Swimming with shark pups

This story originally appeared in bioGraphic, an online magazine about nature and sustainability powered by the California Academy of Sciences.

Photograph by Jordi Chias.

This small spotted catshark (Scyliorhinus canicula) took only a few hours to emerge from its egg case. Capturing the event, however, required a whole lot more time. "I first spotted this egg five months before hatching," says photographer Jordi Chias, who returned regularly to the spot – nearly 25 meters (80 feet) below the water's surface, off the northeast coast of Spain – in hopes of witnessing the young shark's arrival into the world.

Trying to be there at that precise moment, though, presented a challenge. The time required for embryos of this species to develop varies with water temperature. The shark's geographic distribution stretches from the warm waters of the Mediterranean to the frigid seas of Norway, so hatching can take anywhere from 5 to 11 months after fertilization. Here in the Balearic Sea, it was anyone's guess.

For Chias, that meant frequent dives into the chilly waters in the hope of timing one of those visits just right. It also meant spending considerable time underwater, at great depth. "When I arrived late in the afternoon on the day of hatching, the shark already had its head out," he says. "I waited more than an hour, without moving, until it started to wriggle free."

When small spotted catsharks first emerge, they measure just 3 inches long. By adulthood, they can grow up to 3 feet in length and weigh nearly 3 pounds. Mature catsharks spend the majority of their time near the ocean floor, hunkered down by day, and cruising along the sand by night in pursuit of crustaceans, mollusks, and small fish. These habits put the sharks directly in the path of fishing trawlers and bottom nets intended to catch other bottom-dwelling species.

While there is a market for catsharks in parts of Europe, this species is not targeted as relentlessly as larger species of sharks. In fact, most small spotted catsharks are thrown back. Studies show that the vast majority of these individuals survive to swim, feed, and breed another day – and to lay a new batch of egg cases along the ocean floor.