Comyns et al : Spatial and temporal variability in growth and mortality of fish larvae in the Gulf of Mexico 



19 



7292 larvae survive to a length of 6 mm. Houde (1987) 

 published a projection on the mortality of larvae exposed 

 to hypothetical levels of mortality and growth rates, but 

 the theoretical exercise used relatively long larval-stage 

 durations (45-56 days). Results of our study show that 

 even in a subtropical climate where larval stage durations 

 may be as short as two weeks, relatively small changes 

 in observed larval growth rates, particularly when com- 

 bined with small differences in mortality, can have a large 

 impact on cumulative larval survival. To what extent 

 the observed differences in growth rates at small spatial 

 scales are fine-scale "noise" that is ultimately smoothed 

 by larger-scale processes is not known. Future research is 

 needed to further characterize the small-scale variability 

 in growth rates of larvae, particularly with regard to mi- 

 crozooplankton patchiness and the temporal and spatial 

 pattern of potential predators. Small-scale spatial vari- 

 ability in larval growth rates may in fact be the norm, 

 and understanding the implications of this subtle mosaic 

 may help us to better evaluate our ability to partition the 

 causes of recruitment variability. 



Acknowledgments 



Collections serving as the basis of this research were sup- 

 ported by the SEAMAP program (Southeast Area Moni- 

 toring and Assessment Program) and the NOAA/NMFS 

 MARFIN program (Marine Fisheries Initiative). Several 

 cruises were also conducted by personnel from National 

 Marine Fisheries Service in Pascagoula, Mississippi. 

 Sorting of these plankton samples was made possible by 

 funding provided by the U.S Fish and Wildlife Service 

 through the Wallop Breaux program. This program is 

 administered in Mississippi by the Department of Marine 

 Resources (DMR) whose personnel must be thanked for 

 providing support. Sorting of the plankton samples was 

 made possible by the efforts of several people, including 

 Mae Blake, Cindy Gavins, Pam Bond, Dianne Scott, Ngoc 

 Bui, and Jean Bennett. We also thank Pam Bond for many 

 contributions, including acting as field party leader during 

 cruises, for larval identifications, much of the data entry 

 and management, and for preparing otoliths. We are also 



grateful to Chet Rakocinski for providing help with statis- 

 tical analyses. 



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