Description: Recordings from the PerenniAL Acoustic Observatory in the Antarctic ocean (PALAOA) show seasonal acoustic presence of 4 Antarctic ice-breeding seal species (Ross seal, Ommatophoca rossii, Weddell seal, Leptonychotes weddellii, crabeater, Lobodon carcinophaga, and leopard seal, Hydrurga leptonyx). Apart from Weddell seals, inhabiting the fast-ice in Atka Bay, the other three (pack-ice) species however have to date never (Ross and leopard seal) or only very rarely (crabeater seals) been sighted in the Atka Bay region. The aim of the PASATA project is twofold: the large passive acoustic hydrophone array (hereafter referred to as large array) aims to localize calling pack-ice pinniped species to obtain information on their location and hence the ice habitat they occupy. This large array consists of four autonomous passive acoustic recorders with a hydrophone sensor deployed through a drilled hole in the sea ice. The PASATA recordings are time-stamped and can therefore be coupled to the PALAOA recordings so that the hydrophone array spans the bay almost entirely from east to west. The second, smaller hydrophone array (hereafter referred to as small array), also consists of four autonomous passive acoustic recorders with hydrophone sensors deployed through drilled holes in the sea ice. The smaller array was deployed within a Weddell seal breeding colony, located further south in the bay, just off the ice shelf. Male Weddell seals are thought to defend underwater territories around or near tide cracks and breathing holes used by females. Vocal activity increases strongly during the breeding season and vocalizations are thought to be used underwater by males for the purpose of territorial defense and advertisement. With the smaller hydrophone array we aim to investigate underwater behaviour of vocalizing male and female Weddell seals to provide further information on underwater movement patterns in relation to the location of tide cracks and breathing holes. As a pilot project, one on-ice and three underwater camera systems have been deployed near breathing holes to obtain additional visual information on Weddell seal behavioural activity. Upon each visit in the breeding colony, a census of colony composition on the ice (number of animals, sex, presence of dependent pups, presence and severity of injuries-indicative of competition intensity) as well as GPS readings of breathing holes and positions of hauled out Weddell seals are taken.

Description: The dataset presents maps for the year-round habitat suitability of the Antarctic minke whales (Balaenoptera bonaerensis) in the Southern Ocean. These maps represent predictions from dynamic species distribution models using MaxEnt software. In these models, species visual observations were spatiotemporally matched with contemporaneous environmental conditions, predicting habitat suitability both in time and space. Models were evaluated on spatial- and temporal-block cross-validation, attempting to correct for spatial sampling bias. More details on the models and methods implemented are given in El-Gabbas et al. 2021 (doi:10.3389/fmars.2021.802276). The dataset provides maps for the mean daily, weekly, and monthly habitat suitability between June 2002 and December 2019. Further, we also provide maps that summarize long-term daily habitat suitability into monthly maps.

Description: The dataset presents maps for the year-round habitat suitability of the Antarctic blue whales (Balaenoptera musculus intermedia) in the Southern Ocean. These maps represent predictions from dynamic species distribution models using MaxEnt software. In these models, species visual observations were spatiotemporally matched with contemporaneous environmental conditions, predicting habitat suitability both in time and space. Models were evaluated on spatial- and temporal-block cross-validation, attempting to correct for spatial sampling bias. More details on the models and methods implemented are given in El-Gabbas et al. 2021 (doi:10.3389/fmars.2021.802276). The dataset provides maps for the mean daily, weekly, and monthly habitat suitability between June 2002 and December 2019. Further, we also provide maps that summarize long-term daily habitat suitability into monthly maps.

Description: The dataset presents maps for the year-round habitat suitability of the fin whales (Balaenoptera physalus) in the Southern Ocean. These maps represent predictions from dynamic species distribution models using MaxEnt software. In these models, species visual observations were spatiotemporally matched with contemporaneous environmental conditions, predicting habitat suitability both in time and space. Models were evaluated on spatial- and temporal-block cross-validation, attempting to correct for spatial sampling bias. More details on the models and methods implemented are given in in El-Gabbas et al. 2021 (doi:10.3389/fpls.2021.629962). The dataset provides maps for the mean daily, weekly, and monthly habitat suitability between June 2002 and December 2019. Further, we also provide maps that summarize long-term daily habitat suitability into monthly maps.

Description: The dataset presents maps for the year-round habitat suitability of the humpback whales (Megaptera novaeangliae) in the Southern Ocean. These maps represent predictions from dynamic species distribution models using MaxEnt software. In these models, species visual observations were spatiotemporally matched with contemporaneous environmental conditions, predicting habitat suitability both in time and space. Models were evaluated on spatial- and temporal-block cross-validation, attempting to correct for spatial sampling bias. More details on the models and methods implemented are given in El-Gabbas et al. 2021 (doi:10.3389/fmars.2021.802276). The dataset provides maps for the mean daily, weekly, and monthly habitat suitability between June 2002 and December 2019. Further, we also provide maps that summarize long-term daily habitat suitability into monthly maps.

Description: Killer whales (Orcinus orca) are highly social top predators distributed throughout the worldʼs oceans. They are divided into different ecotypes according to foraging specializations, phenotype, and social organization. For Northern Hemisphere killer whale ecotypes, acoustic behaviour has been shown to relate to foraging strategies and social organization. In contrast to the intensively studied Northern Hemisphere ecotypes, distribution patterns, social structures, and acoustic behaviour of the Southern Hemisphere killer whale ecotypes are poorly known. One of the Southern Hemisphere ecotypes, the Antarctic Ecotype C killer whale, is known to occur in regions with dense pack ice. The limited accessibility of these areas make passive acoustic monitoring (PAM) methods a very effective investigation tool to derive information on ecotype-specific abundance and distribution. During 2 d in February 2013, it was possible to collect concurrent visual and acoustic information of Ecotype C killer whales off the Antarctic continent. From these events, a call type catalogue was compiled. The 2,238 examined calls were subjectively classified into 26 discrete call types. Ten percent of the examined calls were re-classified by two additional independent observers to examine robustness of the classification. Mean classification accordance among observers was 68%. Most call types were composed of more than one call part. Sixty-five percent of all call types were monophonic, and 35% were biphonic. Almost two-third of all call types started with a short, broadband pulse. The variability within call types was relatively high. The Ecotype C vocal repertoire contained typical acoustic features such as biphonation, high call complexity, and generally high variability in frequency modulation. For future studies, the distinct characteristics of some of the call types described herein could potentially serve as acoustic markers for PAM-based differentiation of killer whale ecotypes in the Southern Ocean.

Description: Evaluation of the performance of computer-based algorithms to automatically detect mammalian vocalizations often relies on comparisons between detector outputs and a reference data set, generally obtained by manual annotation of acoustic recordings. To explore the reproducibility of these annotations, inter- and intra-analyst variability in manually annotated Antarctic blue whale (ABW) Z-calls are investigated by two analysts in acoustic data from two ocean basins representing different scenarios in terms of call abundance and background noise. Manual annotations exhibit strong inter- and intra-analyst variability, with less than 50% agreement between analysts. This variability is mainly caused by the difficulty of reliably and reproducibly distinguishing single calls in an ABW chorus made of overlaying distant calls. Furthermore, the performance of two automated detectors, based on spectrogram correlation or subspace-detection strategy, is evaluated by comparing detector output to a “conservative” manually annotated reference data set, which comprises only analysts' matching events. This study highlights the need for a standardized approach for human annotations and automatic detections, including a quantitative description of their performance, to improve the comparability of acoustic data, which is particularly relevant in the context of collaborative approaches in collecting and analyzing large passive acoustic data sets.

Description: The eastern Atlantic Ocean is considered to provide important breeding and wintering habitats for several migratory cetacean species. The spatio-temporal distributions and migratory behaviors of cetaceans off southern Africa are nevertheless still poorly understood. This study investigated the temporal patterns of acoustic occurrence of baleen whales in a presumed baleen whale breeding area off Namibia using passive acoustic recordings collected between November 2011 and May 2013. Our results show seasonal acoustic presence of humpback whales Megaptera novaeangliae, fin whales Balaenoptera physalus and Antarctic minke whales B. bonaerensis from November to January and from June to August. Their acoustic absence from February to May possibly indicates that most animals migrated to other areas (presumably in higher latitudes) in austral summer to feed. By contrast, Antarctic blue whales B. musculus intermedia were acoustically present throughout the recording period, indicating that part of the population remains at lower latitudes year-round. Our findings support the presumed ecological importance of the oceanic area off Namibia, providing (part of) a suitable cetacean wintering and, possibly, breeding range or migratory corridor. Furthermore, the occurrence of Antarctic blue and minke whales off Namibia, concurrent with their reported acoustic presence in high-latitude feeding areas, adds to growing evidence that baleen whale migration is not obligate but much more dynamic than has long been assumed.

Description: Both marine mammals and hydroacoustic instruments use underwater sound to communicate, navigate and/or infer information about the marine environment. Concurrent timing of acoustic activity and/or the use of similar frequency regimes may result in (potentially mutual) masking of acoustic signals when both sources are within reception range. Earlier studies have provided evidence that marine mammal fitness might be negatively impacted both on individual and population level when animal sounds are masked by anthropogenic sound sources. Hydroacoustic studies on the other hand may generate low quality data or suffer data loss as a result of bioacoustic interference. In analogy to landscape planning, the concept of soundscape planning aims to reconcile potentially competing uses of acoustic space by managing the anthropogenic sound sources. We here present a conceptual framework to explore the potential of soundscape planning in reducing (mutual) acoustic interference between hydroacoustic instrumentation and marine mammals. The basis of this framework is formed by the various mechanisms by which acoustic niche formation occurs in species-rich communities that acoustically coexist while maintaining hi-fi soundscapes, i.e., by acoustically partitioning the environment on the basis of time, space, frequency and/or signal form. Hydroacoustic measurements often exhibit certain flexibility in the timing, signal characteristics and even instrument positioning, potentially offering the opportunity to minimize the underwater acoustic imprint. We evaluate how the principle of acoustic niches (i.e., the partitioning of the acoustic space) could contribute to reduce potential (mutual) acoustic interference based on actual acoustic data from three recording locations in polar oceans.