1.000 



0.900- 



o.aoo 



o.soo 



g °- S0 ° 



0.100 



0. 300 



0. 100 



fOO COMSUMP1IOM 



Minmiii" 



0.7 3.7 8.7 S.7 12.7 15.7 18.7 21.7 

 PLRNKTON CONCENTRATION (CHL/LITRE> 



FIGURE 17.— Caloric energy expenditure for the major bio- 

 energetic parameters at 8°C of winter flounder larvae summed 

 for all dry weights from hatching to metamorphosis at different 

 planktonic prey concentrations. 



than is used for growth at lower prey densities. 

 Also, the food requirements are higher at the 

 lower densities which causes problems because 

 food is harder to obtain at lower densities. 



In conclusion, these experimental studies and - 

 model simulations demonstrate that there is 

 strong evidence for a "critical period" of mortality 

 in the larval stage of winter flounder and that 

 planktonic prey density is one of the most impor- 

 tant factors affecting survival during the larval 

 stage. Additionally, the bioenergetic model devel- 

 oped presents a means to assess other trophic 

 interactions in the marine, planktonic commun- 

 ity. Larval fish are planktonic carnivores and the 

 food requirements predicted by the model in com- 

 bination with biomass estimates of larvae and 

 prey and survival estimates of larvae can be used 

 to predict the impact of larval grazing on their 

 prey. This type of research is currently being pur- 

 sued in continuing studies. 



ACKNOWLEDGMENTS 



I am grateful to B. Burns, K. Dorsey, T. Hala- 

 vik, and A. Smigielski for their help with labora- 

 tory experiments and data analyses. Thanks also 

 go to B. Brown, J. Colton, R. Hennemuth, E. 

 Scura, and K. Sherman for their critical review of 

 the manuscript. 



FISHERY BULLETIN: VOL. 75. NO. 3 



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544 



