FISHERY BULLETIN: VOL. 72. NO. 2 



sampling schedule. The second, begun 5 May, 

 provided most of the specimens used in the 

 description, although certain additional measure- 

 ments (e.g., size at hatching) were made on 

 specimens from the first culture. 



Series A Cultures 



One thousand eggs were pipetted from the 

 washed plankton of a surface tow with a 505 /j 

 mesh meter net in south Kaneohe Bay, Oahu, 

 on 22 February 1971. These eggs were placed 

 in a 78-liter fiberglass and glass aquarium 

 which had been filled with triple CUNO^ filtered 

 (5 /J effective pore size) bay water. The water was 

 previously exposed to long-wave ultraviolet light 

 for 1 min. Penicillin (to a concentration of 50 

 mg/liter) and Polymixin B (to a concentration 

 of 8 mg/liter) were added before introduction of 

 the eggs. These antibiotics have been shown to 

 substantially reduce bacterial counts in cultures 

 and materially increase hatching success of 

 omaka eggs (Struhsaker, Hashimoto, Girard, 

 Prior, and Cooney, 1973). A Chlorella sp. culture 

 was added initially to an approximate cell count 

 of 10 X 10" cells/ml. 



■•Reference to trade names does not imply endorsement 

 by the National Marine Fisheries Service, NOAA. 



Salinity, oxygen, and temperature in the tank 

 were usually measured daily. Salinity remained 

 nearly constant throughout the experiment at 

 35 /CO, the value in the bay at the time of 

 collection. Oxygen values ranged from 6.1 to 9.5 

 mg/liter during the subsequent 36 days. The 

 maximum range of temperature in the tank was 

 21.5 to 25.9°C, with a 36-day mean of 24.5°C. 

 The bay surface temperature at the time of 

 collection was 24.4°C. 



The tank was continuously illuminated by two 

 40 watt fluorescent "daylight" bulbs. The light 

 intensity at the surface of the water was approxi- 

 mately 6.5 X 10^ flux. The tank was aerated with 

 a single airstone, with airflow adjusted to produce 

 a slow single stream of bubbles. 



Food was added daily from the third day 

 after hatching. Through day 11 the food was the 

 75-150 Ai fraction of wild zooplankton attracted 

 to a night light suspended in the bay. On day 

 12 the addition of wild plankton was replaced 

 with additions ofArtemia nauplii. Wild plankton 

 and Artemia were added each time to a concen- 

 tration in the tank of 5/ml and 1/ml, respectively. 

 No doubt the culture tank supported other 

 (unknown) populations of plankters and micro- 

 organisms. 



Usually ten larvae were captured by dipping or 

 pipetting at about two-day intervals from hatch- 

 ing (the day after introduction of the eggs) 

 until 36 days after that time (Table 1). No 

 attempt was made to select particular sized 

 larvae. 



Series B Cultures 



Larvae reared for yolk-sac-stage description 

 were hatched from eggs taken from Kaneohe 

 Bay on 5 May 1972. At the time of collection 

 (midafternoon), eggs were found in both late 

 middle stage and early stage, i.e., from two 

 spawnings. Only the latter (in blastodisc stage) 

 were selected for culture. (The exact time of 

 fertilization is unknown; hence the duration of the 

 early stage was estimated.) Extrapolating from 

 the subsequent rate of development, we estimate 

 the eggs had been fertilized for about 2 h 

 before capture. 



Two hundred eggs were placed in each of four 

 4-liter beakers of unfiltered seawater obtained 

 about two miles offshore from Kaneohe Bay. 

 This "offshore" water contained less plankton 



498 



