FISHERY BULLETIN: VOL. 74, NO. 4 



the population increased in average size of in- 

 dividuals in succeeding quarters, the largest 

 females being proportionately most abundant in 

 the first quarter (January-March). 



Diet (Table 5) 



The single S. inequalis taken by DSB III had a 

 calanoid copepod in its stomach. 



Sergja hisulcata (Wood-Mason 1891) 



Vertical Distribution (Figure 27) 



As with S. bigemmea, equality in size of the 

 sexes and small daytime catches indicate that 5. 

 hisulcata was avoiding the trawl. Immature 

 shrimp were mostly taken between 675 and 750 m 

 during the daytime, adults mostly from 700 to 900 

 m, with a few catches as deep as 1,100 m. The 

 December 1970 cruise took 19 individuals, includ- 

 ing both immatures and adults, in an open tow 

 from 650 to 680 m, with much smaller catches down 

 to 1,200 m. At night, immature shrimp occurred 

 between 175 and 300 m, adults mostly from 225 to 

 350 m, with occasional captures as deep as 450 m. 

 Moonlight depressed the population below 300 m; 

 two tows at 450 m during the June 1973 cruise took 



200 

 400 

 600 

 800 

 1000 

 1200 



4 8 12 16 20 24 28 

 CFWflPflCE LENGTH IMM) 



10 20 

 NO. PEH 105 m3 



10 and 8 individuals, respectively. There was no 

 evidence of full moon nonmigration. 



Population Size, Growth, and 

 Reproduction (Figure 28) 



Sergia bisiilcata was the second most abundant 

 all-red sergestid in the Teuthis collection, though 

 far below S. gardineri in numbers. The average 

 population density figure from all horizontal tows 

 was 1.35 per 100 m'-. The figure for tows on moonlit 

 nights was higher, 1.96 per 100 m-', probably a 

 sampling artifact. The two oblique series produced 

 similar numbers; September 1972 gave 1.19 and 

 May 1973 gave 0.82 per 100 m-. 



While quarterly variations in the size-frequency 

 distributions of most Hawaiian sergestids suggest 

 that they live about 1 yr, only in S. hisulcata is 

 there evidence for a longer life span. Small imma- 

 ture shrimp around 7-9 mm CL were recruited in 

 the second quarter (April-June) and grew to 

 sexual maturity at about 14-18 mm CL in 1 yr. 

 They continued to grow at a rate of approximately 



SERGIA BISULCATA 



d 



-\ JAN - MAR 



hM 



OH 1 1—"— 1 — ' *! " ^ T 



6 10 14 18 22 26 



gj APR-JUN 



Jl 



PI 



r In , 



10 14 18 22 26 



JUL -SEP 



P . np , r 



Cl 



6 10 14 18 22 



10 14 18 22 26 



_ OCT -DEC 



j£y 



11 



Ah 



1 I r^ T r^ 



18 22 6 10 



CARAPACE LENGTH (mm) 



-r 



26 



Figure 27.-Vertical distribution of Sergia hisulcata. 



Figure 28.— Quarterly size-frequency distribution of Sergia 



hisulcata. 



822 



