PLANKTON OF THE GULF OF MAINE 



267 



Gloucester Harbor (Esterly, in Bigelow, 1914, p. 116). Farran (1910) has classed 

 it as a tropical and temperate form, which is corroborated by Willey's (1919) failure 

 to find it in the collections of the Canadian fisheries expedition off Nova Scotia 

 and Newfoundland or in the Gulf of St. Lawrence, where it has never been reported, 

 and by its absence from the plankton collections made by Herdman off the Straits of 

 BeUe Isle (Herdman, Thompson, and Scott, 189S); but it ranges eastward along 

 Nova Scotia for some distance past Cape Sable, for the Grampus took it at three 

 stations across the continental shelf off Shelburne, Nova Scotia, on June 23, 1915 

 (stations 10291, 10293, and 10294), and the Albatross found it again near Koseway 

 Bank (station 20074) and outside the continental edge on this fine (station 20077) 

 on March 19, 1920. 



Paracalanus parvus may have been overlooked in the earlier towings in the 

 Gulf of Maine because it is so tiny (it is the smallest of calanoids), but the collec- 

 tions of 1915, 1920, and 1921 prove it present in the gulf in every month in the 

 year except July and November, when no hauls were made — that is, a year-round 

 resident. In spite of its brief history in our towings its records extend widespread 

 over the gulf, indifferently outside the continental edge, over the offshore banks, 

 in both sides of the deep basin, and all around the coastal belt (fig. 80). There are 

 also records over the continental shelf off Marthas Vineyard (stations 10331 to 

 10333; table, p. 298). 



In spite of the seasonal fluctuations outlined below, the regional distribution is 

 as general in the cold half of the year as in the warm half, and Paracalanus occurs 

 in all parts of the gulf and about as regularly in one region as another. The plotted 

 records might suggest a concentration in the inner parts of the gulf, but in reality 

 this merely reflects the greater number of hauls which have been made there, and 

 more especially the fact that no towing was done in the southern or eastern parts 

 of the basin or on Georges Bank during the summer of 1915. In short, this copepod 

 is to be expected anywhere in the region at any time of year. I have not been 

 able to subdivide the guff into regions "rich" or "poor" for this species, whether 

 for the year as a whole or for the individual months, the stations where 

 catches were larger than the monthly average being widely distributed (fig. 81) 

 (having reference to the regional distribution of the hauls in different years and 

 seasons) both for the winter-spring and for summer-autumn; but we have taken 

 it in much larger numbers off Marthas Vineyard (station 10332 and 10333) than 

 anywhere east or north of Nantucket, suggesting that the waters over the conti- 

 nental shelf south of southern New England are a center of abundance for it. 



Seasonal fluctuations. — P. parvus has been taken at the following percentages of 

 the stations for 1915, 1920, and 1921 (tables, p. 298): 



Date 



March, 1920 and 1921 



April, 1920. 



May, 1915 and 1920.. 



June, 1915 



August, 1915 



Percent- 

 age of 

 stations 



29 

 23 

 80 

 100 

 100 



Date 



September, 1915, 

 October, 1915.... 

 December, 1920. 

 January, 1921. . 



Percent- 

 age of 

 stations 



75 

 93 

 60 

 40 



