FISHERY BULLETIN: VOL. 74, NO. 4 



SERGIA SCINTILLANS 



40 - JUL - SEP 



1 

 



CARAPACE LENGTH (mm) 



Figure 20.-Quarterly size-frequency distribution of Seryia 



ncintillans. 



Diet (Table 5) 



The DSB III material showed that 5. scintiUans 

 ate the usual variety of zooplanktonic Crustacea, 

 including calanoid copepods, amphipods, and an 

 ostracod. The 0.4- to 0.6-mm size fraction was also 

 taken; bivalve larvae, foraminifera, and cyclopoid 

 copepods were found in many individuals. Other 

 food items included the large cyclopoid copepod 

 Sapphirina, a larval decapod, and masses of an 

 unidentified greenish, fibrous material. 



Sergi'a gardineri (Kemp 1913) 



Vertical Distribution (Figure 21) 



Sergia gardineri was usually found between 650 

 and 775 m during the daytime, although shrimp 

 smaller than 5 mm CL seldom occurred below 700 

 m. The extremely high values in this range were 

 largely due to the catches of the November 1972 

 cruise. On certain occasions the population seemed 

 to extend downward to at least 1,200 m. The June 

 1973 cruise took 59 specimens in three tows 

 between 850 and 1,050 m, and only 8 specimens in 

 four tows between 650 and 850 m. The December 

 1970 cruise caught only nine specimens in an open 

 tow at 650-680 m, but tows below 800 m caught 



large numbers, including 77 in a tow from 1,150 to 

 1,250 m. On the other hand, all four daytime tows 

 on the May 1972 cruise between 650 and 950 m took 

 only one shrimp. 



The nighttime distribution was strongly 

 influenced by large catches from the May 1973 

 cruise. It showed a concentration in the upper 150 

 m, with shrimp less than 6 mm CL restricted to 

 25-100 m. All large shrimp in the upper 25 m were 

 females, the result of a single tow in May 1973 that 

 fished between 15 and 45 m, taking 36 adult 

 females and 1 very small male. A tow at 20 m on 

 the same cruise took no S. gardineri, indicating 

 that this species probably does not reach the 

 surface. There were a few captures below the 

 normal range on moonless nights, notably a 250-m 

 tow in September 1971 that took four, and a 480- to 

 550-m tow in November 1972 that took five. 



Most captures of 5. gardineri on nights with 

 much moonlight were at the daytime depth, except 

 for the March 1971 cruise, which took 16 shrimp at 

 320-340 m and 20 shrimp at 100-150 m, although a 

 tow at 170-200 m did not take any. Three open tows 

 near full moon on the December 1970 cruise took 

 207 S. gardineri between 700 and 1,000 m, while a 

 550- to 600-m tow took 9. Later in the cruise when 

 the moon was waning, they were captured at 80 

 and 30 m (but not at 100-110 or 50 m!). The 



6 8 10 13 



CflRflPflCE LENGTH (MM) 



16 60 \i 



NO. PER 10= 



Figure 21.- Vertical distribution of Sergia gardineri. 



818 



