244 Charles J. Fish 



in April 1932, the numbers were everywhere relatively sparse except in three widely 

 separated localities where more than 1,000 per minute were taken in oblique hauls with 

 half metre nets of number 10 mesh. Two of these were near the Nova Scotian coast, 

 one approximately 25 miles east of Briar Island (3,999 per minute) and the other off 

 Halifax (3,744 per minute). A third (2,470 per minute) was located off the inner 

 margin of Georges Bank between the middle and western channels. 



Varying numbers, usually small, were taken at all stations east of Mt. Desert in the 

 Gulf, the Bay of Fundy, and along the west and south coasts of Nova Scotia. West 

 of Mt. Desert, Microsetella appeared at but five of ten stations in the inner Gulf, 

 and in the outer Gulf at but four of nine stations. The two eastern centres of abund- 

 ance coincided with similar local concentrations of O. similis (Fish, 1936 c), the 

 numbers of the two species off Halifax being approximately the same. The richest 

 hauls of both species in the inner Gulf, at this time, were also obtained at the same 

 location, St. 24a, seaward of the 100 metre contour off Casco Bay. 



With observations restricted to the inner Gulf and Bay during the balance of the 

 season, it was not possible to determine the duration of the three Microsetella con- 

 centrations observed in April. The distribution in succeeding months reveals a pro- 

 gressive shoreward movement of the eastern and western adult-copepodite stocks and 

 gradual expansion to a seasonal peak everywhere in the inner Gulf seaward of the 

 100 metre contour (Fig. 2). Here the members ranged from 1,360 to 5,662 per cubic 

 metre in August. 



Contrasted with 1932, records for August 1931 show much smaller numbers at all 

 comparable stations, although the local swarm near Monhegan Island (p. 243) yielded 

 the highest counts of the two seasons. By September the numbers in the Bay of Fundy 

 had declined greatly both in 1931 (188 per cubic metre) and in 1932 (179 per cubic 

 metre). 



PRODUCTION AND DISPERSAL 



There are few available data on the biology of Microsetella norvegica, in fact 

 the developmental stages, some of which are shown in Fig. 3, have not yet been 

 described to the author's knowledge. The seasonal occurrence of adults south of Cape 

 Cod would suggest that, like Pseudocalanus, spawning may begin at the southern 

 portion of its range as early as November or December. It is not known, however, 

 whether propagation continues offshore in deeper water after the species disappears 

 from neritic areas south of the Cape with rising spring temperatures. 



Distribution of eggs and larvae in 1932 



By mid-April propagation in the Gulf was most advanced in the outer part of the 

 western basin between Georges Bank and Cape Cod. Here late nauplius stages up to 

 1 ,544 per minute were found at two stations. Farther east in the outer Gulf spawning 

 was still taking place and egg sacs up to 926 per minute were found coinciding with 

 the local concentration of adults. Smaller numbers of early nauplii (309 per minute) 

 appeared at one station in this region. Still farther east along the outer Nova Scotian 

 coast neither eggs nor larvae were found. In the inner Gulf spawning had just begun 

 in the eastern basin (up to 1,666 egg sacs per minute) and small numbers of eggs were 

 found extending into the Bay of Fundy. Only one station (St. 29) west of Petit Manan 

 yielded eggs at this time, and no larvae appeared anywhere in the inner Gulf or Bay, 



