The Structure Of Game Fishes
( Originally Published Early 1900's )
A FISH may be termed a cold-blooded, gill-breathing, backboned animal, adapted to life in the water, through which it moves by the aid of fins, which correspond to the limbs of other animals. The true fishes are represented by the types treated in this volume, and a glance at the skeleton, divested of skin and flesh, affords the angler an idea of its structure, and the relation of its parts one to another. The skeleton of a typical bony fish like the perch appears to have two backbones, but the central one (68) is the vertebra, made up of sometimes two hundred sections. Each vertebra is hollow on the ends, the space so formed being filled with a glutinous substance, the edges of the bones being connected by ligaments, which allow more or less lateral motion —a vast amount in the eel, very little in the tuna. The long bones attached to the backbone are the ribs which form the frame of the abdominal section, while projecting upward from the vertebrae are bones which may be termed braces to the upper and fleshy portion of the fish. The pseudo-backbone above is the framework of the top or dorsal fin, certain spinous bones extending downward, embedded or anchored in the flesh forming the base of the dorsal spines, which extend upward clear of the body and there connected by a web or membrane, or not, as the case may be, become the dorsal fin. Sometimes there is but one, as in the. tarpon ; again two, as in the perch The head is a complicated organ made up of many bones ; the jaws armed with teeth. The lower jaw has a wide range of movement, and if a fish is hooked here, the mouth is pulled open and the contest is not so interminable as when it is hooked in the upper jaw, when it can close its mouth upon the hook. In tuna fishing this often makes a vast difference in time; hence some facile anglers claim that the fish should be hooked with a lateral motion instead of an upper; in other words, the lower jaw should be hooked, if possible, when the game is large.
The large bone is the cover, or door, to the gill chamber, which opens and closes convulsively when a fish is landed. The fish smells but does not breathe by its nostrils, the nasal aperture being shown at.
In the skeleton the arrangement and use of the limbs, or fins, is readily seen. The top or dorsal fins are balancers, upper centre-boards, capable in some fishes of a decided screw movement, enabling them to move. It also is an expressive organ, erect when the fish is excited, low or folded at other times, and incapable of movement in certain forms. In the tuna it fits into a scabbard, or notch. The tail, caudal fin, is the most useful locomotive organ, controlled by powerful muscles and lashed about by the entire sweep of the body; it is readily seen that by it the salmon makes its tremendous leaps and the tuna literally whirls itself into the air, nearly all fishes using it as a screw. The peculiar motions are readily observed in a soft-tailed fish, like the perch, in confinement.
Directly below the second dorsal fin, near the tail, is the anal fin and its bones, held in place by spines, which are placed firmly in the muscular tissue. It is these interspinous and rib-bones which make fishes so " bony," as in some species, like the shad, they are very long and, slender, giving the impression that this popular fish must be very uncomfortable. This anal fin is not a locomotive organ, being merely a balancer to aid in preserving the equilibrium of the fish, a sort of centre-board and a rest when the fish is reclining on the bottom. The limbs which correspond to the locomotive organs of other animals are the pectoral and ventral fins. The former are the most important next to the tail as locomotive organs. Fishes, as the California sheepshead, the parrot-fishes, tautog, and others, rely upon them to a decided extent, the flapping or waving motion being readily observed ; but when rapid and sudden motion is desired, the tail is brought into play, finding its most remarkable development, at least in my estimation, in the California flying-fish, where it twists violently about, hurling the fish into the air with such force that, supported by the broad pectorals and ventrals, the fish becomes an animate aeroplane and soars over the sea, never flying, for over an eighth of a mile. The pectoral fins are modified into forearms, paddles ; and many of the corresponding bones among higher animals are seen, as a pectoral arch, scapula, clavicle, ulna, and radius. These fins are found in the greatest variety from the long, slender, sabre-like fin of the albacore, to the enormous webbed, winglike organ of the flying-fishes, resembling a true fore limb in the peculiar fish, the periophthalmus, which uses its pectoral fins as feet to hop along the muddy shores out of water, in search of food. Below the pectorals we find the ventral fins, rays, attached to the pelvic bone, representing the hind legs of higher animals, though all the bones of the limbs are not present. These fins are of little if any use as swimming organs, but the fish rests upon them when on the bottom, and they are balancers, aiding, as do the others, in preserving the perfect equilibrium of, the body while the fish poises. The angler who makes a diversified catch, as is often the case in Florida, will be highly edified by a comparison of these fins in the different fishes, suggestive of their habits and game qualities.
We have taken a superficial glance at the framework of the game fish. It is a marvellous machine, built, framed, fitted, joined, provided with paddles and screws to give it speed, endurance, resisting power in a word, perfectly adapted by nature to its environment. Now to look at its internal economy, not thoroughly, as text-books are at hand, but merely to afford the angler between strikes a general idea of how his game eats, breathes, and makes so determined and gallant a fight. Lifting the gill-covers near where the fish should be gaffed, we see the gills, blood-red membraneous leaflets supported by cartilaginous arches, separated by slits. These are situated in branchial chambers or breathing rooms on each side of the head, and are the lungs or breathing organs of the fishes, though in some forms the air bladder assumes this function when the fish leaves the water. The fish obtains its oxygen at second hand, using minute particles of air which are held in the water. Storms and winds raise a sea which forces air-bubbles down below the surface, aerating the water in sufficient quantities to support life. To demonstrate this it is but necessary to place a fish in an aquarium and allow the water to run in from below; the fish in a short time languishes and rises to the surface and dies. Introduce the water from above, imitating the action of a wave so that it falls upon the surface with force, carrying down air, which is seen permeating the water in a cloud of minute bubbles, and the fish is immediately at ease. The deep-sea forms obtain the limited oxygen which they need from slow-moving currents which sweep along the bottom of the ocean at the greatest depths, passing from the surface to the abysmal regions laden with oxygen. The gills are permeated with blood-vessels, which give them their rich color, and their office is to take oxygen from the water, the operation being as follows. Watching a fish in confinement, a continued movement of the mouth and gills is observed, an endless opening and shutting ; indeed, the fish's mouth is never closed. It is taking in water which passes over the gills, bathing them in an endless stream. As it passes, the gills take up the oxygen contained in the fluid ; this is absorbed by the blood, which is being pumped by the heart to the gills for this purpose, as blood in man is pumped to the lungs to receive the oxygen taken in at the nostrils. The water so used is thrown out at the gill openings by the depression of the operculum, or door, or cover of the gill chamber. The passage of blood through man is rapid, and he is warm-blooded ; in fishes it moves very slowly, and the temperature of the blood is lower than that of the surrounding medium ; hence the fishes are said to be cold-blooded. But in the tuna, bonito, and others the movements are so energetic that the temperature is higher than that of the water. When a fish is taken out of the water, it gasps and opens its gills, and doubtless is killed in part by too much oxygen, the reverse of the drowning process.
The digestive organs of fishes are simple. The prey is not chewed, the teeth being intended to hold the victim, which is swallowed entire at one or two gulps, though the tuna often crushes its prey. Food is quickly digested, and the capacity of some fishes, as the tuna, bluefish, and others, is remarkable. The mouth and teeth are modified or adapted to the requirements of the fishes. Those which live on oysters, as the sheepshead, have crushing organs. The shark, not a true fish, cuts its food or tears it. The fish is enabled to hold its position at various levels without effort by the aid of its air or swimming bladder, possessed by most individuals. This is a silvery air sac or balloon lying directly beneath the vertebra, longer or shorter according to species, absent in some. It contains gas, principally nitrogen, and by it the fish is enabled to retain a certain specific gravity.
The brain of the fish is very small, and the latter has limited intelligence. Its powers of smell are fairly well developed, and the hearing is more or less acute; the organs of hearing being small cavities on each side of the head, containing a liquid in which float two ear-stones or otoliths. In some fishes, as the California "groupers," the stones are an inch in length, pearl tinted and flinty, — attractive objects in demand as "head-stones" and " good luck stones."
The fish is enveloped in scales, which in the game fishes described overlap each other like shingles. They grow out of the little pockets in the skin and are moistened or lubricated by a secretion or slime, always noticed in a fish, which exudes beneath them, and particularly along the median line, an undulating line extending from the. head to the base of the tail. The game fishes mentioned in this volume all increase by depositing eggs or spawn, the eggs—minute spherical objects — often forming enormous masses. The caviare of commerce is the roe of the sturgeon. The number of eggs is inconceivable. In the cod it is estimated at five millions. This is a wise provision of nature, as fishes feed upon their own kind. Sardines, herrings, and many birds devour spawn, and out of every million eggs deposited, a very small percentage, certainly not ten, attain the adult stage. There are great concerted movements at the spawning period. Some fishes pair. The female, as a rule, pays no attention to the eggs or young, and in nearly all instances where nests are constructed, as in the case of the stickleback, the sunfish, Semotilus, lamprey, and many more, it is the male which builds the nest. The Acara carries the eggs and later the young in its mouth.
The spawn is deposited in the open sea, in the case of the tuna, albacore, bonito, and other pelagic fishes ; at the surface in bays, as in the case of the flying-fish. Some fishes, as certain California sculpins, attach eggs in great clusters to rocks ; others again, as the rock-bass, form a simple nest, while others, as the salmon, deposit the eggs on sandy or gravelly bottom ; some, as the blackfish, among weeds or grass. Over the eggs the male distributes the milt which impregnates them, and in a greater or less time the young appear, immediately becoming the prey to a thousand enemies. Some fishes possess the schooling instinct, as the herring, sardine, California barracuda, mullet, and others ; the majority separate. Many young of pelagic fishes attach themselves to large jellyfishes ; others to the physalia, and some adults enter the intestinal tube of holothurians.
There are two other methods of reproduction among fishes and the fishlike animals. In some, as the surf-fishes and certain sharks, the young are born alive. The young of twenty or thirty or more surf-fishes school and swim together. Other fishes are ovoviviparous, the eggs being retained in the body until the young are hatched.
In the vast concourse of fishes of the world every possible habit is seen. Originally all were doubtless salt-water forms, but they have entered rivers and streams, and in time have become adapted to their environment. Some fishes, like the salmon, enter fresh water to spawn. Others, like the eel, seem to reverse this. Certain fishes hibernate when water disappears. Others cross overland to reach water, while the strange periophthalmus and another genus leave the water and wander along the shore in search of food.
The fishes are found at various depths of the ocean, some at a depth of several miles being blind. Those living in these abysmal regions are adapted by nature to the peculiar conditions. The pressure where they live is sufficient to powder glass; at the surface it is fifteen pounds per square inch, but increases rapidly, so that at a mile below the surface it is almost beyond comprehension.
To overcome this the skeleton of deep-sea forms is cavernous, porous, and the water appears to circulate through them as through a sponge, and although fierce and carnivorous creatures, they are so fragile out of water that when taken from the nets they almost drop in pieces. The most remarkable feature of these fishes and many surface forms is their phosphorescence, many having illuminating organs — torches - of one or more colors, which constitute a part of the illumination of the deep sea, and serve possibly as a signal language by which the sexes are attracted, or predaceous forms lure their prey. I have seen a tuna come up at night, having a train of light several feet in length, but this was due to the luminous animals in the water — the peridinium, salpa, and others.
The game fishes available to the rod fisherman constitute a small proportion of the fishes, due to the fact that many are deep-water forms, or so essentially pelagic, like the dolphin — a splendid game fish — that it is beyond the reach of the angler who cannot spend his time in the forechains of some ship. This is exemplified by the statement that nearly all the available large oceanic game fishes of America, except the striped bass, are included in this volume ; but as each is a game fish of several sizes, in the course of its career the angler finds endless variety. He can begin with a fly-rod on a two-pound bluefish, and will need his stiff rod on the adult. There are in California and Florida an infinite variety of small fishes, usually neglected, which, if approached with a rod, afford profitable sport.