National Geographic : 1922 Jan
CERTAIN CITIZENS OF THE WARM SEA BY Louis L. MOWBRAY DIRECTOR, MIAMI AQUARIUM AND BIOLOGICAL LABORATORY VEN man's most terrific wars against his fellows have a respite; they are but cataclysms in the normal course of the world; but the bat tle of fish against fish-furious, quarter less, to the death-is everlasting. So, within the warm balmy waters of the Gulf Stream off the Florida coast, where the lazy waves of the surface seem to typify peace, the never-ending Armaged don of the finny world rises to its highest pitch. It is almost impossible for the human mind to conceive the continuous struggle for existence that in these warm seas goes on beneath the surface of the water. If such conditions existed on land and the resultant mental strain were not pro vided for by Nature, few would survive the constant tension upon the nervous system. A fish starting in pursuit of another frequently attracts the attention of one of a larger species and is in turn pur sued. Often, in southern waters, when an angler hooks a fish, and before it can be drawn into the boat, it is cut in two by the jaws of a larger enemy; for most carnivorous fish seem instantly to sense prey when one of their number is in trouble, and a blood lust becomes epi demic forthwith. Even in the face of this ceaseless strug gle, the waters of the warm seas teem with fish, reptiles, crustaceans, and other creatures. There Nature both pours forth and destroys life with unsparing hands. That species may survive, and even pros per, though surrounded by implacable enemies, she has given all creatures of these waters the power to reproduce themselves an almost unbelievable num ber of times. OBSERVATIONS OF MORE NORTHERLY FISH A single female fish, during the spawn ing period, holds potential life in num bers running into millions. It is esti mated that a 6-pound mackerel produces 1,500,000 eggs at one time; a cod weigh ing 21 pounds, it has been computed, produces 2,700,000 eggs, and a 77-pound cod, 9,100,000; and a close scientific study and research show that a 13-pound pol lock, of the cod family, produces over 2,569,000 eggs, and a 23 2 -pound pollock over 4,000,000 at one spawning. THE SURVIVAL OF THE FITTEST There is no better way to realize the keenness of the sea battle for existence than to picture the result if in the sea the lion should lie down with the lamb! It is not difficult to imagine what would happen if these staggering numbers of eggs were not interfered with by enemies, if all the young hatched out were safe from violent death, and if the young females in turn soon began contributing their millions of eggs. The operation of this tremendous geometrical progression would in a few years fill every cubic foot of the seas, vast as they are, with living creatures; the oceans would be unnavi gable-a compact mass of animal life. The battle of the seas, then-the un ending strife, the seemingly heartless preying of one creature upon another has its definite need in the world's econ omy. The strife of the seas takes many forms. Fishes that feed in shoals have a well-planned method for acquiring their living food, and the same procedure is carried out so often that it resembles the workings of an exceptionally well-trained body of soldiers. When a shoal of smaller fish is located near the shore, the larger fishes encircle the shoal, herding it to an almost compact mass, occasionally darting into it and get ting a mouthful. Sometimes they do not strike the shoal, but continue driving it as bait until somewhat larger fishes at tack it. The great fish then proceed to feed upon those which have been lured by the original prey. During the melee the surface water is lashed into foam, often for an area ex ceeding a mile, and the little fellows are jumping every way in their mad efforts to escape their enemies.