Running on empty: capelin diet after stock collapse
Bibliographic record
Abstract
Abstract The Newfoundland capelin stock in Northwest Atlantic Fisheries Organization Divisions 2J3KL collapsed in 1991 with only a modest recovery over 30+ years. Resource limitation is hypothesized to be a driver of this slow stock recovery. Using detailed seasonal diet data (1999–2022), capelin diet was dominated by calanoid copepods in both spring and autumn, with hyperiid amphipods, euphausiids, and appendicularians increasing in importance with ontogeny. Euphausiids continue to be less important in the diet now compared to the 1970s and 1980s. Capelin spring diet changed around 2011 which corresponded with an increase in appendicularians in the diet, a lower quality prey taxa. Compared to other stocks worldwide, Newfoundland capelin have amongst the lowest ratios of stomach content weight to whole body weight suggesting they are experiencing resource limitations. Using a seasonal (spring and autumn) interval scale (0–4) of stomach fullness, we developed a stomach fullness index ( $$ISFI$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:mi>ISFI</mml:mi> </mml:mrow> </mml:math> ) that covered 42 years (1980–2022) of capelin sampling. Five changepoints were detected during the “boom and bust” periods in the 1980s and early 1990s, with higher mean seasonal $$ISFI$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:mi>ISFI</mml:mi> </mml:mrow> </mml:math> s during boom periods compared to the early 1990s bust period. Average $$ISFI$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:mi>ISFI</mml:mi> </mml:mrow> </mml:math> from 1995 to 2022 is lower than the $$ISFI$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:mi>ISFI</mml:mi> </mml:mrow> </mml:math> from the stock high of the late 1980s and has varied without trend since 1995. Our results provide support for the hypothesis that resource limitation, which could be due to prey availability and/or intra-specific competition, is impacting the recovery potential of Newfoundland capelin, supporting the hypothesis that this stock is bottom-up regulated.
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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 | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.006 | 0.001 |
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".