Got Sharks?
By David Feeley
Can sharks live in an aquarium filled with their favorite food (smaller fish), plus human
divers, without eating the fish or taking a chunk out of the humans?
No problem, says Dan Laughlin, assistant curator and manager of the Giant Ocean Tank
(GOT) at Boston’s New England Aquarium. Laughlin says he and his staff simply feed the
sharks “by hand” — actually using a pole to get some distance — twice a day to make sure
they aren’t hungry. That takes care of the other fish. The second part of the solution isn’t
quite so simple. According to Laughlin, who has been looking after the GOT for 30 years,
“the sharks and divers both respect and carefully watch each other.” Sounds reasonable. As
long as you’re not the human doing the feeding, watching, and respecting, while enclosed in
a 200,000-gallon tank.
The GOT is a massive glass tank that encloses a replica of a Caribbean coral reef inhabited
by 600 to 800 marine animals, encompassing 100 different species. Three sand tiger
sharks, each from eight to nine feet long, and weighing between 200 and 300 pounds, and
a smaller nurse shark also call the tank home. The coral reef spirals up halfway through the
tank, so the big fish that need lots of room usually stay in the top half. Small fish usually
stay below, where they can snatch up food dropped by larger feeding fish. The sand tiger
sharks move freely through most of the tank, while the nurse shark stays on the bottom or
under coral shelves, according to Laughlin.
Moving Day
But how did these hefty sharks come to reside in the GOT? They certainly didn’t swim there.
Sherrie Floyd, senior aquarist at the aquarium and a GOT diver, says shark acquisition
usually begins with a phone call from another aquarium or when a commercial fisherman
has accidentally caught a 2- to 3-foot shark pup in his net. If the GOT curators decide to
give it a home, preparations are made quickly for taking a traveling life-support system to
the shark. The system includes an appropriate size tank that will be filled with water from
the shark’s original environment, an oxygen supply, and circulation and filtration systems.
Temperature inside the tank is important, according to Floyd. If the trip is long, heaters or
coolers are used to gradually adjust the shark to the 76-degree-Fahrenheit (F) temperature
of the GOT. If the trip is short, the shark is acclimated on site before it is placed in the tank.
Floyd says the sand tiger sharks are able to tolerate a wide range of temperatures, but the
nurse shark, a tropical species, needed to adjust to its new environment.
Taking the Plunge
How do you get a 300-pound fish into the GOT? Gently. “The shark is brought in on an
enclosed stretcher,” says Floyd. “He may have been given a medicine to calm him down
while traveling.” Then a “dedicated, caring team of divers” releases the shark at the bottom
of the tank. “They stay near him to help if needed, and they may even coax him up to
higher waters,” says Floyd, quickly adding that for safety and other reasons there is a “notouch policy.” The shark is then allowed to adjust at its own pace. “Each shark is different so
divers stay near and keep the tank’s lights on until he feels comfortable in his new home,”
says Floyd.
Making new Friends
So how do the other fish react to their new, rather large, roommate? According to Floyd, the
other fish are so used to changes in the tank that they hardly react at all. “Predators don’t
waste energy by actively hunting unless they have to,” she says. “So the other fish are safe
as long as our sharks are well fed.” During feeding time, puffers, sea turtles, and smaller
fish are so bold that they often swim too close to snatch food for themselves, Floyd notes,
adding, “Sharks are still predators and so we worry that they might take something that
looks better than what we have to offer or get a fish by accident while going for other food.”
Humans and Sharks in the GOT
How about the divers who must go inside the tank to feed the sharks? According to Floyd,
the sharks don’t recognize her from other divers, but they “do connect seeing us with meal
time and come to us for food.” Feeding is done using a bright yellow or orange, 2- to 3-foot
long, pointed pole, so both the sharks and divers can watch each other. Visiting divers —
one New England Aquarium Dive Club member over age 18 is selected by a lottery each
month to go inside the tank — are not allowed to enter the tank at feeding time.
When entering the GOT, divers act like they’re crossing a street; they look in both directions
and then look again to see what’s happening around them. Floyd likes to feed the sharks at
the “big sand tray,” the most open area of the tank. She moves about halfway down the
tank, keeping the reef to her back so no sharks can come in unseen from behind her. Then
she waits for a lone shark to enter the sand tray. Food (herring, mackerel, squid, capelin, or
smelts, all frozen to kill parasites) is placed on the end of the pole and squeezed to release
its scent into the water. The sharks are also given vitamins, hidden inside their food.
Feeding can get aggressive when all four sharks come at once, or when Floyd finds herself
too near the bottom of the tank, where she has less control of the situation. If this happens,
she stops feeding and moves to a better position and starts again.
“Herring and mackerel are the shark’s favorites,” Floyd says. “Only the most experienced
divers can feed them these fish. The scent stops a shark dead in his tracks! It rolls back its
eyes, turns its snout down, and spins toward the diver,” she says.
Laughlin, who also dives, says, “It’s amazing how fast one of these sharks can change its
actions. One moment they’re just aimlessly swimming around the tank. Then suddenly, one
goes into hunting mode. It spirals down in tight circles from the top to the bottom of the
tank.”
Sharks on Our Menu
Both Laughlin and Floyd want us all to respect, rather than fear, sharks. “There really is no
such thing as a man-eating shark,” says Floyd. But each year humans kill 40 million or more
sharks because of fear or for their fins, liver oil, skin, cartilage, and meat. Millions more are
captured accidentally by commercial fishermen. Countless others die because of human
destruction of their habitats.
“People are seldom on a shark’s menu,” Laughlin says, “As apex (top-order) predators,
sharks are an important part of a healthy ecosystem.” Laughlin encourages ODYSSEY
readers to “join an aquarium near your home, and be an active member, learning all you
can. Then support those working to make life better for sharks, all marine animals, and all
life, including our own.”
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