Dr. Sampsa Vilhunen

Department of Biological and Environmental Sciences,

University of Helsinki

P.O.Box 65

FI-00014

Finland

Title

Evaluating innate and learned determinants for improving antipredator

behaviour of stocked fish

Abstract

A low post-stocking survival is a major problem in reintroductions of endangered salmonid populations. Anti-predator responsiveness of captive stocks weakens during hatchery rearing which is partly causing the high mortality. Hatchery selection and stimulus-poor growth environment are suggested to take the blame. Behavioural observations can provide valuable information that may be used in designing life-skills training procedures that aim at producing ecologically more viable fish. I found that Arctic charr (Salvelinus alpinus) possess sophisticated ability for innate recognition of chemical cues from different predators and their diets, yet individual differences are notable. Charr can further improve their anti-predator responsiveness by learning through direct individual experience of predators or even just their odors. Cultural transmission of predator avoidance from experienced to predator-naïve fish also created later avoidance of predators that was as strong as the one created by direct individual experience. The successfulness of the social learning, however, appeared highly sensitive to changes in group composition. Conditioning prey to avoid chemical cues of predators provided them a survival advantage compared to still predator-naïve fish when confronted individually with predatory fish. Repeated exposure to the predator odors further improved the survival of the prey fish. The inter-individual differences in the innate ability to respond to predator odors associated with the subsequent survival so that charr with stronger innate responses towards chemical cues also survived predation better. Among-individual differences in learning of anti-predator responses seemed not to override individual differences in innate anti-predator behaviour. As an underlying intrinsic factor behind some of the inter-individual variation in the innate behavioral responsiveness to predation threat, higher intra-individual genetic variability proved to associate positively with risk-prone behavior in brown trout (Salmo trutta).

CV

Ph.D. in Biology, University of Helsinki, 1.12.2005.

Licentiate studies in morphological-ecological zoology, graded 5/5

M.Sc. in Biology, Faculty of Science, Department of Ecology and Systematics, University of Helsinki, 22.12.2000.

Master of Science studies in biology from three different Finnish universities: University of Jyväskylä (1992-93), University of Joensuu (1993-96), and University of Helsinki (1996-2000) and one foreign university: Imperial College, London (1999).

Major in ‘morphologic-ecological zoology’. Graded: excellent 5/5. Master of Science thesis in animal ecology: behavioural responses of juvenile trout (Salmo trutta) to chemical cues from burbot: effects of dominance, migration form and population origin. Graded: eximia cum laude approbatur

Matriculation examination, Päiviönsaaren Lukio, Finland, 1991.

Work experience:

Research position at the LUOVA-graduate school 2002-2005. Finnish Ministry of Education / Division of Population Biology, University of Helsinki.

Researcher at the Integrative Ecology Unit -research group, 2000 – 2001, University of Helsinki.

Research assistant for the Metapopulation Biology Research Group of Dr. Ilkka Hanski, University of Helsinki. (09/99, 04/00)

Research assistant for the Integrative Ecology Unit (IKP Fish) 08-10/99.

Six months ‘post-graduate’ project (01-06/99) at the IMPERIAL COLLEGE of Science, Technology and Medicine (University of London, U.K.). Supervisor Dr. Kai Lorenzen; T H Huxley School of Environment, Earth Sciences and Engineering. Topic: the role of behaviour in the reproductive biology of tilapias, solving problems of stunting.

Research assistant for the Integrative Ecology Unit (IKP Fish) 08-11/98.

Publications

Vilhunen S., Tiira, K., Laurila, A. & Hirvonen, H. (submitted) The bold and the variable: fish with high heterozygosity act recklessly in the vicinity of predators.

Vilhunen, S. & Hirvonen, H. (submitted) Natural born survivors: innate responsiveness to predators is associated with survival despite divergent learning opportunities.

Vilhunen S. (2006) Repeated anti-predator conditioning: a pathway to habituation or to better avoidance? J. Fish Biol. 68: 25-43.

Vilhunen S. (2005) Evaluating innate and learned determinants for improving antipredator behaviour of stocked fish. Academic dissertation, Faculty of Biosciences, University of Helsinki. ISBN: 952-91-9315-7. Yliopistopaino, Helsinki.

Vilhunen S., Hirvonen H. & Laakkonen M.V.-M. (2005) Less is more: social learning of predator recognition requires a low demonstrator to observer ratio in Arctic charr (Salvelinus alpinus) Behav. Ecol. Sociobiol. 57: 275–282.