Foraging behaviour of southern elephant seals over the Kerguelen Plateau

M O’Toole,C Guinet,Ma Hindell,Jb Charrassin

doi:10.3354/meps10709

Abstract

A total of 79 (37 juvenile male, 42 adult female) southern elephant seals Mirounga leonina from the Kerguelen Islands were tracked between 2004 and 2009. Area-restricted search patterns and dive behaviour were established from location data gathered by CTD satelliterelayed data loggers. At-sea movements of the seals demonstrated that >40% of the juvenile elephant seal population tagged use the Kerguelen Plateau during the austral winter. Search activity increased where temperature at 200 m depth was lower, when closer to the shelf break, and, to a lesser extent, where sea-surface height anomalies were higher. However, while this model explained the observed data (F1,242 = 88.23, p < 0.0001), bootstrap analysis revealed poor predictive capacity (r2 = 0.264). There appears to be potential overlap between the seals and commercial fishing operations in the region. This study may therefore support ecosystem-based fisheries management of the region, with the aim of maintaining ecological integrity of the shelf.

Highlights

Quantifying animal movement provides information on habitat requirements, which is fundamental to understanding the foraging ecology of a species (Ropert-Coudert & Wilson 2005)
Of the 79 seals tagged in the study, 24% spent some time foraging on the Kerguelen Plateau
Search behaviour of 12 seals was at a single site, while search behaviour of 7 others was in several patches (Fig. S3)

Summary

Introduction

Quantifying animal movement provides information on habitat requirements, which is fundamental to understanding the foraging ecology of a species (Ropert-Coudert & Wilson 2005). Movement data can provide information on turning angles and movement speeds which can be used to infer changes between behavioural states (Morales et al 2004). Increased search effort is typically indicated by reduced transit speed and increased turning frequency within a given area and is often indicative of foraging activity The ongoing development of satellite telemetry and more recent track reconstruction methods have enabled movement and behavioural states to be mapped for a range of marine predators (Jonsen et al 2005, Patterson et al 2008, 2010, Sumner et al 2009, Bestley et al 2010, Pedersen et al 2011, Jonsen et al 2013)

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Results