ALLEN" and DeMARTINI: NEARSHORE DISTRIBUTION AND ABUNDANCE OF PELAGIC FISHES 



period November 1980-March 1981. Xenistius 

 californiensis was consistently more common up- 

 coast(./V= 170 sample fish) than downcoast (N= 13) 

 at night, although its low frequency of overall oc- 

 currence precluded a statistical test for longshore 

 differences. 



TABLE 1. — Number of individuals and frequency of occurrence of 62 

 species/taxa in 643 lampara net samples on 129 cruises from Sep- 

 tember 1979 to March 1981, inclusive. Species/taxa are ranked 

 according to total number of individuals. 





Monthly and Longer Temporal 

 Patterns 



CPUE for total individuals, number of E. mordax, 

 and total individuals minus E. mordax, when plotted 

 on a monthly basis, revealed general temporal pat- 

 terns of abundance (Fig. 2). Catches were generally 

 higher at night for all three categories (see below). 

 Day catches were generally much more variable than 

 night catches, as the standard errors indicate (Fig. 2). 

 The longer term (i.e., "seasonal") temporal changes 

 in the catch of total individuals largely reflect the in- 

 crease in primarily juvenile-sized (<10 cm standard 

 length, Hunter and Leong 1981) E. mordax during 

 the summer months. When the abundances of all 

 species other than E. mordax are combined, the catch 

 remained relatively constant throughout the study 

 period except for a general decline in numbers during 

 October-December of both 1979 and 1980. 



The abundances of Seriphus politus and G. lineatus 

 also remained relatively constant except for the 

 October-December declines. These two species (Fig. 

 3) were primarily responsible for the pattern ob- 

 served for total individuals minus E. mordax. Night 

 catches were higher than day catches for G. lineatus 

 and (especially) S. politus. The abundances of P. 

 simillimus and atherinids in general showed patterns 

 which were similar in terms of seasonality. Both were 

 usually more abundant during cooler water months 

 (December-April). Three species of higher level 

 (mainly piscivorous) carnivores showed dissimilar 

 patterns of nearshore abundance (Fig. 3). Scomber 

 japonicus was more abundant in warmer water 

 months from about June to October. Pacific bonito, 

 Sarda chiliensis, occurred in greatest numbers from 

 March to August, but only during the day. Sphyraena 

 argentea was more abundant during the cooler water 

 months of October through March. 



Diel and Depth Patterns 



Day and night catches of total individuals varied 

 among depth blocks throughout the study (Fig. 4). 

 Day catches were consistently highest at 5-11 m 

 depths, but the variability in catches was high. Night 

 catches did not differ (P > 0.05, Wilcoxon's signed 

 rank test) from day catches in the shallow depth 

 block. However, night catches were higher and less 

 variable than day catches in both the 12-16 mand 18- 

 27 m depth blocks (Fig. 4). 



All categories and species common enough to test 

 showed significant diel, depth, and date (cruise) main 

 effects, as well as diel X depth interactions, based on 

 Wilson's three-way ANO VA with unequal replication 



573 



