Fixed mesh shape reduces variability in codend size selection
Bibliographic record
Abstract
Diamond-mesh codends are the most commonly used in demersal trawls. However, mesh geometry tends to vary in these codends during fishing, which leads to a less well-defined size selection process. This leaves one questioning the rationality of regulating exploitation patterns based on mesh size when size selection and (or) variation between hauls is highly variable. While it has been speculated and theoretically investigated how much the variability in mesh geometry may contribute to the variability in size selection, it remained to be quantified experimentally. Therefore, we conducted field test comparing the size selectivity of a simple diamond-mesh codend, where meshes are subjected to variation in geometry, with a rigid diamond-mesh codend, where the geometry of the meshes were kept constant. For Atlantic cod ( Gadus morhua), the simple diamond-mesh codend was found to have 45% more variation in size selection than the codend with fixed mesh geometry. This confirms theoretical predictions and may guide research toward codend designs with more well-defined size selection properties.
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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 | 0.009 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 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".