Stoner et al : Reproduction and larval abundance in queen conch 



169 



supply sufficient to provide for higher feeding and 

 metaboHc rates (Scheltema and WilHams 1982). Sec- 

 ond, midsummer months are characterized by prevail- 

 ing tradewind conditions (i.e., relatively constant winds 

 and moderate seas from the southeast) in the Exuma 

 Cays. General circulation over the reproductive site 

 during this period was to the northwest, parallel to the 

 Exuma island chain (N.P. Smith, Harbor Branch 

 Oceanogr. Inst., Fort Pierce, FL 34946, unpubl. data). 

 This would facilitate transport of pelagic larvae past 

 the numerous inlets which veligers must enter to reach 

 primary nursery habitats on Exuma Bank. As veligers 

 are carried alongshore on the island shelf, they would 

 readily be drawn through the inlets on flood tides. 

 Northwest drift over the reproductive site may, in fact, 

 explain the close correlation between larval abundance 

 in Adderley Cay cut and reproductive activity occur- 

 ring upcurrent. Winter weather patterns, with fre- 

 quent passage of cold fronts and shifting winds and cur- 

 rents, would be less favorable for transport of conch 

 larvae to the Exuma Bank nurseries. 



On the basis of laboratory growth curves (Boidron- 

 Metairon, unpubl. data), all but the three largest lar- 

 vae collected in this study were less than approximately 

 2 weeks old in a larval life stage near 30 days. There 

 are several possible explanations for the scarcity of ad- 

 vanced stage larvae: Late stages occupy habitats dif- 

 ferent from those of early-stage larvae (on or near the 

 bottom), the abundance of older stages in the water col- 

 umn is reduced due to natural mortality, and/or the late 

 stages are advected to different locations. Virtually 

 nothing is known about transport or behavior of queen 

 conch larvae in the field. Given the great significance 

 of recruitment processes to management of this rapidly 

 depleted fishery species, future research should include 

 studies of larval transport and settlement. 



In summary, highest reproductive activity occurred 

 near Lee Stocking Island at a time of stable circula- 

 tion patterns, high temperature (28-30°C), and long 

 photoperiod. Maximum larval abundance in July and 

 August placed high numbers of veligers in the water 

 column at a time favorable for both high rates of 

 development and transport to nursery habitats. Prox- 

 imal mechanisms affecting short-term and seasonal 

 variation in reproduction in queen conch may include 

 temperature, rates of temperature change, photo- 

 period, wave-induced turbulence, and other variables 

 associated primarily with season. 



Acknowledgments 



This research was supported by a grant from the 

 Undersea Research Program of the National Oceanic 

 and Atmospheric Administration (U.S. Department of 



Commerce) to the Caribbean Marine Research Center. 

 We thank R.I. Wicklund, Director of the Caribbean 

 Marine Research Center, for providing bottom-water 

 temperature data for the reproductive site. Thanks to 

 P. Bergman, N. Christie, K. McCarthy, 0. Monterrosa 

 and E. Wishinski for assistance in the field. R. Appel- 

 doorn, P. Colin, L. Jones, J. Shenker, J.-P. Thonney, 

 and anonymous reviewers provided helpful comments 

 on the manuscript. 



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