population into the 100- to 200-m range, although 

 some remained shallower. A few nighttime cap- 

 tures were made in the daytime depth range. The 

 December 1970 cruise took large numbers near full 

 moon at 550-600 m (up to 40), and also at 150-200 m 

 (up to 21). Apparently at least 50^;^ of the popula- 

 tion was not migrating. Later in the cruise, when 

 the moon was waning, large numbers of S. orien- 

 folis were taken in tows between 30 and 120 m (up 

 to 70). There was no evidence of full moon nonmi- 

 gration during the December 1973 cruise. 



Population Size, Growth, and 

 Reproduction (Figure 10) 



Sergci^tes orientalis was moderately abundant 

 in Hawaiian waters. The average population 

 density estimated by all the horizontal tows was 

 1.32 per 100 m'-, daytime and night tows giving 

 similar figures. The oblique series of September 

 1972 yielded a higher figure of 8.43 per 100 m'-', S. 

 oriental h being the second most abundant species 

 in the shallow night tows. On. the other hand, it 

 was much scarcer during the oblique series of May 

 1973, which gave a population density of only 0.64 

 per 100 m'-. Sergestes orientalis was particularly 

 abundant during the December 1970 cruise, when 

 as many as 70 were taken in a single 3-h IKMT 

 tow. 



The seasonal size-frequency histograms are all 

 very similar to one another. Shrimp smaller than 6 

 mm CL were proportionally most abundant during 

 the first quarter (January-March), but the dif- 

 ference was not statistically significant 

 (Kolmogorov-Smirnov test, P> 0.05). 



Diet (Table 5) 



Only two individuals from DSB III were ex- 

 amined. One had an empty stomach; the other had 

 eaten an ostracod. 



Sergestes tantillus Burkenroad 1940 



Vertical Distribution 



Because of the rarity of 5. tantillus, little can be 

 inferred about its vertical distribution. Single 

 shrimp were taken in daytime tows between 410 

 and 915 m. The largest night catch was at 50 m 

 (four shrimp), with individual captures to about 

 200 m. A tow between 635 and 715 m on a moonlit 

 night took six shrimp. 



812 



FISHERY BULLETIN: VOL. 74; NO. 4 



U 6 8 10 12 14 16 8 16 



200 

 400 

 600 



800 

 1000 

 1200 



200 

 MOO 

 600 

 800 

 1000 

 1200 



200 

 400 

 600 

 800 

 1000 

 1200 



DRT 



o mt^ 



m 



NIGHT 



m 



mo 



MOON 



m 





■r 

  



200 



uoo 



500 



800 



1000 



1200 



200 

 400 

 600 

 800 

 1000 

 1200 



• 200 



400 



600 



800 



1000 



1200 



8 10 12 14 15 



15 

 nS m3 



CflRRPHCE LENGTH IMMl NO. PER 10= M^ 



Figure 9.- Vertical distribution of Sergestes orientalis. 



SERGESTES ORIENTALIS 



CAR4PACE LENGTH (mml 



Figure lO.-Quarterly size-frequency distribution of Sergestes 



orientalis. 



Growth, reproduction, and diet were not studied 

 because of the small sample size. 



