PLANKTON OF THE GULF OF MAINE 177 



fishery grounds off Ireland, most commonly in autumn, it may prove a more im- 

 portant ingredient in the food of the European mackerel than it is ever likely to 

 be off the seaboard of eastern North America. 



Acartia longiremis Liilljeborg 



Tins species is of minor importance in the Gulf of Maine but is recorded suffi- 

 ciently often to deserve brief mention. In the Atlantic A. longiremis ranges from the 

 polar basin on the north, where it has been taken at many localities both on the 

 European side and along the Arctic coast of Canada (Willey, 1921), to the Mediter- 

 ranean on the one side and southward to Chesapeake Bay on the other. It is also 

 reported from the Gulf of Suez. Its distribution, in general, has recently been charted 

 by Steuer (1923). 



It has usually been described as more or less neritic, though less so than A. clausi. 

 According to Farran (1910 and 1911) it is mainly a littoral form in the more southern 

 parts of its range, though often found in the open sea off Norway. Herdman, 

 Thompson, and Scott (1S9S) record it regularly in the Gulf of St. Lawrence, out to 

 the Straits of Belle Isle, and again between longitude 31° 40' W. and the British 

 coastal waters, but not at all in the intervening zone. It was not found at Woods 

 Hole either by Wheeler (1901) or by Sharpe (1911), nor was it found in Rhode Island 

 waters by Williams (1906 and 1907) or off New Jersey by Fowler (1912). Probably, 

 however, it is to be expected all along southern New England, for Fish (1925) found 

 it at Woods Hole from January to May, while Dr. C. B. Wilson contributes the 

 statement that it occurs in and about Chesapeake Bay, though less abundantly than 

 A. clausi. 



The only previous records for A. longiremis in the Gulf of Maine are as fol- 

 lows: Station 10020 (about 4 per cent of the copepods), Gloucester Harbor, and 

 6 miles off Cape Porpoise (2 per cent of the copepods) during the summer of 1912; 

 station 10251, off Cape Elizabeth, August 14, 1914 (especially interesting because 

 upwards of 90 per cent of the hundreds of copepods taken in the surface net were 

 adults and juveniles of A. longiremis) 93 ; and Passamaquoddy Bay, January 16, 1920, 

 when A. longiremis (adult and young) constituted 13 per cent of the copepods taken 

 (Willey, 1921). 



During the cruises of 1915 and 1920 this species proved much less plentiful and 

 less generally distributed in the gulf than A. clausi, its status in the gulf differing 

 widely from year to year. In 1920 it was not detected at all in February. In March 

 (fig. 60) it occurred at 38 per cent of the stations, confined to four distinct regions: 

 (1) the coastal zone from Cape Cod to Cape Elizabeth, (2) the eastern part of Georges 

 Bank and the deep water to the north, (3) Browns Bank, and (4) the shallows off 

 western Nova Scotia out to German Bank. In every case the number of specimens 

 taken was trifling, the highest frecpiency in the vertical hauls being only 95 per square 

 meter of sea surface. The scarcity of this species during March appears also from 

 its percentage in the total copepod catch (0-30 per cent; average 2>2 per cent). 



" Identified by Dr. C. O. Esterly. 



