Cetacean Ecology and Acoustics Laboratory, School of Veterinary Science, The University of Queensland, Gatton, QLD 4343, Australia; Wildlife Endocrinology Lab, School of Agriculture and Food Science, The University of Queensland, Gatton, QLD 4343, Australia.
Wildlife Endocrinology Lab, School of Agriculture and Food Science, The University of Queensland, Gatton, QLD 4343, Australia.
Gen Comp Endocrinol. 2020 May 15;291:113436. doi: 10.1016/j.ygcen.2020.113436. Epub 2020 Feb 11.
Baleen whales are vulnerable to environmental impacts due to low fecundity, capital breeding strategies, and their reliance on a large amount of prey resources over large spatial scales. There has been growing interest in monitoring health and physiological stress in these species but, to date, few measures have been validated. The purpose of this study was to examine whether blubber cortisol could be used as a measure of physiological stress in humpback whales. Cortisol concentrations were initially compared between live, presumably 'healthy' whales (n = 187) and deceased whales (n = 35), which had died after stranding or entanglement, or washed ashore as a carcass. Deceased whales were found to have significantly higher cortisol levels (mean ± SD; 5.47 ± 4.52 ng/g) than live whales (0.51 ± 0.14 ng/g; p < 0.001), particularly for those animals that had experienced prolonged trauma (e.g. stranding) prior to death. Blubber cortisol levels in live whales were then examined for evidence of life history-related, seasonal, or sampling-related effects. Life history group and sampling-related factors, such as encounter time and the number of biopsy sampling attempts per animal, were found to be poor predictors of blubber cortisol levels in live whales. In contrast, blubber cortisol levels varied seasonally, with whales migrating north towards the breeding grounds in winter having significantly higher levels (0.54 ± 0.21 ng/g, p = 0.016) than those migrating south towards the feeding grounds in spring (0.48 ± 1.23 ng/g). These differences could be due to additional socio-physiological stress experienced by whales during peaks in breeding activity. Overall, blubber cortisol appears to be a suitable measure of chronic physiological stress in humpback whales.
须鲸由于繁殖能力低、资本繁殖策略以及对大量猎物资源的依赖，容易受到环境影响，这些资源分布在大的空间尺度上。人们越来越关注监测这些物种的健康和生理压力，但迄今为止，很少有措施得到验证。本研究的目的是研究鲸脂皮质醇是否可作为座头鲸生理压力的衡量指标。皮质醇浓度最初在活体（假定“健康”）鲸鱼（n=187）和死亡鲸鱼（n=35）之间进行了比较，这些死亡鲸鱼是在搁浅或缠绕后死亡，或作为尸体冲上岸。研究发现，死亡鲸鱼的皮质醇水平（平均值±SD；5.47±4.52ng/g）明显高于活体鲸鱼（0.51±0.14ng/g；p<0.001），特别是那些在死亡前经历了长时间创伤（例如搁浅）的动物。然后检查活体鲸鱼的鲸脂皮质醇水平是否存在与生活史相关、季节性或采样相关的影响。研究发现，生活史组和采样相关因素（例如遭遇时间和每只动物的活检采样尝试次数）均不能很好地预测活体鲸鱼的鲸脂皮质醇水平。相反，鲸脂皮质醇水平具有季节性变化，冬季向北迁徙到繁殖地的鲸鱼的水平明显较高（0.54±0.21ng/g，p=0.016），而春季向南迁徙到觅食地的鲸鱼水平较低（0.48±1.23ng/g）。这些差异可能是由于繁殖活动高峰期鲸鱼经历的额外社会生理压力所致。总体而言，鲸脂皮质醇似乎是座头鲸慢性生理压力的合适衡量指标。
