How do you measure free-roaming sharks without being bitten?

Measuring a shark out of water can be a risky, time-consuming effort, so shark researchers from Australian universities have come up with a novel approach to safely measuring these fish underwater.

The Save Our Seas foundation is funding a project to measure the growth of sharks in Palau — the researchers use cameras, a good distance, and the power of ratios to determine the lengths of these oceanic carnivores:

Paired video cameras in housings film the sharks and a diode (light) in the front of the cameras allows the researchers to synchronize frames of the video. Using principals originally developed for aerial photography, these researchers are then able to calculate the length of any body part and total size of the animal with a precision of a few millimeters. The technique is so accurate that the researchers can recognize individual animals by their body proportions. By repeatedly filming the same animals over a number of years, they will be able to measure growth rate of these sharks.

How do you measure free-roaming sharks without being bitten?S

[Spotted on The Scuttlefish. Photos via Peter Verhoog]