Use of invasive and non-invasive sampling techniques to assess physiological stress in marine mammals.

Clémence Finet

Marine mammals are increasingly impacted by multiple anthropogenic pressures (i.e exposure to direct or indirect effects of fishing, whaling, noise pollution, boat traffic, contaminants); and by environmental alteration due to natural phenomenon (i.e storms, temperature) and global warming (i.e. changes in sea level, ice cover). Sustained exposure to those extrinsic and intrinsic events are harmful to the animals leading to variable stress responses. Stress responses play a crucial role in coping with stressors and adapting to homeostasis disruption undergone by the animal. Quantification and interpretation of stress response can help understand the combined effects of health, physiological constraints, habitat quality, and anthropogenic disturbances on the individual and on the population, consequently improving species management and conservation. Here, we systematically reviewed, categorized, and referenced information from 83 publications that attempted to quantify stress biomarkers on marine mammals using different sampling approaches. We give an overview of the state of the physiological stress research in marine mammals and present the different sampling techniques used to date with their advantages and disadvantages for use within wild and captive populations. The choice of sampling techniques should depend on the aim of the study and the species sampled, which type of stress is investigated (acute/chronic) and should consider being the less invasive as possible.