414 BULLETIlSr OF THE BUREAU OF FISHERIES 



Grand Banks and along the eastern coast of Labrador when they are following 

 capelin. Cod even strand on the Labrador beaches while harrying schools of the 

 latter, and occasionally, though less often, cod follov/ herring up to the surface in 

 the Gulf of Maine, though perhaps they never strand there. For instance, we have 

 knowTi largo cod to be gaffed from a vessel's side in Northeast Harbor, Mount Desert 

 Island, in September, when they were chasing "sardines." 



During the first year after the young cod take to bottom (p. 417) many of them 

 live in very shoal water, even along the littoral zone, and many young fry have 

 been taken at Gloucester and elsewhere along the shores of New England. We 

 have yet to learn, however, whether others seek the deeper bottoms of the offshore 

 banks at this early stage. As a rule large cod lie below 10 fathoms in summer. 

 In winter time, however, especially in Ipswich Bay, the fishing is often good in 

 only 3 to 5 fathoms of water, and many small cod are caught about the rocks only 

 a fathom or two deep even in summer. At the other extreme, comparatively few 

 cod are caught much deeper than 100 fathoms in the Gulf of Maine, and although 

 fishermen sometimes do well at much greater depths on the slopes of the offshore 

 banks, the 10 and 75 fathom contours probably include the great majority of all 

 the cod living in the Gulf, summer or winter. 



The cod is typically a ground fish except when following prey or on some 

 journey (a subject to be discussed later), usually lying within a fathom or so of the 

 bottom, and as a general rule large ones keej) closer to the ground than small ones, 

 and consequently the closer to bottom one fishes the larger the cod are apt to run. 



Type of bottom frequented. — Cod are caught chiefly on rocky and pebbly ground, 

 on gravel, sand, and on a particularly gritty type of clay with broken shells — 

 seldom on soft mud — "cod" and "hake" bottoms being so distinct that a trawl 

 fine set from a hard patch out over the soft surrounding ground will often catch the 

 former at one end and the latter at the other. Cod also frequent the deeper slopes 

 of ledges along shore where they forage among the " Irish moss " (Chondrus crispus) 

 and other seaweeds. Young ones are especially common in these situations and 

 sometimes one catches a large "rock cod," as these fish (almost always red in such 

 environments) are called. 



The thermal migrations and the relationship of the spawning of the cod to 

 temperature are discussed below (p. 418). The adult cod finds any temperature 

 from 35° to 50° favorable — that is, all but the superficial layers of the Gulf of Maine 

 at all seasons. Experience at the Woods Hole hatchery, however, proves that 

 freezing, by the formation of anchor ice, for instance, is fatal. Lai^e cod do not 

 live anywhere in water warmer than about 50°, but small ones are less sensitive 

 to heat, a fact reflected in their batliic occurrence. 



Food. — When the larval cod first breaks from the egg it subsists on the yolk 

 with which its abdomen is distended (fig. 206), as do most other sea fish. This 

 source of nutriment is completely absorbed by the sixth day after hatching, how- 

 ever, and the future existence of the little fish depends as much on finding a plentiful 

 supply of food as on escaping the enemies by which it is encompassed. Unfor- 

 tunately little is known of the feeding habits of the larvae, but it is certain that they 

 feed on plankton during the several months that they live in the upper layers of 



