A century-long time series reveals large declines and greater synchrony in Nass River sockeye salmon size-at-age
Bibliographic record
Abstract
The ability to comprehend the nature of changes in body size is often limited by time series of relatively short duration. Using archival records of 118 573 individual measurements, we developed a 106-year time series of mean size-at-age, by sex, of Nass River sockeye salmon ( Oncorhynchus nerka). Size-at-age declined during the last century in several distinct stanzas. Until the 1930s, there was weak covariation in size-at-age among age classes of both sexes. Thereafter, all time series exhibited a coherent cyclical pattern, superimposed on an underlying decline, reaching smallest average size-at-age in 2019. Age classes sharing the same years of ocean growth had more similar patterns of variation than those sharing a common brood year, suggesting a dominant role of marine life history. Since 1914, mean size-at-age declined from 5% up to 13% depending on age class and sex, resulting in an estimated 7%–19% decline in fecundity, which is likely to reduce the productivity of these populations. In the absence of increased survival, management targets based on fixed adult escapements may result in overexploitation.
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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 | 0.001 |
| 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 | 0.000 |
| 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".