o 



I I SURFACE TO 30 METER 

 OBLIQUE TOWS 



30-150 METER 

 OBLIQUE TOWS 



Figure 18. — Distribution of biomass in spring 1963 as wet weight in grams per 30-minute tow. (The 183- and 1,829-m. 



depth contours are shown.) 



largest numbers occurred at 30 m, at station 

 8, and within the upper 30 m. at station 17 

 (table 6). These slight differences in distribu- 

 tions may have been affected by the bright 

 moonlight during the sampling at station 8 and 

 the absence of moonlight at station 17. 



All euphausiids, with the possible exception 

 of jr. longipes were more numerous in the 

 upper 150 m. during dusk, midnight, and dawn 

 than at noon or afternoon. T. longipes showed 

 evidence of vertical migration at station 17, 



but not at station 8 (table 7), Differences in 

 sampling time and vertical distribution of tem- 

 perature and salinity at these two stations may 

 have affected the differences in distribution. 

 T. longipes was found in the upper 150 m. 

 during the afternoon at station 8, where a 

 well-mixed surface layer, about 60 m. thick, 

 existed above a sharp thermocline; it was not 

 taken at station 17 at noon where these physical 

 features were missing (fig. 19). Brinton 

 (1962a) noted that the vertical movements of 



19 



