December when coverage extended south only to San Cristobal Bay 

 (line 123) . The area off southern Baja California (lines 140- 

 157) was surveyed in March, June, and September. Coverage 

 extended seaward to stations 120 or 130 (approximately 300-400 

 miles offshore) on some lines in the main sampling area but 

 typically did not extend beyond station 90 (approximately 160-250 

 miles offshore) . Offshore coverage was greatest between January 

 and July and generally diminished during later cruises. 



Six vessels were employed on these cruises: the Black 

 Douglas, of NMFS, the Crest, Horizon, and Paolina T of SIO, and 

 the N. B. Sco field and Yellowfin of CDFG. Two to four vessels 

 participated on each cruise with three being the usual number. 

 The Crest was used on all cruises except 5112 and the Black 

 Douglas on all but 5101 and 5112. The other four vessels 

 participated on a total of 13 cruises (Ahlstrom, 1953) . 



SAMPLING GEAR AND METHODS 



The standard CalCOFI net used from 1949 to 1969 had a 1-m 

 diameter mouth opening (0.785 m 2 area) and an overall length of 

 about 5 m. The net was constructed of 3 0xxx gauze, a heavy duty 

 grade of silk bolting cloth, with a mesh size of 0.55 mm after 

 shrinkage. The last 40 cm of the cone and the cod end were 

 constructed of 56xxx grit gauze which had a mesh size of 0.25 mm 

 after shrinkage. The net ring was fastened to a short 3-lead 

 bridle connected to several meters of line which attached to the 

 towing cable by a clamp. A current meter was suspended in the 

 center of the net mouth to measure volume of water filtered (see 

 Kramer et al., 1972, for further details). 



The standard tow from 1951 through 1968 was an oblique haul 

 to 14 m depth (to 15 m of the bottom in shallow areas) designed 

 to filter a constant amount of water per depth interval (ca. 

 3m 3 /m of depth) over the vertical range of most ichthyoplankters. 

 Hauls were made at a ship speed of 1.5-2.0 knots and initiated by 

 clamping the net line to the towing cable with the 45 kg terminal 



•^CalCOFI lines are arranged perpendicular to the coastline and 

 extend from the Canadian border (line 10) to below Cape San 

 Lucas, Baja California (line 157) . Stations were established 

 on the basis of a perpendicular to line 80 (off Pt. Conception) 

 at a point designated as station 60. Stations were plotted 

 seaward and shoreward from station 60 on each line. Cardinal 

 CalCOFI lines (those ending in "0") are 120 miles apart and 

 usually bracket two ordinal lines (ending in "3" or "7", so that 

 lines are 40 miles apart over most of the pattern. Cardinal 

 stations are 40 miles apart and typically these are separated by 

 a station number ending in "5" so that stations are 20 miles 

 apart out to station 90 on most lines. Stations are placed at 

 closer intervals near the coast and islands to accommodate these 

 features (see Kramer et al., 1972 for further details). 



