Moser and Pommeranz: Distribution of eggs and larvae of Engraulis mordax 



923 



rMar 29- 



NIGHT 

 Manta-tow *18 19 2021 22 



and body lengths were measured to 

 0.1 mm. 



We used analysis of variance 

 (AN OVA) to compare the pre- and 

 poststorm densities of anchovy eggs 

 and larvae for shallow strata and 

 also for deep strata at the inshore 

 and offshore stations. Day and night 

 data were pooled for each of these 

 categories because the data did not 

 indicate a diurnal shift in vertical 

 distribution of eggs or larvae. All 

 data were log-transformed for sta- 

 tistical analyses because the origi- 

 nal data were highly skewed. Data 

 from the shallow strata included the 

 Manta tows, the MESSHAI shallow 

 tows (0-50 m), and the upper 40 m 

 from the MESSHAI deep tows. Data 

 for the deep strata were from below 

 40 m from the deep MESSHAI tows. 

 A two-way AN OVA was performed for 

 the shallow strata, the two factors 

 being station (inshore and offshore) 

 and tow type (Manta, MESSHAI 

 shallow, and MESSHAI deep). Inter- 

 action terms were included in the 

 analysis. One-way ANOVA was per- 

 formed for data from the deep strata 

 to compare anchovy larval density at 

 inshore and offshore stations. 



In the analysis of prestorm and 

 poststorm conditions two separate 

 ANOVAs were performed because 

 an initial ANOVA of anchovy eggs 

 from the shallow strata indicated a 

 strong interaction between tow type 

 and pre- or poststorm period; one 

 analysis was based on data from 

 shallow and deep MESSHAI tows 

 and the other was based on Manta 

 tows only. A single two-way ANOVA 

 test was performed for anchovy lar- 

 vae because the density of anchovy larvae in Manta 

 tows was low and the analysis adequately described 

 the effect of the storm on larval density based on both 

 shallow and deep MESSHAI tows. 



Results 



Environmental features 



The thermal structure of the study area was typical 

 for March-April in that region of the SCB, with a 



29 30c) 32n 



Figure 3 



Diagram showing the chronology of MESSHAI tows, depth strata sampled, and 

 isotherms at the inshore station. Symbols and labels are the same as those in 

 Figure 2 (from Pommeranz and Moser. 19S7i. 



pool of relatively warm water subject to intrusions 

 of advected upwelling plumes from the Point Con- 

 ception area (Lasker et al., 1981; Lynn et al., 1982). 

 The mixed layer was about 30-40 m deep at the off- 

 shore station (Fig. 2) and only about 10-30 m deep 

 at the inshore station (Fig. 3). Overall, the water was 

 colder at the inshore station, which lacked the promi- 

 nent 16.0^ isotherm present offshore. Average tem- 

 perature was higher at the offshore station in all 

 depth strata except 160-200 m (Fig. 4, A and B). At 

 the inshore station after the storm the thermocline 

 shoaled to 15-20 m and water temperature was lower 



