Armstrong et al.: Food habits of Leptocottus armatus 



46! 



c 

 'a. 



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u 



c 

 o 



C 



o 

 a 

 o 



x=80mm 



■!■■ 



APRIL 





0+ 

 1=91 mm 



■III 



; a S s S 5 S ; 



EARLY JUNE 



n=62 



IU.il 



II 



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0* 

 x-95 mm 



assssKsss, 



JULY 



n=6\ 



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AUGUST 



n=227 

 o* 



x~ 105 mm 



Length intervals (mm) 



Figure 3 



Staghorn sculpin, Leptocottus armatus, length-frequency histograms and inferred age classes 

 (0+ and 1+ and older) from Grays Harbor, Washington, April-August 1989. Vertical line indi- 

 cates upper size cut-off of 0+ from 1+ sculpin. Mean sizes of the age class are given by x , n = total 

 number offish examined, both age classes combined. 



sculpin diets during these months and Crangon spp. 

 for 10% and 11% IRI. 



Sculpin age-class and prey composition 



Sculpin length-frequency histograms by trip were 

 examined and fish were separated into two age 

 groups based on size (Fig. 3). The diets of 0+ and >1+ 

 sculpin were compared to determine whether there 

 were differences in prey composition based on fish 

 size. Both sculpin age groups had the same propor- 

 tion of empty stomachs (5%) and the same mean 

 number of prey species (3.4) per predator, indicating 



similar feeding success rates. Small (0+) sculpins 

 primarily consumed N. brandti (50% IRI), N. 

 californiensis (13% IRI), Crangon spp. (11% IRI), C. 

 magister (9% IRI), bivalve siphon tips, and miscella- 

 neous or unidentified crustaceans (5% IRI each; Fig. 

 7). Larger sculpins consumed less N. brandti and 

 crangonid shrimp (23% and 5% IRI) but more 

 thalassinid shrimp (N. californiensis [31% IRI] and 

 U. pugettensis [12% IRI]) and large gammarid am- 

 phipods (E. confervicola [8% IRI]). Dietary overlap 

 was significant (S IO =0.6). Sculpins over the entire 

 size range sampled (70-215 mm TL) consumed young 

 Dungeness crab (9% of IRI in the summer diet of both 



