A chrono logical listing of California Cooperative Oceanic Fisheries 

 Investigations cruises for 1956, vdth information of the area covered and 

 the nimibers of stations occupied on each ciTjise follows: 



Number of stations occupied 



112 



1:32 



135 



179 



239 



210 



203 



36 



36 



42 



40 



42 



The tables in this report contain a record of the "wet" plankton volumes 

 of all plankton samples taken on routine survey cruises off the Pacific Coast 

 during 1956 (colijnins 9 and 10), and contain basic information on each haul, 

 including station number (column l) , location (columns 2 and 3)> date and 

 time of collection (colimins 4 and 6), volume of water strained (column 7) 

 and the estimated depth of the haul (column 8), 



Wet plankton volumes are determined as follows: the plankton is separated 

 from its preserving liquid {3% formalin) by filtering, allowed to drain and the 

 displacement volume is obtained by placing drained wet plankton in a graduated 

 cylinder with a known volume of water. Two volumes are recorded for each 

 station: (l) the total wet volumes standardized to the amount in one thousand 

 (1,000) cubic meters of water strained, and (2) the volume of smaller organisms 

 after removal of larger organisms, such as jellies, fish, squid, salps, pyro- 

 somes, larger molluscs and larger crustaceans. The criterion used for a larger 

 organism (except in the case of juvenile or adult fish) is one viiose volume 

 exceeds five cubic centimeters (5 cc.)« 



The charts in this report are based on the volume of dmaller organisms. 

 In order to obtain a good contrast between light and heavy concentrations of 

 plankton, five categories have been used to divide the abundance of planlcton as 

 follows: (1) light, to 33 cc. of plankton per 1,000 cubic meters of water 

 strained; (2) moderate, 34 to 100 cc. of plankton per 1,000 cubic meters of 

 water strained j (3) average, 101 to 300 cc. of plankton per 1,000 cubic meters 

 of water strained; (4) fairly heavy, 301 to 900 cc. of plankton per 1,000 cubic 

 meters of v;ater strained; (5) heaA^^, more than 900 cc. of plankton per 1,000 

 cubic meters of water strained. 



Ti/o types of plankton nets were used in the collection of samples: 

 (1) constructed of No. 30xxx grit gauze (an extra heavy type of silk bolting 

 cloth); (2) constmicted of nylon, but v;hose dimensions and mesh sizes are ap- 

 proximately one hundred and forty (140) meters deep to the surface (depth of 

 water permitting) . 



