154 



Fishery Bulletin 102(1) 



is more evident in the juvenile stage than during the egg 

 and larval stages when random mortality independent of 

 fish size is more likely to occur (e.g. dispersal of eggs and 

 larvae away from suitable nursery areas). In addition, vari- 

 ation in size, which provides a "template" for size-selective 

 processes, increases during the juvenile stage as larval size 

 is constrained by egg size. Sogard ( 1997) cited a number of 

 recent studies that suggest the early juvenile period plays 

 a greater role in determining year-class strength than 

 previously thought. 



We were unable to determine if salinity influenced incre- 

 ment width (a surrogate for somatic growth) at early life 

 stages. Understanding the relationship between salinity 

 and growth is critical because Everglades restoration will 

 most likely result in increased freshwater flows to Florida 

 Bay, and during low rainfall periods, salinities in the north 

 central portion of the bay can exceed 45 ppt (Orlando et 

 al., 1997; Boyer et al., 1999). But, salinities were moderate 

 and similar at most stations where juvenile trout were col- 

 lected in the bay during 1995 I Fig. 4). Very few fish were 

 collected at low salinities; in fact, juvenile spotted seatrout 

 are not commonly collected at low-salinity stations (Table 

 1; Florida Department of Environmental Protection 1 ), and 

 hyperhaline conditions were not observed in 1995. There- 

 fore, we were only able to determine if temperature could 

 influence increment widths. The curvilinear relationship 

 between otolith growth rate and temperature, although 

 a statistically strong relationship, is difficult to explain 

 biologically. Temperature could mask other factors, e.g. 

 temporal variability in prey and predator availability, and 

 optimal temperatures for growth (Rooker et al., 1999). We 

 were able to demonstrate that one cohort grew faster than 

 five other cohorts, possibly indicating differential prey 

 availability in 1995. An individual-based bioenergetics 

 model for spotted seatrout now in preparation (Wuenschel 

 et al. 2 ) should add to our understanding of the effects of 

 salinity and temperature on larval and juvenile spotted 

 seatrout 



Acknowledgments 



We are especially grateful to Al Crosby, Mike Greene, Mike 

 LaCroix, and other Beaufort staff that participated in the 

 field work. We thank James Waters of the NMFS Southeast 

 Fisheries Science Center for computer programing assis- 

 tance and Jon Hare of our laboratory for performing the 

 circular statistics. We are grateful to Dean Ahrenholz, Jon 

 Hare, Patti Marraro, Joseph Smith, and three anonymous 

 reviewers for their valuable reviews of the manuscript. We 

 also thank Steve Bobko at Old Dominion University for 

 the image analysis macro used to obtain otolith increment 

 widths. 



2 Wuenschel, M. J., R. G. Werner, D. E. Hoss, and A. B. Powell. 

 2001. Bioenergetics of larval spotted seatrout (Cynoscion 

 nebulosus) in Florida Bav. Florida Bay Science Conference, 

 April 23-26, 2001, p. 215-216. Westen Beach Resort, Key 

 Largo, Florida. Abstract. Center for Coastal Fisheries and 

 Habitat Research, Beaufort Laboratory, 101 Pivers Island Road, 

 Beaufort, NC 28516. 



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