Context-dependent lateralized feeding strategies in blue whales.

Lateralized behaviors benefit individuals by increasing task efficiency in foraging and anti-predator behaviors [1-4]. The conventional lateralization paradigm suggests individuals are left or right lateralized, although the direction of this laterality can vary for different tasks (e.g. foraging or predator inspection/avoidance). By fitting tri-axial movement sensors to blue whales (Balaenoptera musculus), and by recording the direction and size of their rolls during lunge feeding events, we show how these animals differ from such a paradigm. The strength and direction of individuals' lateralization were related to where and how the whales were feeding in the water column. Smaller rolls (≤180°) predominantly occurred at depth (>70 m), with whales being more likely to rotate clockwise around their longest axis (right lateralized). Larger rolls (>180°), conversely, occurred more often at shallower depths (<70 m) and were more likely to be performed anti-clockwise (left lateralized). More acrobatic rolls are typically used to target small, less dense krill patches near the water's surface [5,6], and we posit that the specialization of lateralized feeding strategies may enhance foraging efficiency in environments with heterogeneous prey distributions

Evidence for acoustic communication among bottom foraging humpback whales

Humpback whales (Megaptera novaeangliae), a mysticete with a cosmopolitan distribution, demonstrate marked behavioural plasticity. Recent studies show evidence of social learning in the transmission of specific population level traits ranging from complex singing to stereotyped prey capturing behaviour. Humpback whales have been observed to employ group foraging techniques, however details on how individuals coordinate behaviour in these groups is challenging to obtain. This study investigates the role of a novel broadband patterned pulsed sound produced by humpback whales engaged in bottom-feeding behaviours, referred to here as a ‘paired burst’ sound. Data collected from 56 archival acoustic tag deployments were investigated to determine the functional significance of these signals. Paired burst sound production was associated exclusively with bottom feeding under low-light conditions, predominantly with evidence of associated conspecifics nearby suggesting that the sound likely serves either as a communicative signal to conspecifics, a signal to affect prey behaviour, or possibly both. This study provides additional evidence for individual variation and phenotypic plasticity of foraging behaviours in humpback whales and provides important evidence for the use of acoustic signals among foraging individuals in this species

Using accelerometers to determine the calling behavior of tagged baleen whales

Low-frequency acoustic signals generated by baleen whales can propagate over vast distances, making the assignment of calls to specific individuals problematic. Here, we report the novel use of acoustic recording tags equipped with high-resolution accelerometers to detect vibrations from the surface of two tagged fin whales that directly match the timing of recorded acoustic signals. A tag deployed on a buoy in the vicinity of calling fin whales and a recording from a tag that had just fallen off a whale were able to detect calls acoustically but did not record corresponding accelerometer signals that were measured on calling individuals. Across the hundreds of calls measured on two tagged fin whales, the accelerometer response was generally anisotropic across all three axes, appeared to depend on tag placement and increased with the level of received sound. These data demonstrate that high-sample rate accelerometry can provide important insights into the acoustic behavior of baleen whales that communicate at low frequencies. This method helps identify vocalizing whales, which in turn enables the quantification of call rates, a fundamental component of models used to estimate baleen whale abundance and distribution from passive acoustic monitoring.Keywords: Whale, Acceleration, Acoustic

Energetic and physical limitations on the breaching performance of large whales

The considerable power needed for large whales to leap out of the water may represent the single most expensive burst maneuver found in nature. However, the mechanics and energetic costs associated with the breaching behaviors of large whales remain poorly understood. In this study we deployed whale-borne tags to measure the kinematics of breaching to test the hypothesis that these spectacular aerial displays are metabolically expensive. We found that breaching whales use variable underwater trajectories, and that high-emergence breaches are faster and require more energy than predatory lunges. The most expensive breaches approach the upper limits of vertebrate muscle performance, and the energetic cost of breaching is high enough that repeated breaching events may serve as honest signaling of body condition. Furthermore, the confluence of muscle contractile properties, hydrodynamics, and the high speeds required likely impose an upper limit to the body size and effectiveness of breaching whales

Diving behavior and fine-scale kinematics of free-ranging Risso’s dolphins foraging in shallow and deep-water habitats

Funding: SOCAL-BRS project, Chief of Naval Operations Environmental Readiness Division, the US Navy's Living Marine Resources Program, and the Office of Naval Research Marine Mammal Program; ONR grant N00014-15-1-255 and the MASTS pooling initiative (Marine Alliance for Science and Technology for Scotland supported by the Scottish Funding Council, grant reference HR09011, and contributing institutions) (PLT).Air-breathing marine predators must balance the conflicting demands of oxygen conservation during breath-hold and the cost of diving and locomotion to capture prey. However, it remains poorly understood how predators modulate foraging performance when feeding at different depths and in response to changes in prey distribution and type. Here, we used high-resolution multi-sensor tags attached to Risso’s dolphins (Grampus griseus) and concurrent prey surveys to quantify their foraging performance over a range of depths and prey types. Dolphins (N=33) foraged in shallow and deep habitats [seabed depths less or more than 560m, respectively] and within the deep habitat, in vertically stratified prey features occurring at several aggregation levels. Generalized linear mixed-effects models indicated that dive kinematics were driven by foraging depth rather than habitat. Bottom-phase duration and number of buzzes (attempts to capture prey) per dive increased with depth. In deep dives, dolphins were gliding for >50% of descent and adopted higher pitch angles both during descent and ascents, which was likely to reduce energetic cost of longer transits. This lower cost of transit was counteracted by the record of highest vertical swim speeds, rolling maneuvers and stroke rates at depth, together with a 4-fold increase in the inter-buzz interval, suggesting higher costs of pursuing and handling prey compared to shallow-water feeding. In spite of the increased capture effort at depth, dolphins managed to keep their estimated overall metabolic rate comparable across dive types. This indicates that adjustments in swimming modes may enable energy balance in deeper dives. If we think of the surface as a central place where divers return to breathe, our data match predictions that central place foragers should increase the number and likely quality of prey items at greater distances. These dolphins forage efficiently from near-shore benthic communities to depth-stratified scattering layers, enabling them to maximize their fitness.Publisher PDFPeer reviewe

Why whales are big but not bigger : physiological drivers and ecological limits in the age of ocean giants

This research was funded in part by grants from the National Science Foundation (IOS-1656676, IOS-1656656; OPP-1644209 and 07-39483), the Office of Naval Research (N000141612477), and a Terman Fellowship from Stanford University. All procedures in USA were conducted under approval of the National Marine Fisheries Service (Permits 781-1824, 16163, 14809, 16111, 19116, 15271, 20430), Canada DFO SARA/MML 2010-01/SARA-106B, National Marine Sanctuaries (MULTI-2017-007), Antarctic Conservation Act (2009-014, 2015-011) and institutional IACUC committee protocols. Fieldwork, data collection and data processing for M. densirostris were funded by the Office of Naval Research grants N00014-07-10988, N00014-07-11023, N00014-08-10990, N00014-18-1-2062, and 00014-15-1-2553, and the U.S. Strategic Environmental Research and Development Program Grant SI-1539. PLT gratefully acknowledges funding from funding the MASTS pooling initiative (The Marine Alliance for Science and Technology for Scotland). MASTS is funded by the Scottish Funding Council (HR09011) and contributing institutions.The largest animals are marine filter feeders, but the underlying mechanism of their large size remains unexplained. We measured feeding performance and prey quality to demonstrate how whale gigantism is driven by the interplay of prey abundance and harvesting mechanisms that increase prey capture rates and energy intake. The foraging efficiency of toothed whales that feed on single prey is constrained by the abundance of large prey, whereas filter-feeding baleen whales seasonally exploit vast swarms of small prey at high efficiencies. Given temporally and spatially aggregated prey, filter feeding provides an evolutionary pathway to extremes in body size that are not available to lineages that must feed on one prey at a time. Maximum size in filter feeders is likely constrained by prey availability across space and time.PostprintPeer reviewe

Multiple-stage decisions in a marine central-place forager

Air-breathing marine animals face a complex set of physical challenges associated with diving that affect the decisions of how to optimize feeding. Baleen whales (Mysticeti) have evolved bulk-filter feeding mechanisms to efficiently feed on dense prey patches. Baleen whales are central place foragers where oxygen at the surface represents the central place and depth acts as the distance to prey. Although hypothesized that baleen whales will target the densest prey patches anywhere in the water column, how depth and density interact to influence foraging behaviour is poorly understood. We used multi-sensor archival tags and active acoustics to quantify Antarctic humpback whale foraging behaviour relative to prey. Our analyses reveal multi-stage foraging decisions driven by both krill depth and density. During daylight hours when whales did not feed, krill were found in deep high-density patches. As krill migrated vertically into larger and less dense patches near the surface, whales began to forage. During foraging bouts, we found that feeding rates (number of feeding lunges per hour) were greatest when prey was shallowest, and feeding rates decreased with increasing dive depth. This strategy is consistent with previous models of how air-breathing diving animals optimize foraging efficiency. Thus, humpback whales forage mainly when prey is more broadly distributed and shallower, presumably to minimize diving and searching costs and to increase feeding rates overall and thus foraging efficiency. Using direct measurements of feeding behaviour from animal-borne tags and prey availability from echosounders, our study demonstrates a multi-stage foraging process in a central place forager that we suggest acts to optimize overall efficiency by maximizing net energy gain over time. These data reveal a previously unrecognized level of complexity in predator–prey interactions and underscores the need to simultaneously measure prey distribution in marine central place forager studies.This is the publisher’s final pdf. The published article is copyrighted by The Royal Society and can be found at: http://rsos.royalsocietypublishing.org/Keywords: diving, predator-prey interactions, foraging decision

Redirecting research efforts on the diversification-performance linkage: The search for synergy

We review the literature on the diversification-performance (D-P) relationship to a) propose that the time is ripe for a renewed attack on understanding the relationship between diversification and firm performance, and b) outline a new approach to attacking the question. Our paper makes four main contributions. First, through a review of the literature we establish the inherent complexities in the D-P relationship and the methodological challenges confronted by the literature in reaching its current conclusion of a non-linear relationship between diversification and performance. Second, we argue that to better guide managers the literature needs to develop along a complementary path – whereas past research has often focused on answering the big question of does diversification affect firm performance, this second path would focus more on identifying the precise micro-mechanisms through which diversification adds or subtracts value. Third, we outline a new approach to the investigation of this topic, based on (a) identifying the precise underlying mechanisms through which diversification affects performance; (b) identifying performance outcomes that are “proximate” to the mechanism that the researcher is studying, and (c) identifying an appropriate research design that can enable a causal claim. Finally, we outline a set of directions for future research

A View from the Past Into our Collective Future: The Oncofertility Consortium Vision Statement

Today, male and female adult and pediatric cancer patients, individuals transitioning between gender identities, and other individuals facing health extending but fertility limiting treatments can look forward to a fertile future. This is, in part, due to the work of members associated with the Oncofertility Consortium. The Oncofertility Consortium is an international, interdisciplinary initiative originally designed to explore the urgent unmet need associated with the reproductive future of cancer survivors. As the strategies for fertility management were invented, developed or applied, the individuals for who the program offered hope, similarly expanded. As a community of practice, Consortium participants share information in an open and rapid manner to addresses the complex health care and quality-of-life issues of cancer, transgender and other patients. To ensure that the organization remains contemporary to the needs of the community, the field designed a fully inclusive mechanism for strategic planning and here present the findings of this process. This interprofessional network of medical specialists, scientists, and scholars in the law, medical ethics, religious studies and other disciplines associated with human interventions, explore the relationships between health, disease, survivorship, treatment, gender and reproductive longevity. The goals are to continually integrate the best science in the service of the needs of patients and build a community of care that is ready for the challenges of the field in the future