Availability of holding habitat in lakes and rivers affects the incidence of spring (premature) upriver migration by Atlantic salmon
Bibliographic record
Abstract
Premature migration is a key component of the biocomplexity of anadromous fishes, yet remains poorly understood. Many Atlantic salmon (Salmo salar) populations leave the ocean in spring, months prior to spawning, though this curtails feeding in productive marine environments. We hypothesized that habitat features encourage the evolution of this trait by providing fish with physical and thermal refuge during their long freshwater holding period. We document substantial variation in Atlantic salmon return-migration timing across 70 Irish rivers using 8 years of angling data, validated with electronic-counter data from 23 of the rivers. A higher frequency of spring migrating salmon was observed in rivers with accessible lakes and larger rivers in general. Spring migration may have evolved in rivers with suitable holding habitat as a strategy to minimize cumulative marine mortality, which is traded off against additional marine feeding. More research on this neglected topic is needed, given the value of large spring migrating Atlantic salmon to anglers, ongoing declines in their abundance in Ireland and elsewhere, and the widespread occurrence of premature migration in salmonids generally.
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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 | 0.001 |
| 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) | 0.002 | 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".