Institute for the Oceans and Fisheries, Marine Mammal Research Unit, University of British Columbia, Vancouver, BC, Canada.
Department of Statistics, University of British Columbia, Vancouver, BC, Canada.
PLoS One. 2024 May 15;19(5):e0302758. doi: 10.1371/journal.pone.0302758. eCollection 2024.
Measuring breathing rates is a means by which oxygen intake and metabolic rates can be estimated to determine food requirements and energy expenditure of killer whales (Orcinus orca) and other cetaceans. This relatively simple measure also allows the energetic consequences of environmental stressors to cetaceans to be understood but requires knowing respiration rates while they are engaged in different behaviours such as resting, travelling and foraging. We calculated respiration rates for different behavioural states of southern and northern resident killer whales using video from UAV drones and concurrent biologging data from animal-borne tags. Behavioural states of dive tracks were predicted using hierarchical hidden Markov models (HHMM) parameterized with time-depth data and with labeled tracks of drone-identified behavioural states (from drone footage that overlapped with the time-depth data). Dive tracks were sequences of dives and surface intervals lasting ≥ 10 minutes cumulative duration. We calculated respiration rates and estimated oxygen consumption rates for the predicted behavioural states of the tracks. We found that juvenile killer whales breathed at a higher rate when travelling (1.6 breaths min-1) compared to resting (1.2) and foraging (1.5)-and that adult males breathed at a higher rate when travelling (1.8) compared to both foraging (1.7) and resting (1.3). The juveniles in our study were estimated to consume 2.5-18.3 L O2 min-1 compared with 14.3-59.8 L O2 min-1 for adult males across all behaviours based on estimates of mass-specific tidal volume and oxygen extraction. Our findings confirm that killer whales take single breaths between dives and indicate that energy expenditure derived from respirations requires using sex, age, and behavioural-specific respiration rates. These findings can be applied to bioenergetics models on a behavioural-specific basis, and contribute towards obtaining better predictions of dive behaviours, energy expenditure and the food requirements of apex predators.
测量呼吸频率是一种估算氧气摄入量和代谢率的方法，可用于确定虎鲸（Orcinus orca）和其他鲸目动物的食物需求和能量消耗。这种相对简单的方法还可以了解环境胁迫对鲸目动物的能量影响，但需要在它们处于不同行为状态（如休息、游动和觅食）时了解呼吸率。我们使用无人机（UAV）拍摄的视频和动物佩戴的标记物上的同期生物记录数据，计算了南方和北方居留地虎鲸在不同行为状态下的呼吸率。使用时间深度数据和带有标记的无人机识别行为状态的轨迹（与时间深度数据重叠的无人机镜头）的层次隐藏马尔可夫模型（HHMM）对潜水轨迹的行为状态进行预测。潜水轨迹是持续时间≥10 分钟的潜水和水面间隔的序列。我们计算了轨迹预测行为状态下的呼吸率和估计的耗氧量。我们发现，与休息（1.2）和觅食（1.5）相比，游动时幼鲸的呼吸率更高（1.6 次/分钟）；与觅食（1.7）和休息（1.3）相比，成年雄性游动时的呼吸率更高（1.8）。根据个体比容潮气量和氧气提取量的估计，我们研究中的幼鲸的耗氧量估计为 2.5-18.3 L O2 min-1，而成年雄性的耗氧量为 14.3-59.8 L O2 min-1，所有行为都包括在内。我们的研究结果证实，虎鲸在潜水之间只进行单次呼吸，这表明呼吸产生的能量消耗需要使用性别、年龄和特定行为的呼吸率。这些发现可以应用于基于行为特异性的生物能量学模型，并有助于更好地预测潜水行为、能量消耗和顶级捕食者的食物需求。
