Page:Encyclopædia Britannica, Ninth Edition, v. 19.djvu/136

Rh PIS C I C II L T IT K E PISCICULTURE. This art as at present pursued is not limited to those animals which are grouped by zoologists in the class of Pisces. &quot; Fishery &quot; is now under stood to signify the exploitation of all products of the sea, lake, and river, the capture of whales, turtles, pearls, corals, and sponges, as well as of fish proper. The pur pose of fish-culture (or aquiculture, as it is in France more appropriately named) is to counteract by reparative and also by preventive measures the destructive effects of fishery. The possibility of exterminating aquatic animals within the restricted limits of a lake or a river cannot be doubted ; authorities are decidedly at variance, however, as to the extent of the influence of man upon the abundance of life in the open seas. Distinction must be made between the extermination of a species, even in a restricted locality, and the destruction of a fishery; the former is very unusual, and is seemingly impossible in the case of oceanic species, but the latter, especially for limited regions, is of almost yearly occurrence. Aquatic mammals, such as seals, may be en tirely exterminated, especially when, like the fur seal, they forsake the water for a season and resort to the land for breeding purposes. The fur seals of the Pacific and Ant arctic are now nearly gone, except in two groups of islands, the Pribylovs in Alaska and the Commander Islands in Siberia, where they enjoy Government protection, the islands being leased to the Alaska Commercial Company by whom only a stated number, all non-breeding males, may be killed each year, the permanence of the fishery being thus perfectly secured. Aquatic mammals also which never leave the water, like whales and sirenians, being conspicuous by reason of their size, and incapable of rapid multiplication, may, especially when they breed near the shore, suffer extermination. As examples may be cited the Arctic sea cow (Rhytina steHeri) and the Pacific grey whale (Rkachianectes glaucus), the former extinct, the latter having practically become so within the present century. The sperm whale is also rapidly dis appearing. In the case of fixed animals like the oyster, the corals, and the sponges, again, the colonies or beds may be swept out of existence exactly as forests are hewn down. The native oyster beds of Europe are for the most part gone, and still more rapid has been the recent destruc tion of the oyster reefs in Pocomoke Sound, Maryland, a large estuary, formerly very productive the result being due more directly to the choking up of the beds by the rubbish dragged over them by dredges, and the demolition of ledges suitable for the reception of young spat, than to the removal of all the adult oysters, which could, of course, never have been effected. The preservation of oyster-beds is a matter of vital importance to the United States, for oyster-fishing, unsupported by oyster-culture, will soon destroy the employment of tens of thousands and a cheap and favourite food of tens of millions of the people. Some thing may undoubtedly be effected by laws which shall allow each bed to rest for a period of years after each season of fishing upon it. It is, however, the general belief that shell-fish beds must be cultivated as carefully as are garden beds, and that this can be done only by giving to indivi duals rights in submerged lands, similar to those which may be acquired upon shore. It is probable that the present unregulated methods will prevail until the dredging of the natural beds shall cease to be remunerative, and that the oyster industry will then pass from the improvi dent fishermen to the painstaking oyster-grower, with a corresponding increase in price and decrease in consump tion. Such a change has already taken place in France and Holland, and to a large extent in England, but there appear to be almost unsurmountable difficulties in the way of protecting the property of oyster-culturists from depre dations difficulties apparently as formidable in England as in America. Fishes in ponds, lakes, or streams are quickly exter minated unless the young be protected, the spawning season undisturbed, and wholesale methods of capture prohibited. Salmon and trout streams are preserved in all countries of northern Europe ; and in Canada also a large service of fishery wardens is maintained. In the United States there are in many of the older common wealths excellent codes of laws for the preservation of fish and game, which are enforced by anglers clubs. A river may quickly be emptied of its anadromous visitors, salmon, shad, and alewives, by over-fishing in the spawning season, as well as by dams which cut off the fish from their spawning-grounds. Numerous rivers in Europe and America might be named in which this has occurred. la the same way, sea fishes approaching the coasts to spawn in the bays or upon the shoals may be embarrassed, and the numbers of each school decimated, particularly if, as in the case of the herring, the eggs are adhesive and become entangled in nets. Sea fishes spawning in estuaries are affected much in the same manner as the salmon in rivers, though in a less degree, by wholesale capture in stationary nets. The shad and alewife fisheries of the United States are protected by an extensive code of laws, varying in the several States and in the different rivers of each State. The most satisfactory laws appear to be those which regulate the dates when fishery must commence and end, and prescribe at least one day in each week, usually Sunday, during which the ascent of the fish may not be interrupted. Migratory, semi-migratory, or wandering fishes, ranging singly or in schools over broad stretches of ocean, the mackerels, the tunnies, the sardines or pilchards, the menhaden, the bluefish, the bonitoes, and the sque- teague, stand apparently beyond the influence of human agency, especially since, so far as is known, they spawn at a distance from the coast, or since the adults, when about to spawn, cannot be reached by any kind of fishery apparatus. Their fecundity is almost beyond comprehension, and in many instances their eggs float free near the surface, and are quickly disseminated over broad areas. The conclu sions gained by Prof. Baird, U.S. commissioner of fisheries, agree exactly with those of Prof. Huxley, that the number of any given kind of oceanic fish killed by man is perfectly insignificant when compared with the destruction effected by their natural enemies. Almost any body of water, be it a bay or sound, or be it the covering of a ledge or shoal at sea, may be over-fished to such a degree that fishing becomes unprofitable, especially if fishing be carried on in the spawning season. In this manner, no doubt, have the coasts of England been robbed of the formerly abundant supplies of turbot and sole. The character of the various destructive influences which man brings to bear upon the inhabitants of the water and their effects having thus been briefly noticed, the student of fish culture is confronted by the question, What can be done to neutralize these destructive tendencies ? There are evidently three things to do: (1) to preserve fish waters, especially those inland, as nearly as it may be possible in their normal condition ; (2) to prohibit waste ful or immoderate fishing ; and (3) to put into practice the art of fish breeding (a) to aid in maintaining a natural supply, (&) to repair the effects of past improvi dences, and (c) to increase the supply beyond its natural limits rapidly enough to meet the necessities of a con stantly increasing population. The preservation of normal conditions in inland waters is comparatively simple. A reasonable system of forestry and water-purification is all that is required ; and this is needed not only by the fish in the streams but by the