NWT RESEARCH DATABASE

Tags: aquatic ecosystems, limnology, fish, sediment, environmental baseline, fisheries assessment

Objective(s): To collect baseline data on water chemistry, limnologic profiles, sediments, plankton, benthic invertebrates and aquatic habitat; and, fish presence and collection of fish tissue for metal analysis.

Project Description: The primary objective of this research program is to collect baseline data on: 1) water chemistry, limnologic profiles, sediments, plankton, benthic invertebrates and aquatic habitat; and, 2) fish presence and collection of fish tissue for metal analysis. Aquatics: The Aquatics field program will be conducted in the spring of 2013. During the field program, the following samples will be collected: water chemistry, sediment chemistry, phytoplankton (taxonomy, biomass), zooplankton (taxonomy, metals analysis), and benthic invertebrates (taxonomy, biomass, metals analysis). Limnologic/water chemistry profiles will be collected at each station (every 1 m) with a YSI multimeter; parameters include temperature, pH, conductivity, and dissolved oxygen. Water chemistry samples will be collected at surface and bottom at all sample sites with a Van Dorn sampler; the Van Dorn sampler will also be used to collect phytoplankton samples at 1 m depth. A plankton net will be used to collect zooplankton samples (one vertical 5 m tow) at each site while a Petite Ponar will be used to collect sediment and benthic invertebrates. An underwater camera will also be used to conduct an aquatic habitat assessment in the area of the proposed diffuser and effluent pipeline options. Fisheries: The Fisheries field program will take place in May/June or August/September 2013. Five areas will be investigated, as outlined previously. Preliminary target species include Northern Pike (Esox lucius; predatory fish), Lake Whitefish (Coregonus clupeaformis; forage fish), and Lake Chub (Couesius plumbeus; small-bodied fish). A total of 20 adult specimens of each species will be collected and sacrificed for tissue sampling from each of four areas: Back Bay, near the proposed effluent diffuser, Baker Creek Outlet, Mosher Island - Greater Yellowknife Bay, and Horseshoe Island Bay. The Yellowknife Bay Foreshore Tailings area will be investigated for fish presence only; no tissue sampling will occur. Fish will be captured with multi-panel gillnets and long lines. A single-panel small mesh gillnet will also be used to target the small-bodied species. Alternate capture methods (backpack electrofishing, trap nets, cod traps) will be used if necessary to obtain the required number of fish. All captured fish will be identified to species, enumerated, weighed and measured, and examined for any abnormalities. Fish will be released alive if captured in good condition, unless they are selected for tissue sampling. Fish will be euthanized, if necessary, for tissue sampling. Each sacrificed fish will be further processed in the field laboratory. Fish will be weighed and measured again and the following tissues sampled: ageing structures, left and right dorsal fillets, two lateral halves of the liver, and the viscera. Field personnel will also examine the stomach contents and look for a determination of gender and maturity. Weights of the liver, gonads and final carcass will also be recorded. All tissue samples and ageing structures collected will be appropriately stored (i.e., frozen) in anticipation of laboratory analysis. Data and analysis on surface water quality and fisheries work in and around Yellowknife Bay, will be available to local residents, organizations and the community for review through the current Environmental Assessment of the Giant Mine Remediation Project. The information will provide residents, organizations and the community with a scientific overview of the local surface water quality and fisheries, which can be used for various purposes (e.g., land use planning, economic development). Results of the baseline study will be communicated to local residents and nearby communities through the Environmental Assessment of the Giant Mine Remediation Project. The fieldwork for this study will be conducted from May 15, 2013 to September 30, 2013.