Evaluation of Lethal Fish Sampling and the Nonlethal Alternative Under the Canadian Metal and Diamond Mining Environmental Effects Monitoring Program.

The Environmental Effects Monitoring (EEM) program, federally mandated to metal and diamond mines and mills in Canada, aims to ensure that fish, fish use, and their environment are sufficiently protected by the Metal and Diamond Mining Effluent Regulations (MDMER). Concerns have been raised regarding lethal fish sampling conducted for the program and the potential risk to fish populations. This study endeavored to calculate the extent of fish sacrificed during lethal EEM fish surveys to provide a more informed characterization for stakeholders. By extrapolating data from 28 studies conducted at 8 metal mines in Saskatchewan between 2004 and 2017, it was conservatively estimated that 60 060 ± 19 978 fish have been sacrificed for the program nationwide since its promulgation in 2002. This is almost 2 times greater than guidance recommendations due to numerous factors. Challenges faced when implementing the nonlethal fish population survey alternative were also evaluated, and some of these included data interpretation inconsistencies due to the lack of critical effect sizes (CES) included in the regulations for nonlethal effect endpoints, and reliance on capturing young of the year fish to assess the prescribed effect endpoints. Finally, a case study conducted to evaluate the congruity of lethal and nonlethal fish population survey results identified that the effect endpoints often produced conflicting conclusions for the same response variable. Ultimately, this study highlights that in order to strengthen and promote the use of nonlethal fish sampling as an alternate to the current standard of conducting lethal fish population surveys under the EEM program, the effect endpoints, study designs, and adoption of CES need to be thoroughly evaluated and included in the MDMER. If nonlethal sampling designs adequately provide the required data and meet program objectives, then there would be no need to continue sacrificing fish for the Canadian metal and diamond mining EEM program. Integr Environ Assess Manag 2019;00:1-10. © 2019 SETAC.

Can natural variability trigger effects on fish and fish habitat as defined in environment Canada's metal mining environmental effects monitoring program?

The Metal Mining Effluent Regulations (MMER) took effect in 2002 and require most metal mining operations in Canada to complete environmental effects monitoring (EEM) programs. An "effect" under the MMER EEM program is considered any positive or negative statistically significant difference in fish population, fish usability, or benthic invertebrate community EEM-defined endpoints. Two consecutive studies with the same statistically significant differences trigger more intensive monitoring, including the characterization of extent and magnitude and investigation of cause. Standard EEM study designs do not require multiple reference areas or preexposure sampling, thus results and conclusions about mine effects are highly contingent on the selection of a near perfect reference area and are at risk of falsely labeling natural variation as mine related "effects." A case study was completed to characterize the natural variability in EEM-defined endpoints during preexposure or baseline conditions. This involved completing a typical EEM study in future reference and exposure lakes surrounding a proposed uranium (U) mine in northern Saskatchewan, Canada. Moon Lake was sampled as the future exposure area as it is currently proposed to receive effluent from the U mine. Two reference areas were used: Slush Lake for both the fish population and benthic invertebrate community surveys and Lake C as a second reference area for the benthic invertebrate community survey. Moon Lake, Slush Lake, and Lake C are located in the same drainage basin in close proximity to one another. All 3 lakes contained similar water quality, fish communities, aquatic habitat, and a sediment composition largely comprised of fine-textured particles. The fish population survey consisted of a nonlethal northern pike (Esox lucius) and a lethal yellow perch (Perca flavescens) survey. A comparison of the 5 benthic invertebrate community effect endpoints, 4 nonlethal northern pike population effect endpoints, and 10 lethal yellow perch effect endpoints resulted in the observation of several statistically significant differences at the future exposure area relative to the reference area and/or areas. When the data from 2 reference areas assessed for the benthic invertebrate community survey were pooled, no significant differences in effect endpoints were observed. These results demonstrate weaknesses in the definition of an "effect" used by the MMER EEM program and in the use of a single reference area. Determination of the ecological significance of statistical differences identified as part of EEM programs conducted during the operational period should consider preexisting (background) natural variability between reference and exposure areas.