FISHES OF THE GULF OF MAINE 



195 



spawning season has passed before the tempera- 

 ture drops to its winter minimum, although some 

 cod spawn there through the coldest season (mini- 

 mum temperature 33°-37°). The temperature 

 range through which the cod breed on the offshore 

 grounds cannot be stated so precisely, for want 

 of data for autumn and for early winter. 



In the Gulf of St. Lawrence, cod are known to 

 spawn in water as cold as 32° F. or even slightly 

 colder, 4 though the eggs develop at higher tem- 

 peratures for they rise to the upper water layers. 

 Around Newfoundland, the cod appear to seek 

 temperatures of 35°-40° F. (1.5-4.4° C.) for spawn- 

 ing, with the chief production of eggs taking place 

 at 37°-41°F. (3-5° C).* 



Cod spawn in rather colder water on the whole 

 in the Gulf of Maine (still more so in the Gulf of 

 St. Lawrence and on the Newfoundland Banks) 

 than they do in the other side of the North At- 

 lantic, or about Iceland, where the chief production 

 of eggs takes place at temperatures of 40°-45° F. 

 Probably no cod spawn in water fresher than 

 about 32 per mille nor saltier than about 32.8 per 

 mille, either on the Ipswich Bay grounds or on 

 the Massachusetts Bay grounds. And our records 

 (as far as they go) point to a salinity of about 

 32.6 per mille as typical for the spawning of the 

 cod on Georges Bank. This is water much less 

 saline than ripe cod seek in European seas, and 

 necessarily so, the Gulf of Maine being decidedly 

 fresher at all times of the year than the Norwegian 

 Sea or the waters around Iceland. 



On the Massachusetts Bay spawning ground the 

 specific gravity of the water is high enough to 

 insure that the eggs shall float throughout the 

 breeding season, but in Ipswich Bay the spring 

 freshets often so lighten the surface that late- 

 spawned cod eggs and haddock eggs may fail to 

 rise to the uppermost water layers, a phenomenon 

 which hinders the operations of the hatchery but 

 which does not militate against the successful 

 incubation of the eggs in nature, since the eggs 

 merely float suspended at some deeper level. 

 This subject is discussed at greater length in 

 connection with the haddock (p. 208). 



We have yet to learn what proportion of the 

 cod larvae that are hatched in the Gulf of Maine 

 (doubtless a very small one) survive to grow to 



' HJort, Canadian Fish. Eiped. (1914-1915) 1919, p. XXVII. 

 •Thompson, Research Bull. 14, Newfoundland Dept. Nat. Resources, 

 1943, p. 89. 



market size. And what few bits of evidence we 

 have in this regard are contradictory. 6 



Importance.- — In 1945, the most recent year for 

 which detailed statistics of the catch are available 

 for the coastlines of Massachusetts and Maine, 

 as well as for the offshore Banks, the Gulf of 

 Maine yielded about 62,500,000 pounds of cod 

 to United States fishermen; 7 some 8,000,000- 

 9,000,000 to Canadian fishermen; 8 or a grand 

 total of some 70-71 million pounds, plus an inde- 

 terminate amount landed in small Nova Scotian 

 harbors between the Yarmouth County line and 

 Cape Sable. This is about the same amount as 

 the Gulf had yielded in 1919 (about 67,000,000 

 pounds) ; nor is there anything in the catches of 

 intervening years to suggest that any very pro- 

 nounced fluctuations had taken place meantime 

 in the abundance of cod within our Gulf. 



A representative yield, in round numbers, 

 broken down into the statistical areas now em- 

 ployed by the U. S. Fish and Wildlife Service, 

 would be about 7,000,000 pounds along the west- 

 ern coast of Nova Scotia and along the lower 

 Nova Scotian shore of the Bay of Fundy; about 

 380,000 pounds for the upper Nova Scotian shore 

 of the Bay; about 1,600,000 pounds for the 

 New Brunswick shore of the Bay near its mouth; • 

 about 500,000 pounds for eastern Maine; about 

 4,500,000 pounds for central Maine; about 

 3,350,000 pounds along western Maine; about 

 600,000 pounds from the small fishing grounds in 

 the inner-central part of the Gulf; about 5,000,000 

 pounds off eastern Massachusetts: a little less 

 than 5,000,000 pounds for the grounds from Cape 

 Cod out to the so-called South Channel; about 

 17,000,000 pounds for Georges Bank as a whole; 

 about 2,000,000 pounds for the western part of 

 Browns Bank; and about 2,200,000 pounds for 

 Nantucket Shoals. 



During the early days of the fishery, the entire 

 Gulf of Maine catch of cod was made on hook 

 and line; on hand lines at first, but with long or 



• Fish (Bull. U. S. Bur. Fish., vol. 43, 1929, p. 266) caught no cod larvae 

 in Massachusetts Bay, though eggs were abundant there, but the Albatrosf 11 

 towed several hundred little cod (4 to 9>4 mm.) off the tip of Cape Cod near- 

 by, on May 28, 1927. Tho paucity of our other catches of cod larvae (80 to 

 90 all told) for other parts of the Gulf of Maine may have been accidental. 



» Total landings in New England ports were about 139,700,000 pounds, 

 but something over 77,000,000 of this was taken on the grounds along outer 

 Nova Scotia. 



• About 9,259.900 pounds In 1944, about 8,226,000 pounds in 1945, and about 

 8,174,800 pounds in 1946. 



1 No cod are mentioned for the head of the Bay on the New Brunswick 

 side in the Canadian statistics of late years. 



