FISHERY BULLETIN: VOL 78, NO. y 



nearly equal numbers of species were collected 

 during the day (14) and night (15) (Table 2); how- 

 ever, significantly greater numbers of individuals 

 and biomass were obtained during the night (Ta- 

 ble 3). The PS value between day and night sam- 

 ples was higher for numbers (68.5%) than for 

 biomass (43.3%). In February, nearly equal num- 

 bers of species were collected during the day (9) 

 and night (10). Greater numbers of individuals 

 were collected at night but the difference was not 

 significant. Even though the total biomass ob- 

 tained during the day in February was greater 

 than that at night, the night samples were more 

 frequently and significantly larger based on 

 paired day-night abundances of each species using 



the Wilcoxon signed-ranks test (Table 3). The dis- 

 crepancy was due to the exceptionally large day- 

 time contribution (34,246 g) of M. californicus 

 compared with its much smaller contribution 

 (3,402 g) to the night samples. The PS value be- 

 tween day and night samples was much higher for 

 numbers (83.3% ) than for biomass (40.5% ). In May, 

 more species were collected at night (14) than dur- 

 ing the day (8). Greater numbers of individuals 

 and biomass were obtained at night but the differ- 

 ence was significant only for numbers. The PS 

 value between day and night samples was higher 

 for numbers (60.3%) than for biomass (42.0%). In 

 August, nearly equal numbers of species were col- 

 lected during the day (eight) and night (seven). 



Table 2. — Relative numbers and biomass (expressed as percentage) offish species collected in four daytime (0900-1800 h> and four 

 nighttime (2100-0600 h) seine hauls for each sampling period and the total collection in Morro Bay. (Species ranking as in Table 1.) 



February 1976 



May 1975 



August 1975 



Table 2.— Continued. 



November 1974 



Totals 



762 



