young salmon was consistently the 

 benthic amphipod, C. salmonis , at the 

 three sites. Diptera was the other 

 identifiable food item. 



stream sites indicating higher avail- 

 ability of prey organisms in that 

 area . 



Pacific tomcod length frequen- 

 cy and IRI categories are shown in 

 Figure 5. Most of the 1978 fish 

 fall into two age groups though a 

 smaller size group appears at Jetty 

 A and a few larger fish at the In- 

 terstate Bridge. Prey items varied 

 considerably between the four sites. 

 The IRI indicated anchovy, amphi- 

 pods , mysids, and crangon shrimp 

 were all extensively utilized. 

 The 1979 survey indicated tomcod 

 were present at the two marine sta- 

 tions, but only one age group was 

 represented. Benthic amphipods and 

 mysids were numerically important 

 food items, whereas digested fish 

 and crangon shrimp accounted for 

 most of the weight. 



The demersal Pacific staghorn 

 sculpin size group and food utili- 

 zation is shown in Figure 6. Inter- 

 gradation of sculpin length obscured 

 any size grouping during both sur- 

 veys though the larger sculpin were 

 found off Tongue Point in October 

 and at Tansy Point in May. Epiben- 

 thic fauna diversity typified the 

 diet of sculpin caught in October. 

 Benthic amphipods, C. salmonis and 

 Anisogammarus confervicolus , and 

 fish were the essential diet items 

 of sculpin in May. 



Dietary organisms for the fish 

 varied dramatically during the Oct- 

 ober survey depending upon species 

 and where they were caught. The 

 May survey results indicated a 

 smaller selection of food items and 

 substantial use of both calanoid 

 copepods and benthic amphipods. The 

 incidence of empty stomachs was some- 

 what less in the fish captured at up- 



Particle size ranged from medi- 

 um gravel (8mm) down to clay (0.00 to 

 2mm). The proportional average value 

 of ten samples for each site was de- 

 termined and plotted by size cate- 

 gory (Figure 7). The unbroken lines 

 indicate results from the fall 1978 

 survey, while the dotted lines re- 

 present results from May 1979. Sev- 

 eral characteristics were noted. 

 (1) Medium grain sand (0.25-0. 5mm) 

 was the major size category of sedi- 

 ments at all sites. (2) The high 

 proportion of medium grain sand was 

 unchanged at all sites between the 

 two surveys. (3) Slightly higher 

 proportions of both larger and finer 

 sediments were found at sites above 

 Jetty A. (4) The scour sites are 

 essentially homogeneous substrate 

 habitats with little evidence of 

 sediment accumulation or seasonal 

 change. 



Total volatile solids (TVS) 

 were analyzed in each sediment core 

 with the range and average for each 

 site and survey shown in Figure 7. 

 The sediment was essentially clean 

 sand with average levels of two per- 

 cent or less, though two samples 

 exceeded the EPA six percent level. 



Averages of two water quality 

 parameters (salinity and temperature) 

 gathered with sediment and benthic 

 infauna samples also appear in Fig- 

 ure 7. The values are represented 

 from readings taken at the surface 

 (S) or bottom (B) . The salinity 

 levels ranged from marine to fresh 

 from Jetty A to Tongue Point, and 

 from bottom to surface. Salinities 

 change dramatically with season and 



445 



