Influence of Predation Risk on the Overwinter Mortality and Energetic Relationships of Young-of-Year Walleyes
Bibliographic record
Abstract
We investigated three potential mechanisms—size-dependent overwinter energy loss, size-specific predation, and size-dependent predator-induced metabolic costs—to determine the role of body size and predators on the overwinter survival and energy reserves of young-of-the-year walleyes Stizostedion vitreum. Walleyes were reared in outdoor hatchery ponds in Westport, Ontario, for three overwinter periods (1997-1998, 1998-1999, 1999-2000) in the presence or absence of predators (burbot Lota lota or adult walleyes). Other young-of-the-year fishes were provided as potential prey items. We predicted that (1) smaller individuals of a young-of-the-year walleye cohort would have lower prewinter energy stocks and would deplete them at a higher rate; (2) no size-dependent overwinter survival would occur in walleyes reared without predators; and (3) physiological stress, in combination with size-selective predation on smaller individuals, would lead to size-dependent overwinter mortality in young of the year reared with predators. Prediction 1 was not supported by lipid, protein, or specific-energy content data; indeed, smaller walleyes actually gained energy over the winter, whereas larger walleyes lost energy. Prediction 2 was supported but prediction 3 was not, as no significant survival differences were observed between four size-class quartiles in any pond or year. However, young-of-the-year walleyes reared over winter in the presence of predators lost significantly more weight and energy and had significantly lower lipid concentrations at the end of winter than did those reared in the absence of predators. Although no differences in overwinter survivorship were detected between young-of-the-year walleyes reared in predator and predator-free ponds, the presence of significant predator-induced energetic costs in the absence of size-selective mortality suggests that the size-selective mortality observed in some natural walleye populations is the direct effect of the presence of predators.
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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) | 0.001 | 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".