Abstract
Foraging behaviour of marine top predators is increasingly being used to identify areas of ecological importance. This is largely enabled by the ability of many such species to forage extensively in search of prey that is often concentrated in oceanographically productive areas. To identify important habitat in the Southern Indian Ocean within and around South Africa’s Prince Edward Islands’ Marine Protected Area (MPA), satellite transmitters were deployed on 12 lactating Subantarctic fur seals Arctocephalus tropicalis at Prince Edward Island (PEI) itself. Switching state space models were employed to correct ARGOS tracks and estimate behavioural states for locations along predicted tracks, namely travelling or area restricted search (ARS). A random forest model showed that distance from the study colony, longitude and distance from the Subantarctic Front were the most important predictors of suitable foraging habitat (inferred from ARS). Model-predicted suitable habitat occurred within the MPA in relatively close access to the colony during summer and autumn, but shifted northwards concurrently with frontal movements in winter and spring. The association of ARS with the MPA during summer-autumn was highly significant, highlighting the effectiveness of the recently declared reserve’s design for capturing suitable foraging habitat for this and probably other marine top predator species.
Highlights
Quantifying habitat use of animals is vitally important for understanding their biophysical requirements, such as nutrition and reproduction, and for predicting areas of ecological significance [1,2,3]
To improve our understanding of foraging requirements of marine top predators breeding at Prince Edward Island, and assess this in relation to the current PEI Marine Protected Area (MPA), this study focuses on the foraging distribution of Subantarctic fur seal A. tropicalis females breeding at Prince Edward Island
sea surface height anomalies (SSHA), possibly associated with eddies around the fronts was an important predictor of area restricted search (ARS)
Summary
Quantifying habitat use of animals is vitally important for understanding their biophysical requirements, such as nutrition and reproduction, and for predicting areas of ecological significance [1,2,3]. Breeding and foraging grounds are especially important for conservation as those areas constitute crucial habitats in animals’ lifecycles [4]. In this regard, numerous studies have documented relationships between the foraging areas of marine predators, mainly surface-feeding seabirds and epipelagic foraging marine mammals, and specific oceanographic processes and features that influence their prey distribution [5]. PLOS ONE | DOI:10.1371/journal.pone.0152370 May 10, 2016
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