Evidence of post-larval growth-selective mortality in Atlantic mackerel revealed by the collection of young-of-the-year juveniles ingested by the northern gannet
Bibliographic record
Abstract
The growth-survival paradigm predicts that year-class strength is determined by growth-dependent mortality during the larval stage. In Atlantic mackerel Scomber scombrus, the possibility that strong growth-dependent mortality extends into the early juvenile stage has not previously been tested because of the difficulty in sampling young-of-the-year (YOY) juveniles. The present study determined the timing of the ‘endpoint’ during the early ontogeny, when growth-selective mortality decreases and recruitment is set. We relied on regurgitations from one of the main predators of mackerel, the northern gannet Morus bassanus, as a source of YOY juveniles. Early growth trajectories of YOY mackerel were reconstructed from the otolith microstructure and were compared to those of 1-yr-old (OYO) juveniles from the same cohort for the year classes of 2015 and 2017. In both cohorts, the early growth trajectory of OYO fish was faster than that of YOY juveniles, indicating that growth-selective mortality extended beyond the larval stage. For the 2017 cohort, the comparison of larval growth trajectories between 2-mo-old YOY, 3mo-old YOY and OYO juveniles indicated that strong selection for fast growth persisted until the pre-wintering period, but that winter mortality likely did not play an important role in shaping year-class strength. These findings suggest that in Atlantic mackerel, the endpoint when the relative strength of cohorts is fixed occurs at the age of 3 mo. These results highlight the importance of considering growth-dependent mortality processes occurring beyond the larval stage to obtain a better understanding of causes of recruitment variability.
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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 | 0.000 | 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".