Population age structures confirm occurrence of the unconfined-resident, life-history form in a bull trout metapopulation
Bibliographic record
Abstract
Juvenile bull trout ( Salvelinus confluentus Suckley, 1859) of migratory populations most often remain in natal creeks 2–3 years before moving downstream. Because migratory adult bull trout then begin to return to spawn as age-5 fish, abundant age-4 fish in the natal creek would indicate the nonmigratory life-history form. Population-specific, age-length keys, age-specific length frequencies, and Monte Carlo simulation were used to assign ages 0–5 to bull trout ( n = 14 553) electrofished annually (1998–2023) from eight proximate populations in the St. Mary River catchment, north-central Montana, USA. Resident (that is, nonmigratory) bull trout, characterized as fish < 330 mm total length that had coloration and external morphology indicative of mature fish, were obvious in four populations and regularly captured from distinctive, high-gradient reaches that included large boulders and deep plunge pools. These resident bull trout were not of the common isolated life-history form, which occur upstream from a physical barrier to upstream movement, but were consistent with the unconfined resident form. Age structures showed age-4 residents were abundant in three of the populations; the fourth population had inadequate age-length data. Size-based, assortative mating may preclude resident interbreeding with the larger migratory bull trout and thus foster sympatric speciation.
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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 | 0.001 | 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".