The lure of sharks - A Fascination for Fish: Adventures of an Underwater Pioneer - page 105

first problem is the actual capture of the animal; second is the method
used to transport the shark to the aquarium; and third is the design of
the tank where the shark will live. Although these problems are some-
what independent, they are also linked. And of the three, the third is
perhaps the most telling. For obviously, if you don't have a suitable hold-
ing tank ready for the shark to live in, you won't know if the first two
steps were done right.
With no prior experience to help me out, I made my best guess and
designed a relatively inexpensive, behind-the-scenes tank that I hoped
would meet the needs of a pelagic creature like the blue shark. Trying
to think like a shark—which is not easy, I found out—I reasoned that
because blue sharks are rarely found near shore, they may be able to
sense when they are approaching shallow water. They probably don't
like sharp corners, since none exist in their watery world, and, because
they swim constantly, they would most likely do best in as large a tank
as possible. With those parameters in mind I designed a circular tank
with a bottom that sloped up, becoming shallower toward the outer
perimeter. Its size, fifty feet in diameter, was limited by how much
money was available for the whole project. Bigger would obviously have
been better, but you work with what you can get.
While the tank was under construction, we experimented with cap-
ture and transport methods. I had fished for blue sharks with rod and
reel before from my own boat and knew from experience that they have
a keen sense of smell and good vision. Our method of finding them
was to take advantage of that sense of smell and allow them to find us.
A fifty-pound burlap sack of ground mackerel was towed slowly be-
hind the boat for half a mile or so, leaving a trail of odor that would
smell like lunch to an almost-always-hungry blue shark.
For transport, we had a seven-feet-long-by-two-feet-wide plastic-
lined tank made. It was restricted in size—but, I hoped, not too tight—
because we were working out of a small, but fast, eighteen-foot out-
board that didn't have much room or weight-carrying capacity. Know-
ing that the blue shark normally swims constantly in order to pass water
over its gills, I made a flattened plastic mouthpiece that fit inside the
animal's mouth. The mouthpiece had five holes on each side that the-
oretically lined up with the five gill slits of the shark. Through this de-