CHAPTER III. NOTES ON ICHTHYOLOGY, OR THE SCIENCE OF FISHES. THE practical angler is all the more likely to obtain sport if he understand thoroughly the habits of his quarry. Similarly other sportsmen are more likely to be successful when they are possessed of analogous knowledge. Of course when stating these platitudes I am not about to draw the inference that technical knowledge is alone sufficient. It is possible for a man to be able to enumerate the characteristics of a far-off country, and yet were he deposited in its midst by virtue of Aladdin's lamp or some other magical emigration agency, he very probably would not recognise the land. In like manner more than one learned pundit in piscine anatomy has never caught a salmon, and only knows its habits in theory. It, therefore, is not likely that a chapter on ichthyology will make a fisherman, although the theory, combined as it should be with practice, will probably advance the angler considerably before his uneducated compeers in the gentle craft. A competent knowledge also of ichthyology is useful to the traveller angler in other lands, and the exquisite wonders of the fresh water and ocean become additionally attractive when the angler-naturalist can with the certainty afforded by a few distinct and well defined rules settle the family, if not the species, of a new or novel capture. The various remarks I shall make in this chapter will be as practical as possible, and I shall avoid introducing matter which is not necessary to the fresh-water angler in the connection indicated. The wonders of our native waters are manifold, but the practical angler, much as he may appreciate the acquirement of knowledge, will not thank me for a long dissertation on the monsters of the ocean and the curious habits they make manifest. The "divine" Du Bartus, as Walton calls him, has sufficiently spoken of the extraordinary marine animals, and further than his quaint enumeration of them I shall not at this moment go. He says: God quickened in the sea and in the rivers As well as earth, vines, roses, nettles, melóns. As also rams, calves, horses, hares and hogs, Were shown the Norway and Polonian prince. Of course this curious old devout is remarkably figurative, and the excerpt from his " Contemplation" is only introduced as a curiosity; nevertheless, however, the similitudes he traces are not all in vain, and even in fresh water some not less interesting creatures are resident, although mermaids and "mitred priest and cowlèd friar" may not there be found. The whole of the British fresh-water fishes are included in four orders and embraced in seven families. I cannot do better than give a list of them as arranged by Mr. Pennell in his "Angler Naturalist" after Cuvier. It runs as follows: CLASSIFICATION OF BRITISH FRESH-WATER FISH. Order I. SPINY-FINNED FISH. Family 1. Perches-PERCIDE. Species. Perch. (Perca fluviatilis.) Ruffe, or Pope. (Acerina vulgaris.) Family 2. FISH WITH HARD CHEEKS. Species. Bullhead, or Miller's Thumb. (Cottus gobio.) Gasterosteus pungitius.) Order II. SOFT-FINNED FISH with ventral fins on the belly. Family 1. Carps-CYPRINIDE. Species, Common Carp. (Cyprinus carpio.) Crucian, or German, Carp. (Cyprinus carassius.) Prussian, or Gibel, Carp. (Cyprinus gibelio.) Gold Carp. (Cyprinas auratus.) Barbel. (Barbus vulgaris.) Gudgeon. (Gobio fluviatilis.) Tench. (Tinca vulgaris.) Bream, or Carp Bream. (Abramis brama.) White Bream, or Bream-flat. (Abramis blicca.) Pomeranian Bream. (Abramis Buggenhagii.) Dace. (Leuciscus vulgaris.) Roach. (Leuciscus rutilus.) Double Roach. (Leuciscus dobula.) Salmon. (Salmo salar.) Bull Trout. (Grey Trout, Sewin, or Roundtail.) (Salmo eriox.) Common Trout. (Salmo fario.) Great Lake Trout. (Salmo ferox). Loch Leven Trout. (Salmo levenensis.) Charrs. Grayling. (Thymallus vulgaris.) Gwyniad. Coregonus Pennanti.) Powan. (Coregonus Cepedei.) Pollan. (Coregonus pollan.) Vendace or Vendis. (Corregonus Willughbii.) Order III. SOFT-FINNED FISH. having lower arms. Family 1..Cod-GADIDE. Species. Burbot, or Eel-pout. (Lota vulgaris.) Order IV. SOFT-FINNED FISH lacking ventral fins. Species. Sharp-nosed Eel. (Anguilla acutirostris.) 2ND SERIES. CARTILAGINOUS FISH. Order II. FISH WITH FIXED GILLS. Family 1. Fish with mouth formed into a sucker-CYCLOSTOMATA. Species. Lamprey, or Sea Lamprey. (Petromyzon marinus.) An example of the above may be thus written. The Perch is a fish of the first series of true or bony fish, of the first order of Acanthopterygian or spiny-finned fishes of the first family of Perches (percido) and of the species Perca fluviatilis. Another example may be further written with advantage that no possible difficulty may be experienced by the reader in understanding the classification given. Thus the common Carp is also of the first series of true or bony fish (as distinct from the cartilaginous, instance lamprey), but of the second order of soft-fined with ventral fins on body, or Malacopterygia adominales, and its species is Cyprinus carpio. As will be perceived, the chief difference between the commonest fresh-water fishes is the absence or presence of spines in the fins. when the absolute novice takes a fish he first examines the fins and finds If it has spines and no ventral fins, he has determined, if he have the above table in his memory-first, that it belongs to the true fish as distinct from cartilaginous (for no cartilaginous fish can have spines); second, that it belongs to first order of spiny finned fishes or Acanthopterigians; and, thirdly, if it has spines on the back, it is of the percida family. Herein lies one of the practical uses of ichthyology. The determination of the different genera in the same genus of fishes requires more minute and careful comparison than a decision of the order. The tyro, for example, would probably find it difficult to instantly distinguish between the dace and chub, and, indeed, when both are young, the difference is infinitesimal. As I intend to revert to each fish in the order above given, I shall reserve any further remarks on the distinctive characteristics of each until that time. It may now be well to consider in a succinct manner the various principal qualities and attributes which fish have in common. First, then, if we disregard the idea which has obtained in reference to eels being viviparous, or bringing forth their young alive, it may be stated that, in scientific phraseology, all fish are oviparous vertebrata, or creatures with articulated backbones bringing forth eggs. They have a double circulation, and breathe through the medium of water. Like other animals of the same class, they have a spinal column formed of four parallel sections, two of which receive nerves of sensation from the surface of the body, and the other receive the nerves of volition or action. The spinal cord enlarges at one end of this column and forms the brain, which in the pike is in weight as 1 in 3000 in proportion to the body, and in carp (the subtlest of the soft-finned fish) as 1 in 500. The Branchia or gills, or breathing apparatus, are, as need scarcely be stated, compactly arranged in the opercula or gill covers of the creature, and consists of four or five cartilaginous fringed arches. Under the microscope these present a very beautiful appearance, as they continue their work, receiving the water, separating the air from it, and passing it on through the anterior opening, together with whatever of carbon is given off. And here it is worthy of remark that the water is not decomposed, but the oxygen is only mechanically separated from the water. A fish cannot live in a tumbler of water placed in the receiver of an air pump. Some fish will, however, continue to live out of water a considerable time. In the ordinary way the gill filaments get stuck together as they dry, and the fish then becomes asphyxiated and dies. The fins of a fish serve variously in the different families and species. Generally speaking the following description of their functions is a correct one. I extract it from "Paley's Natural Theology," (the author of which probably got it chiefly from Goldsmith's "History of Animated Nature,'') because it states the results of experiments, which I have myself repeated, better than any words of mine could do. It says that in most fish "beside the great fin the tail, we find two pairs of fins upon the sides, two single fins upon the back and one upon the belly, or rather between the belly and the tail. The balancing use of these organs is proved in this manner: of the large-headed fish, if you cut off the pectoral fins, i. e., the pair which lies close behind the gills, the head falls prone to the bottom; if the right pectoral fin only be cut off, the fish leans to that side; if the ventral fin on the same side be cut away, then it loses its equilibrium entirely; if the dorsal and ventral fins be cut off, the fish reels to the right and left. When the fish dies, that is, when the fins cease to play, the belly turns upwards. The use of the same parts for motion is seen in the following observation upon them when put in action. The pectoral, and more particularly the ventral, fins serve to raise and depress the fish; when the fish desire to have a retrograde motion, a stroke forward with the pectoral fin effectually produces it; if the fish desire to turn either way, a single blow with the tail the opposite way sends it round at once; if the tail strike both ways, the motion produced by the double lash is progressive, and enables the fish to dart forwards with an astonishing velocity. The result is not only in some cases the most rapid, but in all cases the most gentle, pliant, easy, animal motion with which we are acquainted. However, when the tail is cut off the fish loses all motion, and gives itself up to where the water impels it. The rest of the fins, therefore, so far as respects motion, seem to be merely subsidiary to this. In their mechanical use, the anal fin may be reckoned the keel, the ventral fins the outriggers, the pectoral muscles the oars, and if there be any similitude between these parts of a boat and a fish, observe that it is not the resemblance of imitation, but the likeness which arises from applying similar mechanical means to the same purpose.' 66 In reference to the foregoing, one error needs correction, and one observation may be added. The error is in asserting that if the tail be lost in the fish it loses all motion. This it does not do. The posterior parts are still exercised as if the tail still remained, and the resulting movement is what anglers term a wobble," but, nevertheless, a progressive movement. The addition is one the truth of which anyone may verify by watching the progression of the sticklebacks in a tank at the Royal Westminster Aquarium. The fish distinctly advance by a series of jerks caused by the pectoral fins. The tail has nothing to do with progression, and seems only to make a quivering movement to maintain equilibrium. I know of no other fresh-water fish with the same peculiarity. |