% 



13' 



w 



■^ 



F"^ 



"i'y 





M^iL£ 





^i:MMk 



'-'F-MU-y-"lvi-ir 



yr^ 



■-•'^i. 





■Sa^ 





■nr 



"=3r 



3J- 



/f. 



■SO 



Figure 36. — Calibration curve for flowmeter #1179 obtained by plotting two sets of calibrations and drawing the curve 

 on the average of the calibration points. The data of the first calibration are shown in Figure 35, the second, a simi- 

 lar set, made after cruise 6607-J are not illustrated. 



Set II derives the plankton volume per 1,000 m^ 

 water strained by the following formula: 



y = 



' p/m3 — 





1,000 



where F 



p/m3 



plankton volume per 1,000 m' 

 water strained. 



plankton volume collected in net 

 tow (from plankton measured) . 

 Vw = cubic meters of water strained 

 (from Set I). 



Set III combines all the station data for pub- 

 lication. 



Set IV adjusting for percent plankton sorted 

 multiplies the SHF by reciprocal of the fraction 

 sorted, e.g., 50% (one-half) of sample, multiply 

 SHF by 2, 25% (one-fourth) sorted, multiply 

 SHF by 4, etc. 



Note: It has often been found that when some organ- 

 ism such as rare and/or larger fish larvae are scarce, 

 fractioning a sample tends to give an erroneous count 

 of actual numbers present, where it is highly probable 

 that the few specimens in a sample can be left in the 

 unsorted portion of the plankton. Therefore, it has been 

 our policy of late to sort 100% of all samples. 



With automatic data processing only two sets 

 are printed out, one to obtain volumes of water 

 strained, the standard haul factor for each 

 plankton haul as for Set I above, and the other 

 to produce station data and plankton volumes 

 as for Set III above. 



These data sheets are prepared by using 20 

 items from plankton tow sheet (circled numbers 

 on the tow sheet) , the plankton volumes and the 

 data of the computer's calibration curve de- 

 scribed above. 



For the new Set I, a printout will include sta- 

 tions indicating errors or omissions of meter 



35 



