The SharkCam project was carried out in 2013 by researchers from the Woods Hole Oceanographic Institution (WHOI), in Massachusetts, USA. The intent was to use an AUV to study shark behaviour in deeper waters (around 100 m). Although much is known about shallow water shark behaviour, little was understood about what sharks did at depth.
Figure 1. The REMUS 100 AUV used by WHOI for SharkCam 
BUT FIRST... WHY USE AN AUV?
Other methods have been used to track large animals, such as tagging them or using Remotely Operated Vehicles (ROVs) or gliders instead of AUVs (see MARINE VEHICLES - TYPES for more information on these vehicles). The disadvantages of these other methods include:
Using a REMUS 100 AUV, WHOI scientists planned to follow sharks off the coast of Mexico over a one-week period, visually capturing their behaviour . To do this, scientists mounted six high-definition video cameras on the REMUS vehicle to provide a panoramic view of its surroundings (see FIGURE for resultant footage).
SCIENTIFIC AND ENGINEERING CHALLENGES
- had to survive depths up to 350 m (sharks do not dive below 311 m)
- must stay on shark for multiple days
- Must be recoverable (made slightly positively buoyant)
- Houses a small camera for a "shark's-eye" view
- Has a release mechanism: will release if:
1. Vehicle approaches 350 m depth (save the shark and instrument)
2. Acoustically commanded to (at end of study)
- If vehicle is too far from shark (>20 m)
- Accelerate to maximum speed to close the gap
- If at close range (<=10 m)
- Slow down
- Continue past the shark and circle back
Why was this a challenge?
Since the SharkCam relied on receiving an acoustic signal back from the shark it was tracking, it could not just go to the location where it believed that the shark was, since the shark would already have moved away from this location. Thus, the SharkCam had to predict where the shark was going to be based on an estimate of where it was. Moreover, unlike a classic cops-and-robbers chase in the city, an AUV-and-sharks chase is basically a three dimensional free for all, since the sharks could move to virtually any location in both the vertical and horizontal directions.
How was this overcome?
Researchers used known patterns of shark behaviour.
Figure 2. The proposed tracking method 
HOW DID IT WORK?
The success of this mission depended on the AUV’s ability to make decisions on the fly. Using the machine version of echolocation, it would emit two sounds that would bounce off a device attached to the shark. Based on the time delay between sending these signals and receiving their echoes, along with knowledge of how sharks behave, the AUV calculated the shark's location and reset its course based on this location, landing at the calculated position within minutes and sometimes seconds.
Figure 3. Graphical representation of SharkCam tracking a shark 
WHAT WERE THE RESULTS?
- The first deep water attacks were recorded
- Attack behaviour showed that sharks tend to begin by quickly pushing the tail up; likely to incapacitate the prey and prevent it from escaping
- Attacks usually lasted 10-15 s, whereupon the shark would swim away and monitor its prey from a nearby location; likely waiting for its prey to become incapacitated
- Report noted that sharks were motivated by feeding to attack
- The majority of attacks happened in shallower depths (?); researchers guessed that the vehicle had higher visibility to sharks that stay below 100 m, as they have a better view above them and their prey have a harder time spotting them
- Sharks in Guadalupe make use of the water clarity to look for their prey's silhouette against the sky
- Footage was captured of sharks aggressively ramming the vehicle; this is believed to be a demonstration of 'intraspecific competition', where members of a species (in this case, sharks), attempt to establish their dominance - without actually fighting - when they require a shared resource. LIKE DOGS.
Note: all results were taken from 
WHOI scientists reported during their 2012 testing phase in Chatham, Massachusetts, Chatham white sharks did not show any tendency to approach the AUV from behind. However, footage from 2013 showed that sharks in Guadalupe did approach the AUV from behind, and although capturing this behaviour resulted in a reduced speed, researchers decided that the footage was worth the compromised speed - an example of balancing scientific curiousity with engineering optimization.
 WHOI. (n.d.). REMUS SharkCam deployed off Chatham, Mass., in 2012. Retrieved from http://www.whoi.edu/page.do?pid=136616&tid=7842&cid=96553
 Baehr, L.G. (2013). Swimming with Sharks: An underwater robot learns how to track great whites. Oceanus. 50(2):42-48. Retrieved from http://www.whoi.edu/oceanus/feature/swimming-with-sharks
 WHOI. (2016). Robotic Vehicles Offer a New Tool in Study of Shark Behavior. Retrieved from http://www.whoi.edu/news-release/sharkcam-paper
 Atlantas Marine Ltd. (n.d.). VideoRay Pro 4 - Filming Great White Sharks in HD. Retrieved from http://www.atlantasmarine.com/news/videoray-pro-4-filming-great-white-sharks-in-hd
 Kukulya, A. L., Stokey, R., Littlefield, R., Jaffre, F., Padilla, E. M. H., and Skomal, G. (2015). 3D real-time tracking, following and imaging of white sharks with an Autonomous Underwater Vehicle. In MTS/IEEE OCEANS 2015 - Genova: Discovering Sustainable Ocean Energy for a New World. Retrieved from http://ieeexplore.ieee.org/document/7271546/
 Packard, G. E., Kukulya, A., Austin, T., Dennett, M., Littlefield, R., Packard, G., Stokey, R., and Skomal, G. (2013). Continuous Autonomous Tracking and Imaging of White Sharks and Basking Sharks Using a REMUS-100 AUV. In Oceans - San Diego, 2013. Retrieved from https://www.whoi.edu/cms/files/SharkCam_paper_173464.pdf
Last revised: August 2, 2017
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