DAILY AND SUMMER- WINTER VARIATION IN MASS SPAWNING 

 OF THE STRIPED PARROTFISH, SCARUS CROICENSIS 



Patrick L. Colin ^ 



ABSTRACT 



The "striped" phase of the striped parrotfish, Scarus croicensis, engaged in mass spawning during 

 afternoon periods on a deep (24 m) coral pinnacle off Discovery Bay, Jamaica. During morning periods 

 the fish occurred in a large foraging group on shallow reefs and moved to the spawning site in etirly 

 afternoon. The occurrence of spawning rushes per day in June was about six times that during January. 

 Chromis cyanea and Clepticus parrai fed on freshly released eggs of S. croicensis. Mass spawning by S. 

 croicensis was similar to that of Sparisoma rubripinne. 



The striped parrotfish, Scarus croicensis Bloch 

 (Figure 1), is the smallest (reaching 25 cm SL, 

 standard length) but the most common member of 

 this genus in the tropical western North Atlantic 

 (Randall 1968; Bohlke and Chaplin 1968). Like 

 other scarids, S. croicensis is a benthic herbivore 

 grazing on algal-covered rock and coral surfaces 

 and is seldom found at depths below 30 m. The 

 species possesses dimorphic color phases, termed 

 the "striped" phase (male and female) and the 

 "terminal" phase (male only), believed derived 

 from striped phase females by protogynous sex 

 reversal (Ogden and Buckman 1973). 



Aspects of the general biology of this fish have 

 been reported on by several authors. Ogden and 

 Buckman (1973) followed movements of tagged 

 individuals in Panama and found daily migrations 

 between feeding and sleeping areas. Feeding was 

 largely carried out in foraging groups of up to 500 

 individuals with a characteristic set of associate, 

 but less numerous species. Buckman and Ogden 

 (1973) described territoriality by striped phase 

 females and terminal phase males. Barlow (1975) 

 discussed the sociobiology of S. croicensis in com- 

 parison with three other species of parrotfishes 

 and described their feeding pattern, group sizes, 

 density, and color variation. He also added some 

 notes on spawning behavior of S. croicensis. 



Randall (1963) reported both mass spawning by 

 the striped phase of S. croicensis and pair spawn- 

 ing by terminal phase males and striped phase 

 females. Randall and Randall (1963) described 

 pair spawning at St. John, V. I., during February, 



'Depsirtment of Marine Sciences, University of Puerto Rico, 

 Mayaguez, PR 00708. 



Manuscript accepted May 1977. 



FISHERY BULLETIN: VOL. 76, NO. 1, 1978. 



Figure l. — Striped parrotfish, Scarus croicensis, with "con- 

 trast" color pattern approximately 100 mm standard length at 

 Discovery Bay, Jamaica. 



March, April, June, and August, and with their 

 limited observations they felt that pair spawning 

 accounted for most of the reproduction of the 

 species. Buckman and Ogden (1973) commonly 

 observed pair spawning at depths of 9-13 m, but 

 also as shallow as 3 m, in Panama. Munro et al. 

 (1973) found females of the striped parrotfish in 

 ripe condition from March to May near Jamaica. 

 In August 1971 a large spawning group of 

 striped parrotfish was encountered on a deep coral 

 platform (24 m) offshore from the Discovery Bay 

 Marine Laboratory on the north coast of Jamaica. 

 This species is by far the most common parrotfish 

 along this coast, which is heavily fished using An- 

 tillean fish pots. This spawning group consisted of 

 several hundred individuals. Its reproductive ac- 

 tivity was sufficiently regular and observable that 

 investigation of diel patterning of spawning 

 seemed feasible. Widely scattered observations 

 from 1971 to 1975 indicated the continued pre- 

 sence of this group. During January and June 



117 



