Table 2. — Area covered and number of stations occupied on monthly CalCOFI 



cruises during 1960 



Month 



Cruise 

 number 



Area covered 

 station lines 



Number of 

 stations occupied 



January 



February 



March 



April 



May 



June 



July 



August 



September 



October 



6001 



6002 



6003 



6003 Special 



6004 



6005 



6006 



6007 



6008 



6009 



6010 



-307 

 172 

 163 



-344 

 153 

 191 

 211 

 72 

 52 

 172 



-Three Gulf of California stations, 151G40; 157G25, and 157G40 not included. 



2/ 



-Four Gulf of California stations, 157G40; 157G70; 157G130, and 157G150 not included. 



The equipment and procedures used to 

 collect plankton samples during I960 have 

 been standard since 1951. Oblique tows from 

 a depth of about 140 m. to the surface, except 

 in shallow water, are taken at a retrieval rate 

 of 20 m. per minute. A calibrated current 

 naeter is fastened in the mouth of the net to 

 determine the volume of water filtered on each 

 haul. The nets are about 5 m. long, 1 m. in 

 diameter at the mouth, and constructed of 

 No. 30 XXX grit gauze {an extra heavy grade 

 of silk bolting cloth). 



The wet plankton volume of each sample is 

 determined by displacement. The plankton is 

 separated from its preserving liquid (5 per- 

 cent Formalin •■■) by filtering, allowed to drain, 

 then placed into a graduated cylinder to which 

 is added a known volume of 5 percent For- 

 malin. Two volumes are obtained and recorded 

 in cubic centimeters for each sample: (1) the 

 total volume of all plankton material and (2) 

 the volume of smaller organisms after re- 

 moval of larger organisms, such as jellies, 

 squid, salps, pyrosomes, larger moUusks and 

 larger crustaceans. "Larger" organisms are 

 those with individual volumes greater than 5 

 cc. Juvenile and adult fishes (not considered 

 "planktonic") are removed before volume de- 

 termination and are not included in either 

 volume. The plankton volumes are then stand- 

 ardized to ,the number of cubic centimeters 

 in 1,000 m. of water strained. 



■'• Trade name referred to In this publication does not 

 Imply endorsement of a commercial product. 



The distribution charts in this report are 

 based on the volume of small organisms per 

 1,000 m. of water strained and are of two 

 types: the average plankton volume at each 

 station during the year (fig. 2), and a series 

 of monthly charts which accompany the plank- 

 ton volume data (figs. 4-13). Five categories 

 of abundance are designated: (1) very light, 

 <34 cc. of plankton, (2) light, 34 to 100 cc. of 

 plankton, (3) nnoderate, 101 to 300 cc. of 

 plankton, (4) heavy, 301 to 900 cc. of plankton, 

 and (5) very heavy, >900 cc. of plankton. 



The major table in this report (table 5) 

 serves a dual purpose: as a record of basic 

 data for all plankton tows made during I960, 

 and as a record of the volume of plankton 

 obtained in each haul. The basic information 

 included for each haul is station number, 

 position, date and time of collection, volunne 

 of water strained, depth of haul (calculated 

 on a straight line relation between the wire 

 angle and the amount of wire out), and the 

 standardized plankton volume. 



In this report a comparison of the I960 

 plankton volumes with those of previous years 

 is made for the two areas most consistently 

 occupied since 1951--one off central Califor- 

 nia and adjacent northern Baja California, and 

 the other off central Baja California. These 

 areas include CalCOFI survey lines 80-107 

 and 110-137, respectively (fig. 1). No com- 

 parison is made for the years 1949 and 1950 

 because hauls in those years were from a 

 depth of 70 m. to the surface- -half the depth 

 range of hauls in later years. 



