the net is torn beyond mending at sea, 

 replace the net. 

 k. Recheck sheet to be sure that all items 

 are filled in. Nonroutine items should 

 be included in Remarks section, e.g., odd 

 meter readings, prolonged stops at sta- 

 tions, delays between stations, etc. 

 1. The accepted position, item 16, may be 

 listed when the station is occupied or at 

 the end of the cruise when the captain 

 has compiled a complete list of the po- 

 sitions of all stations, 

 m. The occupancy code, item 2, is filled in, 

 onshore, at the end of the cruise. This 

 is usually one of a series of numbers 

 used by the programmer to describe the 

 type of tow or the station occupied. 

 15. The sheet is set up for the next station: 

 items 1,3,4, 5, 11, 12, and H are entered. 

 Item 14 should be the final reading of the 

 preceding tow and should be rechecked be- 

 fore starting next tow. 



Additional Data Collections 



A tow for plankton is made at every station 

 occupied during a CalCOFI survey. Additional 

 work and data collection at each station include: 

 Collection of meteorological data; a bathyther- 

 mogram with the expendable bathythermograph 

 (XBT), a surface temperature reading taken 

 with a bucket thermometer, a sample of water 

 from 10-m depth with a Nansen bottle from 

 which shipboard analysis is made of salinity and 

 nutrients including phosphate, nitrate, nitrite 

 and sulphite; drift bottle releases at specified 

 station, secchi disc reading at all day stations 

 and Pacific saury (Cololabis saira) observations 

 at all night stations. 



The XBT is dropped from a launching tube, 

 located aft near a ship's rail, to record temper- 

 ature profiles to 1,000 ft (450 m) deep. The re- 

 cording is made electronically in a sheltered 

 space (laboratory, etc.) on the vessel (Saur and 

 Stewart, 1967; Saur and Stevens, 1972). The 

 XBT has replaced the former BT which was 

 launched and retrieved on a cable with a small 

 winch located aft near a ship's rail recording 

 temperature profiles on a smoked slide to 450 or 

 900 ft (137 or 355 m). 



PROCESSING PLANKTON AND 



STANDARDIZING DATA 



Processing of plankton is begun at the labora- 

 tory when the collections are brought back from 

 sea. This is carried out in several steps: Mea- 

 suring the volume of plankton in each sample, 

 sorting out and enumerating all fish eggs and 

 larvae, identifying all larvae, measuring certain 

 larvae, identifying certain fish eggs and staging 

 (ageing) some, and finally, curating all fish eggs 

 and larvae. All data are standardized (see be- 

 low) and now are subjected to automatic data 

 processing (ADP) for final analyses and pub- 

 lication. Two methods for standardization are 

 described, one, the old method of hand calcula- 

 tion and two, the ADP which are described 

 wherever changes have been affected, and for 

 which a flow diagram is depicted in Figure 19. 



Plankton Volume Determination 



Plankton volumes are determined by displace- 

 ment, (sometimes termed "wet volumes") re- 

 corded to the nearest milliliter. Two volumes are 

 recorded for each sample: 



1. Total volume — includes everything in the 

 sample except small adult fishes, juvenile 

 fishes, squid, octupi, and adult pelagic crabs 

 (Pleuroncodes) none of which are consid- 

 ered planktonic. 



2. Total volume minus large organisms — large 

 planktonic organisms are jellies and tuni- 

 cates whose individual volumes exceed 5 ml. 



The plankton volumes for a cruise are recorded 

 on a Plankton Volumes data sheets (Fig. 20) be- 

 ginning with data from the original tow sheets, 

 first listing all the stations occupied in their nu- 

 merical order and noting the number of jars used 

 for each sample. The plankton samples are re- 

 moved from their boxes and readied for measur- 

 ing their volumes by arranging them in the nu- 

 merical order of stations. The procedure for 

 determining volumes is as follows: 



1. Each quart jar sent to sea is calibrated and 

 etched with a number (see Fig. 22) that 

 represents its total volume when filled to a 

 level at which a mark on one device (a 

 float) matches a mark on another (a T- 

 guide)— Figs. 21 and 22. When the cali- 

 brated jar contains a plankton sample, the 



19 



