FISHERY BULLETIN: VOL. 69, NO. 3 



5. The main mechanisms of dissolved-phos- 

 phate supply in the upper 50 m of water during 

 summer are in situ regeneration by zooplankton 

 and upwelling. Regeneration supplies signifi- 

 cant amounts of phosphate (perhaps more than 

 is provided by upwelling) in the summer, but in- 

 creased turbulence and upwelling in winter 

 maintain high levels of nutrients throughout the 

 upper 100 m of water. 



6. The seasonal cycle and factors limiting pro- 

 ductivity are similar to those at station "P" (lat 

 50° N, long 145° W), but some significant dif- 

 ferences exist. Productivity in the study area 

 is nearly twice that at station "P," and zooplank- 

 ton biomass is also much greater. The change 

 in measured phosphate concentrations at station 

 "P" over the productive season can be accounted 

 for by phosphate utilized by the algae and by 

 phosphate supplied by upwelling. South of the 

 Aleutian Islands, however, phosphate regener- 

 ated in situ must be invoked to balance the phos- 

 phate budget. 



7. Annual primary production in the area 

 studied is about 80 to 100 g C/m^. 



ACKNOWLEDGMENTS 



I am especially indebted to Thomas Elwel! and 

 Frederick Galassi for their technical assistance, 

 particularly for their efforts at sea. I thank 

 Dr. F. A. Richards for volunteering the services 

 of chemists at the Department of Oceanography, 

 University of Washington, to analyze the nitrate- 

 nitrite samples. I wish also to express my appre- 

 ciation to Dr. G. C. Anderson and Dr. Karl Banse, 

 Deinirtment of Oceanography, University of 

 Washington, for their many helpful criticisms 

 of the manuscript. 



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