FISHERY Bl'LLETIN: VOL. 83, NO. 3 



could explain their absence in collections taken off- 

 shore (Richards 1981). 



We have provided substantial evidence that 

 French grunts recently recruited from the plankton 

 are fertilized about 15 d earlier, and that these pro- 

 cesses most closely correlate with the quarter moons 

 and intermediate tidal excursions. Is this a general 

 pattern that occurs throughout the Caribbean and 

 western Atlantic where French grunts are most 

 abundant? Or is the lunar-tidal correlation the result 

 of local conditions? We have no answer at present, 

 because it requires repeating the investigation in 

 other localities. Different current regimes and local 

 hydrographic conditions in other regions might elicit 

 different recruitment patterns. The much weaker 

 weekly fertilization and settlement patterns, for ex- 

 ample, that are associated with full and new moons 

 (Table 3) might dominate recruitment in other 

 locales. 



There is a seeming order in the rain of young 

 French grunts from the plankton. Over the period of 

 this study young grunts following a semilunar time- 

 table appeared on over half of the census sites 70% 

 of the time (range 59 to 94%). Although we could not 

 discern any special characteristics of these sites that 

 attracted grunts, the sites were never preoccupied 

 by other species. Settlement certainly did not appear 

 to be a random phenomenon. The recurrent order in 

 the occupation of space by settling French grunts, 

 however, may reflect only their high abundance in 

 the reef communities at St. Croix (Gladfelter and 

 Gladflelter 1978). Large populations produce large 

 numbers of offspring and this alone might swamp 

 available sites. In this regard we stress that the cen- 

 sus settlement sites are not main reefs, but isolates 

 adjacent to them. Indeed, large coral domes in the 

 census area which sustained large populations of 

 older juvenile French grunts never sustained popula- 

 tions of PL-l's. Without manipulative studies of 

 grunts on the settlement sites, however, it is impossi- 

 ble to ascertain to what extent recruitment is in- 

 fluenced by a resident population (Shulman et al. 

 1983). We can conclude only that the recruitment of 

 French grunts from the plankton has high temporal 

 and spatial predictability at St. Croix. 



Fishes in the family Haemulidae represent a domi- 

 nant component of the tropical reef fish community 

 and constitute a major part of the trap fishery in 

 western Atlantic and Caribbean waters (Dammann 

 1980; McFarland 1980). The findings presented in 

 this study provide insights that are critical to the 

 management of any fishery for grunts. For example, 

 the relatively short larval existence in French 

 grunts, which also occurs in white and tomtate 



grunts (Brothers and McFarland 1981), implies that 

 dispersal does not occur over very long distances. 

 Whether local populations of grunts are self-sustain- 

 ing or dependent on interisland transport is 

 unknown. Answers will require precise knowledge of 

 spawning habits of each species of grunt, careful 

 analysis of local and general current regimes, and, if 

 possible, the behavior of the larvae. If local popula- 

 tions are self-sustaining, then overly lenient limits on 

 the harvest of adult grunts could seriously limit 

 recruitment. In contrast, if recruitment shows large 

 spring and fall peaks in other species of grunts, as it 

 does in French grunts, and the seasonality in recruit- 

 ment is geographically widespread (e.g. Munro et al. 

 1973), then closure of a grunt fishery for a few mon- 

 ths during periods of peak recruitment would prob- 

 ably assure maintenance of the local populations. 



ACKNOWLEDGMENTS 



We thank Jack Sobel for his technical help in con- 

 tinuing the daily census routines when we could not 

 be present, and Kim Benson who assisted in the 

 otolith analysis. Numerous students at the West In- 

 dies Laboratoiy assisted as diving buddies; we thank 

 them all. This project was supported by National 

 Science Foundation Grant OCE-7918569. 



LITERATURE CITED 



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