Prioritizing contaminants of concern in the Fraser River watershed: a risk-based evaluation for outmigrating juveniles and returning adult salmon
Bibliographic record
Abstract
The Fraser River watershed is home to 54 unique spawning populations of salmon, including 19 Chinook (Oncorhynchus tshawytscha) populations. Fraser Chinook provide 80-90% of the food source consumed by Southern Resident killer whales (SRKW, Orcinus orca) in the spring and summer. Over 90% (15/16) Fraser Chinook populations are at risk. Extensive forestry, agricultural, industrial and urban activities take place in the Fraser Valley that expose early life stages of emigrating salmon and returning adult salmon to a mix of legacy and emerging contaminants. Many of which, can elicit adverse health effects in vertebrates, including endocrine disruption and reproductive effects. However, there is limited information on the nature of contaminants discharged into British Columbia’s salmon habitat and their associated effects, hampering solution-oriented opportunities for natural resource managers and stakeholders. Surface water samples were collected monthly (2018-2020) from seven urban and semi urban sites in the Fraser River watershed, and one site in the Serpentine River, a lower discharge river that flows directly into SRKW critical habitat. Samples were analyzed for over 800 contaminants in order to prioritize contaminants of concern to outmigrating juveniles and retuning adult salmon, with a special focus on Chinook salmon. Measured chemical concentrations were compared to water quality guidelines for the protection of aquatic life and chemical-specific biological activities determined in high-throughput (ToxCast) in vitro assays. A risk-based evaluation using a combination of toxicity quotients and exposure activity ratios was performed to prioritize contaminants for long-term monitoring and to identify chemicals suspected of posing a potential risk to salmon. This study is the first step toward a comprehensive risk-based evaluation for contaminants of concern to salmon in the Fraser River. Results will support the Government of Canada’s Whales Initiative in its quest to identify contaminants of greatest concern to Chinook salmon and to guide SRKW recovery efforts.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.002 | 0.003 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.001 |
| Bibliometrics | 0.002 | 0.001 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".