Table 5. — Number and percentage of euphausiid species collected in spring 1963 at depth intervals 

 of surface to 30-m. and 30- to 150-m. at stations 2, U, 7, 8, 11, 12, 13, 16, 17, and 18 



Species 



Euphausiids 

 collected 



Surface- 

 30 m. 



Percentage 



species caught 



in each interval 



Surface- 

 30 m. 



30- 



150 m. 



Frequency 

 of occurrence 



Surface- 

 30 m. 



30- 



150 m. 



Number 



Percent 



Percent 



Euphausia pacifica 



Thysanoessa spinifera . • . . 



Ttiysanoessa lon^ipes 



Nematoscelis difficilis . . 

 Tessarabrachion oculatus . 

 Nematobraehlon flexipes . . 

 Stylocheiron maximum 



Table 6 Numbers of euphausiids collected at different depths and periods of the day in 



horizontal tows at stations 8 and 17, spring 1963 



Depth 



Station 8 



Dusk Midnight Dawn Afternoon 



Station 17 



Midnight 



Dawn 



Noon 



Number 



Number 



<45 

 



17 



T. longipes in the northern part of their range 

 were different from those farther south. 



The vertical distribution and migration of 

 some of the euphausiid species differed slightly 

 from the description by Brinton (1962a). He 

 stated that 'X. spinifera was restricted to 

 depths of less than 100 m. and showed no 

 evidence of diurnal vertical migration, whereas 

 we did not take adults of this species in the 

 upper 150 m. of the water column during noon 

 or afternoon periods. The absence of adults 

 may indicate vertical migration or avoidance 

 of the trawl by the animals. Brinton also 

 found N. difficilis common in the upper 

 140 m. and no clear evidence of diurnal 

 vertical migration. There was slight evidence 

 for such movements at station 17 (table 7), 

 however. 



Other Groups 



At dusk, midnight, and dawn, a substantial 

 part of the biomass was collected at the sur- 

 face at station 8 but not at station 17 (figs. 16 

 and 17). At station 8, the largest catch, taken 

 from 75 m. at midnight, contained at least seven 

 times as many crab larvae ( Cancer sp.) as 

 any of the other samples. The surface samples 

 taken at dusk, midnight, and dawn contained 74 

 to 94 percent crab larvae, by number. Large 

 concentrations of crab larvae and euphausiids 

 were not found at the same depths (tables 6 

 and 8), but large numbers of crab larvae and 

 postlarval benthic fishes (table 9) were caught 

 together at dusk, midnight, and dawn. The 

 fishes were from the families Scorpaenidae 

 and Cottidae. 



20 



