194 



FISHERY BULLETIN OF THE FISH AND WILDLIFE SERVICE 



at its height in Massachusetts Bay, nor were as 

 many as 50 percent of the Ipswich Bay fish ripe 

 before mid-March. Commencing to spawn later 

 there and near Cape Ann than they do off Ply- 

 mouth, they also continue later, i. e., until the 

 end of April or even into the first part of May, as 

 appears from the following table of cod-egg col- 

 lections supplied by the Gloucester hatchery: 



Off the western coast of Maine, according to 

 Capt. E. E. Hahn, former superintendent of the 

 Boothbay Harbor hatchery, cod spawn from late 

 February or early March until the last of May, 

 with the production of eggs at its peak in March; 

 they spawn from March through May off the 

 eastern Maine coast, and cod eggs (and hence 

 spawning cod) have been recorded in spring in the 

 Bay of Fundy. 



On Georges Bank cod spawn in abundance in 

 February, 98 March, and April. 



The records of the hatcheries just summarized 

 tell when eggs are produced in maximum abund- 

 ance, but they throw little light on the limits 

 of the spawning season, for it was oidy during 

 the period when there were enough ripe fish to 

 warrant the effort and expense that spawn taking 

 was carried on. And occasional ripe cod of both 

 sexes are seen long before the bulk of the fish 

 breed, and long after. Thus Earll " reports the 

 first ripe female as taken near Cape Ann on 

 September 2 during the season of 1S7S-79, while 

 we have taken cod eggs, far enough advanced in 

 incubation for positive identification as such, off 

 Shelbui-ne (Nova Scotia) on September 6; near 

 Mount Desert on September 15; and off Penob- 

 scot Bay on October 6 (all in 1915). 



93 This fact has long been common knowledge, and W. F. Clapp, formerly 

 of the Museum of Comparative Zoology, has seen many cod with eggs 

 running, caught on Georges Bank in February and March. 



» Rept. U. S. Comm. Fish. (1878) 1880, p. 713. 



On the other hand Earll saw ripe fish about 

 Cape Ann as late as June. And our tow-nettings 

 make it likely that some may even spawn in 

 midsummer in the coastal zone east of Cape 

 Elizabeth, for we have occasionally found eggs 

 identifiable as either cod or haddock by their 

 black pigment, and probably the former, near 

 Mount Desert Island on July 19; near Wooden 

 Bell Island at the mouth of Penobscot Bay on 

 August 6 and near Cape Elizabeth on Septem- 

 ber 30. 



This sporadic summer breeding of cod in our 

 Gulf is hardly comparable to the so-called "after- 

 spawning" that has been observed off the north 

 coast of Iceland by Schmidt, 1 in the North Sea, 

 and in the Baltic. 2 But it is not unusual for cod 

 to breed in summer off the outer coast of Nova 

 Scotia where ripe fish are reported by local 

 fishermen in June and July. Similarly, spawning 

 cod were caught from the deck of the Grampus 

 (Capt. E. E. Hahn in command) on Bradelle 

 Bank in the Gulf of St. Lawrence late in August 

 many years ago, while gadoid eggs (probably 

 cod) were towed at various localities there during 

 June, July, and August of 1915 by the Canadian 

 Fisheries Expedition. 3 



Cod spawn chiefly if not altogether in summer 

 on the Grand Banks where Arctic temperatures 

 prevaU during the spring. 



Corresponding to the prolonged period of repro- 

 duction, spawning takes place over rather a wide 

 range both of temperature and of salinity in our 

 Gulf. On the Ipswich Bay grounds, for example, 

 some are spawning late in November when the 

 bottom water at the depth in question (p. 193) is 

 at its warmest for the year (near 48°) ; they ripen 

 regularly in temperatures of 41°-43° F. (January) ; 

 spawning is at its height in the minimum temper- 

 atures of the year (35°-37.5°), and some spawning 

 continues until the bottom water has once more 

 warmed to 38°-41° (mid-May). 



On the Massachusetts Bay ground, spawning 

 fish appear in numbers (late November) when the 

 bottom water is still as warm as 47°-48°; the chief 

 production taking place in temperatures of 36°-42° 

 (December through January), hence in warmer 

 water than in Ipswich Bay. And the peak of the 



' Rapp. et Proc. Verb., Cons. Perm. Internat. Explor. Mer., vol. 10, 1909, 

 pp. 21, 123. 



» Ehrenbaum (Nordisches Plankton, vol. 1, 1905-1909, p. 225) and Fulton 

 (Cons. Perm. 1'Explor. Mer, Pub. de Circonstance, No. 8, 1904). 



' Dannevig, Canadian Fish. Exped. (19H-15) 1919, p. 22. 



