These datasets and accompanying syntheses provide a greater understanding of fundamental ecosystem processes in the Southern Ocean, support modelling of predator distributions under future climate scenarios and create inputs that can be incorporated into decision making processes by management authorities. In this data paper, we present the compiled tracking data from research groups that have worked in the Antarctic since the 1990s. The data are publicly available through biodiversity.aq and the Ocean Biogeographic Information System. The archive includes tracking data from over 70 contributors across 12 national Antarctic programs, and includes data from 17 predator species, 4060 individual animals, and over 2.9 million observed locations.Scientific Data | (2020) 7:94 | https://doi.org/10.1038/s41597-020-0406-x www.nature.com/scientificdata www.nature.com/scientificdata/ circum-Antarctic synthesis yet exists that crosses species boundaries. This deficiency prompted the Expert Group on Birds and Marine Mammals (EG-BAMM) and the Expert Group on Antarctic Biodiversity Informatics (EGABI) of the Scientific Committee on Antarctic Research (SCAR; www.scar.org) to initiate in 2010 the Retrospective Analysis of Antarctic Tracking Data (RAATD). RAATD aims to advance our understanding of fundamental and applied questions in a data-driven way, matching research priorities already identified by the SCAR Horizon Scan 9,21 and key questions in animal movement ecology 22 . For these reasons, we worked on the collation, validation and preparation of tracking data collected south of 45 °S. Data from over seventy contributors (Data Contacts and Citations 23 ) were collated. This database includes information from seventeen predator species, 4,060 individuals and over 2.9 million at-sea locations. To exploit this unique dataset, RAATD is undertaking a multi-species assessment of habitat use for higher predators in the Southern Ocean 24 .RAATD will provide a greater understanding of predator distributions under varying climate regimes, and provide outputs that can inform spatial management and planning decisions by management authorities such as the Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR; www.ccamlr.org). Our synopsis and analysis of multi-predator tracking data will also highlight regional or seasonal data-gaps.Scientific Data | (2020) 7:94 | https://doi.

Determining the movement of marine animals is logistically difficult and is currently primarily based on VHF and satellite-tracking telemetry, GPS, acoustic telemetry, and geolocation, all of which have substantial limitations in accurately locating the fine-scale movements of these animals. A recent development-that of dead-reckoning-is being increasingly used to examine the fine-scale movement of animals underwater. The advantages and drawbacks of this approach are quite different to those incurred by the other methods. This paper considers the advances that deadreckoning can bring to the study of the often cryptic movement and behaviour of marine animals at sea. Methods used in determining position via dead-reckoning are presented and consideration is given to results derived from the use of deadreckoning on cetaceans, pinnipeds, penguins and sea turtles; these are complemented by data on cormorants and albatrosses acquired using GPS systems. Suggestions are made as to how movement data derived from these devices can be analysed using indices that allow interpretation over a large variety of temporal and spatial scales. r

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International audienceOver the last decade, several hundred seals have been equipped with conductivity-temperature-depth sensors in the Southern Ocean for both biological and physical oceanographic studies. A calibrated collection of seal-derived hydrographic data is now available, consisting of more than 165,000 profiles. The value of these hydrographic data within the existing Southern Ocean observing system is demonstrated herein by conducting two state estimation experiments, differing only in the use or not of seal data to constrain the system. Including seal-derived data substantially modifies the estimated surface mixedlayer properties and circulation patterns within and south of the Antarctic Circumpolar Current. Agreement with independent satellite observations of sea ice concentration is improved, especially along the East Antarctic shelf. Instrumented animals efficiently reduce a critical observational gap, and their contribution to monitoring polar climate variability will continue to grow as data accuracy and spatial coverage increase

ObjectiveSatellite telemetry was used to investigate the migratory behaviour of southern elephant seals (Mirounga leonina). The seal studies were part of the German-Argentinean cooperation project and carried out at Stranger Point on King George Island between September 1996 and February 1997. Stranger Point (62°14'S; 58°40'W) is the southernmost breeding site of elephant seals. Elephant seals are able to dive to depths in excess of 1500 m and feed on squid and fish. The objective of this study was to identify the wintering areas and feeding grounds of elephant seals of this true Antarctic breeding colony. The results can potentially be compared between years or sites, in order to monitor differences in migratory and foraging behaviour that can be attributed to environmental changes in physical parameters (e.g. sea ice distribution) or to human impact on prey resources of these top predators. Field methodsAdult female elephant seal with satellitelinked dive recorder (SDR). SDRs were glued to the hair on the backs of 7 two month-old juveniles and on the heads of 13 moulted cows. To attach the instruments, seals were sedated with a combination of ketamine, xylazin, and diazepam. The initial doses of the drugs were either administered by hand (juveniles) or by a dart gun (adults) with automatically evacuating syringes. To maintain an immobilization of 1.5 to 3 h, small additional doses of ketamine and/or diazepam were administered by hand while the transmitters were being attached and the epoxy resin allowed to set.Satellite-linked dive recorder. Two types of ARGOS (CLS/Service Argos, Toulouse, France) transmitters were used in this study: 1) Satellite transmitters (ST-10 Telonics, Mesa, AZ, USA) are designed to provide the seals' at-sea locations. 2) In addition to transmissions of locations, satellite-linked dive recorders (SDR T-6 Wildlife Computers, Redmond, WA, USA) also process data on dive depths in the form of histograms. The histograms are encoded into messages and transmitted to a polar-orbiting satellite. The accessed data provide the horizontal extent of the seals' migrations and the distribution of their dive depths. Results and DiscussionComputer animation: To obtain a comprehensive picture of the seal's foraging activity in its three-dimensional marine environment the data need to be interpreted in the context of both biological and physical parameters. In our first attempt, a computer animation was developed to relate the animals behaviour to sea ice cover. A QuickTime (Apple Computer, Inc.) animation shows the tracks of the satellite tagged elephant seals in conjunction with seasonal changes in sea ice cover in the Antarctic Peninsula region from