924 



Fishery Bulletin 97(4), 1999 



than before the storm at all depths below 80 m (Figs. 

 2; 3; 4, C and D). 



Wind and sea-state observations taken during the 

 cruise and supplemented by data from the Naval Air 

 Station at San Clemente Island, southwest of the 

 offshore station, and the San Onofre Nuclear Gener- 

 ating Station, just southeast of the inshore study area 

 (Fig. 1), indicated an oscillating land-sea system 

 whigh was more evident at San Onofre than at San 

 Clemente (Fig. 5). During the night and morning, 

 winds typically were from the NNE, after which they 

 shifted through the south to the NW until late after- 

 noon or evening. Average wind speed was about 10 

 knots at the offshore station and about 6 knots at 

 the inshore station; average swell height was about 



9 10 11 12 13 14 15 16 



_l I I I I I I 



120-160- 



1 12 13 14 



1 1 I 



0-10- 



16 



_L_ 



17 

 -J 



Inshore 



10 11 12 13 14 



11 12 13 14 15 16 

 I I I I I 



Post-Storm 



Pre-storm 



Temperature (C") 



Figure 4 



Average temperatures for strata samplfd with the MESSHAI, based on data 

 from the ME.SSHAI temperature sensor lAi Deep tows at inshore (dotsi and 

 ofTshore (circle.s) stations; (B) shallow tows at inshore (dots) and offshore (circles) 

 stations; (C) deep tows at inshore station before the storm (dots) and after the 

 storm (circles); (Dl shallow tows at inshore station before the storm (dots) and 

 after the storm (circles). 



1.7 m and about 1 m at the two sites, respectively 

 (Fig. 6). At the inshore station wind speed was more 

 than 24 knots during the storm. 



Prior to the storm at the inshore station there was a 

 moderate to strong chlorophyll maximum at 18-29 m 

 (Fig. 7). Following the storm, the chlorophyll peak 

 became shallower and generally broader. The peak 

 was at 15 m on the morning of 3 April; by the evening 

 of 4 April, the maximum was near the surface. On 

 the following two days the peak reappeared and be- 

 gan to deepen and strengthen. Average plankton vol- 

 umes of Manta and MESSHAI samples from the 

 upper 40 m were distinctly higher at the inshore sta- 

 tion than at the offshore station (Fig. 8, A and B). 

 Average volumes were generally higher in strata 

 within the upper 40 m in poststorm 

 samples compared with those taken 

 prior to the storm (Fig. 8, C and E). 

 Average plankton volume increased 

 markedly in the 40-80 m stratum, 

 whereas there was little change in 

 deeper strata (Fig. 8E). 



Engraulis mordax eggs 



A total of 67,157 E. mordax eggs 

 were collected in the MESSHAI and 

 Manta nets. Anchovy eggs had a 

 slightly shallower distribution than 

 larvae, with approximately 95% of 

 eggs in the upper 30 m ( Fig. 9, A and 

 Bl. In shallow strata (including 

 Manta, shallow MESSHAI, and the 

 0-40 m stratum of the deep MES- 

 SHAI tows), average density was 

 greater at the offshore station than 

 at the inshore station (F-^ gr,=4.72, 

 P=0.003 ). Yet egg density in the deep 

 strata was similar at the two stations. 

 Average egg density in the surface 

 layer was more than double that in 

 the 0-10 m stratum (Fig. 9B). In the 

 shallow strata at the inshore station, 

 egg densities in MESSHAI tows were 

 reduced after the storm (Fj 32=12.73, 

 P=0.001), whereas egg densities did 

 not change much in Manta tows 

 (F, ,,^=1.58, P=0.048) and in deep (>40 

 F,,,„=2.67, P= 



m) MESSHAI tows 

 0.132) (Fig. 9, C and F). 



Fish larvae 



A total of 95,552 fish larvae were taken 

 in the MESSHAI and Manta nets, 



