Despite the importance of fine-scale spatial use in understanding an animal's foraging ecology, these data cannot readily be collected for free-ranging marine mammals. We used an acoustic positioning system to quantify, for the first time, the fine-scale 3-dimensional (3D) spatial use of free-ranging Weddell seals swimming under ice. Unlike many other phocid species, lactating Weddell seals spent up to 25% of their time diving. Given the limited foraging range imposed on the seals by the fast ice upon which they breed, this could lead to prey depletion and even inter-specific competition. The seals focused their underwater activity on a relatively small region associated with a steep bottom contour, using the entire water column, with very little time spent at the bottom. This behaviour is consistent with feeding on bentho-pelagic prey such as Pleurogramma antarcticum. The 3D profile of individual dives consisted of the seals making simple, directed dives which gradually converged with the ocean floor. There was some variation from this pattern, usually associated with increased searching time. Such focused foraging activity may result in local prey depletion and intra-specific competition.

Item Type:	Refereed Article
Research Division:	Environmental Sciences
Research Group:	Environmental management
Research Field:	Wildlife and habitat management
Objective Division:	Environmental Management
Objective Group:	Coastal and estuarine systems and management
Objective Field:	Assessment and management of coastal and estuarine ecosystems
UTAS Author:	Hindell, MA (Professor Mark Hindell)
ID Code:	25177
Year Published:	2002
Web of Science® Times Cited:	64
Deposited By:	Zoology
Deposited On:	2002-08-01
Last Modified:	2011-08-02
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