JUDKINS and FLEMINGER: FOREGUT CONTENTS OF Sergestes limilis 



METRIDIA 



CALANUS 



PLEUROMAMMA 



RHINCALANUS 



EUCHAETA 



EUCALANUS 



SCOLECITHRICELLA 



CANDACIA 



ZJ 



Figure 2. — Frequencies of calanoid genera occurring in 

 10% or more of night-net (black), day-net (open), and 

 fish (strippled) samples. 



calanoid prey. In day-net samples Calanus num- 

 bers are considerably below those of Metridia 

 which remained high. However, the difference 

 between the median sample means of Calanus 

 in day- and night-net samples is not significant 

 (P > 0.20) . This is also true of the other seven 

 genera. 



Metridia was numerically dominant in fish 

 samples, although it occurred in lower numbers 

 than in net samples. Differences between the 

 median sample means of Metridia in net and 

 fish samples, however, are not significant 

 (P > 0.40). Differences between net-and-fish- 

 caught S. similis in the median values of Euca- 

 lanus, Euchaeta, and Rhincalanus are significant 

 at P values falling between 0.10 and 0.20. Dif- 

 ferences among the remaining calanoid genera 

 are significant at P values between 0.02 and 0,10. 



DISCUSSION 



Metridia jyacifica, Calanus pacificus, Pleuro- 

 mamma abdominalis , Rhincalanus nasutu^, Eu- 

 cakinus bungii californicus, and Candacia bipin- 

 nata are among the 24 most abundant and 

 frequently occurring of 176 calanoid species 

 found in zooplankton samples collected on Cal- 

 COFI Cruises 5804, 5807, 5810, and 5901 (Flem- 

 inger, 1967). Significantly, these are also the 

 principal species of six of the eight genera most 

 frequently occurring in the foreguts examined 

 in the present study. Adults of these species 

 exceed 3 mm in length. It appears, then, that 

 the principal prey of S. similis are the more 

 abundant, relatively large, adult copepods in- 

 habiting the uppermost 200 to 300 m in the Cal- 

 ifornia Current region. 



Additional items found in both net and fish 

 samples are euphausiids, chaetognaths, ostra- 

 cods, amphipods, and radiolarians. Of these, 



Table 4. — Median of sample means and overall mean in calanoid genera occurring in more than 10% of foreguts. 



[Means expressed as number of prey per foregut.] 



Prey 



Night-net 



Day-net 



Median 



Range 



Mean 



Median 



Range 



Mean 



Median 



Fish 



Range 



Mean 



Metridia 0.30 0-4.10 0.95 0.56 0- 



Calanus .40 0-5.90 1.16 



Pleuromamma .30 0-1.10 .36 .10 



Rhincalanus .20 0-2.00 .35 



Euchaeta .10 0- .20 .10 



Eucalanus 0- .30 .10 



Scolecithricella .10 0- .40 .13 .10 



Candacia 



Number samples 10 10 



Total number foreguts 86 65 



1.60 

 .80 

 .80 

 .30 

 .40 

 .50 

 .30 



0.78 

 .17 

 .15 

 .09 

 .14 

 .11 

 .12 







0.36 



























.10 

 10 

 88 



0-2.90 



0- .09 



0- .06 



0- .50 



0.69 

 



.02 

 



.01 

 

 



.11 



221 



