Deep-Sea Fish Trap Sheds Light on Ocean's Slowest Denizens

May 31, 2007

A new, high-tech fish trap is bringing to light why life in the cold abyss of the deep dark sea moves really, really slow.

The trap has thick, pressure-retaining steel walls that allow scientists to capture fish in the deep sea and bring them alive to the surface to study their exceedingly slow metabolism.

Sea creatures caught several thousand yards deep with nets or cages like those used to snare lobster and crab almost always die on their way to the surface.

"It's very frustrating working on dead things," said Jeffrey Drazen, a marine biologist at the University of Hawaii at Manoa who designed the new device.

The trap is a 6-foot-long (1.8-meter-long) cylinder with two- to three-inch (five- to eight-centimeter) thick stainless steel walls. It weighs about 1,500 pounds (680 kilograms).

One of the end caps is fitted with a door that opens inward. A baited hook dangles on the end of a spring-loaded steel cable. When a fish takes the bait, the hook sweeps the fish into the trap and the door snaps shut.

The trap is attached under an array of spherical glass floats that provide enough buoyancy to lift the trap to the surface once the researchers jettison iron ballast that weighs the contraption down.

Instruments and cameras inside the trap allow scientists to monitor a captured fish's behavior and biology.

Preliminary tests with the trap allowed Drazen and colleagues to snare fish at depths of 11,500 feet (3,500 meters) and study them at the surface for several days.

Slow Zone

The animals' metabolic rate—how quickly they use energy—is of key interest.

"The pace of life down there is incredibly slow," Drazen said. The researchers measured metabolic rates about ten times lower than at the surface.

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