Sharks like to eat seals.  Everyone knows that.
 
NPR has a story about some shark researchers in South Africa, who lure sharks to strike simply by floating surfboards on the water.

"To a shark, apparently, a nice little six-foot swallowtail does a near-perfect imitation of a seal. When retrieved, the decoys were often missing hubcap-sized chunks from their sides"

Correction: sharks like to eat things shaped like seals.

Here’s a site dedicated to "all things sharky…and other aquatic antics."