RESEARCH ARTICLE


Competitor Density and Size Effects on Aggression and Feeding in Cutthroat Trout: Implications for Aquaculture



Matthew M. Wipf1, Michael E. Barnes2, *
1 Giant Springs State Fish Hatchery, Montana Department of Fish, and Wildlife, and Parks, 4801 Giant Springs Road, Great Falls, Montana 59405 USA
2 McNenny State Fish Hatchery, South Dakota Game, Fish, and Parks 19619 Trout Loop, Spearfish, South Dakota 57783 USA


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© 2011 Wipf and Barnes

open-access license: This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 International Public License (CC-BY 4.0), a copy of which is available at: (https://creativecommons.org/licenses/by/4.0/legalcode). This license permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

* Address correspondence to this author at the McNenny State Fish Hatchery, South Dakota Game, Fish, and Parks 19619 Trout Loop, Spearfish, South Dakota 57783 USA; Tel: 605-642-1262; Fax: 605-642-6921; E-mail: mike.barnes@state.sd.us


Abstract

Competitor density and aggressive behavior influences the ability of fish to use food resources during aquaculture production. Using cutthroat trout Oncorhynchus clarkii (Richardson) from the same filial generation, this study investigated the effects of both body size and rearing density on aggression and feeding behavior. Four experiments were conducted using different numbers of both small and large trout obtained after grading. In each experiment, regardless of the number of each size of fish, small fish made significantly fewer attempts to forage in comparison to large fish. However, the number of aggressive interactions increased as small fish densities increased. These results suggest that grading and rearing differently-sized fish separately during rearing will likely maximize growth and rearing efficiencies in wild-strain cutthroat trout during hatchery rearing.

Keywords: Cutthroat trout, Oncorhynchus clarkii, aggression, aquaculture, grading.