Comparisons of isotopic niche between females and male alternative reproductive tactics of Chinook salmon (Oncorhynchus tshawytscha) from Lake Ontario
Bibliographic record
Abstract
Chinook salmon ( Oncorhynchus tshawytscha ) have complex life histories with two distinct male alternative reproductive tactics (ARTs). The larger and older “hooknose” males battle for position to spawn with nesting females whereas the precociously maturing “jack” males use a sneaking tactic to gain access to females. Although dietary niche is known to differ between ARTs of other fish taxa, no research to date has examined these differences in a salmonid. Here, we used δ 15 N and δ 13 C stable isotope analyses to compare the dietary niches of female, hooknose male, and jack male Chinook salmon sampled from a Lake Ontario tributary. We found that all three life histories shared similar δ 15 N values, whereas jack males had greater δ 13 C values compared to hooknose males, with females having intermediate values. Jack males also had notably little overlap in their isotopic niche space with hooknose males and females, indicating that jack males occupy a distinct isotopic niche in Lake Ontario. We discuss habitat partitioning and differences in dietary niche as explanatory factors. Altogether, these data unveil novel distinctions in isotopic niche within the complex life history strategies of Chinook salmon in Lake Ontario that can inform management decisions and provide avenues for future research.
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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 | 0.001 |
| 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".