Do harbour seals in fact target juvenile salmon of conservation concern? Biased diet sampling has provided an illusory perspective of seal impacts
Bibliographic record
Abstract
Harbour seals forage throughout coastal waters and typically exhibit restricted foraging ranges. A small fraction of the population resides in estuaries of salmon-bearing rivers. Seals are known to consume salmon, but are also thought to target salmon species of conservation concern and deemed responsible for stock declines. DNA metabarcoding and hard part analysis were used to estimate diet from scat collections ( n = 2705) undertaken at multiple haul out sites in the Strait of Georgia between 2015 and 2019, including both estuary and nonestuary sites. Proportions varied by salmon species with a range of 0.5%–5.1% and were on average 4.5 times higher in estuary sites. These results are contrasted with previous collections made between 2012 and 2014 ( n = 1435), which predominantly focused on estuary sites for which mean salmon proportions were 2–7 times higher. These contrasting results underscore the variation in seal diets between sampling locales and years, and the subsequent propagation of bias to estimates of total consumption of salmon when extrapolating spatially and temporally restricted mean diet estimates to the seal population as a whole.
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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 | 0.001 | 0.003 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| 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".