Observations on the biology ol" Micro.\eicllu nurvcwicu 



247 



By September few eggs and young remained in the Bay, the largest number of nauplii, 

 374 per cubic metre, being taken in New Brunswick waters off Point Lipreau. 



Table II 

 Mean numbers of adults and egg sacs of Microsetella norvegica in successive months. 

 April-June: number per minute. August-September: number per cubic metre. 



.■ no observations 



DISCUSSION AND CONCLUSIONS 

 Annual cycle 



Possibly because of its very unequal distribution during the early season, develop- 

 mental stages of Microsetella were not taken in sufficient numbers to permit tracing 

 with certainty successive generations in different areas until August. 



Considering the region as a whole, it appears probable that, like Oifhona, there are 

 at least three and possibly four generations of the stock spawning in late March and 

 reaching late nauplius stages in mid-April. A second breeding period is indicated by 

 an increase in egg sacs in the Gulf in late May (Table 11) followed by an increase of 

 copepodite-adults in June. The abundance of late nauplius-copepodite stages com- 

 bined with relatively few egg sacs in August (Table III) suggests a maturing of the 

 second generation and the appearance of a third crop of eggs in July. Egg sacs in the 

 Bay of Fundy on September 15-16 may represent a fourth relatively unimportant 

 generation. There would thus appear to be propagation periods in March, May, 

 July and possibly September, with a cycle of approximately two months. 



Table III 

 Mean numbers (per cubic metre) o/' Microsetella norvegica /// different areas in 



and 1932 



193 



Total Gulf 



1931 



1932 



Aug. 

 21-26 



Aug. 

 8-15 



Egg sac 376 



Early nauplius 162 



Late nauplius 698 



Copepodite-Adult 2922 



Regarding regional production, Microsetella norvegica appears tirsi as an otlshorc 

 species which later penetrates and propagates in the inner Gulf some lime after 

 augmentation has taken place in the region of the outer banks. The brood in the 



