Hundreds of Spinner Sharks Filmed Off Texas Coast in Rare Congregation

Hundreds of spinner sharks have been filmed swimming off the Texas coast, in a rarely seen congregation.

Footage captured by PhD student Kelsey Martin, a researcher at the Center for Sportfish Science and Conservation, shows the "massive" congregation swimming around an artificial reef, in the Gulf of Mexico near Port O'Connor.

The artificial reef was created by the Texas Parks and Wildlife foundation and the Coastal Conservation Association to provide more habitat for marine life.

The Gulf of Mexico has very few naturally occurring reefs, meaning that man-made structures like this one give invertebrates such as barnacles, corals, and clams the surface they need to thrive. Over time, the reef has become a valuable part of the food chain, providing a habitat and source of sustenance for other fish species.

Sharks congregate in areas where there is plenty of prey. The spinner shark congregation is "solid evidence" that the artificial reef has become a valuable part of the ecosystem, Texas Park and Wildlife said in a Facebook post, which can be found here.

More sharks indicate more prey in the area, meaning that the reef has developed a "diverse and healthy fishery," it said. In another Facebook post, the Center for Sportfish Science and Conservation said the video was a "world class example" of shark congregating behavior.

Texas-based marine biologist and shark expert Jonathan Davis told Newsweek that a shark congregation is rare because large sharks are quite solitary.

"[Spinner sharks] do not have complex social communities and generally only come together for mating or dense opportunistic feeding events," he said. "The fact that there are in fact so many spinner sharks suggests that their population is doing fine ... and they are adapting to these new reef systems and food sources quite well. Also, these reefs are a great thing, showing they bring together a solitary species."

The sharks were filmed in close proximity with a diver. The sharks did not appear aggressive towards them.

Spinner sharks are known for their distinctive spinning behavior while hunting. The sharks spin as they move through the water, snapping up fish. While doing this, they often jump out the surface of the water and spin through the air. Sometimes they jump as high as 20 feet above the water surface.

The spinner shark is found across the western Atlantic to the southern waters of Brazil. They are known to migrate off the Florida and Louisiana coasts and in the Gulf of Mexico, moving inshore during spring and summer to mate and feed.

They are considered a near threatened species in most places, however they are vulnerable in the northwest Atlantic Ocean because of habitat loss.

Because it is attracted to inshore waters, spinner sharks are particularly susceptible to habitat destruction—the Gulf of Mexico in particular is a hotspot for commercial and recreational fishing and diving.

Spinner sharks reach an average size of about 6.4 feet, however can grow to over nine feet. The spinner shark is not considered particularly dangerous to humans, with only 16 unprovoked attacks recorded.

This article was updated to include quotes from Jonathan Davis.