PLANKTON OF THE GULF OF MAINE 233 



meters, irrespective of the season. In August, 1913, for example, every such haul 

 captured it, and in the spring of 1920, 80 per cent of the deep hauls took it. In 

 fact, we have learned to expect it in every deep haul (it is made very conspicuous in 

 the catch by its large size and by the brilliant blue egg clusters borne by the adult 

 females) and to regard it as almost as typical of the bottom waters of the gulf below, 

 say, 150 meters as Calanus finmarchicus is of the upper 100 meters. The plotted 

 positions (lig. 73) do not suggest that its area of regular occurrence in the gulf under- 

 goes any expansion or contraction with the change of the seasons. 



Although so nearly universal in appropriate depths, E. norvegica "is never 

 abundant in the Gulf of Maine in the sense that Calanus or any of the other small 

 copepods can be so described" (Bigelow, 1915, p. 292), the richest horizontal hauls 

 yielding a few thousands at most, as is described in detail below. Since the passage 

 of even the deeper vertical hauls through the stratum regularly inhabited by Eucha»ta 

 is necessarily brief everywhere in the gulf, 28 the result has been that the vertical 

 hauls have often missed it at stations where it has been taken in the horizontals, 

 and consequently do not give a true picture of its distribution. For example, it 

 does not appear in the list of copepods for the vertical haul in the eastern basin on 

 June 10, 1915 (station 10283), though considerable numbers were taken in the hori- 

 zontal haul as they had been a month previous also (station 10273). 



Contrasted with its universal distribution in the basin of the gulf and its con- 

 stant occurrence there, we have few records of this species inside the general 100- 

 meter contour, whether in the coastwise zone or over the offshore banks — Georges 

 and Browns. Records of it in Massachusetts Bay (fig. 73) — apparent exceptions — ■ 

 are all located in the deep sinks off Gloucester where Euchreta is apparently a 

 permanent inhabitant of the deepest water below, say, 60 to 70 meters. 



Present knowledge suggests that E. norvegica regularly ranges closer in to the 

 land — and in shoaler water — off the Eastport-St. Andrews region, just within the 

 entrance to the Bay of Fundy, than elsewhere in the gulf, Willey (1921) having 

 reported 7 per cent of this species in a 10-fathom tow off Eastport on August 2, 1916, 

 and having found a quantity of Euchasta in the stomachs of pollock caught about 

 Campobello Island, New Brunswick. E. norvegica also entered the mouth of the 

 St. Croix River to abreast of St. Andrews on February 23, 1917 (Willey, 1921), this 

 being the only record of its presence in any estuarine situation tributary to the Gulf 

 of Maine. Our failure to take this species at any of the stations in the deep eastern 

 and northern channels is instructive in connection with the possibility of its immi- 

 gration into the gulf. 



Although the geographic range of E. norvegica follows the continental edge as 

 far as the longitude of Delaware Bay (p. 232), it has been found at only about 50 per 

 cent of our deep stations abreast the mouth of the Gulf of Maine, and only once 

 (the station noted, p. 232) beyond the longitude of Nantucket in this direction, 

 although a number of hauls were made along the slope southward to the latitude of 

 Chesapeake Bay in the summers of 1913 and 1916. Longitude 70° may therefore 

 be set as about the western boundary to its regular presence along the North Ameri- 

 can coast. 



» In explanation I may point out that only the deepest hair of a vertical haul from 200 meters is likely to take Euchseta. 



