Interspecific competition between stream-dwelling brown trout and Alpine bullhead

Holmen, J., Olsen, E.M., & Voellestad, L.A. (2003). Interspecific competition between stream-dwelling brown trout and Alpine bullhead. Journal of Fish Biology 62 (6) 1312-1325. 10.1046/j.1095-8649.2003.00112.x.

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Abstract

Density and composition of benthic invertebrates and the diet of brown trout Salmo trutta and Alpine bullhead Cottus poecilopus were studied at two sites in one Norwegian stream. The sites were separated by an impassable waterfall, and brown trout density was five to 10 times higher at the upper, allopatric site than downstream where it lived in sympatry with the Alpine bullhead. Benthic invertebrate communities did not differ between sites; however, the size distribution of chironomids and trichopterans were skewed towards lighter individuals at the sympatric site. Diet composition suggested that sympatric brown trout foraged more on invertebrate drift and from the surface than allopatric brown trout. Alpine bullhead diet did not differ significantly from brown trout diet, except that the Alpine bullhead fed on heavier individual prey within a few taxa and did not consume chironomid pupae or surface insects. The collected data support the hypothesis that brown trout living in sympatry with Alpine bullhead feed at locations with higher predation risk, which is a probable explanation for their lower population density.

Item Type:	Article
Uncontrolled Keywords:	Allopatry; Alpine bullhead; Brown trout; Competition; diet; Sympatry
Research Programs:	Adaptive Dynamics Network (ADN)
Bibliographic Reference:	Journal of Fish Biology; 62(6):1312-1325 (June 2003)
Depositing User:	IIASA Import
Date Deposited:	15 Jan 2016 02:15
Last Modified:	27 Aug 2021 17:37
URI:	https://pure.iiasa.ac.at/6819

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