New Trap May Take Deep-Sea Fish Safely Out of the Dark

John Roach
for National Geographic News
July 1, 2004

In the cold and dark depths of the seas, some fish attract their prey with bioluminescent lures. Others have huge mouths that allow them to chomp enough food in a single bite to sustain them for weeks.

Scientists are eager to learn more about these creatures, but whenever they try to bring them up to the surface and transport them to a laboratory, they die.

"You can only learn so much from studying dead things, and it gets really frustrating," said Jeffrey Drazen, a marine biologist at the Monterey Bay Aquarium Research Institute in Moss Landing, California.

The fish die from the tremendous and sudden changes in temperature and pressure. Many of these species live at depths of several kilometers, where temperatures are slightly above freezing and the pressure is of several hundred atmospheres. At sea level, air pressure is equal to one atmosphere, or about 15 pounds per square inch (7 kilograms per every 7 square centimeters).

As the fish are brought to the surface, their bodies, which are adapted to cold, dark, high-pressure environments, cannot cope.

For example, said Edward Seidel, enzymes, which are essential for functions such as digesting food, have specific shapes that allow them to function under the extreme pressure of the deep sea. Seidel is a curator at the Monterey Bay Aquarium in California.

"When you release that pressure, the shape of the enzyme changes, and since it changes, it no longer functions and the animal no longer can survive," he said.

To remedy the problem, Drazen has designed a high-pressure fish trap. The trap should allow him to capture fish at the bottom of the ocean and bring them up to the surface at the same pressure and temperature that exists in their native home.

"From there you could perform a variety of controlled experiments on them and do all those things intertidal marine biologists have been doing for decades, but that we have not been able to do," he said.

Drazen is keeping details of the trap under wraps until he and his colleagues publish the first of their scientific results in a peer-reviewed journal. He anticipates this sometime early next year.

Trap Applications

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