"The ocean banks of moderate depths are the favorite resorts of the cod, but it is by no means confined to those localities. The fish, indeed, occasionally enters into fresh, or at least brackish, water. According to Canadian authorities, it is found 'well up the estuary of the St. Lawrence, though how far up is not definitely stated, probably not beyond the limits of brackish water.' Even as far south as the Delaware River it has been known to enter the streams. Dr. C. C. Abbott records that in January, 1876, 'a healthy, strong, active codfish, weighing nearly four pounds, was taken in a draw-net in the Delaware River near Trenton, New Jersey; the stomach of the fish showed that it had been in river-water several days. Many of them had been taken about Philadelphia between 1856 and 1869.'
"The cod ranks among the most voracious of ordinary fishes, and almost everything that is eatable, and some that is not, may find its way into its capacious maw. Years ago, before naturalists had the facilities that the dredge now affords, cods' stomachs were the favorite resort for rare shells, and some species had never been obtained otherwise than through such a medium, while many filled the cabinet that would not otherwise have been represented. In the words of Mr. Goode, 'codfish swallow bivalve fish of the largest size, like the great sea-clams, which are a favorite article of food on certain portions of the coast'; further, 'these shells are nested, the smaller inside of the larger, sometimes six or seven in a set, having been packed together in this compact manner in the stomachs of the codfish after the soft parts have been digested out. Some of them had shreds of the muscles remaining in them and were quite fresh, having evidently been but recently ejected by the fish.' Even banks of dead shells have been found in various regions, which are supposed to be the remains of mollusks taken by the cod. Shell-fishes, however, form probably but the smaller portion of its diet, and fishes of its own class contribute materially to its food,—such as the herring family, the capelin, etc.
"The codfish in its mode of reproduction exhibits some interesting peculiarities. It does not come on the coast to spawn, as was once supposed, but its eggs are deposited in mid-sea and float to the surface, although it does really, in many cases, approach the land to do so. Prof. C. O. Sars, who has discovered its peculiarities, 'found cod at a distance of twenty to thirty Norwegian miles from the shore and at a depth of from one hundred to one hundred and fifty fathoms.' The eggs thus confided to the mercy of the waves are very numerous; as many as 9,100,000 have been calculated in a seventy-five-pound fish. 'When the eggs are first seen in the fish they are so small as to be hardly distinguishable; but they continue to increase in size until maturity, and after impregnation have a diameter depending upon the size of the parent, varying from one-nineteenth to one-seventeenth of an inch. A five- to eight-pound fish has eggs of the smaller size, while a twenty-five-pound one has them between an eighteenth and a seventeenth.' There are about 190,000 eggs of the smaller size to a pound avoirdupois. They are matured and ejected from September to November."
Unlike most fishes, the cod spawns in cooling water, a trait also found in the salmon family.
The liver of the cod yields an easily digested oil of great value in the medical treatment of diseases causing emaciation.
The Alaska cod, Gadus macrocephalus, is equally abundant with the Atlantic species, from which it differs very slightly, the air-bladder or sounds being smaller, according to the fishermen, and the head being somewhat larger. This species is found from Cape Flattery to Hakodate in Japan, and is very abundant about the Aleutian Islands and especially in the Okhotsk Sea. With equal markets it would be as important commercially as the Atlantic cod. In the codfish (Gadus) and related genera there are three dorsal and two anal fins. In the codfish the lateral line is pale and the lower jaw shorter than the upper.
Fig. 486.—Skull of Haddock, Melanogrammus æglifinus.
Fig. 487.—Haddock, Melanogrammus æglifinus (L.). Eastport, Me.