Table l. — Incidence of anchovy eggs in stomachs of northern anchovy collected in March 1976 and 1977 in the Los Angeles Bight. 



Collections 1-9. night trawls, March 1976: collections 10-25, night trawls, March 1977: collections 26-28 night lampara sets, March 1977: and collections 

 29-31 day lampara sets, March 1976. 

 ^ Volume stomach contents/volume maximum contents x 100, Maximum stomach volume was size specific and derived from the relationship developed in the text. 



at the time of capture, except for the day collec- 

 tions where formaldehyde preservation was used. 

 A standard oblique plankton tow (Smith and 

 Richardson 1977) from 70 m (depth of water 

 permitting) to the surface, was taken before and 

 after each night trawl sample using aim ring net 

 (505 ^im mesh) or Bongo net (333 /xm mesh) and 

 was preserved in lO'yf Formalin. The 505 ;um 

 mesh net was corrected for extrusion of eggs using 

 the coefficient of Lenarz (1972). These collections 

 were used to estimate the abundance of northern 

 anchovy eggs in the regions where anchovy were 

 sampled by night trawls. For one of the day 

 samples, two plankton tows were taken in front 

 and two taken behind the school. The plankton 

 samples were taken with a 0.5 m ring net with 102 

 /xm mesh, towed for 2 min at 15 m (the depth of the 

 school as determined acoustically). These two sets 

 of plankton samples enabled us to measure direct- 

 ly the effect of feeding by a school on the egg 

 density. No plankton tows were associated with 

 the commercial lampara net samples. 



Use of trade names does not imply endorsement by the 

 National Marine Fisheries Service, NOAA. 



For each fish we determined standard length 

 ( SL) and weight, numbers of eggs and larvae in the 

 stomach, and compacted stomach volume. The 

 stomach volume was compacted by centrifuging 

 the contents for 6 min at 3,700 r/min and then was 

 measured to the nearest 0.1 ml. Volumes were 

 expressed as a percentage of the maximum stom- 

 ach volume. Maximum volume (V) was deter- 

 mined using the same volumetric technique for 

 northern anchovy fed to satiation with adult 

 Artemia salina in the laboratory; it was expressed 

 as a function of standard length (Din centimeters, 

 where In V = 2.051 In L - 3.954 and r^ = 0.759. 

 The length range was 4.6-13.5 cm. 



To estimate the ration from observed incidence 

 of eggs in the stomach, the rate of gastric evacua- 

 tion of eggs must be known. To estimate this rate, 

 we fed only northern anchovy eggs to 155 northern 

 anchovy for 1 h at a density of 38 eggs/1 at 15.2° C, 

 which approximates typical spawning tempera- 

 tures. After feeding, fish were transferred to a 

 tank without food and 10-15 fish sampled at 2-h 

 intervals until 10 h after feeding. The rate of 

 gastric evacuation was expressed as the slope of 

 the regression of natural logarithm of the mean 



812 



