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Fishery Bulletin 93(3), 1995 



summer. Entry of small sculpin into our 

 sampling areas in June was inferred by 

 the decrease in mean sculpin size and wet 

 weight (Table 1) and supported by exami- 

 nation of length-frequency histograms 

 (Fig. 3). 



Diet composition changed appreciably 

 from month to month. During the spring, 

 sculpin primarily consumed the gammarid 

 amphipod E. confervicola (46% IRI), 

 Crangon spp. shrimp (24% IRI), and fish 

 (13% IRI) in April (Fig. 5), whereas the 

 nereid polychaete N. brandti (34% IRI), 

 the thalassinid shrimps N. californiensis 

 (45% IRI), and U. pugettensis (12% IRI) 

 were the most abundant prey in stom- 

 achs in May (Fig. 5). Sculpin consumed 

 few crab, reflecting the relative scarcity 

 of 0+ instars in late spring; Jl instars 

 were found in only 5% of sculpin stom- 

 achs in May and represented less than 

 1% IRI. Minimal settlement of Dunge- 

 ness crab during May was indicated by 

 low catches of 0+ crabs (Fig. 6; only three 

 Jl were caught in 10 trawls). 



In early June, juvenile Dungeness crab recruited 

 to the estuary (Fig. 6) and became the second most 

 important diet category (24% IRI, Fig. 5). The nereid 

 polychaete N. brandti was first in dietary importance, 

 accounting for 59% IRI, and Crangon spp. shrimp 

 ranked third ( 10% IRI) in early June. The major pulse 

 of 0+ crab settlement had occurred during late May- 

 early June (after the mid-May sampling; Fig. 6) and 

 thus Jl and J2 crab had become readily available 

 prey by the beginning of summer. Nereid polycha- 



etes continued as the most important prey item 

 through mid-June (88% IRI), whereas C. magister 

 juveniles accounted for only 4% IRI and were con- 

 sumed by 24% of the sculpin examined. 



During the mid and later part of summer, decapod 

 crustaceans represented the majority of staghorn 

 sculpin diet. In July and August nereid worms were 

 rarely found in stomach contents, but thalassinid 

 shrimp, N. californiensis and U. pugettensis, together 

 totalled 70% IRI in July and 54% IRI in August (Fig. 

 5). Juvenile crab accounted for 15% and 13% IRI of 



