Long-term monitoring of trace metals and persistent organic pollutants in lake trout from Kusawa Lake and Lake Laberge, Yukon

This project has been monitoring contaminants in lake trout from Lake Laberge and Kusawa Lake in the Yukon, since 1993, and annually since 2001. In the fall of 2018 and early winter of 2019, 15 lake trout were collected from Kusawa Lake and 21 from Lake Laberge. Otoliths were aged and liver and muscle samples from these fish are currently being analyzed for a suite of elements, new contaminants (fluorinated and brominated compounds) and older organochlorine pesticides. Previous data from this project are being gathered and curated prior to being analyzed and reported. Mercury levels in muscle from lake trout from Lake Laberge and Kusawa Lake averaged 0.25 and 0.24 g·g-1 respectively, about half the recommended guideline level of 0.50 g·g-1 for commercial sale. Mercury is declining over time in lake trout from both lakes although there is considerable annual variation. Arsenic concentrations in lake trout muscle decreased over time in Lake Laberge but not in Kusawa Lake, while selenium increased over time in Kusawa Lake but not in Lake Laberge. Both changes were small and likely of little biological significance. Outreach programs were conducted with the Yukon Fisheries Field Assistant Program and the Yukon Fisheries Management Program at Yukon College in Whitehorse, YT. The first group was able to use the recently acquired Direct Mercury Analyzer to measure mercury in their fish. Ta’an Kwach’an Council and Champagne and Aishihik First Nations are integrally involved in fish collections for this project and in the ongoing refinement of the communication of results. We have been developing our communication capacity, and are including Yukon Contaminants Committee, Yukon Environment (Fisheries) and Kwanlin Dun First Nation in discussions. As we move forward with this collaborative approach we anticipate many new opportunities for value-added consultation and communication activities.

本项目自1993年起便持续监测育空（Yukon）地区拉贝热湖（Lake Laberge）和库萨瓦湖（Kusawa Lake）中湖鳟的污染物水平，并自2001年起开展年度监测。2018年秋季与2019年初冬期间，研究团队从库萨瓦湖采集15尾湖鳟，从拉贝热湖采集21尾湖鳟。研究人员将借助耳石完成样本的年龄鉴定，并对其肝脏与肌肉组织开展多元素分析，同时检测新型氟代、溴代污染物以及经典有机氯农药。本项目的既往监测数据目前正在整理与质控，以待后续分析与报告发布。拉贝热湖与库萨瓦湖湖鳟肌肉中的汞平均含量分别为0.25与0.24 μg·g⁻¹，约为商业销售推荐限值0.50 μg·g⁻¹的一半。两座湖泊的湖鳟肌肉汞含量均随时间呈下降趋势，但年度波动幅度较大。拉贝热湖湖鳟肌肉中的砷浓度随时间呈下降趋势，库萨瓦湖则未出现该变化；而库萨瓦湖湖鳟肌肉中的硒浓度随时间有所上升，拉贝热湖无此现象。上述两种元素的变化幅度均较小，生物学意义有限。本项目与育空渔业野外助理项目、位于怀特霍斯（Whitehorse）的育空学院（YT）的育空渔业管理项目开展了科普推广活动，其中育空渔业野外助理项目团队已可使用新购置的直接测汞仪（Direct Mercury Analyzer）开展鱼类样本的汞含量检测。塔安克瓦昌理事会（Ta’an Kwach’an Council）与尚帕涅和艾希克第一民族（Champagne and Aishihik First Nations）深度参与了本项目的鱼类样本采集工作，并持续优化研究结果的传播方案。目前团队正持续提升成果传播能力，已邀请育空污染物委员会、育空环境部（渔业板块）以及克兰林邓第一民族（Kwanlin Dun First Nation）参与相关讨论。依托这一协作模式推进后续研究，我们预计将涌现诸多增值咨询与传播活动的新机遇。