Though a bit unnerving at first to dive with so many sharks in the water, after a few days we became quite accustomed to these magnificent animals circling us throughout out dives. Unfortunately, this is becoming an increasingly rare sight as more than 90 percent of the world’s large predators, including sharks, have been eliminated over the past 50 years due to overfishing. Sharks certainly have more to fear from us than we do from them. Areas like Jardines de la Reina in southern Cuba are called “predator-dominated ecosystems” because of the presence of many large predators, including sharks and groupers. These predators play an important role in maintaining the health and integrity of marine ecosystems, and this was the healthiest marine ecosystem any of us had seen in the Caribbean. The corals were vibrant, as were the fish populations. Jardines de la Reina is part of the largest marine protected area in the Caribbean and has been protected since 1997. Fishing is not permitted within the reserve, and the positive effects of this policy are striking.
If you heard The Ocean Doctor Radio Show or saw the YouTube video (below) of my very first dive with these sharks, you’re probably as curious as I was as to how our divemaster, Noel, who was snorkeling, was able to grab a large silky shark by the tail, place it on his lap, and pet it, without being torn to shreds! It turns out that folding the shark’s tail in a particular way causes a nervous system reaction that temporarily puts the animal into a trance-like state known as tonic immobility, a natural state of paralysis. Scientists have taken advantage of this phenomenon to better study sharks, including attaching tracking tags (with far less harm to the animal than first catching them on hook and line). You’ll see in the video that Noel never lets go of the tail. It appears to work quite well, though Noel later told us he’s been bitten four times!
Please: Never do this! These are wild animals and need to be treated as such. There are numerous examples of humans treating animals as pets and paying a dear price for it. I am sharing this video with the hope that it helps focus attention to the importance of these animals to the health of marine ecosystems around the world.
–David E. Guggenheim