NWT RESEARCH DATABASE

Regions: North Slave Region, South Slave Region

Tags: aquatic ecosystems, biology, mining impacts, fish, habitat, fisheries

Objective(s): The major objectives of this study are to: a) to provide annual documentation of shoal habitat use by Lake Trout in the vicinity of the mine site (FA Clause 8.1.3); b) to ground truth hydroacustic equipment by capturing fish to identify species, collect life history data, tag, and then release.

Project Description: Consistent with the DFO authorization, the major objectives of this study are to: 1) to provide annual documentation of shoal habitat use by Lake Trout in the vicinity of the mine site. FA Clause 8.1.3 2) to ground truth hydroacustic equipment by capturing fish to identify species, collect life history data, tag, and then release As stated in the Authorization for Works or Undertakings Affecting Fish and Fish Habitat (DFO File No. SC98001), Diavik Diamond Mines Inc. (DDMI) was authorized to conduct a Fish Habitat Utilization Study prior to in-lake dike construction, including the requirement to develop and conduct an annual monitoring program for habitat use in and around the mine. Specifically, Subsections 8.1.1 to 8.1.3 of the Fisheries Authorization state: 8.1.1 Two years prior to in-lake dike construction activities, approximately 25 fish are to be tagged, approximately half from an area near the dike and the others from high quality habitat in another part of Lac de Gras. The tagged fish shall be monitored to determine the linkage between these fish and habitat usage (including spawning, feeding, over-wintering habitat). 8.1.2 Link information obtained in the radio-tagging component of the study to existing habitat mapping work that has been conducted for Lac de Gras. 8.1.3 Monitor the fish habitat use in the vicinity of the mine (including shoals) on an annual basis, to determine if use of these habitats has been altered, as indicated in the Project Plan. 1. Study locations for 2007 to be as per 2006 and will continue to include areas along the A154 dike. 2. The monitoring locations are in the vicinity of both the A154 and A418 mine areas. 3. Hydroacoustic surveys are to be conducted during the early morning or evening hours. The objective is to conduct the survey at roughly the same time each year (first week of September). Actual timing can be adjusted depending upon spawning condition. 4. In 2007, the attempt to standardize a fish collection protocol at each shoal to “ground truth” hydroacoustic surveys will be continued as per the 2006 program. Intent is to determine an appropriate fixed interval for angling that would yield about 6 fish per shoal. This angling effort would then be spent half before and half after the acoustic survey. Each lake trout caught would be processed immediately for length, weight, species, and maturity, tagged and released. The location of the catch will be recorded with GPS. 5. There will continue to be a greater effort on fish capture and tagging to provide additional habitat use information (FA Clause 8.1.1). The target will be to tag 24 lake trout per year with a maximum effort of about 3 days (4 hours morning and 4 hours evening). Fish would be processed as in 4 above. 6. Monitoring around A21 will be deferred pending a review of the results of the A418 and A154 area monitoring. Final report will be sent out to Communities and Government for review and comment. Fieldwork will be conducted from September 17 to October 15, 2007 on Lac de Gras, NT.