studied: fish study – non lethal sampling of slimy sculpin as the sentinel species, benthic invertebrate study, water quality sampling, and sediment quality sampling. Based on lessons learned from previous EEM cycles at the Cantung Mine, backpack electrofishing will be the primary capture method used to target slimy sculpin. Backpack electrofishing has been a successful method in capturing YOY slimy sculpin. Other methods, such as baited minnow traps, have also been used but with very limited success. Electrofishing will target both young of the year (YOY) and non-YOY habitats throughout each study site. Electrofishing sampling effort rate will be standardized to correspond to 1 to 2 seconds (electrofisher on time) per square meter sampled in each study site. Some study sites may have a higher total effort (total seconds of electrofishing) than other sites, depending the length of each study site, but will have a similar sampling effort rate between sites. A qualified crew trained in electrofishing will sample fish using a type 20B Smith-Root electrofisher. The anode will be 12” diameter and covered in 1/8” net mesh to aide in capturing fish, particularly YOY. For sample sites that require more than one day of sampling, processed fish from the first sample day will be held in a 1/8” mesh live well until sampling is complete in that section, at which time they will be processed and released back into the river. Consistent with previous EEM studies, a Hess sampler with a 500 µm mesh and an area of 0.086 m2 will be used to sample benthic invertebrates. The sampler will be inserted into the substrate and the substrate will be hand scrubbed for 5 minutes, consistent with previous EEM studies at this facility. Research will be conducted by two trained biologist with extensive experience in EEM activities. A report summarizing the results and analysis of the data collected will be prepared as required by the Metal Mining Effluent Regulations. The report will be submitted to the North American Tungsten Corporation Ltd. and to the appropriate government agencies. The fieldwork for this study will be conducted from August 15, 2017 to September 25, 2017.