期刊
ECOLOGICAL MONOGRAPHS
卷 91, 期 4, 页码 -出版社
WILEY
DOI: 10.1002/ecm.1472
关键词
body condition; carcass recovery; contaminants; disease; distribution; Enhydra lutris; foraging success; gene transcription; population decline; predation; sea otter; southwest Alaska
类别
资金
- U.S. Geological Survey
- U.S. Fish and Wildlife Service (Office of Marine Mammals Management)
- Monterey Bay Aquarium
- Exxon Valdez Oil Spill Trustee Council
- National Science Foundation [DPP-8421362, DPP-9101134, 0647635, PLR-1316141]
- North Pacific Research Board (NPRB) [717]
- Directorate For Geosciences
- Division Of Ocean Sciences [0647635] Funding Source: National Science Foundation
Sea otter populations in southwest Alaska significantly declined over the past 25 years, with densities dropping to around 5% of the environmental carrying capacity. The decline was primarily attributed to predation or other density-independent factors rather than nutritional limitation, disease, or environmental contaminants.
Sea otter (Enhydra lutris) populations in southwest Alaska declined substantially between about 1990 and the most recent set of surveys in 2015. Here we report changes in the distribution and abundance of sea otters, and covarying patterns in reproduction, mortality, body size and condition, diet and foraging behavior, food availability, health profiles, and exposure to environmental contaminants over this 25-yr period. The population decline, which resulted in densities on the order of 5% of environmental carrying capacity, ranged from Attu Island in the west to about Castle Cape (on the south side of the Alaska Peninsula) in the east. Remaining sea otters moved closer to shore and into shallow, protected habitats. Reproductive rates appeared unchanged with the decline. Although the demographic cause of the decline was clearly elevated mortality, stranded carcasses were rare or absent. The net rate of energy gain by foraging sea otters, body length and condition, and prey biomass density, all increased after the decline and varied inversely with sea otter population density beyond the area of decline. Sea otters within the area of decline showed no increases in health anomalies, disease, contaminant exposure, or abnormal gene transcription patterns as compared to animals outside the area of decline. These collective findings are inconsistent with nutritional limitation, disease, or environmental contaminants, and consistent with predation (or possibly some other density-independent factor) as the reason for the sea otter population decline. Our approach and analyses provide a broad conceptual template for thinking about and assessing the causes of wildlife population declines.
作者
我是这篇论文的作者
点击您的名字以认领此论文并将其添加到您的个人资料中。
推荐
暂无数据