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There are some shark species that seem to do okay in aquariums.
You’ll see a lot of nurse sharks, zebra sharks, some reef sharks and sand tiger sharks. But not the great white.
For decades, aquariums have tried to contain the world’s largest predatory fish.
Institutions like Marineland, SeaWorld and the Steinhart Aquarium repeatedly took in white sharks during the 1970s, 80s and 90s, at times drawing huge crowds.
But they never lasted long. Some needed help swimming. None of them would eat.
The longest one lasted was just 16 days.
A 1984 report by the Steinhart Aquarium put it this way:
"In most cases it could be said that all these captive sharks were merely in the process of dying, with some taking longer than others."
They had constructed an elaborate transport tank with a harness and IV fluids, but still couldn’t keep the sharks alive.
It wasn’t until 2004 that the Monterey Bay Aquarium proved that it was possible to keep white sharks for at least six months.
It took a massive effort, and no one’s done it since.
Our approach was one of sort of a systematic, logical sequence of things leading up to our success and it started with designing a tank.
The Monterey Bay Aquarium had a million gallon, egg-shaped tank, 35 feet deep, designed for open-ocean animals like tuna and sharks.
So you need a big tank. You also need a small shark.
Adult great whites reach 15 feet on average.
The Monterey Bay Aquarium nabbed one in 2004 that was 4 feet, 4 inches, less than a year old.
That made it easier to move and easier to keep.
When they’re young they feed on fish. And as they get older they transition to feeding more on mammals.
And so we were targeting the age bracket where we knew we were more able to feed their natural diet.
And once they collected the shark, they didn’t take it straight to the aquarium.
Instead, the Monterey Bay team set up a 4 million gallon pen right there in the ocean.
That way they could monitor the shark and see if it would feed before they moved it into a transport tank to travel from southern California where the sharks were born up to the aquarium.
Sharks, like all fish, need to have water continually passing through their gills in order to get oxygen.
Most species can open and close their mouths to pump the water through. But white sharks
and a couple dozen other species don’t do that. To breathe, they have to move forward
through the water with their mouths open. That’s why white sharks start to weaken
as soon as they’re caught in a net. And that’s why they needed a custom built transport
tank with mobile life support.
JON HOECH: Everything from oxygen sensors and video cameras and lighting and filtration systems that were needed for what turned out
to roughly be 9 to 11 hour transport time.
Aquarium attendance jumped 30 percent while the shark was on display.
After 6 and a half months, they decided to
release it because it had killed 2 other sharks.
Over the next 6 years, the aquarium displayed 5 more baby white sharks - some they paid
fishermen to hand over, some they caught themselves. Their stays ranged from just 11 days up to
5 months. The Monterey Bay Aquarium had succeeded in doing what no one else could.
But it did take a toll on the sharks. They developed visible sores from bumping into the sides of the tank.
SEAN VAN SOMMERAN: We actually snuck in with
photographers and took pictures of the sharks as they were beginning to attrit and fail
due to the constant scraping against the walls basically. As we viewed it, it was a vase
of flowers that would be kept for the visitors. Historically, aquariums kept sharks that lived
near the seabed or near reefs. That makes sense - it’s easier to recreate those
habitats in a tank. But in recent decades, aquariums have wanted to bring in bigger,
more pelagic sharks, those that spend time roaming the open ocean.
They’ve even been able to exhibit the largest shark in the world, the whale shark,
if they have a big enough tank. But pelagic sharks are used to being able
to swim long distances without obstructions, changing directions only as they please.
So the faster-moving sharks like the white shark, mako shark, and blue shark,
they have trouble with walls when they’re put in a tank.
That’s what was happening with the Monterey Bay Aquarium’s sixth white shark in 2011.
They decided to release it after 55 days and its tracking tag revealed that the shark died
shortly after being released. They’re not  sure why.
But since then, they haven’t tried bring in another great white shark.
JON HOECH: It’s just a very very very resource intensive program and we felt like we had
accomplished our goal of introducing the general public to a live white shark.
It took a huge, carefully planned system to keep a white shark alive. And even then,
the sharks didn’t quite fit there. We can’t seem to stop trying though.
Earlier this year, an 11.5-foot great white shark was taken to an aquarium in Okinawa, Japan
after getting caught in a fisherman's net. It was the only adult white shark ever to
be put on display, and within 3 days
it was dead.
I wanted show you a great resource online called the Biodiversity Heritage
Library - it’s the product of a couple dozen museums and libraries all agreeing to scan millions of
pages from books related to biodiversity. They’ve got a bunch of great albums on Flickr,
including one that's all about sharks. Some of these go back to the 16th and 17th centuries,
back when the naturalists used to call sharks “sea dogs”
which is funny because as we now know
sharks were roaming the oceans for about 300 million years
before the first mammals showed up.
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為什麼水族館都沒有大白鯊? (Why no aquarium has a great white shark)

12452 分類 收藏
韓澐 發佈於 2017 年 10 月 9 日    Debra Liu 翻譯    Crystal Wu 審核
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