Related Experiment Video
Updated: Oct 26, 2025
10:56
Long-term Behavioral Tracking of Freely Swimming Weakly Electric Fish
Published on: March 6, 2014
12.7K
Basking shark sub-surface behaviour revealed by animal-towed cameras
Jessica L Rudd1, Tiago Bartolomeu2, Haley R Dolton3
1Hatherly Laboratories, University of Exeter, College of Life & Environmental Sciences, Exeter, United Kingdom.
Plos One
|July 28, 2021
Summary
Animal-borne cameras revealed basking sharks (Cetorhinus maximus) spend most daylight hours near the seabed, not just the surface. This study also documented novel sub-surface behaviors, including courtship and grouping, offering insights into their ecology.
Area of Science:
- Marine Biology
- Animal Behavior
- Ecology
Background:
- Biologging tags provide ecological data, but understanding marine vertebrate movement and activity drivers remains challenging due to observation difficulties.
- Basking sharks (Cetorhinus maximus), the world's second-largest shark, aggregate at foraging sites, yet their breeding ecology and sub-surface behavior are poorly understood.
- Advances in camera technology offer potential for environmental context and validating telemetry data for marine species.
Purpose of the Study:
- To investigate the sub-surface behavior and ecological context of basking sharks using animal-borne cameras.
- To validate movement and activity patterns recorded by conventional telemetry.
- To gain unprecedented insight into the social and environmental drivers of basking shark behavior.
Main Methods:
- Six basking sharks were tagged with towed cameras, time-depth recorders, and satellite telemetry at a foraging site in the Sea of Hebrides, Scotland.
- Collected 123 hours of video data over an average 64-hour deployment per shark.
- Analyzed video footage to determine water column position, feeding events, tail beat frequencies, and observed behaviors.
Main Results:
- Basking sharks spent up to 88% of daylight hours near the seabed, with feeding events occurring within one meter of the surface.
- Tail beat frequencies remained consistent regardless of depth or activity (feeding, swimming).
- Documented the first complete breaching event, sub-surface courtship displays (nose-to-tail chasing, parallel swimming), and grouping behavior near the seabed.
Conclusions:
- Animal-borne cameras provide crucial insights into the social and environmental context of basking shark behavior, extending beyond surface observations.
- Observed grouping behavior may be short-term and sporadic, potentially facilitating mate finding for breeding in this typically solitary species.
- The study significantly advances our understanding of basking shark ecology, particularly their little-known sub-surface activities and social interactions.
