Relative contribution of spring- and summer-spawned bluefish cohorts to the adult population: effects of size-selective winter mortality, overwinter growth, and sampling bias
Bibliographic record
Abstract
Length distributions of juvenile bluefish (Pomatomus saltatrix) are bimodal, consisting of spring- and summer-spawned fish. Research during the 1990s from the northeastern United States suggested that the summer cohort contributes little to the adult population and that overwinter mortality may limit their survival. We examined length distributions of juvenile bluefish from before and after winter and found that the mean length of the summer cohort increased during winter. Based on a winter-growth experiment and temperatures from the two winters examined, changes in mean length were due to size-selective mortality for one year class and growth for the other. Despite evidence for winter mortality, summer-spawned bluefish were commonly caught at age 1. We reexamined the relative contribution of each cohort to the adult population using archived scales from North Carolina fisheries. Cohort origin of adults was determined by back-calculating length at age 1. One-third of adults consisted of summer-spawned fish, contrasting with previous research from the northeast. The differences in relative cohort abundance between the northeastern and southeastern United States arise from sized-based migration in age-1 and age-2 bluefish (the dominant age groups sampled in these studies) and the size-selective gear and sampling season in which they were collected.
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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 | 0.004 | 0.008 |
| 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 | 0.001 | 0.001 |
| Open science | 0.001 | 0.001 |
| 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".