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Longer lives from a mass death
Pat Ryan
December 02, 1968
Dying salmon may help science in its study of man's longevity
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December 02, 1968

Longer Lives From A Mass Death

Dying salmon may help science in its study of man's longevity

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In a most unlikely place—the trackless land of British Columbia, where bald eagles still wheel over evergreen ridges that shelter moose, mountain sheep and bear—today's medical scientists are fishing in some of the world's finest salmon waters for a fountain of youth. What they are seeking, specifically, are clues to aging in the Pacific salmon, a fish programmed by nature to die within weeks of leaving the ocean to spawn in the river of its birth. In those short weeks the salmon ages as much as a man does in 20 to 40 years.

Intrigued by the phenomenon of these salmon, the Scripps Institution of Oceanography in La Jolla, Calif. invited 37 specialists, 12 of them medical doctors and 25 of them biological scientists, to go fishing for facts on the Bella Coola and Dean rivers in British Columbia. The group included blood, brain, bone and heart experts, specialists in tropical and children's diseases, a milk biochemist from Penn State's Department of Dairy Sciences and an authority on liver enzymes from the Hadassah School of Medicine in Jerusalem. As they headed south from Juneau, Alaska last August on Scripps' 133-foot, 300-ton floating laboratory, the Alpha Helix, Professor Gerard Milhaud of the University of Paris admitted he had never touched a live fish (and it took him a couple of weeks on the Bella Coola before he would pick up a squirming salmon).

The fishing equipment on board was as unsophisticated as Huck Finn's, but the scientific gear was something else. The Alpha Helix carried a $35,000 electron microscope that magnified objects up to 40,000 times their size, an $8,000 centrifuge that separated various elements in blood samples and diamond knives that could slice tissue specimens as thin as one-millionth of an inch. The $1.4 million ship was built three years ago so that biochemists and medical men could study various scientific problems on the spot, make conclusions on an experiment and then quickly proceed to the next question.

For the Scripps' salmon fishing party the original goal was to determine if coho, sockeye and pink salmon contract heart disease in the stress of spawning and if this is actually what kills them. For five years Dr. Robert Van Citters, a cardiovascular physiologist at the University of Washington, who was the one avid fisherman included in the expedition, had been sectioning the hearts of fish he caught on Northwest rivers. In spawning steelhead trout he had almost always found evidence of coronary disease. However, the steelhead taken at sea, before they entered the freshwater rivers to spawn, showed few traces of coronary degeneration. Unlike the Pacific salmon, the steelhead does not die upon spawning but returns to the ocean. When these fish reentered the salt water, Dr. Van Citters discovered, they recovered from the coronary disease. An earlier study showed salmon also suffered coronary trouble—similar to that found in people affected by hardening of the arteries. The scientists hoped that from the salmon and steelhead they could learn something significant about the causes and cure of heart disease.

Soon after their arrival in the town of Bella Coola a few of the group went 40 miles north to the Dean in search of steelhead. With the approval of national and local fishery departments, they set about stringing nets across the river. In the fast current they slipped, splashed, lost their nets and almost were swept out to sea. The next day they tried fishing with light tackle. Again, no success. That ended the steelhead study.

Meanwhile, back at the ship, pulmonary specialists investigating the hearts of the spawning salmon found a lower incidence of heart trouble than they had expected. Instead, the scientists found themselves fascinated with the spectacle of death in the river. Even as salmon moved up the Bella Coola to spawn, they were rotting. Some living salmon were without tails. They spawned and within hours were dead.

"The phenomenon of death was overpowering," Dr. Eberhard Trams, a neurochemist, recalls. "If you see a lot of ants die you don't give a damn. But the larger the animal, the closer it gets to home. These were magnificent, highly organized beings suffering mass death. A whole society dies; every fish of that spawning age born in that river was dying. They become senile, and you watch the disintegration of the nervous system, muscles and bone. The fish literally seem to die of death. The fisheries and wildlife people accept this death. They consider it entirely natural. No one considered it odd."

The scientists decided to concentrate their study on the salmon's strange process of aging. In their investigation they have been trying to determine whether the death of a salmon in a particular year is caused by a factor in its genetic makeup, such as its homing device, or whether its aging and precipitous death is physically triggered when it leaves the salt water and enters the river to spawn and die.

"We have learned to delay death and aging in man to an astonishing degree," Dr. Trams says. "With different diets and antibiotics, the life span of man has increased almost 40% in the last 60 years. Perhaps we can learn something to further extend man's life by using the spawning salmon as a laboratory tool."

Analyzing the metabolic decline of the salmon at Bella Coola took many forms—the calcium in the blood of fish just coming into the river was contrasted with that in the blood offish that had spawned and were dying. Comparisons were made in the pigment in their skin and flesh, the fat in their bodies, their brains, glands, hormones, livers, muscles, cells and circulation. To do this testing, a variety of equipment was employed. The dimensions of a salmon's swim bladder were found by putting a small fish in a giant mayonnaise jar filled with water and lodging the necessary pipes and gauges for measurement in the cap of the jar. Oxygen consumption in salmon was figured by putting the fish in plastic cylinders in the river, pumping a certain amount of water into the cylinders and then measuring the oxygen in the outflowing water. The circulation of a salmon's blood was charted by using an X-ray machine or by pumping radioactive Xenon 133 into its heart and then using Geiger counters to register the amount of radioactivity that had moved out to the various organs.

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