MASON and MACfflDORI: POPULATIONS OF SYMPATRIC SCULPINS 



range of species biomass levels commensurate 

 with those encountered in nature and suggest 

 that the availability of drift foods for the trout 

 was determined by the intensity of grazing by 

 sculpins on the stream benthos. 



From the present study, the restricted ability 

 of both species of sculpins to surmount obstacles 

 in the streambed, coupled with the life history 

 features of planktonic young and downstream 

 spawning migrations, lend themselves to the po- 

 tential development of a management strategy 

 for enhancing the production of salmonid smolts 

 to the sea. If the findings of Brocksen et al. (1968) 

 can be corroborated in stream simulator systems 

 more closely approximating the natural envi- 

 ronment, studies on the locomotory ability of 

 these sculpins relative to the performance of their 

 communal salmonids could provide the design 

 criteria for physical barriers to be located on test 

 streams at suitable sites above the influence of 

 high tide. 



LITERATURE CITED 



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1968. Competition, food consumption, and production 

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 Hartley, p. H. T. 



1948. Food and feeding relationships in a community 

 of fresh-water fishes. J. Anim. Ecol. 17:1-14. 



Hunter, J. G. 



1959. Survival and production of pink and chum salmon 

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Larkin, p. a. 



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 MANN, R. H. K., AND D. R. O. ORR. 



1969. A preliminary study of the feeding relationships 

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Mason, J. C. 



1974a. Movements of fish populations in Lymn Creek, 

 Vancouver Island: A summary from weir operations 

 diu-ing 1971 and 1972, including comments on species 

 life histories. [Can.] Dep. Environ., Fish. Mar. Serv. 

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1967. Intra-stream movement and food habits of a popu- 

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