Alternative routes to piscivory: contrasting growth trajectories in brown trout (Salmo trutta) ecotypes exhibiting contrasting life history strategies

Hughes, M. R., Hooker, O. E., Van Leeuwen, T. E., Kettle-White, A., Thorne, A., Prodöhl, P. and Adams, C. E. (2019) Alternative routes to piscivory: contrasting growth trajectories in brown trout (Salmo trutta) ecotypes exhibiting contrasting life history strategies. Ecology of Freshwater Fish, 28(1), pp. 4-10. (doi:10.1111/eff.12421)

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Abstract

Large and long‐lived piscivorous brown trout, Salmo trutta, colloquially known as ferox trout, have been described from a number of oligotrophic lakes in Britain and Ireland. The “ferox” life history strategy is associated with accelerated growth following an ontogenetic switch to piscivory and extended longevity (up to 23 years in the UK). Thus, ferox trout often reach much larger sizes and older ages than sympatric lacustrine invertebrate‐feeding trout. Conventional models suggest that S. trutta adopting this life history strategy grow slowly before a size threshold is reached, after which, this gape‐limited predator undergoes a diet switch to a highly nutritional prey source (fish) resulting in a measurable growth acceleration. This conventional model of ferox trout growth was tested by comparing growth trajectories and age structures of ferox trout and sympatric invertebrate‐feeding trout in multiple lake systems in Scotland. In two of the three lakes examined, fish displaying alternative life history strategies, but living in sympatry, exhibited distinctly different growth trajectories. In the third lake, a similar pattern of growth was observed between trophic groups. Piscivorous trout were significantly older than sympatric invertebrate‐feeding trout at all sites, but ultimate body size was greater in only two of three sites. This study demonstrates that there are multiple ontogenetic growth pathways to achieving piscivory in S. trutta and that the adoption of a piscivorous diet may be a factor contributing to the extension of lifespan.

Item Type:Articles
Additional Information:Funding Information: European Union's INTERREG IVA Programme. Grant Number: Project 2859 “IBIS”.
Keywords:Diet switch, ferox trout, life history, ontogenetic shift, piscivory, Salmo trutta.
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:HUGHES, Martin and Adams, Professor Colin and Van Leeuwen, Dr Travis
Authors: Hughes, M. R., Hooker, O. E., Van Leeuwen, T. E., Kettle-White, A., Thorne, A., Prodöhl, P., and Adams, C. E.
College/School:College of Medical Veterinary and Life Sciences > Institute of Biodiversity Animal Health and Comparative Medicine
Journal Name:Ecology of Freshwater Fish
Publisher:Wiley
ISSN:0906-6691
ISSN (Online):1600-0633
Published Online:01 July 2018

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Project CodeAward NoProject NamePrincipal InvestigatorFunder's NameFunder RefLead Dept
489201IBIS (SCENE 2)Colin AdamsEuropean Commission (EC)2589RI BIODIVERSITY ANIMAL HEALTH & COMPMED