42 BULLETIN OF THE BUREAU OF FISHERIES 



nauplii (besides copepod eggs), larval Anemones, and young Staurophora down to 



30 meters, overlying a sparse adult Calanus-Sagitta-Pleurobrachia community in 

 the deeper strata of water. 



There is some evidence that the wave of reproduction of copepods continues to 

 spread offshore with the advance of the season until it covers the southwestern part 

 of the gulf generally; and it certainly endures later into the spring in the open gulf 

 than in Massachusetts Bay, for the presence of nauplii showed that in 1920 these 

 little crustaceans were breeding actively from Cape Cod to Georges Bank as late as 

 May 16 and 17. In the spring of 1915 nauplii were abundant on the surface 

 off the Cape, with older stages deeper down, as late as the 26th of the month (station 

 10279), although they had been almost entirely replaced by the older larvse and by 

 half-grown Calanus (fig. 29) as early as the 4th of that month off Gloucester (station 

 10266). Similarly, the presence of copepod nauplii in the sink off the Isles of 

 Shoals on May 14, 1915 (station 10278), coupled with a decided increase in young 

 copepods between April 26 and May 14 to 16, 1913 (Bigelow, 1914a, p. 407), though 

 with diatoms still abundant there on both these occasions, 19 suggests that copepods 

 do not begin to multiply this far offshore until well into May, although repro- 

 duction is under way more than a month earlier than this inshore off the Merrimac 

 River. 



We have no evidence that the coastal waters east of Penobscot Bay ever see a 

 local reproduction of copepods comparable to the waves of production just described 

 for Massachusetts Bay. 



As to local production of copepods along the eastern (Nova Scotian) side of the 

 gulf, I can only say that our hauls near Lurcher Shoal on March 23 (station 20082) , 

 and again off Yarmouth, on German Bank, and near Cape Sable on April 13 to 15, 

 1920 (stations 20102, 20103, and 20104), yielded nauplii and older larval copepods 

 in some numbers, which probably marks the beginning of a period of active propaga- 

 tion, for in 1915 we found both nauplii and the older juvenile stages of Calanus 

 plentiful on the surface of the eastern basin near by on May 6. 



The vernal wave of production of these little crustaceans reaches its apex by the 

 end of May or the first of June in the northern and eastern parts of the gulf, for we 

 found a typical Calanus plankton reestablished off Boothbay (station 10280), in the 

 Fundy Deep (station 10282), and off Mount Desert Island (station 10284) by May 



31 to June 11 in 1915. 



An important problem in the natural economy of the gulf is how far the vernal 

 augmentation of the zooplankton of the offshore parts of the gulf — say, outside the 

 100-meter contour — is due to local propagation there and how far to a migration of 

 the copepods out from the coastal zone where they are produced in such enormous 

 numbers. To answer this question definitely demands a more critical study of our 

 towings than opportunity has yet allowed. One thing is clear, however. None of 

 our offshore hauls at any season has ever yielded copepod nauplii or the later larval 

 stages in numbers to compare with their abundance in Massachusetts Bay. It is 

 equally suggestive that in May, when the coastwise copepod plankton is juvenile, 

 large Calanus have invariably been an important element in the total copepod catches 

 in the deep basin, just as is the case in summer, which points to the coastwise waters 



10 In 1913 they were diminishing in numbers locally by that time. 



