FISHERY BULLETIN: VOL. 79, NO. 4 



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Kuntz and Radcliffe (1917) found that develop- 

 ment in the laboratory required "not over" 43 h, 

 but did not give temperature data. 



During the cruise, all the eggs collected were 

 spawned on 5 different days. Those spawned dur- 

 ing the afternoon of the first sampling day (batch 

 III) were the only ones sampled from spawning 

 to hatching. 



Batches of developing embryos spent roughly 

 3 h in each of the developmental stages listed 

 in Table 5, except for the very early cell stages. 

 From these data we derived a timetable of em- 

 bryonic development (Table 6). Blastopore closure 

 occurred about 12 h after spawning. Eggs were 

 in middle stages of development, i.e., between 

 blastopore closure and first appearance of the tail 

 bud, for about 9 h. Hatching occurred about 15 h 

 after tail bud formation. 



The numbers of eggs in each batch are plotted 

 according to developmental stage and time of day 

 in Figure 6. Number of eggs taken varied widely 

 from tow to tow; hence, we could not estimate 

 mortality within any batch. In most tows, how- 

 ever, several obviously malformed late stages 

 occurred in which embryos usually had ruptured 

 yolks and shortened, rather wide tails. We assume 

 that the condition of these embryos was not due to 

 handling. These embryos, which composed up to 

 5.2% of an egg batch (Table 7), would probably not 

 have survived to hatch. 



The numbers of eggs taken at different times of 

 day vary as batches are spawned and as they hatch 

 (Figure 7). Because the eggs are spawned during 

 only one period of the day (1500-1800 h), we would 

 expect the maximum numbers of eggs to occur at 



Table 6. — Timetable of development of Atlantic whiting eggs 

 based on collections made during the vertical distribution study 

 of ichthyoplankton in the Middle Atlantic Bight, July 1974. 



Time 



Hours from 

 spawning 



Developmental stage 



C31 ra (1) 

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Day 1: 

 1500 

 1800 

 2100 

 2400 

 0300 

 0600 

 0900 



Day 2: 

 1200 

 1500 

 1800 

 2100 

 2400 

 0300 

 0600 

 0900 







3 



6 



9 



%2 



15 



18 



21 

 24 

 27 

 30 

 33 

 36 

 39 

 42 



Precell 



Cell stage 

 Early blastula 

 Blastodermal cap 

 Early germ ring 

 Germ ring '2-^4 down 

 Early middle 



Middle middle 



Late middle 



Tail Ve around yolk 



Tail ^/4 around yolk 



Tail 's around yolk 



Full circle 



Tail IVb around yolk — hatching 



Tail 1 ' 8 around yolk — hatching 



714 



