Breeding failure of seabirds in relation to fish depletion: Is there one universal threshold of food abundance?
Bibliographic record
Abstract
Many populations of seabirds are in decline across the world and one proposed cause is the global collapse of fish stocks. Recently, it has been shown that breeding success starts to decline at some critical threshold (CT) of maximum prey abundance (MPA). Here, we estimated this empirical threshold for a large seabird, the northern gannet Morus bassanus, and discuss its relevance under various conditions. Using a time series starting at the end of the 1970s that included estimated biomass of fish, gannet population and food consumed by gannets, we found a positive and non-linear relationship between fish biomass and breeding success. This correlation was supported by the results of a bio-energetic model indicating that gannets extract a substantial fraction of the available biomass. In addition, distribution and time spent at sea (derived from GPS recordings) increased considerably when food abundance was low. In contrast to the general CT previously proposed (34%), we found that breeding success of gannets started to decline at about 8% of MPA. Moreover, when corrected for the sizes of prey available that may be eaten by the birds and the removal of fish by the fishing industry, the observed threshold was further reduced, indicating that such effects should be included in the context of ecosystem based management. Theoretical considerations are offered to further explain the discrepancy between the results of our study and a previously published meta-analysis, which included the effect of diet on feeding profitability and the effect of population size.
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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 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 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 teacher head, 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".