Sustainability of the grizzly bear hunt in British Columbia, Canada
Notice bibliographique
Résumé
ABSTRACT The sustainability of the grizzly bear (Ursus arctos) hunt in British Columbia, Canada has been questioned and is a high profile issue, particularly in the media. To investigate the hypothesis that the hunt is unsustainable, we examined the sustainable human‐caused mortality rate for grizzly bears using recent data on vital rates and population projection models and compare these to rates used by the management agency; examined the age and sex ratio of the kill and how the sex ratio changes with age for the entire province, each population unit, and cohorts born each year between 1977 and 1990; summarized population density estimates in hunted population units in British Columbia and compared these to unhunted areas in adjacent jurisdictions; and reviewed case studies of population units that have been highlighted as most likely to have had unsustainable kill levels. Because the natural mortality rate of adult grizzly bears is 1–2% and lower than was estimated when sustainable human‐caused mortality targets were developed, estimated sustainable kill rates are 4–10%, and generally higher than the 4–6% used in British Columbia. We estimated that males have been 3–4 times more vulnerable to being killed by hunters than females, yet males dominate the kill at all ages and the proportion of males increased with age, which is opposite of what is predicted for a heavily hunted population. The average age of female and male grizzly bears killed by hunters increased from 7.1 years and 7.4 years, respectively, in the 1980s to 7.7 years and 8.7 years, respectively, in the 2000s. An average of 107.4 females and 204.9 males per cohort born between 1977 and 1990 were eventually killed by people and recorded, suggesting that many more females than males died for unknown reasons. There have been more population inventories of grizzly bears in British Columbia than in any other jurisdiction. The average density estimate of 21 inventories in hunted areas without salmon (Oncorhynchus spp.) in British Columbia (31.2 bears/1,000 km2) was as high as or higher than nearby unhunted areas. The case studies had the highest kill densities or among the highest kill rates in the province and hunting targets were commonly exceeded and seasons closed or the hunter kill target reduced. Although population inventories in these areas found moderate or even high densities of bears, some are now in decline. Hunter kill data from declining populations had a high proportion of males and these were older, demonstrating that these indices of kill rates are sometimes unreliable. Although more population density, trend, and vital rate measurements would be beneficial, the hypothesis that the grizzly bear hunt has been unsustainable was not supported by our investigation of available information. © 2016 The Wildlife Society.
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Comment cette classification a été obtenuedéplier
Prédiction machine sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Le volet Gemma est une étiquette directe du modèle pour chaque travail de la base, lue sur la notice réduite au titre. Le volet Codex est un classifieur appris des 10 348 étiquettes directes de Codex et calibré sur les taux pondérés de l'échantillon; les champs sans appui suffisant ne portent aucun appel Codex. Le mode candidate est l'union des deux volets; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont pas des étiquettes humaines.
Scores du classifieur distillé par catégorie (deux têtes)
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,001 | 0,002 |
| Méta-épidémiologie (sens strict) | 0,000 | 0,000 |
| Méta-épidémiologie (sens large) | 0,000 | 0,000 |
| Bibliométrie | 0,002 | 0,003 |
| Études des sciences et des technologies | 0,003 | 0,001 |
| Communication savante | 0,001 | 0,000 |
| Science ouverte | 0,001 | 0,001 |
| Intégrité de la recherche | 0,000 | 0,000 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,002 | 0,000 |
Scores machine (provisoires)
Les deux têtes enseignantes du modèle étudiant, lues sur ce travail. Un score ordonne la base pour la relecture; il n'affirme jamais une catégorie, et le statut de validation accompagne chaque rangée tel quel.
Scores de référence d'un modèle non mature (critères de maturité non atteints, 7 itérations). Un score ordonne; il n'affirme jamais une catégorie.
score_only:v0-immature-baseline · tel quel depuis la passe de notation : score_only signifie que le nombre peut ordonner les travaux, et qu'aucune étiquette de catégorie n'en découleClassification
machine, non validéePrédiction automatique; un appel candidat d’une seule source (Gemma direct ou Codex distillé), pas un consensus.
Le détail, modèle par modèle et score par score, se trouve en fin de page sous « Comment cette classification a été obtenue ».