Return migration to fresh water and overwintering locations used by sympatric anadromous populations of <scp>Arctic</scp> char ( <i>Salvelinus alpinus</i> ) and <scp>Dolly Varden</scp> ( <i>Salvelinus malma malma</i> )
Bibliographic record
Abstract
Anadromous Arctic char (Salvelinus alpinus) and northern form Dolly Varden (Salvelinus malma malma) are highly valued by Indigenous communities in northern Canada. Rapid, ongoing environmental changes are affecting populations of both of these iteroparous species, and understanding variability in life-history tactics is essential for assessment of current and future impacts. The Coppermine River, Nunavut, provides a unique opportunity to study anadromous life-history types of Dolly Varden and Arctic char that occur in sympatry in fresh water and have documented inter- and intra-specific variability in overwintering locations. We used acoustic telemetry and physical samples from community collection programs to infer that Arctic char overwintered in easily accessible habitats in the lower reaches of the Coppermine River, likely in non-spawning years, and that spawning likely occurs in rivers other than the Coppermine. Younger and smaller Dolly Varden overwintered in the river below a substantial obstacle (a large cascade), along with some larger adults that we suggest skipped spawning. Larger Dolly Varden, including potential spawners, migrated above the cascade and overwintered in the upper reaches of the Coppermine River. Arctic char exhibited distinct patterns of return migration to fresh water that were consistent with intent to overwinter below the cascade. Dolly Varden that overwintered above the cascade exhibited distinct patterns of return migration that were consistent with directed movements. Patterns of return migration to fresh water for Dolly Varden that overwintered below the cascade suggested some individuals intended to overwinter below the cascade, whereas others may have attempted to overwinter in the upper reaches of the river but failed to ascend the cascade. The patterns and variability we observed in overwintering location and return migration to fresh water have important implications for community-based management of the local fishery, provide insights into the ecology and adaptability of Arctic char and Dolly Varden, and highlight a need for additional information regarding spawning locations and spawning frequency in this system.
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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 | 0.001 | 0.000 |
| Science and technology studies | 0.001 | 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".