RANGE CONTRACTION MAY NOT ALWAYS PREDICT CORE AREAS: AN EXAMPLE FROM MARINE FISH
Bibliographic record
Abstract
Our goal was to identify the core areas of six severely depleted marine fish species on the Scotian Shelf, Canada, using the theory of ideal free distribution (IFD). We tested for density‐dependent distribution on both regional and local scales. At the regional scale, a density‐dependent response was observed in the majority of populations. At the local scale, density was expected to remain stable in areas of high density and to change more rapidly in marginal areas, in response to changes in regional abundance. Lower local density responses were associated with areas of higher density, but deviations were evident, in part due to the magnitude of decline and in part due to fishing effects. Former areas of high density can be eroded if the population has severely declined. Fishing directed at an area of high density can cause local depletion when recolonization rates are low relative to the intensity of fishing. Thus, areas occupied during periods of low regional abundance do not of necessity reflect the historical array of core areas. We do not recommend the use of IFD theory to identify core areas of heavily exploited species. Instead, we recommend a precautionary approach that assumes the existence of low‐mixing populations that can be differentially affected by fishing. For species at risk, only data derived before significant population declines should be used to identify high‐density areas. Such areas would represent those with the potential to support higher densities as well as the historical array of subpopulations. Our study provides insight into the practical aspects of analyzing exploited species using ecological theory.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| 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) | 0.108 | 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; both teacher heads agree on what is shown here.
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".