Читать книгу The Earth as Modified by Human Action - George P. Marsh - Страница 39

The introduction and successful breeding of fish or foreign species appears to have been long practised in China, and was not unknown to the Greeks and Romans. [Footnote: The observations of COLUMELLA, de Re Rustica, lib. viii., sixteenth and following chapters, on fish-breeding, are interesting. The Romans not only stocked natural but constructed artificial ponds, of both fresh and salt water, and cut off bays of the sea for this purpose. They also naturalized various species of sea-fish in fresh water.] This art has been revived in modern times, but thus far without any important results, economical or physical, though there seems to be good reason to believe it may be employed with advantage on an extended scale. As in the case of plants, man has sometimes undesignedly introduced now species of aquatic animals into countries distant from their birthplace. The accidental escape of the Chinese goldfish from ponds where they were bred as a garden ornament, has peopled some European, and it is said American streams with this species. Canals of navigation and irrigation interchange the fish of lakes and rivers widely separated by natural barriers, as well as the plants which drop their seeds into the waters. The Erie Canal, as measured by its own channel, has a length of about three hundred and sixty miles, and it has ascending and descending locks in both directions. By this route, the fresh-water fish of the Hudson and the Upper Lakes, and some of the indigenous vegetables of these respective basins, have intermixed, and the fauna and flora of the two regions have now more species common to both than before the canal was opened. [Footnote: The opening or rather the reconstruction of the Claudian emissary by Prince Torlonia, designed to drain the Lake Fucinus, or Celano, has introduced the fish of that lake into the Liri or Garigliano which received the discharge from the lake.—Dorotea, Sommario storico dell' Alieutica, p. 60.]The opening of the Suez Canal will, no doubt, produce very interesting revolutions in the animal and vegetable population of both basins. The Mediterranean, with some local exceptions—such as the bays of Calabria, and the coast of Sicily so picturesquely described by Quatrefages [Footnote: Souvenire d'un Naturaliste, i., pp. 204 et seqq.]-is comparatively poor in marine vegetation, and in shell as well as in fin fish. The scarcity of fish in some of its gulfs is proverbial, and you may scrutinize long stretches of beach on its northern shores, after every south wind for a whole winter, without finding a dozen shells to reward your search. But no one who has not looked down into tropical or subtropical seas can conceive the amazing wealth of the Red Sea in organic life. Its bottom is carpeted or paved with marine plants, with zoophytes and with shells, while its waters are teeming with infinitely varied forms of moving life. Most of its vegetables and its animals, no doubt, are confined by the laws of their organization to a warmer temperature than that of the Mediterranean, but among them there must be many whose habitat is of a wider range, many whose powers of accommodation would enable them to acclimate themselves in a colder sea.

We may suppose the less numerous aquatic fauna and flora of the Mediterranean to be equally capable of climatic adaptation, and hence there will be a partial interchange of the organic population not already common to both seas. Destructive species, thus newly introduced, may diminish the numbers of their proper prey in either basin, and, on the other hand, the increased supply of appropriate food may greatly multiply the abundance of others, and at the same time add important contributions to the aliment of man in the countries bordering on the Mediterranean. [Footnote: The dissolution of the salts in the bed of the Bitter Lake impregnated the water admitted from the Red Sea so highly that for some time fish were not seen in that basin. The flow of the current through the canal has now reduced the proportion of saline matter to five per cent, and late travellers speak of fish as abundant in its waters.]

Some accidental attraction not unfrequently induces fish to follow a vessel for days in succession, and they may thus be enticed into zones very distant from their native habitat. Several years ago, I was told at Constantinople, upon good authority, that a couple of fish, of a species wholly unknown to the natives had just been taken in the Bosphorus. They were alleged to have followed an English ship from the Thames, and to have been frequently observed by the crew during the passage; but I was unable to learn their specific character. [Footnote: Seven or eight years ago, the Italian government imported from France a dredging machine for use in the harbor of La Spezia. The dredge brought attached to its hull a shell-fish not known in Italian waters. The mollusk, finding the local circumstances favorable, established itself in this new habitat, multiplied rapidly, and is now found almost everywhere on the west coast of the Peninsula.] Many of the fish which pass the greater part of the year in salt water spawn in fresh, and some fresh-water species, the common brook-trout of New England for instance, which under ordinary circumstances never visit the sea, will, if transferred to brooks emptying directly into the ocean, go down into the salt water after spawning-time, and return again the next season. Some sea fish have been naturalized in fresh water, and naturalists have argued from the character of the fish of Lake Baikal, and especially from the existence of the seal in that locality, that all its inhabitants were originally marine species, and have changed their habits with the gradual conversion of the saline waters of the lake-once, as is assumed, a maritime bay-into fresh. [Footnote: Babinet, Etudes et Lectures, ii, pp. 108,110.] The presence of the seal is hardly conclusive on this point, for it is sometimes seen in Lake Champlain at the distance of some hundreds of miles from even brackish water. One of these animals was killed on the ice in that lake in February, 1810, another in February, 1846, [Footnote: Thompson, Natural History of Vermont, p. 38, and Appendix, p. 18. There is no reason to believe that the seal breeds in Lake Champlain, but the individual last taken there must have been some weeks, at least, in its waters. It was killed on the ice in the widest part of the lake, on the 23d of February, thirteen days after the surface was entirely frozen, except the usual small cracks, and a month or two after the ice closed at all points north of the place where the seal was found.] and remains of the seal have been found at other times in the same waters.

The intentional naturalization of foreign fish, as I have said, has not thus far yielded important fruits; but though this particular branch of what is called, not very happily, pisciculture, has not yet established its claims to the attention of the physical geographer or the political economist, the artificial breeding of domestic fish, of the lobster and other crustacea, has already produced very valuable results, and is apparently destined to occupy an extremely conspicuous place in the history of man's efforts to compensate his prodigal waste of the gifts of nature. The arrangements for breeding fish in the Venetian lagoon of Comacchio date far back in the Middle Ages, but the example does not seem to have been followed elsewhere in Europe at that period, except in small ponds where the propagation of the fish was left to nature without much artificial aid. The transplantation of oysters to artificial ponds has long been common, and it appears to have recently succeeded well on a large scale in the open sea on the French coast. A great extension of this fishery is hoped for, and it is now proposed to introduce upon the same coast the American soft clam, which is so abundant in the tide-washed beach sands of Long Island Sound as to form an important article in the diet of the neighboring population. Experimental pisciculture has been highly successful in the United States, and will probably soon become a regular branch of rural industry, especially as Congress, at the session of 1871–2, made liberal provision for its promotion.

The restoration of the primitive abundance of salt and fresh water fish, is perhaps the greatest material benefit that, with our present physical resources, governments can hope to confer upon their subjects. The rivers, lakes, and seacoasts once restocked, and protected by law from exhaustion by taking fish at improper seasons, by destructive methods, and in extravagant quantities, would continue indefinitely to furnish a very large supply of most healthful food, which, unlike all domestic and agricultural products, would spontaneously renew itself and cost nothing but the taking. There are many sterile or wornout soils in Europe so situated that they might, at no very formidable cost, be converted into permanent lakes, which would serve not only as reservoirs to retain the water of winter rains and snow, and give it out in the dry season for irrigation, but as breeding ponds for fish, and would thus, without further cost, yield a larger supply of human food than can at present be obtained from them even at a great expenditure of capital and labor in agricultural operations. [Footnote: See Ackerhof, Die Nutzung der Seiche und Gewasser. Quedlinburg, 1860.] The additions which might be made to the nutriment of the civilized world by a judicious administration of the resources of the waters, would allow some restriction of the amount of soil at present employed for agricultural purposes, and a corresponding extension of the area of the forest, and would thus facilitate a return to primitive geographical arrangements which it is important partially to restore.

Destruction of Fish.

The inhabitants of the waters seem comparatively secure from human pursuit or interference by the inaccessibility of their retreats, and by our ignorance of their habits—a natural result of the difficulty of observing the ways of creatures living in a medium in which we cannot exist. Human agency has, nevertheless, both directly and incidentally, produced great changes in the population of the sea, the lakes, and the rivers, and if the effects of such revolutions in aquatic life are apparently of small importance in general geography, they are still not wholly inappreciable. The great diminution in the abundance of the larger fish employed for food or pursued for products useful in the arts is familiar, and when we consider how the vegetable and animal life on which they feed must be effected by the reduction of their numbers, it is easy to see that their destruction may involve considerable modifications in many of the material arrangements of nature. The whale [Footnote: I use WHALE not in a technical sense, but as a generic term for all the large inhabitants of the sea popularly grouped under that name. The Greek kaetos and Latin Balaena, though sometimes, especially in later classical writers, specifically applied to true cetaceans, were generally much more comprehensive in their signification than the modern word whale. This appears abundantly from the enumeration of the marine animals embraced by Oppian under the name <Greek: kaetos>, in the first book of the Halieutica.

There is some confusion in Oppian's account of the fishery of the <Greek: kaetos> in the fifth book of the Halieutica. Part of it is probably to be understood of cetaceans which have GROUNDED, as some species often do; but in general it evidently applies to the taking of large fish—sharks, for example, as appear by the description of the teeth—with hook and bait.] does not appear to have been an object of pursuit by the ancients, for any purpose, nor do we know when the whale fishery first commenced. It was, however, very actively prosecuted in the Middle Ages, and the Biscayans seem to have been particularly successful in this as indeed in other branches of nautical industry. [Footnote: From the narrative of Ohther, introduced by King Alfred into his translation of Orosius, it is clear that the Northmen pursued the whale fishery in the ninth century, and it appears, both from the poem called The Whale, in the Codex Exoniensis, and from the dialogue with the fisherman in the Colloquies of Aelfric, that the Anglo-Saxons followed this dangerous chore at a period not much later. I am not aware of any evidence to show that any of the Latin nationals engaged in this fishery until a century or two afterward, though it may not be easy to disprove their earlier participation in it. In mediaeval literature, Latin and Romance, very frequent mention is made of a species of vessel called in Latin baleneria, balenerium, balenerius, balaneria, etc.; in Catalan, balener; in French, balenier; all of which words occur the many other forms. The most obvious etymology of these words would suggest the meaning, whaler, baleinier; but some have supposed that the name was descriptive of the great size of the ships, and others have referred it to a different root. From the fourteenth century, the word occurs oftener, perhaps, in old Catalan, than in any other language; but Capmany does not notice the whale fishery as one of the maritime pursuits of the very enterprising Catalan people, nor do I find any of the products of the whale mentioned in the old Catalan tariffs. The WHALEBONE of the mediaeval writers, which is described as very white, is doubtless the ivory of the walrus or of the narwhale.] Five hundred years ago, whales abounded in every sea. They long since became so rare in the Mediterranean as not to afford encouragement for the fishery as a regular occupation; and the great demand for oil and whalebone for mechanical and manufacturing purposes, in the present century, has stimulated the pursuit of the "hugest of living creatures" to such activity, that he has now almost wholly disappeared from many favorite fishing grounds, and in others is greatly diminished in numbers.

What special functions, besides his uses to man, are assigned to the whale in the economy of nature, wo do not know; but some considerations, suggested by the character of the food upon which certain species subsist, deserve to be specially noticed. None of the great mammals grouped under the general name of whale are rapacious. They all live upon small organisms, and the most numerous species feed almost wholly upon thesoft gelatinous mollusks in which the sea abounds in all latitudes. We cannot calculate even approximately the number of the whales, or the quantity of organic nutriment consumed by an individual, and of course we can form no estimate of the total amount of animal matter withdrawn by them, in a given period, from the waters of the sea. It is certain, however, that it must have been enormous when they were more abundant, and that it is still very considerable. In 1846 the United States had six hundred and seventy-eight whaling ships chiefly employed in the Pacific, and the product of the American whale fishery for the year ending June 1st, 1860, was seven millions and a half of dollars. [Footnote: In consequence of the great scarcity of the whale, the use of coal-gas for illumination, the substitution of other fatty and oleaginous substances, such as lard, palm-oil, and petroleum for right-whale oil and spermaceti, the whale fishery has rapidly fallen off within a few years. The great supply of petroleum, which is much used for lubricating machinery as well as for numerous other purposes, has produced a more perceptible effect on the whale fishery than any other single circumstance. According to Bigelow, Les Etats-Unis en 1863, p. 346, the American whaling fleet was diminished by 29 in 1858, 57 in 1860, 94 in 1861, and 65 in 1862. The number of American ships employed in that fishery in 1862 was 353. In 1868, the American whaling fleet was reduced to 223. The product of the whale fishery in that year was 1,485,000 gallons of sperm oil, 2,065,612 gallons of train oil, and 901,000 pounds of whalebone. The yield of the two species of whale is about the same, being estimated at from 4,000 to 5,000 gallons for each fish. Taking the average at 4,500 gallons, the American whalers must have captured 789 whales, besides, doubtless, many which were killed or mortally wounded and not secured. The returns for the year are valued at about five million and a half dollars. Mr. Cutts, from a report by whom most of the above facts are taken, estimates the annual value of the "products of the sea" at $90,000,000.

According to the New Bedford Standard, the American whalers numbered 722, measuring 230,218 tons, in 1846. On the 31st December, 1872, the number was reduced to 204, with a tonnage of 47,787 tons, and the importation of whale and sperm oil amounted in that year to 79,000 barrels. Svend Foyn, an energetic Norwegian, now carries on the whale fishery in the Arctic Ocean in a steamer of 20 horse-power, accompanied by freight-ships for the oil. The whales are killed by explosive shells fired from a small cannon. The number usually killed by Foyn is from 35 to 45 per year.—The Commerce in the Products of the Sea, a report by Col. R. D. Cutts, communicated to the U. S. Senate. Washington, 1872.] The mere bulk of the whales destroyed in a single year by the American and the European vessels engaged in this fishery would form an island of no inconsiderable dimensions, and each one of those taken must have consumed, in the course of his growth, many times his own weight of mollusks. The destruction of the whales must have been followed by a proportional increase of the organisms they feed upon, and if we had the means of comparing the statistics of these humble forms of life, for even so short a period as that between the years 1760 and 1860, we should find a difference possibly sufficient to suggest an explanation of some phenomena at present unaccounted for. For instance, as I have observed in another work, [Footnote: The Origin and History of the English Language, &c., pp. 423, 424.] the phosphorescence of the sea was unknown to ancient writers, or at least scarcely noticed by them, and even Homer—who, blind as tradition makes him when he composed his epics, had seen, and marked, in earlier life, all that the glorious nature of the Mediterranean and its coasts discloses to unscientific observation—nowhere alludes to this most beautiful and striking of maritime wonders. In the passage just referred to, I have endeavored to explain the silence of ancient writers with respect to this as well as other remarkable phenomena on psychological grounds; but is it not possible that, in modern times, the animalculae which produce it may have immensely multiplied, from the destruction of their natural enemies by man, and hence that the gleam shot forth by their decomposition, or by their living processes, is both more frequent and more brilliant than in the days of classic antiquity?

Although the whale does not prey upon smaller creatures resembling himself in form and habits, yet true fishes are extremely voracious, and almost every tribe devours unsparingly the feebler species, and even the spawn and young of its own. [Footnote: Two young pickerel, Gystes fasciatus, five inches long, ate 128 minnows, an inch long, the first day they were fed, 132 the second, and 150 the third.—Fifth Report of Commissioners of Massachusetts for Introduction of Fish. 1871. p. 17.] The enormous destruction of the shark [Footnote: The shark is pursued in all the tropical and subtropical seas for its fins—for which there is a great demand in China as an article of diet—its oil and other products. About 40,000 are taken annually in the Indian Ocean and the contiguous seas. In the North Sea and the Arctic Ocean large numbers are annually caught. See MERK. Waarenlexikon—a work of great accuracy and value (Leipzig, 1870), article Haifisch.] the pike, the trout family, and other ravenous fish, as well as of the fishing birds, the seal, and the otter, by man, would naturally have occasioned a great increase in the weaker and more defenceless fish on which they feed, had he not been as hostile to them also as to their persecutors.

Destruction of Aquatic Animals.

It does not seem probable that man, with all his rapacity and all his enginery, will succeed in totally extirpating any salt-water fish, but he has already exterminated at least one marine warm-blooded animal—Steller's sea cow—and the walrus, the sea lion, and other large amphibia, as well as the principal fishing quadrupeds, are in imminent danger of extinction. Steller's sea cow, Rhytina Stelleri, was first seen by Europeans in the year 1741, on Bering's Island. It was a huge amphibious mammal, weighing not less than eight thousand pounds, and appears to have been confined exclusively to the islands and coasts in the neighborhood of Bering's Strait. Its flesh was very palatable, and the localities it frequented were easily accessible from the Russian establishments in Kamtschatka. As soon as its existence and character, and the abundance of fur animals in the same waters, were made known to the occupants of those posts by the return of the survivors of Bering's expedition, so active a chase was commenced against the amphibia of that region, that, in the course of twenty-seven years, the sea cow, described by Steller as extremely numerous in 1741, is believed to have been completely extirpated, not a single individual having been seen since the year 1768. The various tribes of seals [Footnote: The most valuable variety of fur seal, formerly abundant in all cold latitudes, is stated to have been completely exterminated in the Southern hemisphere, and to be now found only on one or two small islands of the Aleutian group. In 1867 more than 700,000 seal skins were imported into Great Britain, and at least 600,000 seals are estimated to have been taken in 1870. These numbers do not include the seals killed by the Esquimaux and other rude tribes.] in the Northern and Southern Pacific, the walrus [Footnote: In 1868, a few American ships engaged in the North Pacific whale fishery turned their attention to the walrus, and took from 200 to 600 each. In 1869 other whalers engaged in the same pursuit, and in 1870 the American fleet is believed to have destroyed not less than fifty thousand of these animals. They yield about twenty gallons of oil and four or five pounds of ivory each.] and the sea otter, are already so reduced in numbers that they seem destined soon to follow the sea cow, unless protected by legislation stringent enough, and a police energetic enough, to repress the ardent cupidity of their pursuers. The seals, the otter tribe, and many other amphibia which feed almost exclusively upon fish, are extremely voracious, and of course their destruction or numerical reduction must have favored the multiplication of the species of fish principally preyed upon by them. I have been assured by the keeper of several young seals that, if supplied at frequent intervals, each seal would devour not less than fourteen pounds of fish, or about a quarter of his own weight, in a day. A very intelligent and observing hunter, who has passed a great part of his life in the forest, after carefully watching the habits of the fresh-water otter of the North American States, estimates their consumption of fish at about four pounds per day. Man has promoted the multiplication of fish by making war on their brute enemies, but he has by no means thereby compensated his own greater destructiveness. [Footnote: According to Hartwig, the United Provinces of Holland had, in 1618, three thousand herring busses, and nine thousand vessels engaged in the transport of these fish to market. The whole number of persons employed in the Dutch herring fishery was computed at 200,000.

In the latter part of the eighteenth century, this fishery was most successfully prosecuted by the Swedes, and in 1781, the town of Gottenburg alone exported 136,649 barrels, each containing 1,200 herrings, making a total of about 164,000,000; but so rapid was the exhaustion of the fish, from this keen pursuit, that in 1799 it was found necessary to prohibit the exportation of them altogether.—Das Leben des Meeres, p. 182.

In 1855, the British fisheries produced 900,000 barrels, or almost enough to supply a fish to every human inhabitant of the globe.

On the shores of Long Island Sound, the white fish, a species of herring too bony to be easily eaten, is used as manure in very great quantities. Ten thousand are employed as a dressing for an acre, and a single net has sometimes taken 200,000 in a day.—Dwight's Travels, ii. pp. 512, 515. The London Times of May 11, 1872, informs us that 1,100 tons of mackerel estimated to weigh one pound each had recently been taken in a single night at a fishing station on the British coast.

About ten million eels are sold annually in Billingsgate market, but vastly greater numbers of the young fry, when but three or four inches long, are taken. So abundant are they at the mouths of many French and English rivers, that they are carried into the country by cart-loads, and not only eaten, but given to swine or used as manure.] The bird and beast of prey, whether on land or in the water, hunt only as long as they feel the stimulus of hunger, their ravages are limited by the demands of present appetite, and they do not wastefully destroy what they cannot consume. Man, on the contrary, angles to-day that he may dine to-morrow; he takes and dries millions of fish on the banks of Newfoundland and the coast of Norway, that the fervent Catholic of the shores of the Mediterranean may have wherewithal to satisfy the cravings of the stomach during next year's Lent, without violating the discipline of the papal church; [Footnote: The fisheries of Sicily alone are said to yield 20,000 tons of tunny a year. The tunny is principally consumed in Italy during Lent, and a large proportion of the twenty millions of codfish taken annually at the Lofoden fishery on the coast of Norway is exported to the Mediterranean.] and all the arrangements of his fisheries are so organized as to involve the destruction of many more fish than are secured for human use, and the loss of a large proportion of the annual harvest of the sea in the process of curing, or in transportation to the places of its consumption. [Footnote According to Berthelote, in the Gulf of Lyons, between Marseilles and the easternmost spur of the Pyrenees, about 5,000,000 small fish ate taken annually with the drag-net, and not lees than twice as many more, not to spekak of spawn, are destroyed by the use of this act.

Between 1861 and 1865 France imported from Norway, for use as bait in the Sardine fishery, cod-roes to the value of three million francs.—Cutts, Report on Commerce in the Products of the Sea, 1872, p. 82.

The most reckless waste of aquatic life I remember to have seen noticed, if we except the destruction of herring and other fish with upawn, is that of the eggs of the turtle in the Amazon for the sake of the oil extracted from then. Bates estimates the eggs thus annually sacrificed at 48,000,000.-Naturalits inthe Amazon, 2d edition, 1864, p. 805.] Fish are more affected than quadrupeds by slight and even imperceptible differences in their breeding places and feeding grounds. Every river, every brook, every lake stamps a special character upon its salmon, its shad, and its trout, which is at once recognized by those who deal in or consume them. No skill can give the fish fattened by food selected and prepared by man the flavor of those which are nourished at the table of nature, and the trout of the artificial pouds in Germany and Switzerland are so inferior to the brook-fish of the same species and climate, that it is hard to believe them identical. The superior sapidity of the American trout and other fresh-water fishes to the most nearly corresponding European species, which is familiar to every one acquainted with both continents, is probably due less to specific difference than to the fact that, even in the parts of the New World which have been longest cultivated, wild nature is not yet tamed down to the character it has assumed in the Old, and which it will acquire in America also when her civilization shall be as ancient as is now that of Europe. [Footnote: It is possible that time may modify the habits of the fresh-water fish the North American States, and accommodate them to the new physical conditions of their native waters. Hence it may be hoped that nature, even unaided by art, will do something towards restoring the ancient plenty of our lakes and rivers. The decrease of our fresh-water fish cannot be alone to exhaustion by fishing, for in the waters of the valleys and flanks of the Alps, which have been inhabited and fished ten times as long by a denser population, fish are still very abundant, and they thrive and multiply under circumstances where no American species could live at all. On the southern slope of those mountains, trout are caught in great numbers, in the swift streams which rush from the glaciers, and where the water is of icy coldness, and so turbid with particles of fine-ground rock, that you cannot see an inch below the surface. The glacier streams of Switzerland, however, are less abundant in fish.]