LASKER: FIELD CRITERIA FOR SURVIVAL 



described here, using laboratory-reared larvae for 

 field tests of possible larval feeding areas, proba- 

 bly can be extended to older larvae and other 

 species as vi^ell. An on-board electronic counter can 

 give a rapid first evaluation of particle size and cell 

 numbers. Microscopic examination of subsamples 

 can be used to verify the shipboard counts and give 

 additional information on species composition of 

 phytoplankters. Chlorophyll profiles can be 

 analyzed routinely on most oceanographic vessels. 

 With information on the biology of the larvae be- 

 ing investigated, it may be possible to determine 

 routinely the quality and extent of larval feeding 

 grounds and v^^ith comprehensive temporal infor- 

 mation on the food of the larvae, the degree of 

 larval mortality due to inadequate food may be 

 predictable. 



ACKNOWLEDGMENTS 



Thanks go to Eileen Setzler, Anne N. Dodson, 

 Dale Kiefer, and the able crew of the NOAA RV 

 David Starr Jordan for their invaluable assis- 

 tance during this study, and to Richard Eppley for 

 stimulating discussions which led to the examina- 

 tion of chlorophyll maximum layers as possible 

 feeding grounds for larval fish. Roderick K. Leong 

 provided the fish larvae on demand; without his 

 help this study would not have been possible. 



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