6. According to Linnæus, the great naturalist, about four hundred species of fish have come to our knowledge; and he presumes, that those which remain unknown are still more numerous. Notwithstanding this great variety, the chief attention of fishermen is confined to a few kinds, which are the most easily caught, and which are the most valuable when taken.
7. Every place which contains many inhabitants, and which is located in the vicinity of waters well stored with fish, is supplied with these animals by men who make fishing a business; still, these fisheries may be considered local in their benefits, and perhaps do not require particular notice in this article. We will only remark, therefore, that, in large cities, fresh fish are sold either in a fish-market, or are _hawked_ about the streets. The wives of the fishermen are very often employed in selling the fish caught by their husbands. The fisheries which are of the greatest consequence, in general commerce, are those which relate to herring, mackerel, salmon, seal, and whale.
8. _Herring Fishery._--There are several species of herring; but, of these, four kinds only are of much importance, viz., the common herring, the shad, the hard head, and the alewife; of which, the first is the most valuable, being by far the most numerous, and being, also, better adapted than the others for preservation.
9. The winter residence of the common herring is within the arctic circle, whence it emigrates, in the spring, to more southern portions of the globe, for the purpose of depositing its spawn. The first body of these migratory animals, appears on the coasts of both Europe and America, in April, or about the first of May; but these are only the precursors of the grand shoals which arrive in a few weeks afterwards.
10. Their first approach is indicated by the great number of birds of prey, which follow them in their course; but, when the main body appears, the number is so great, that they alter the appearance of the ocean itself. In this last and principal migration, the shoals are five or six miles in length, and three or four in breadth; and, before each of these columns, the water is driven in a kind of ripple. Sometimes, the fish sink together ten or fifteen minutes, and then rise again to the surface, when they reflect, in clear weather, the rays of the sun, in a variety of splendid colors.