LARRANCE: PRIMARY PRODUCTION IN MID-SUBARCTIC REGION 



I70°E 180° I70°W 



Figure 1. — Tracks of Bureau of Commercial Fisheries cruises in 1966-68 in the Subarctic Pacific Region during 



which primary productivity was measured. 



were calculated from Secchi disk readings con- 

 verted to extinction coefficients (Poole and At- 

 kins, 1929). Sampling depths of the morning 

 stations were computed from the preceding day's 

 Secchi-disk readings. Duplicate light-bottle 

 samples under the neutral-light filters were in- 

 cubated on deck in daylight and cooled with 

 running sea water. After incubation, samples 

 were filtered through Millipore' filters, pore size 

 0.45 fi. for radioassay. 



Stock solutions of Na2"C03 were prepared ac- 

 cording to Strickland and Parsons (1965) but 

 were standardized by using liquid-scintillation 

 techniques. A 1.00-ml portion from an ampoule 



containing the stock carbonate solution was in- 

 troduced in 10 ml of a suitable phosphor solu- 

 tion, and its count rate determined in a Packard 

 Tri-Carb' scintillation spectrometer. One liter 

 of phosphor solution contained 800 ml toluene, 

 200 ml Sterox" (a surfactant required to make 

 the water miscible in toluene) , 5.0 g PPO (2, 5- 

 diphenyl-oxazole), and 0.3 g bis-MSB (p-bis- 

 (o-methylstyrl) -benzene) . Counts of an external 

 radium standard were also recorded and the ab- 

 solute activity (dpm) was determined from a 

 quench correction curve relating efficiency to the 

 count rate of the external standard (Wang and 

 Willis, 1965). Although scintillation counting 



^ Millipore Corp., Ashby Rd., Bedford, Mass. 01730. 

 References to trade names in this publication do not imply 

 endorsement of commercial products by the National Ma- 

 rine Fisheries Service. 



' Packard Instrument Co., Inc., 2200 Warrenville Rd., 

 Downers Grove, 111. 60515. 



" Jefferson Chemical Co., P.O. Box 53300, Houston, 

 Tex. 



597 



