Figure 22. — T-^ide in use in first step in measuring plankton volume. Tlie jar is cali- 

 brated to 892 ml, liquid alone or liquid plus plankton. Liquid is being removed to match 

 the etched lines on the float and T-guide (see Fig. 19 for directions for use). 



pacity: 12 jars in eggcrate partitions) con- 

 structed of 1/2-iiich (12.7 mm) plywood 

 with hinged lids. If laboratory and storage 

 space on shipboard are reasonably dry, the 

 original cardboard containers can be used 

 to store jars of plankton at sea. 

 8. Pint jars with plankton are packed in nu- 

 merical order of stations into cardboard 

 cartons, and the outside of the cartons are 

 labelled with cruise number and numerical 

 listing of the stations in the box stored to 

 be visible on shelves. 



Plankton Sorting 



Each measured sample delivered to the sorting 

 laboratory is sorted for all fish eggs and larvae 

 of which all are enumerated. Some fish eggs and 

 larvae are identified, some are scanned and cat- 

 egorized as "few", "many", or "abundant", and 

 some fish larvae are measured (Table 2). 



Although techniques may vary with individual 

 sorters, the general method for sorting is as 

 follows: 



The plankton is removed from its preserv- 

 ative by straining it through a 333-/i. mesh 

 nylon draining cone (the same kind used 

 when measuring plankton), and the plank- 

 ton, with about 2 liters of fresh water plus 

 a few drops of full strength formaldehyde, 

 is put into a 3-liter beaker. The original 

 preservative is kept in its original jar. 

 Fresh water is used because it has been 

 found that prolonged exposure to concen- 

 trations of Formalin in handling, stirring 

 and under their eyes, even 3 to 5%, may 

 cause sorters to become sensitive and aller- 

 gic to fumes and liquid. A sample can be 

 kept as long as 1 month in the weak solution 

 of fresh water with formaldehyde. This 

 does not imply that such length of time is 

 necessary for sorting any single sample. 

 The average sorting time is about one sam- 

 ple (100 ml plankton) per day per sorter. 

 The plankton is stirred and poured into a 

 small beaker (200 ml). This, in turn, is 

 stirred and poured into a number of Syra- 

 cuse dishes (ground-glass sides) from 



23 



