Base de données de recherche des TNO

Régions: Inuvialuit Settlement Region, Gwich'in Settlement Area

étiquettes: water quality, biology, fish habitat, fish, community based monitoring, whitefish

Objectif(s): To maintain a community-based monitoring program in the Peel River watershed, based in the communities of Fort McPherson, Aklavik, and Tsiigehtchic.

Description du projet: The objective of this project is to maintain a community-based monitoring program in the communities of Fort McPherson, Aklavik, and Tsiigehtchic. Data collected in this community-based monitoring program and other previous research has shown that ocean-migrating broad whitefish use the Peel River as spawning habitat, and that these fish also make extensive migrations between rivers in the lower Mackenzie Delta. As harvester catches are comprised of fish with very different migration patterns and which occupy different sets of habitats, it is likely that the fish will be differently exposed to and impacted by cumulative environmental impacts. Because of this vulnerability and the importance of this species for communities in the region, this project looks to detect any changes to whitefish distribution and population health that may emerge over time. Additionally, this work helps to assess the vulnerability of fish with different migratory strategies. Using data collected across multiple years, the team will identify the population values for fish size-at-age, body condition, and catch-per-unit-effort, and will describe how these values vary through time. The research team have identified that Mackenzie watershed whitefish exhibit varied migrations and rely upon multiple rivers. However, the current ability to identify high-resolution spatial movements is hindered by a lack of spatially-comprehensive elemental "fingerprints" across the watershed, which have been used to match the Sr (strontium) signatures in the fish to their habitats. In some fish, the team have identified "fingerprints" in the otolith that do not match the six locations where the team currently have water Sr signatures. The research team seek to remedy this by collecting additional water samples at primary tributaries and in the Delta, and developing a model that will integrate values between sample locations to create a high-resolution map of Sr signatures (an “isoscape”). This will provide a tool to match fish to specific locations in the watershed, on a scale relevant to local disturbances and subsistence fishing access. Because this isoscape can be applied to analysis of fish otolith from any species, this model will further illuminate which areas of that Mackenzie River watershed are important to organisms and the access to subsistence resources. The research team collaborate with harvesters who assist to sample harvested whitefish. Broad whitefish have been observed in spawning migrations from July-October, with a return migration in October-November after the ice freezes. The sampling takes place during harvest season, beginning in July and continuing through October (or when ice forms). Some under-ice harvest may also take place, if harvesters are able. Harvesters sample 5-10 fish per day, for two consecutive days every other week, and capture fish with 5-inch mesh gillnets to target migrating broad whitefish. Once fish are captured, monitors sample for a suite of biological data: 1) length, 2) weight, 3) photograph, 4) spawning condition, 5) otolith extraction, 6) fin clip, 7) enumerate and identify all fish captured in the set, and 8) collect other tissue samples for contaminant analysis (once per week). On each data collection day, harvesters also note qualitative observations about water conditions (level of sedimentation, amount of debris, and water level). The research team calculate annual and cumulative population means and inter-annual variability in whitefish attributes including body condition, size-at-age, catch per unit effort and migratory patterns. Otoliths are aged and, where relevant, processed using a standard procedure for otolith microchemistry. The research team intend to process fin clip samples to identify fish nitrogen and carbon isotopic ratios. This identifies fish trophic level and diet, and the habitats in which they feed. Samples will be processed for 10 individuals sampled in early August and 10 sampled in late September at each sample location in 2018 (~80 samples total), the same fish for which otoliths are to be analyzed in 2018. To develop a high-resolution strontium map, the research team will sample up to 42 additional locations in the lower Mackenzie watershed in 2019, to supplement the six locations where the team currently have Sr signatures. Sample locations are proposed based on geological variability (the source of Sr variability in water) and locations of significant tributaries. Sample collection will consist of a grab-sample in acid-washed plastic bottles; these samples are then filtered and acidified to remove microbial activity and stabilize the sample before analysis. Four sites will be collected in triplicate to measure sample error. Results from this project will be communicated to communities and government organizations through presentations to local audiences annually and through a database of raw data that will be developed 2 years after collection that will be shared with all organizations.