Figure 25. — Arrangement of plankton sorter's work. Unsorted plankton on left side 

 of microscope, sorted organisms on the right. (See text for procedures.) 



mitted light, all fish eggs and larvae are 

 picked out with pipettes and fine quality 

 (stainless steel) forceps and transferred to 

 their appropriately labelled dishes. 



Note: Research quality microscopes are used be- 

 cause any of inferior quality would be detrimental 

 to the eyesight of persons engaged in this type of 

 week-long work for 6 to 8 hr per day. 



When the fish eggs and larvae are sorted 

 from a dish, its remaining contents are 

 poured into a 3-liter beaker labelled 

 "Sorted." 



Each dish of sorted organisms is checked 

 for final identification when its contents are 

 enumerated and/or measured as noted in 

 Table 2. Fish larvae are measured to the 

 nearest one-half millimeter on a transpar- 

 ent millimeter rule (specifications below). 

 Each measured species is tabulated on the 

 form illustrated and described in Figure 26. 



Note: The scale for measuring fish larvae is a 

 transparent plastic rule, about 0.5 mm thick, on 

 which the markings, in millimeters, are etched on 

 the plastic. A piece of the rule, about 50 mm, 

 is taped between two thin pieces of glass — usually 

 standard microscope slides 76 x 51 x 1 mm- 

 The larvae are piled in a small mass on the slide. 



and individual specimens are gently dragged over 

 the top of the scale with a clean dissecting needle. 

 After measuring, they are dragged away into an- 

 other pile until all are measured. Finally they are 

 placed in a vial and labelled. 



6. The sorted plankton (invertebrates) is 

 poured into the mesh cone to drain off the 

 water, and the plankton is returned to its 

 original jar and preservative. (When a 

 cruise is completed the samples are sent to 

 SIO for curation and study of selected in- 

 vertebrates.) 



7. When the checking in step 5 is done an- 

 other form, the sorter's work sheet (Fig. 

 27), is filled out listing the numbers of or- 

 ganisms of each type sorted. The form also 

 includes other information as illustrated. 

 Whole larvae, head sections and tail sections 

 are listed and totaled for all species mea- 

 sured and for other fish larvae. Totals 

 listed for measured larvae should be the 

 same as those on the tabulation sheets; (ex- 

 ceptions noted in caption for sorter's work 

 sheet — Fig. 27) the totals of head and tail 

 sections should equal the DIS on the tab- 

 ulation sheets (Fig. 26). 



25 



