Change in habitat associations and geographic distribution of thorny skate (<i>Amblyraja radiata</i>) in the southern Gulf of St Lawrence: density‐dependent habitat selection or response to environmental change?
Bibliographic record
Abstract
Abstract We describe changes in the habitat associations and geographic distribution of thorny skate during their feeding season in the southern Gulf of St Lawrence, based on 32 yr of monitoring by a bottom‐trawl survey. In the 1990s, geographic range contracted sharply and distribution shifted into a narrow band of warm deep waters. These changes appeared to reflect altered habitat selection by individual skates, rather than local depletion of the skates that had habitually occupied the vacated areas or a change in the timing of seasonal migrations. Changes in skate distribution coincided with a decline in skate biomass and a cooling of bottom waters. The contraction in the geographic range of skates appeared to be a density‐dependent response, more closely linked to the decline in skate abundance than to the change in environmental conditions. The cause of the shift in habitat associations is less certain. An index of the distribution shift was more strongly correlated with skate biomass than with an index of temperature conditions, and the change in temperature associations is in the direction predicted by density‐dependent bioenergetic considerations. However, the shift into deeper waters is into a depth zone where skate condition is relatively low, contrary to the expectation that fish should be concentrated in optimal habitat at low population size. On the other hand, while the shift into warm deep waters coincided with a cooling of waters at intermediate depths, distribution failed to shift back to the earlier pattern as these waters warmed in the late 1990s.
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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 | 0.001 | 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".