464 



Fishery Bulletin 93(3), 1995 



3 





e 

 o 



'€ 



e 



o. 

 o 



APRIL 1989 



n=786 



Mid JUNE 1989 



n=l,577 



5 10 IS 20 25 30 35 40 45 S0S5 6O65 70 75 80 85 9O951O0 



.11 -llll. 



5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95100 



JULY 1989 



n= 1,204 



5 10 IS 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95100 



Early JUNE 1989 



n=2,089 



5 10 IS 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95100 



AUGUST 1989 



n=I,937 



•lllll 



«* 



5 I0 15 2O25 30 3540 45 50 55 6065 70 75 80 85 9O95100 



5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95100 



Carapace width (mm CW) 

 Figure 6 



Dungeness crab, Cancer magister, length-frequency histograms from Grays Har- 

 bor, Washington, April to August 1989. Note first occurrence of 0+ crab in May ( 6 

 mm CW) and peak settlement in early June. Summer growth of 0+ crab is evi- 

 dent by 0+ size modes attaining 30-35 mm CW by August. 



forniensis, H. oregonensis, and pea crabs, Pinnixa 

 spp. (Tasto, 1975). A multi-species assemblage of crab 

 including Pugettia producta, Cancer productus and C. 

 gracilis, Pinnixa spp., Scleroplax granulata (pea crabs), 

 Hemigrapsus nudus, H. oregonensis, and Pagurus spp. 

 accounted for 25—30% of the spring diet (by volume) of 

 staghorn sculpins >100 mm TL in an estuary of 

 Vancouver Island, British Columbia (Mace, 1983). 



The summer diet of staghorn sculpins from Grays 

 Harbor, Washington, corroborates Tasto's (1975) ob- 

 servation that the diet of staghorn sculpin >70 mm 

 TL consists of crustaceans, especially decapods in- 

 cluding ghost and mud shrimp (N. californiensis and 

 U. pugettensis), sand shrimp (Crangon spp.), and 

 seasonally abundant 0+ Cancer magister. From IRI 



analysis, it was determined that 

 Dungeness crab represented about 

 9% of the overall total summer diet 

 of sculpin. Over 30% of all stag- 

 horn sculpin collected during June 

 and 23% during July and August 

 had 0+ Dungeness crab in their 

 stomachs. Two other decapods that 

 composed even greater proportions 

 of the overall sculpin summer diet 

 were Neotrypaea californiensis 

 and Crangon spp. (27% and 13% 

 IRI, respectively). 



Other prey 



Staghorn sculpin also consume 

 prey species such as nereid poly- 

 chaetes, fish, and bivalves that are 

 seasonally abundant and readily 

 available (see Gunderson et al., 

 1990, for list of infaunal and epi- 

 faunal prey in Grays Harbor). 

 These sculpin have relatively plas- 

 tic feeding behavior and their diet 

 changes month to month, fluctu- 

 ating with relative prey abun- 

 dance and accessibility. Despite 

 this plasticity, the majority of this 

 species' diet (85-99% IRI) gener- 

 ally consisted of only 4 or 5 prey 

 species (Fig. 5; Table 2). In April, 

 before crab were available, sculpin 

 consumed amphipods, especially 

 E. confervicola, and Crangon spp. 

 shrimp. Nereid polychaetes and 

 the thallassinid shrimp Neotrypaea 

 californiensis were primary prey in 

 May. Dungeness crab were incor- 

 porated into the diet as they 

 settled in June and were ranked second in IRI im- 

 portance after N. brandti. 



The late spring or early summer predominance of 

 N. brandti polychaetes in the diet of sculpin was 

 somewhat unexpected because polychaetes have not 

 often been reported as a major diet item by other 

 researchers from Washington (Smith, 1980; Thorn- 

 burgh, 1980; Dinnel et al., 1990), or British Colum- 

 bia (Mace, 1983), although they are mentioned as 

 prey among fish from California (Jones, 1962; Tasto, 

 1975). The importance of this polychaete during 

 spring and early summer to sculpin in Grays Harbor 

 suggests that adult worm reproductive activity (Bass 

 and Brafield, 1972; Giese and Pearse, 1975; Durchon, 

 1984) might make them vulnerable to sculpin preda- 



