Autonomous underwater videography and tracking of basking sharks

Abstract

Background Biologging studies have revealed a wealth of information about the spatio-temporal movements of a wide range of vertebrates large enough to carry electronic tracking tags. Advances in autonomous underwater vehicles (AUVs or UAVs) and unmanned aerial vehicles (commonly known as drones), which can carry far larger payloads of sensor technologies, have revealed insights into the environment through which animals travel. Some AUVs have been used to film target animals, but are generally limited to periods as long as a drone operator can actively follow an animal. In the present study, we use an AUV, the REMUS-100 SharkCam, paired with a custom transponder tag attached to the shark, to autonomously follow three basking sharks for a cumulative total of 10.9 h to collect video and environmental data on their sub-surface behaviour. The basking shark is the second largest fish in the world and is endangered globally, but despite being subject to various biologging studies, little is known of this species breeding ecology and their mating grounds remain unknown. Results We detail the first successful autonomous tracking of basking sharks, comprising three missions that filmed basking sharks in mid-water and close to benthic habitats. Sharks spent very little time feeding, and travelled relatively close to sandy, rocky and algae-covered benthos. One basking shark was observed defecating. Conspecifics were not observed in the three missions, nor were courtship or breeding behaviours. AUV offset distances for videography were determined iteratively through tracking. These offsets varied depending on the trade-off of between water clarity and proximity of the AUV for obtaining useful video data and directly influencing shark behaviour. Conclusions The present study is the first successful use of an AUV to gain insight into the sub-surface behaviour of basking sharks.

An engineering perspective on the development and evolution of implantable cardiac monitors in free-living animals

“…An interest in bear hibernation also prompted an early use of physiological biologgers, pioneered in the early 1970s using custom-designed devices [ 17 ]. Subsequent to this, the field of physiological telemetry emerged, including technological advancements enabling research on both wild and captive animals [ 6 , 18 – 21 ]. Our team has been using devices designed for human clinical uses, or modifications to such devices, for more than two decades in field investigations focused on heart rate (HR) modulations and the physiology of American black bears ( Ursus americanus ) [ 22 – 32 ].…”

“…Subsequent to this, the field of physiological telemetry emerged, including technological advancements enabling research on both wild and captive animals [6,[18][19][20][21]. Our team has been using devices designed for human clinical uses, or modifications to such devices, for more than two decades in field investigations focused on heart rate (HR) modulations and the physiology of American black bears (Ursus americanus) [22][23][24][25][26][27][28][29][30][31][32].…”

Drivers of Spatial Distributions of Basking Shark (Cetorhinus maximus) in the Southwest Pacific

“…Meeting these requirements has prevented any efforts of tagging New Zealand basking sharks to date. In the Atlantic Ocean, basking sharks have been successfully tagged off Cape Cod, Massachusetts and the west coast of Scotland and Isle of Man (Skomal et al, 2009;Doherty et al, 2017;Hawkes et al, 2020) and in the Pacific, off San Diego and Monterey Bay, California (Dewar et al, 2018). By identifying areas of high habitat suitability, research efforts can be directed to specific areas of interest to increase the tagging success.…”

“…Basking sharks may travel or feed in subsurface habitat, and therefore go undetected in aerial surveys. Alternative means of tracking these animals, such as autonomous underwater vehicles (AUV) (Hawkes et al, 2020) offer great potential for the future.…”

Validating a high-throughput tracking system: ATLAS as a regional-scale alternative to GPS

“…Fortunately, alternative systems for tracking animal movement are continuously being developed in an attempt to bridge these gaps (Williams et al, 2020). These form a diverse toolset for biologging, ranging from autonomous underwater videography (Hawkes et al, 2020) to using biomarkers from tail hair to detect movement through landscapes (Kabalika et al, 2020). Despite these advances, few of these technologies can attain the fine-scale tracking of movement paths which are a necessity for identifying decision points of individuals (Collet et al, 2017; Harel et al, 2016) or groups (Strandburg-Peshkin et al, 2015), or correlating movements with precise environmental covariates (Dickie et al, 2020; Eikelboom et al, 2020).…”