There’s a new study out that looks at the phenomenon of “site fidelity.”

That’s like when salmon swim back to the river where they were born.

And this is a pretty neat example of site fidelity: female sand tiger sharks have been spotted returning to the same… shipwrecks.

Researchers led by Avery B. Paxton of Duke University analyzed photos of the sharks taken by volunteers and other researchers, and matched up images that showed the same individual sharks.

Each sand tiger shark has distinctive spots on her skin.

And some of the photos showed certain sharks visiting the same locations in and around shipwrecks, sometimes months or even years apart.

The next big question is: why do they do it?

Paxton and other researchers haven’t figured that part out yet.

Maybe these are landmarks along the path of their migration routes.

Maybe it’s where they mate, like a pirate-themed makeout spot for sharks.

Or they may give birth there.

Nobody knows for sure yet, but now they know where to look.

And that’s important, because that may help explain why the populations of sand tiger sharks have been dropping over the last few decades.

Either that, or they’re all just hiding inside those shipwrecks.

This weekend in the island community of Port Aransas, Texas, just outside Corpus Christi, it’s the Texas Sandfest.

The event bills itself as the largest Native-Sand Sculpture Competition in the country.

You can watch some of the great sand sculpture artisans of our time create their Texas-sized masterpieces, or you can build some of your own.

Or just eat food and listen to music.

Sand Tiger Sharks Return to Same Shipwrecks Off N.C. Coast (Duke University)

Texas SandFest

Photo by The Maritime Aquarium at Norwalk via Flickr/Creative Commons