The distribution of southern elephant seal Mirounga leonina prey encounter events (PEEs) was investigated from the foraging behaviour of 29 post-breeding females simultaneously equipped with a satellite tag, a time−depth recorder and a head-mounted accelerometer. Seal diving depth and PEE were related to water temperature at 200 m (T 200 ), and light level at the surface (L 0 ) and at depth. Approximately half (49%) of all dives were located in waters encompassed between the southern Antarctic Circumpolar Current Front and the Polar Front. Seals dived significantly deeper during the day than at night. Diving and PEE depth increased with increasing T 200 and for a given T 200 according to L 0 and the percentage of surface light reaching 150 m. On average, 540 PEEs per day were recorded. Seals exhibited more PEEs per unit of time spent diving during the twilight period compared with at night, and were least successful during daylight hours. Elephant seals forage in T 200 ranging between −1 and 13°C; however, few PEEs were recorded at depths shallower than 400−500 m at night when the T 200 exceeded 8°C. The diet of female Kerguelen elephant seals appears to be dominated by myctophids (lanternfish), and according to the average mass of their most likely myctophid prey (9 g, Electrona calsbergi and E. antarctica; 30 g Gymnoscopelus nicholsi and G. piabilis), we estimate that seals consumed 4.8−16.1 kg of fish daily. Despite lower catch rates in warmer waters, no relationship was found between the mean T 200 at the scale of the foraging trip and daily or absolute mass gain, suggesting that elephant seals are compensating for lower catch rates by consuming larger/richer prey items in those waters.

No abstract

Animal telemetry is a powerful tool for observing marine animals and the physical environments that they inhabit, from coastal and continental shelf ecosystems to polar seas and open oceans. Satellite-linked biologgers and networks of acoustic receivers allow animals to be reliably monitored over scales of tens of meters to thousands of kilometers, giving insight into their habitat use, home range size, the phenology of migratory patterns and the biotic and abiotic factors that drive their distributions. Furthermore, physical environmental variables can be collected using animals as autonomous sampling platforms, increasing spatial and temporal coverage of global oceanographic observation systems. The use of animal telemetry, therefore, has the capacity to provide measures from a suite of essential ocean variables (EOVs) for improved monitoring of Earth's oceans. Here we outline the design features of animal telemetry systems, describe current applications and their benefits and challenges, and discuss future directions. We describe new analytical techniques that improve our ability to not only quantify animal movements but to also provide a powerful framework for comparative studies across taxa. We discuss the application of animal telemetry and its capacity to collect biotic and abiotic data, how the data collected can be incorporated into ocean observing systems, and the role these data can play in improved ocean management.

Winter use of sea ice and ocean water-mass habitat by southern elephant seals: The length and breadth of the mystery, Progress in Oceanography (2015), doi: http://dx.doi.org/ 10. 1016/j.pocean.2015.05.023 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. Highlights 20• Time-series of 35 elephant seal winter foraging trips to Antarctica were analysed 21• A high resolution dive behaviour dataset was used to predict foraging events 22• The links between foraging and sea ice, hydrography and topography were quantified 23• Foraging strategies depended on the sex of seals 24• The foraging activity was associated with a number of oceanographic discontinuities 25