Density-dependent overwinter survival in young-of-year bluefish (<i>Pomatomus saltatrix</i>)? A new approach for assessing stage-structured survival
Bibliographic record
Abstract
Identifying the life history stages where density-dependent mortality occurs is essential for understanding fish population dynamics. Here we present an approach to evaluate density-dependent survivorship using catch-at-length data on bluefish (Pomatomus saltatrix) from fishery-independent data in the northwest Atlantic, focusing on the stage transition from age-0 to age-1. Abundance indices for each stage were generated by partitioning annual length frequency distributions into catch estimates for individual stages and by using a generalized additive model to standardize survey effort across years. We tested for the existence of density dependence by fitting the data to alternative stage-transition models and using model selection procedures to identify the best-fitting model. We found that that the transition from fall age-0 to age-1 is density dependent and that that significant dampening occurred throughout much of the time series we examined. Estimates of process error were small, suggesting relatively modest variance around the stage-transition model and little interannual variation in survivorship other than that generated by density-dependent effects. Further, we found our conclusions are robust to any potential bias imposed by observation error. We conclude that an improved understanding of bluefish population dynamics might follow from a fuller exploration of the processes dictating overwinter survivorship.
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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 | 0.001 | 0.003 |
| 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 | 0.001 |
| 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".