Legacy and current-use contaminants in Pacific Chinook salmon (<i>Oncorhynchus tshawytscha</i>) stocks and their contribution to Resident killer whale (<i>Orcinus orca</i>) contaminant burdens
Bibliographic record
Abstract
The Endangered Southern Resident killer whales (SRKW, Orcinus orca) face significant threats, including reduced abundance and quality of their primary prey (Chinook salmon, Oncorhynchus tshawytscha) and high levels of endocrine disrupting contaminants while experiencing a decrease in population growth over the past several decades. The sympatric Northern Resident killer whales (NRKW) also primarily consume Chinook but have lower contaminant burdens and have experienced consistent population growth for nearly five decades. This study characterized concentrations of 19 legacy and current-use contaminants in priority Chinook stocks/groups consumed by SRKWs and NRKWs, calculated Chinook contaminant body burden, estimated daily contaminant intake (EDI) from Chinook salmon in SRKW diet across seasons, and compared Chinook salmon-related EDI between SRKW and NRKW during the months of May-October. Shelf Resident Chinook had higher mean muscle ∑contaminant19 concentrations and mean ∑contaminant19 body burdens than Columbia (4.9- and 2.6-fold, respectively) and Far North/Offshore Chinook (5.7- and 2.1-fold, respectively). This resulted in a disproportionately higher contaminant intake by SRKW from Shelf Resident Chinook throughout the year relative to Far North/Offshore Chinook. From May-October, an average SRKW consumed approximately 15% more Shelf Resident Chinook a day than an average NRKW, resulting in a 5.3-fold higher EDI from Shelf Resident Chinook and an overall 1.6-fold higher EDI (1410 μg ∑contaminants19/day) from all three Chinook groups compared with NRKW EDI (869 μg ∑contaminants19/day). Results provide an updated characterization of contaminant exposure for SRKWs and NRKWs, insights into the current levels of priority contaminants in Chinook salmon, and an explanation as to why SRKW have higher contaminant loads than NRKW. Recovering at-risk wild Chinook salmon populations that have a more offshore rearing distribution and lower contaminant body burdens (i.e., Columbia and Far North/Offshore Chinook stocks) should be a top priority to ensure the recovery of SRKW.
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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 | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 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".