科研之友
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摘要
Background: Worldwide, adult harbor seals (Phoca vitulina) typically limit their movements and activity to %26lt;50 km from their primary haul-out site. As a result, the ecological impact of harbor seals is viewed as limited to relatively small spatial scales. Harbor seals in the Pacific Northwest are believed to remain %26lt;30 km from their primary haul-out site, one of several contributing factors to the current stock designation. However, movement patterns within the region are not well understood because previous studies have used radio-telemetry, which has range limitations. Our objective was to use satellite-telemetry to determine the regional spatial scale of movements. %26lt;br%26gt;Methodology/Principal Findings: Satellite tags were deployed on 20 adult seals (n = 16 males and 4 females) from two rocky reefs and a mudflat-bay during April-May 2007. Standard filtering algorithms were used to remove outliers, resulting in an average (+/- SD) of 693 (+/- 377) locations per seal over 110 (+/- 32) days. A particle filter was implemented to interpolate locations temporally and decrease erroneous locations on land. Minimum over-water distances were calculated between filtered locations and each seal%26apos;s capture site to show movement of seals over time relative to their capture site, and we estimated utilization distributions from kernel density analysis to reflect spatial use. Eight males moved %26gt; 100 km from their capture site at least once, two of which traveled round trip to and from the Pacific coast, a total distance %26gt;400 km. Disjunct spatial use patterns observed provide new insight into general harbor seal behavior. %26lt;br%26gt;Conclusions/Significance: Long-distance movements and disjunct spatial use of adult harbor seals have not been reported for the study region and are rare worldwide in such a large proportion of tagged individuals. Thus, the ecological influence of individual seals may reach farther than previously assumed.
- 出版日期2012-6-18
