Sex and size matter: foraging ecology of offshore harbour porpoises in waters around Greenland
Bibliographic record
Abstract
Abstract Individuals of different sex or age can vary in their resource use due to differences in behaviour, life history, energetic need, or size. Harbour porpoises are small cetaceans that rely on a constant prey supply to survive. Here, we use bone collagen carbon (δ 13 C) and nitrogen (δ 15 N) isotope compositions to elucidate sex and size differences in the foraging ecology of harbour porpoises from West Greenland. In this region, populations have a unique offshore, deep-water ecology. Female harbour porpoises are larger than males and we find that females have a higher trophic level than males, and δ 15 N positively correlates with size for females only. This indicates that size may matter in the ability of females to handle larger prey and/or dive deeper to catch higher trophic level prey. These results suggest that females, which also feed their calves, may be under different ecological constraints than males. We also analysed the harbour porpoise data with comparable stable isotope data from Greenland populations of belugas and narwhals. Consistent with their small body size, and a diet consisting primarily of capelin, we find that harbour porpoises have a lower trophic level than belugas and narwhals. Furthermore, harbour porpoises have the largest ecological niche of the three species, which is in accordance with tagging studies indicating they have a wide range in shelf and deep offshore waters of the sub-arctic and North Atlantic.
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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".