In the sea as on the land, all life depends upon vegetation. And the amount of vegetation in turn depends upon the mineral content of the medium in which it grows—the nitrates, phosphates, and scores of other basic chemicals. In the ocean, there is always a tendency for these vital substances to accumulate in the depths, far below the regions where light penetrates and therefore plants can exist and grow. The upper few hundred feet of the sea is the primary source of its life; everything below that level preys, at second or third hand, on the food formed above.
Every spring, as the warmth of the new year seeps down into the ocean, the waters far below respond to the invisible sun. They expand and rise, rifting to the surface, in untold billions of tons, the salts and minerals they bear. Thus fertilized by food from below and sun from above, the floating plants multiply with explosive violence, and the creatures which browse upon them flourish accordingly. And so spring comes to the meadows of the sea.
This was the cycle that had repeated itself at least a billion times before man appeared on the scene. And now he had changed it. Not content with the upwelling of minerals produced by Nature, he had sunk his atomic generators at strategic spots far down into the sea, where the raw heat they produced would start immense, submerged fountains lifting their chemical treasure toward the fruitful sun. This artificial enhancement of the natural overturn had been one of the most unexpected, as well as the most rewarding, of all the many applications of nuclear energy. By this means alone, the output of food from the sea had been increased by almost ten per cent.
And now the whales were busily doing their best to restore the balance.
The roundup would have to be a combined sea and air operation. There were too few of the subs, and they were far too slow, to do the job unassisted. Three of them—including Franklin’s one-man scout—were being flown to the scene of the breakthrough by a cargo plane which would drop them and then co-operate by spotting the movements of the whales from the air, if they had scattered over too large an area for the subs’ sonar to pick them up. Two other planes would also try to scare the whales by dropping noise generators near them, but this technique had never worked well in the past and no one really expected much success from it now.
Within twenty minutes of the alarm, Franklin was watching the enormous food-processing plants of Pearl Harbor falling below as the jets of the freighter hauled him up into the sky. Even now, he was still not fond of flying and tried to avoid it when he could. But it no longer worried him, and he could look down on the world beneath without qualms.
A hundred miles east of Hawaii, the sea turned suddenly from blue to gold. The moving fields, rich with the year’s first crop, covered the Pacific clear out to the horizon, and showed no sign of ending as the plane raced on toward the rising sun. Here and there the mile-long skimmers of the floating harvesters lay upon the surface like the enigmatic toys of some giant children, while beside them, smaller and more compact, were the pontoons and rafts of the concentration equipment. It was an impressive sight, even in these days of mammoth engineering achievements, but it did not move Franklin. He could not become excited over a billion tons of assorted diatoms and shrimps—not even though he knew that they fed a quarter of the human race.
“Just passing over the Hawaiian Corridor,” said the pilot’s voice from the speaker. “We should see the break in a minute.”
“I can see it now,” said one of the other wardens, leaning past Franklin and pointing out to sea. “There they are—having the time of their lives.”
It was a spectacle which must be making the poor farmers tear their hair. Franklin suddenly remembered an old nursery rhyme he had not thought of for at least thirty years:
Little Boy Blue, come blow your horn,
The sheep’s in the meadow, the cow’s in the corn.
There was no doubt that the cows were in the corn, and Little Boy Blue was going to have a busy time getting them out. Far below, myriads of narrow swathes were being carved in the endless yellow sea, as the ravenous, slowly moving mountains ate their way into the rich plankton meadows. A blue line of exposed water marked the track of each whale as it meandered through what must be a cetacean heaven—a heaven from which it was Franklin’s job to expel it as promptly as possible.
The three wardens, after a final radio briefing, left the cabin and went down to the hold, where the little subs were already hanging from the davits which would lower them into the sea. There would be no difficulty about this operation; what might not be so easy would be getting them back again, and if the sea became rough they might have to go home under their own power.
It seemed strange to be inside a submarine inside an airplane, but Franklin had little time for such thoughts as he went through the routine cockpit drill. Then the speaker on his control panel remarked: “Hovering at thirty feet; now opening cargo hatches. Stand by, Number One Sub,” Franklin was number two; the great cargo craft was poised so steadily, and the hoists moved down so smoothly, that he never felt any impact as the sub dropped into its natural element. Then the three scouts were fanning out along the tracks that had been assigned to them, like mechanized sheep dogs rounding up a flock.
Almost at once, Franklin realized that this operation was not going to be as simple as it looked. The sub was driving through a thick soup that completely eliminated vision and even interfered seriously with sonar. What was still more serious, the hydrojet motors were laboring unhappily as their impellers chewed through the mush. He could not afford to get his propulsion system clogged; the best thing to do would be to dive below the plankton layer and not to surface until it was absolutely necessary.
Three hundred feet down, the water was merely murky and though vision was still impossible he could make good speed. He wondered if the greedily feasting whales above his head knew of his approach and realized that their idyll was coming to an end. On the sonar screen he could see their luminous echoes moving slowly across the ghostly mirror of the air-water surface which his sound beams could not penetrate. It was odd how similar the surface of the sea looked from below both to the naked eye and to the acoustical senses of the sonar.
The characteristically compact little echoes of the two other subs were moving out to the flanks of the scattered herd. Franklin glanced at the chronometer; in less than a minute, the drive was due to begin. He switched on the external microphones and listened to the voices of the sea.
How could anyone have ever thought that the sea was silent! Even man’s limited hearing could detect many of its sounds—the clashing of chitinous claws, the moan of great boulders made restive by the ocean swell, the high-pitched squeak of porpoises, the unmistakable “flick” of a shark’s tail as it suddenly accelerates on a new course. But these were merely the sounds in the audible spectrum; to listen to the full music of the sea one must go both below and above the range of human hearing. This was a simple enough task for the sub’s frequency converters; if he wished, Franklin could tune in to any sounds from almost a million cycles a second down to vibrations as sluggish as the slow opening of an ancient, rusty door.
He set the receiver to the broadest band, and at once his mind began to interpret the multitudinous messages that came pouring into the little cabin from the watery world outside. The man-made noises he dismissed at once; the sounds of his own sub and the more distant whines of his companion vessels were largely eliminated by the special filters designed for that purpose. But he could just detect the distinctive whistles of the three sonar sets—his own almost blanketing the others —and beyond those the faint and far-off beep-beep-beep of the Hawaiian Corridor. The double fence which was supposed to channel the whales safely through the rich sea farm sent out of its pulses at five-second intervals, and though the nearest portion of the fence was out of action the more distant parts of the sonic barrier could be clearly heard. The pulses were curiously distorted and drawn-out into a faint continuous echo as each new burst of sound was followed at once by the delayed waves from more and more remote regions of the fence. Franklin could hear each pulse running away into the distance, as sometimes a clap of thunder may be heard racing across the sky.