Abstract

Influence of food abundance on individual behavioural strategy and growth rate in juvenile brown trout (Salmo trutta). Brännäs, E., Johnsson, S, and Lundqvist, H. This study deals with the benefit of being territorial as an effect of food abundance. We measured the proportion of individuals that displayed a territorial, a floating or a non-territorial behaviour and the individual growth rate. Also, the swimming activity was monitored as an indicator of emigration activity. Replicated groups of twelve juvenile brown trout (Salmo trutta) were released into an artificial stream channel, fed according to one of four food regimes during ten days and allocated into one of three behavioural categories. There was no significant relationship between food abundance and the number of territorial individuals. Instead, the proportions of the alternative behavioural strategies, i.e. floating behaviour (individuals that occasionally displayed territorial behaviour) and non-territorial (shoaling) behaviour changed with food abundance. In the lowest food regime, more individuals displayed non-territorial than floating behaviour, but these two strategies were equally represented in the highest food regime. The difference in growth with respect to behavioural category was highest at intermediate food levels. In the highest and lowest food regimes non-territorial fish and floaters grew nearly as fast or as poorly, respectively, as the territorial individuals. The swimming activity between sections in the stream tank was highest with the lowest food abundance and there was a general tendency (not significant) for the highest activity among the floaters

Published in

Canadian Journal of Zoology
2003, Volume: 81, number: 4, pages: 684-691

SLU Authors

• Brännäs, Eva

  • Department of Aquaculture, Swedish University of Agricultural Sciences
    

• Lundqvist, Hans

  • Department of Aquaculture, Swedish University of Agricultural Sciences
    

UKÄ Subject classification

Fish and Aquacultural Science


Publication identifier

DOI: https://doi.org/10.1139/z03-047

Permanent link to this page (URI)

https://res.slu.se/id/publ/926