Investigating the thermal physiology of Critically Endangered North Atlantic right whales Eubalaena glacialis via aerial infrared thermography

Abstract

The Critically Endangered status of North Atlantic right whales Eubalaena glacialis (NARWs) warrants the development of new, less invasive technology to monitor the health of individuals. Combined with advancements in remotely piloted aircraft systems (RPAS, commonly ‘drones’), infrared thermography (IRT) is being increasingly used to detect and count marine mammals and study their physiology. We conducted RPAS-based IRT over NARWs in Cape Cod Bay, MA, USA, in 2017 and 2018. Observations demonstrated 3 particularly useful applications of RPAS-based IRT to study large whales: (1) exploring patterns of cranial heat loss and providing insight into the physiological mechanisms that produce these patterns; (2) tracking subsurface individuals in real-time (depending on the thermal stratification of the water column) using cold surface water anomalies resulting from fluke upstrokes; and (3) detecting natural changes in superficial blood circulation or diagnosing pathology based on heat anomalies on post-cranial body surfaces. These qualitative applications present a new, important opportunity to study, monitor, and conserve large whales, particularly rare and at-risk species such as NARWs. Despite the challenges of using this technology in aquatic environments, the applications of RPAS-based IRT for monitoring the health and behavior of endangered marine mammals, including the collection of quantitative data on thermal physiology, will continue to diversify.

Comparison of infrared thermography of the blowhole mucosa with rectal temperatures in killer whales (Orcinus orca)

“…During this study the camera was held approximately 2 ft high (0.61 m) at each reading. It remains to be seen whether increasing the height of the camera will diminish or magnify sensitivity of the camera in terms of overall accuracy, position angle, and interference of water plumes, however aerial studies of free ranging baleen whales at higher altitudes did not report issues with blowhole vapor interference (Horton et al, 2019;Lonati et al, 2022).…”

“…Work in managed-care whales may also examine temperature variation with increasing camera altitude, as unoccupied aerial systems (drones) fitted with infrared cameras are a practical option for evaluating blowhole temperature in free-ranging animals. Recent studies have used drone infrared thermography to visualize blowholes of North Atlantic right whales, humpback whales, minke, blue, and sperm whales, which appeared as distinct heat anomalies compared to the water surface (Cuyler et al, 1992;Horton et al, 2019;Lonati et al, 2022). Blowholes were observed at an altitude of 9.84 ft (3 m) for the right whales and 65.62 ft (20 m) for the humpback whales (Horton et al, 2019;Lonati et al, 2022), whereas the present investigation used infrared thermography at a close range of ~2 ft (0.61 m).…”

“…Recent studies have used drone infrared thermography to visualize blowholes of North Atlantic right whales, humpback whales, minke, blue, and sperm whales, which appeared as distinct heat anomalies compared to the water surface (Cuyler et al, 1992;Horton et al, 2019;Lonati et al, 2022). Blowholes were observed at an altitude of 9.84 ft (3 m) for the right whales and 65.62 ft (20 m) for the humpback whales (Horton et al, 2019;Lonati et al, 2022), whereas the present investigation used infrared thermography at a close range of ~2 ft (0.61 m). Studies performed only on free-ranging animals lack temperature reference data via direct contact as comparison, and the goal of the present study is to fill those data gaps.…”

Unmanned Aerial Vehicles (UAVs) in Marine Mammal Research: A Review of Current Applications and Challenges

“…Murakami et al [110] proposed a biologging method using a UAV to deploy a logger on sperm whales when they surfaced. UAVs can also be equipped with infrared thermography (IRT) sensors to conduct physiological studies [80]. IRT has already been used to measure vital signs such as respiration rate, heart rate, or body temperature as indicators of the health and physiological condition of humpback whales [109] and North Atlantic right whales (Eubalaena glacialis) [80].…”

“…UAVs can also be equipped with infrared thermography (IRT) sensors to conduct physiological studies [80]. IRT has already been used to measure vital signs such as respiration rate, heart rate, or body temperature as indicators of the health and physiological condition of humpback whales [109] and North Atlantic right whales (Eubalaena glacialis) [80]. Indirect applications such as habitat studies can make use of UAVs.…”