LIVINGSTON: PACIFIC COD PREDATION ON THREE CRAB SPECIES 



ing 1984 compared with 1981 and 1985, the total 

 number of crab consumed increased over the 

 whole time period, reflecting the smaller sizes of 

 crab consumed in 1984 and 1985 (Table 7). 



Total numbers by age of C. bairdi and C. 

 opilio consumed are shown in Figures 7 and 8. 

 Most C. bairdi consumed are age 1, but ages 0, 

 2, and 3 are also represented. This figure does 

 not show the small amount (3 million) of age 5 

 crab eaten in 1981 or the 5 million age 4 crab 

 eaten during 1985. Cod consumption of C. op;7/o 



is mainly directed at crab of ages 1-2. More C. 

 opilio of ages 3-4 are eaten than C. bairdi. 



DISCUSSION 



The geographic distribution of Pacific cod pre- 

 dation on red king crab corresponds to the main 

 area of red king crab abundance from NMFS 

 resource assessment trawl surveys. These sur- 

 veys produce relatively precise abundance esti- 

 mates for crab >75 mm CL (Otto 1986) which is 



Figure 7. — Total number by age group of Chionoecetes bairdi consumed by the 

 Pacific cod population in 1981, 1984, and 1985. 



Figure 8. — Total number by age group of Chionoecetes opilio consumed by the 

 Pacific cod population in 1981, 1984, and 1985. 



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