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05.10.2015 03:17 Age: 2 yrs
Category: Home Slider, ANFOG, WA-IMOS

Ocean glider attacked by shark

An IMOS ocean glider was attacked by a shark off Yanchep, Western Australia. It has been recovered but has come off a little worse for wear.

Bite marks can be seen on the housing of the ocean glider

Sensors, beneath the glider wing, have been bitten off

The attack happened at 09:55 UTC at a depth of 15 m. Telemetry shows a sudden roll of more than 15 degrees and a change of direction to the west

Tracking of the glider indicates a change of direction and erratic movement following the attack

This is not the first time one of these devices, which glide through the water collecting data on ocean salinity, depth, oxygen levels and temperature, have been bitten. Shark attacks on these and similar remotely controlled devices do happen from time to time but this was the worst damage recorded in the program's six years.

Glider pilot Kah Kiat Hong noticed something wrong at 5:55 pm local time on 24 September and ordered an emergency recovery. Despite there being significant damage to the unit, including the loss of one wing and the destruction of sensors that measure salinity, temperature and depth, the glider could still be piloted and was recovered by researchers.

Professor of Coastal Oceanography at the University of Western Australia and leader of the IMOS Ocean Gliders facility, Charitha Pattiaratchi, believes the shark was about four metres long, based on the bite marks on the two-metre long glider.

"It looks like the shark came from beneath and bit it and took the whole thing in its mouth," Professor Pattiaratchi said.

"The glider is about 30cm in diameter and the shark took a pretty big mouthful of it,” he said.

The position of the glider is monitored by the pilot, with direction, orientation and depth being recorded along the way. The chart, shown here on the right, indicates that the attack happened at a depth of 15 metres. The data also show a sudden roll greater than 15 degrees and the heading being spun 90 degrees to the west. After the attack the heading returned to normal and the glider continued as if nothing had happened. 

There is extensive damage to the carbon fibre housing and sensors have either been broken or bitten off completely. Once the housing and sensors are replaced the unit will be redeployed to continue monitoring ocean variables and providing data for future research.

This video, from Woods Hole Oceanographic Institution, shows a great white shark attack on a remotely controlled REMUS ‘SharkCam’.