FISHERY BULLETIN: VOL. 78, NO. 4 



tended from 2 to 269 km offshore and covered a 

 north-south distance of 450 km. Transects were 

 74 km apart and stations on a transect were 46 

 km apart except the most inshore stations which 

 were closer together. The grid covered an area of 

 120,150 km2. 



Oblique 70 cm bongo net tows were made at each 

 station from 150 m ( or just above the bottom ) to the 

 surface. Vessel speed was 2-3 knots and retrieval 

 speed was 20 m/min. The bongos were fitted with 

 0.333 and 0.571 mm mesh Nitex^ nets, TSK flow- 

 meters and a time-depth recorder. Stations were 

 occupied when the ship arrived, day or night. 

 Samples were preserved in 107r buffered Formalin. 



Temperature, salinity, and chlorophyll were 

 monitored at 3 m depth every 9 km along each 

 transect using a flow-through fluorimeter system 

 (AMINCO Fluro-colorimeter). At each bongo sta- 

 tion a bathythermograph cast was made to 140 m 

 depth (or 5 m above the bottom) and a surface 

 bucket temperature was recorded. During the 

 July 1976 cruise, surface drifters, consisting of a 

 labelled plastic tag made buoyant with Styrofoam, 

 were released to provide information on surface 

 water movement. Fourteen drifters were dropped 

 at each bongo station except on the southernmost 

 transect (lat. 43°00' N) where only 10 were re- 

 leased at the 120 km station and none at the 157, 

 194, 232, and 269 km stations. 



Between 18 and 25 July 1977 an acoustic survey 

 was conducted cooperatively by the National 

 Marine Fisheries Service (NMFS) in the same 

 area as the previous ichthyoplankton surveys 

 (Smith ). The same seven transects plus an 

 eighth transect to the south along lat. 42°20' N 

 were surveyed acoustically during daylight using 

 the methods of Smith (1970). Distance covered on 

 each line extended from the 91 m depth contour 

 westward 167 km. In addition to the acoustic work, 

 temperature and salinity at 3 m depth were moni- 

 tored every 9 km using a flow-through salino- 

 graph, and expendable bathythermographs were 

 cast every 9 km on every other transect. Following 

 a day's sonar run, nighttime surface trawls were 

 made with a 40 m modified Cobb pelagic trawl 

 (Smith footnote 10) on the latter half of the sonar 

 track in areas of biological aggregations identified 



and measured by sonar. Standard oblique 60 cm 

 bongo tows (Smith and Richardson 1977) were 

 made at each trawl station from 70 m to the sur- 

 face. Samples were processed at sea using Cal- 

 COFI (California Cooperative Oceanic Fisheries 

 Investigations) techniques (Kramer et al. 1972) 

 except that the 0.333 mm mesh samples were 

 preserved in ethyl alcohol for special studies 

 (Methot"). 



Laboratory Procedures 



Plankton volumes for each 0.333 mm mesh 

 bongo sample from the 1975 and 1976 cruises were 

 determined by displacement (Kramer et al. 1972), 

 and northern anchovy eggs and all fish larvae 

 were sorted. Northern anchovy eggs were enu- 

 merated. Measurements of long and short axes of 

 eggs were made on selected samples using an ocu- 

 lar micrometer in a stereomicroscope. Northern 

 anchovy larvae were identified, enumerated, and 

 measured in 0.5 mm size classes using a plastic 

 rule beneath a glass slide. The 0.333 mm mesh 

 bongo samples only from the 1977 cruise were pro- 

 cessed by personnel from Scripps Institution of 

 Oceanography and the NMFS Southwest 

 Fisheries Center according to techniques de- 

 scribed by Kramer et al. (1972). Numbers of eggs 

 and larvae in each sample were standardized to 

 the number under 10 m^ sea surface (Smith and 

 Richardson 1977): 



C, = 10 {a;^b;^c,d,) 



(1) 



where C, = number of eggs or larvae beneath 

 10 m^ sea surface at station i 



a = mouth area of the bongo net used at 

 station i in square meters 



b = length of tow path in meters estimat- 

 ed from a calibrated flowmeter at 

 station i 



c = number of eggs or larvae in the ith. 

 sample 



d = maximum depth of tow in meters. 



Egg and Larva Census Estimates 



^Reference to trade names does not imply endorsement by the 

 National Marine Fisheries Service, NOAA. 



'"Smith, RE. 1977. Cruise report,^^ David Starr Jordan, 

 7705(111), Mordax North, Leg A, 13-27 July 1977. Rep. dated 5 

 December 1977. On file at National Marine Fisheries Service 

 Southwest Fisheries Center, EO. Box 271, La Jolla, CA 92038. 



Census estimates (i.e., estimates of the total 

 number of northern anchovy eggs and larvae in 



"R.D.Methot, Scripps Institution of Oceanography, Graduate 

 Department, La Jolla, CA 92093, pers. commun. July 1977. 



858 



