McCABE ET AL.: INTERRELATIONSHIPS BETWEEN SALMONIDS 



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SPRING 1980 



Phytoplankton 

 Plant material 

 Turbellaria 

 Polychaeta 

 Corbicula manilensis 

 Macoma balthica 

 Ostracoda 

 Daphnia spp. 

 Bosmina spp. 

 Calanoida 

 Cyclopoida 

 Harpacticoida 

 Mysidacea 

 Neomysis mercedis 

 Corophium salmonis 

 Corophium spinicome 

 Eogammarus spp. 

 Euhaustorius estuaris 

 Crab megalops 

 Diptera adult 

 Diptera larvae 

 Heleidae larvae 

 Chironomid larvae 

 Chironomid pupae 

 Coleoptera adult 

 Trichoptera larvae 

 Hymenoptera adult 

 Homoptera adult 

 Arachnid 

 Sand lance 

 Digested fish 



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Upper 

 pelagic 



Lower 

 pelagic 



Upper 

 intertidal 



Lower 

 intertidal 



FIGURE 3. — Principal prey items of juvenile salmonids and commonly associated nonsalmonids cap- 

 tured in four habitats of the Columbia River estuary during spring 1980. A principal prey item has an 

 IK1 value >50; the prey item with the highest IRI value for each species is indicated by a solid circle. 

 Number of stomachs examined is shown in parentheses. 



Oreg., found that Pacific herring, shiner perch, 

 northern anchovy, and surf smelt, Hypomesus pre- 

 tiosus, were abundant at her beach seine sites. Durkin 

 et aL 3 found that shiner perch, Pacific herring, surf 

 smelt, and northern anchovy were commonly as- 

 sociated with subyearling chinook salmon in inter- 

 tidal areas of the lower Columbia River estuary. 



Considering the nonsalmonid species commonly 

 associated with subyearling chinook salmon and 

 their size characteristics, nonsalmonid predation on 



'Durkin. J. T., S. J. Lipovsky, G. R. Snyder, and M. E. Tut- 

 tle. 1977. Environmental studies of three Columbia River es- 

 tuarine beaches. Unpubl. manuscr., 78 p. Northwest and Alaska 

 Fisheries Center Hammond Field Station, National Marine 

 Fisheries Service, NOAA, P.O. Box 155, Hammond, OR 97121. 



subyearlings in the Columbia River estuary should 

 be minimal. American shad, Pacific herring, surf 

 smelt, longfin smelt, peamouth, threespine stickleback 

 and shiner perch are essentially invertebrate and/or 

 plant eaters. Large Pacific staghorn sculpins and 

 starry flounder could eat subyearling chinook 

 salmon; however, the large individuals of these 

 species are usually not found in intertidal areas of the 

 estuary. Normally the large sculpins and flounders 

 are found in deep demersal habitats of the Columbia 

 River estuary. Although many researchers have 

 studied the use of the estuarine areas as nursery and 

 feeding areas for salmonids (Mason 1974; Levy and 

 Levings 1978; Reimers et aL 1978; Sibert 1979; 

 Healey 1980; Myers 1980), few have documented the 

 food habits of associated nonsalmonid estuarine fish 



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