FISHERY BULLETIN: VOL. 85, NO. 1 



Table 1 .—Composition of the diet of larval sablefish in terms of the Index of Relative Importance (IRI) and its components: numerical 

 percent composition (%N), frequency of occurrence (%F0), and volumetric percent composition (%VOL), by size class and year, with 

 n = sample size and %ZlRI = the contribution of each prey type to the total IRI. 



Prey type 



%N %F0 %VOL IRI %IlRI 



Prey type 



%N %F0 %VOL 



IRI 



%IlRI 



Larval size <12.5 mm 



Larval size 12.6-20.5 mm— Continued - 



1980 



Invertebrate eggs 

 Pteropods 

 Copepod nauplii 

 Copepods <1 mm 

 1-2 mm 

 >2 mm 

 Amphipods 

 Euphausid larvae 

 Appendicularians 

 Other prey 

 n = 



1983 



Invertebrate eggs 



Pteropods 



Copepod nauplii 



Copepods <1 mm 

 1.2 mm 

 >2 mm 



Amphipods 



Euphausid larvae 



Appendicularians 



Other prey 

 n = 



1980 



Invertebrate eggs 



Pteropods 



Copepod nauplii 



Copepods <1 mm 

 1-2 mm 

 >2 mm 



Amphipods 



Euphausid larvae 



Appendicularians 



Other prey 

 n = 



0.5 

 5.8 

 84.0 

 7.4 

 0.8 



0.4 

 0.6 

 0.5 

 165 



0.5 



2.1 



74.3 



21.7 



1.0 



0.4 



49 



7.9 

 25.5 

 96.4 

 66.1 

 14.5 



6.7 

 7.3 

 4.2 



8.2 

 14.3 

 91.8 

 85.7 

 18.4 



4.1 



0.1 

 11.2 

 27.1 

 27.8 



8.0 



15.3 

 7.2 

 3.3 



<0.1 



2.7 



15.9 



66.2 



5.8 



9.3 



4.7 



433.5 



10,710.0 



2,326.7 



127.6 



105.2 

 56.9 

 15.6 



4.9 



68.6 



8,280.4 



7,533.0 



125.1 



39.8 



0.3 

 9.4 

 25.8 

 48.2 

 7.9 

 0.2 



2.4 

 5.4 

 0.4 

 79 



Larval size 12.6-20.5 mm 



5.1 

 38.0 

 70.9 

 93.7 

 49.4 



3.8 



25.3 



17.7 



3.8 



<0.1 



3.7 



1.7 



37.7 



19.3 



5.0 



18.3 



13.7 



0.5 



4.7 



497.8 



1,949.7 



8,048.8 



1,343.7 



19.8 



523.7 



338.1 



3.4 



<0.1 



3.1 



77.7 



16.9 



0.9 



0.8 

 0.4 

 0,1 



<0.1 



0.4 



51.6 



46.9 



0.8 



0.2 



<0.1 

 3.9 

 15.3 

 63.2 

 10.5 

 0.2 



4.1 



2.7 



<0.1 



1983 



Invertebrate eggs 

 Pteropods 

 Copepod nauplii 

 Copepods <1 mm 

 1-2 mm 

 >2 mm 

 Amphipods 

 Euphausid larvae 

 Appendicularians 

 Other prey 

 n = 



1980 



invertebrate eggs 

 Pteropods 

 Copepod nauplii 

 Copepods <1 mm 

 1-2 mm 

 >2 mm 

 Amphipods 

 Euphausid larvae 

 Appendicularians 

 Other prey 

 n = 



1983 



Invertebrate eggs 

 Pteropods 

 Copepod nauplii 

 Copepods <1 mm 

 1-2 mm 

 >2 mm 

 Amphipods 

 Euphausid larvae 

 Appendicularians 

 Other prey 

 n = 



0.2 

 0.3 

 9.9 



83.3 

 3.7 



<0.1 

 0.1 

 2.3 

 0.2 



66 



1.4 



40.6 



11.0 



4.1 



0.5 



0.9 



38.4 



0.2 



23 



0.2 

 0.5 

 0.4 

 71.3 

 9.6 

 4.0 

 8.1 

 5.5 

 0.4 



21 



1.5 

 9.1 



60.6 

 100.0 



48.5 

 1.5 

 4.5 



40.9 

 7.6 



0.1 



0.1 



0.6 



71.6 



10.1 



1.1 



0.2 



15.7 



0.5 



0.5 

 3.6 



636.3 

 15,490.0 



699,3 

 1.8 

 1.4 



736.2 

 5.3 



Larval size 20.6-28.5 mm 



2.9 13.0 <0.1 



30.4 

 95.7 

 87.0 

 69.6 

 17.4 

 17.4 

 73.9 

 8.7 



9.5 

 14.3 

 19.0 

 95.2 

 76.2 

 66.7 

 47.6 

 61.9 

 14.3 



<0.1 



13.2 



10.0 



42.0 



0.4 



2.2 



32.0 



0.1 



<0.1 

 <0.1 

 <0.1 

 24.1 

 12.3 

 41.6 



7.2 

 14.3 



0.4 



39.0 



45.6 



5,148.7 



1,827.0 



3,208.6 



15.7 



53.9 



5,202.6 



2.6 



2.8 



8.6 



9.5 



9,082.1 



1,668.8 



3,041.5 



728.3 



1,225.6 



11.4 



0.1 

 0.1 

 3.6 



88.3 

 3.8 



<0.1 

 0.1 

 4.2 



<0.1 



0.2 



0.3 

 33.1 

 11.8 

 20.6 

 0.1 

 0.3 

 33.5 

 <0.1 



<0.1 

 <0.1 

 <0.1 

 57.6 

 10.6 

 19.3 

 4.6 

 7.8 

 <0.1 



shifted towards smaller copepods (Table 3), espe- 

 cially P. parvus, so that copepods <1 mm ranked 

 highest in IRI value. Evidence for this shift came 

 from numerical data (x^ = 27.30, 2 df , P < 0.001) 

 as well as volumetric data (x^ = 1928.73, 2 df , P 

 < 0.001). 



A comparison of the diet of medium-sized and 

 large larvae showed that despite other dietary dif- 

 ferences, the number of copepods in the diet of 

 medium-sized larvae equalled the number of cope- 

 pods ingested by large larvae in 1980 (x^ = 0.13, 

 1 df , P > 0.75). However, large larvae ingested a 

 greater volume of copepods in 1980 than did 

 medium-sized larvae (x^ = 148.09, 1 df, P < 0.001). 

 In 1983 the numbers of copepods ingested by 

 medium-sized and large larvae were again equiva- 

 lent (x^ = 2.93, 1 df, P > 0.05), although copepods 



contributed more, volumetrically, to the diet of 

 medium-sized larvae (x^ = 657.22, 1 df , P < 0.001). 



Comparison of Oceanographic Conditions 



Because 1983 was a year of anomalous El Nifio 

 conditions, differences in diet between 1980 and 

 1983 may have been due to differing oceanographic 

 conditions in the 2 years. Surface water tempera- 

 tures taken during the ichthyoplankton surveys, 

 were used as an indicator of oceanographic condi- 

 tions. As the two surveys followed the same tran- 

 sects, station coordinates corresponded for the 2 

 years. Temperatures recorded from 20 April to 5 

 May 1980 averaged 10.67°C (s = 0.783), while those 

 from 23 April to 6 May 1983 were significantly 

 higher (P = 0.001) averaging 11.78°C (s = 0.772). 



74 



