Shark Sex Ed.

On our first day in Florida, we went to the Everglades and grandpa Mike (TA) struck up a conversation with a fellow grandpa, who turned out to be Wes Pratt from the Mote Marine Lab! It turned out that Wes was doing a presentation on nurse shark mating at the Ernest F. Coe Visitor Center at the very time that we were visiting. We were psyched! Shark sex!

We learned a lot of interesting details about nurse shark mating (maybe a little too much detail, thanks to one very interested audience member...) Wes and his wife, as their retirement hobby, would sail to the Dry Tortugas 70 miles west of Key West. This area is uninhabited and only disturbed by visitors, so wildlife can be mostly wild and free. Wes would set up a ladder system to observe nurse sharks so that he does not scare off wildlife and harm bottom habitats. They would capture nurse sharks in a large handmade net of trawl line. They would measure the nurse sharks, identify species, and place a tracker to see where sharks were migrating if any. In addition, he would capture footage of nurse sharks mating. 

The females would wade in extremely shallow water in groups, making it difficult for males to climb aboard. The males would attempt to bite the female’s pectoral fin in order to drag them to deeper water and wrap themselves around her to mate. In response, the females would flip themselves over to block the male from mating. The females mate every one to three years and may have a few groups of pups of varying ages with different fathers. The females are tired of being bothered by the males, and they are rejected most of the time. If a male does drag the female into deeper water by her pectoral fin, sometimes the female will give in and agree to mate. The females will migrate to the west coast of Florida while pregnant and likely giving birth. When this cycle is done and they are ready to mate, they come back to the Keys. You can see the published paper by Pratt and others here: Partial migration of the nurse shark, Ginglymostoma cirratum (Bonnaterre), from the Dry Tortugas Islands

We saw these beautiful animals while scuba diving in Pleasure Reef off of Key Largo. These are benthic animals that feed off of bottom fauna and hide on the edges and under reefs most of the time with the other larger animals, like moray eels or blue parrot fish. They were a beautiful site to see!