Sex-selective harvesting of polar bears Ursus maritimus
Bibliographic record
Abstract
We explored limits and consequences of male-biased harvesting of polar bears Ursus maritimus using a simulated population based on empirically-derived estimates of age-specific rates of survival and reproduction. The maximum sustainable yield (MSY) was identified as the total kill in which the number of females that could be taken resulted in ≤5% change in females older than 50 years. MSY depended on the proportion of males in the harvest, although the effect of male selection on the post-harvest population was to reduce the mean age and number of males. A practical limit to the increase in MSY possible from male-selective harvesting was identified at the 3 : 1 (M/F) sex ratio. At 3 : 1 (M/F), all males were eventually harvested as 2-year olds, and males were reduced to 25% of pre-harvest levels. A more conservative harvest strategy of 2 : 1 (M/F) resulted in a 30% reduction of males and a reduction of the mean age of males from 10.0 to 7.7 years post-harvest. We thus recommend that sex-selective harvesting of polar bears do not exceed 67% males (i.e. a harvest ratio of 2 : 1), a demonstrably safe and sustainable harvest strategy, to avoid depletion of males and possibly reduce recruitment by having too few sexually mature males in the population. When females are harvested below MSY, then harvest strategies that select for males at rates > 2 : 1 (M/F) can be conservative because the increase in females also increases the reproductive performance of the population. In the absence of information on density effects, managers should be conservative in their expectations of increases in the female population.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
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) | 0.001 | 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 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".