If you're neither a marine biologist nor a shark, then you likely aren't familiar with the White Shark Cafe. It's an area of the Pacific Ocean half-way between California and Hawaii, where large great white sharks congregate every year. While there, male sharks make dives down to depths of 250 meters (800 feet), up to 150 times a day. Why do they do it? No one knows, which is why scientists from the Monterey Bay Aquarium Research Institute (MBARI) are developing a "shark-cam" tag to stick on their dorsal fins.

The camera-equipped tag was conceived by MBARI white-shark expert Sal Jorgensen, and is being developed by engineer Thom Maughan.

Basically, the plan is that it will be clipped onto large male great whites' dorsal fins while they're still in California, by coming up along beside them in a boat. Over the next nine months, the sharks will travel to the cafe, stay there for two or three months, then return. Once back in California, the tag will automatically release from the fin and float to the surface, where it will send out a satellite signal for subsequent retrieval. After it's scooped out of the water, scientists can view the footage to see what happens during the dives – current theories include feeding or mating behaviour.

Of course, the camera can't record continuously the whole time. Instead, a combination of depth, light, acceleration and temperature sensors will ensure that it only records during the deep dives at the cafe. When at shallower depths, it goes into a battery- and memory space-saving sleep mode.

Prototypes of the tag were tried out on great whites in South Africa last year, for periods of up to five days. Jorgensen and Maughan are continuing to refine the design, and hope to have it ready for deployment to the White Shark Cafe next year.

More information is available in the video below.

Source: MBARI

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