FISHERY BULLETIN: VOL. 76, NO. 1 



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Figure 5. — Daily variation of spawning rushes during June (summer) and January (winter) by a population of striped 

 parrotfish at Discovery Bay, Jamaica. The beginning of period 1 represents midpoint of the day and the end of period 8 

 sunset. Figures represent mean of two observations (periods 1-3) and four observations (periods 4-8). 



data are analyzed on a minute by minute basis, 

 over 90*^ of the spawning rushes observed occur- 

 red during only 33% of the 1-min periods. Since 

 the group engaged in a spawning rush is consider- 

 ably smaller than the total population at the 

 spawning area, it is possible for several groups to 

 carry out a spawning rush separately, but nearly 

 simultaneously. The occurrence of the first rush by 

 a group seems to trigger other groups to spawn. A 

 flurry of rushes lasted a period of 1-4 min and in 

 one case reached a frequency of 35 rushes in a 

 1-min period. This number may be underesti- 

 mated due to the difficulty in observing and count- 

 ing such rapid events. The period between groups 

 of rushes was spent in milling about close to the 

 substrate and feeding on exposed rock surface of 

 the reef. 



The time between episodes of epidemic rushing 

 varied during the day in summer periods. During 

 early periods when some spawning occurred 

 (period 3 and to a lesser extent period 4) often 5-7 

 min would elapse without any rushes occurring. In 

 one case there was 9 min between rushes. Later in 

 the day, at times of peak spawning (periods 5-7), 

 these nonspawning periods were reduced to 1,2, 

 and occasionally 3 min. 



PREDATION 



Mackerel (either cero, Scomberomorus regalis, 

 or king mackerel, S. caualla) twice attempted to 

 prey on Scarus croicensis at the top of the spawn- 

 ing rush, once apparently successfully. These at- 

 tacks interrupted the spawning behavior of the 

 entire group. In one case only 1 rush occurred in 

 the 10 min following the attack even though 67 

 rushes had occurred in the previous 15 min. On a 

 third occasion, a lizardfish, Synodus sp., rushed 

 upward from the substrate in an unsuccessful at- 

 tempt to prey on Scarus croicensis and thus inter- 

 rupted spawning for a short period. 



Chromis cynaeus and Clepticus parrai were ob- 

 served to feed actively on the freshly released eggs 

 of S. croicensis. Within 5-10 s after completion of 

 the spawning rush, numerous Chromis cyaneus 

 converged on the area of egg release, followed 

 shortly by a lesser number of Clepticus parrai, and 

 while remaining in a tightly bunched group ap- 

 parently picked individual eggs from the water. It 

 was estimated that as many as 200 Chromis 

 cyaneus and 20-30 Clepticus parrai composed one 

 group picking eggs released in a single spawning 

 rush. The group remained tightly bunched and fed 



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