Marine Wildlife Conservation: Jon Dohlin Talks Sand Tiger Sharks, Conservation Efforts And New Exhibit [SCIENCE WORLD REPORT EXCLUSIVE INTERVIEW]
In the early days of January, the New York Aquarium, run by the Wildlife Conservation Society, announced the discovery of a sand tiger shark nursery ground in Long Island's Great South Bay. The discovery was confirmed after years of tracking and monitoring area-specific juvenile sharks, and asking around local marinas to see if the fisherman there had helpful information. Sand tiger sharks are defined as a "species of concern" by the U.S. National Marine Fisheries Service, making the nursery ground's discovery a huge step forward in the aquarium's conservation efforts.
Jon Dohlin, the New York Aquarium's vice president and director, believes the find will greatly improve the aquarium's efforts on awareness of the need to save and conserve marine wildlife in the New York Seascape (how the aquarium refers to the local waters), and sand tiger sharks are a key part of that effort.
Sand tigers are an extremely misunderstood species of shark, according to Dohlin. Although about 6- to 10-feet long, boasting a menacing look and somewhat scary characteristics, they generally are not a danger to human beings, with no registered human fatalities to their name, according to the Shark Attack Survivors database. In fact, their mouths are not considered large enough to cause a human fatality. Sand tigers prey on fish and other sharks that are about half their size or smaller, generally combing the sea floor when they hunt, mostly nocturnally.
"They have these 'snaggliy' teeth; they're very shark-y looking sharks. They cruise very slowly - they're coastal sharks so they're slow swimmers - and the fact is they're fairly commonly seen by fishermen in this area because they are around," Dohlin said. "But the truth is they represent absolutely no danger to human beings. Our staff divers dive with these animals on a regular basis. They are, if anything, quite timid in terms of their interactions with human beings."
Sand tigers are commonly sighted around the world, leading to the misconception that they hold solid numbers and are not a species that's at risk for becoming largely endangered. However, due to an unusually low reproduction rate and having their meat highly prized in parts of the world, among many other causes, they're an at-risk species.
"We know, like every other shark species in the world, when these guys migrate they're not always in protected waters. They do move off shore and into deeper waters at certain parts of the year. So they are threatened, they're a vulnerable species right now," Dohlin said about the sand tigers. "Sharks in general, as you know, are subject to tremendous pressures through the fishing industries. So their populations have been hammered. The biggest misconceptions are that sand tigers are doing fine and that they pose a threat to human beings - neither one of those things are true."
The aquarium has been studying sand tigers for more than a decade, using acoustic tagging and tracking their movements. The team uses the data to help in their efforts to save the species and protect them from the dangers around them.
"Our work in tagging sharks, to be honest with you, has always been predicated in some respect of the fact that we have sand tigers in our collection," Dohlin told Science World Report. "We're sort of experts on sand tigers, both from a veterinary health standpoint and from a husbandry standpoint, so it made sense for us to study those animals. We have data from the captive collection and data from the wild; we get both directions."
The nursery ground was discovered through efforts in tagging mainly juvenile sharks. Dohlin won't reveal the location of the ground - which is in his words "interestingly small" - in hopes that the area can be studied without the disturbance of people, for good or bad reasons. He said that although the aquarium has been tagging the sand tigers for about five or six years, it didn't start tagging juveniles until only a couple years ago.
"That's what's really made it interesting, is in the last two to maybe three years we've been tagging these juveniles and getting some pretty good data on them," he said. "But we've been getting returns to that site from animals that we've tagged, and that's what really keyed us off to the site-specific nature of this nursery."
Site-specific behavior is when a species continuously returns to or acts around a singular, specific location - and these juvenile sharks were constantly coming to the Great South Bay when they were within a specific age range, which tipped off the aquarium's team to the potential existence of the nursery ground. Dohlin says they knew almost immediately that this area must be important.
"Knowing that there are these key areas in which they're spending key times of their life cycles, naturally they are important because now that has a big impact. These animals are in these nurseries at their most vulnerable stage," Dohlin said. "They're pups down south of here, and they're quite small when they're pups. Large by numeral standards in terms of fish, but still, for sharks they're quite small - about 8 to 12 inches long. They move up the coast and they enter these nursery areas. And it's not part of the migration pattern, they're very clearly in these sites, these nurseries, for that key period of time. You know, they're moving back and forth themselves, but they're up in these nurseries because they're protected. When they're at their smallest and most vulnerable in terms of predation by others, they are finding these places where they can grow out successfully."
The discovery of the nursery ground also coincided - serendipitously - with the aquarium's building of a new exhibit focusing solely on sharks, called Ocean Wonders: Sharks!. The 57,000-square-foot exhibit is set to open in 2017, and will boast a 500,000-gallon tank that will, of course, contain sand tigers. The tank should hold about a dozen of them, along with somewhere between 12 to 18 sharks of other species that call the New York area waters home, Dohlin says.
The exhibit's main focus will be to echo the aquarium's sentiment about conservation of the New York area's species. It will aim to bring attention to the conservation efforts of the aquarium, and to make the idea of keeping species like the sand tiger shark protected a part of the conversation.
"What's really amazing is New York is this incredible place. It's got this diverse wilderness - marine wilderness - right off shore from this incredibly dense, urbanized area. So those two things being right next to each other is wild, but it's also something that deserves appreciation," Dohlin told Science World Report. "People should appreciate that fact, but also take very seriously their responsibility to protect that wilderness. So this exhibit is all about getting people on board with that."
But the team isn't stopping there. In the next few years, it's seeking to create a national marine sanctuary - the first in the mid-Atlantic region - around the Hudson Canyon, the east coast's largest submarine canyon. If this goal is achieved, it could potentially protect not only sand tigers, but many of the species that make use of the local waters, including gray whales that migrate up and down the coast in the area, according to Dohlin. The creation of a sanctuary in the Hudson Canyon would allow the aquarium to better understand the marine wildlife, which would in turn aid in the protection and conservation of the local species.
"We want to understand the habitat usage of these animals and we want to create this sanctuary around the Hudson Canyon to help protect those animals, and help protect this great marine wilderness that exists right here in New York," Dohlin said.
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