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Size-dependent predator-prey interactions, distribution and mortality in salmon: effects on individuals and populations

Jacobson, Philip (2020). Size-dependent predator-prey interactions, distribution and mortality in salmon: effects on individuals and populations. Diss. (sammanfattning/summary) Sveriges lantbruksuniv., Acta Universitatis Agriculturae Sueciae, 1652-6880 ; 2020:32
ISBN 978-91-7760-582-9
eISBN 978-91-7760-583-6
[Doctoral thesis]

[img] PDF - Published Version


The biomass dynamics of populations is largely determined by the survival, growth, and reproduction of individuals. For fish and other animals, survival, growth, and reproduction depends on the amount of energy an individual obtains via feeding and are therefore food-dependent. As fish often consume whole prey, the potential for a fish to consume prey depends on both its own size and the size of the prey. Furthermore, predation requires that the predator and prey overlap in time and space. Anadromous fish are born in rivers, grow large at sea and return to rivers to spawn. Consequently, anadromous fish populations will be affected by size- and food-dependent processes in the river and at sea. However, we have limited knowledge about the importance of these processes at sea for the dynamics of anadromous fish. Therefore, the objective of this thesis was to assess whether and when size- and food-dependent processes at sea are important for anadromous fish dynamics. I approached this knowledge gap using empirical and theoretical methods with Atlantic salmon, Salmo salar, in the Baltic Sea as my study species. I show that the diet of salmon at sea depends on their body size, the prey community size-structure and where salmon feed at sea, which, in turn, is governed by their body size and population-of-origin. The body condition of salmon at sea increased with prey availability at low prey densities. Moreover, growth and survival at sea differed between salmon originating from different rivers and inter-annual growth variation at sea contributed to explain inter-annual variation in the reproductive potential of salmon populations. I further show that the responses of anadromous fish populations to changes in river productivity and mortality targeting adults depend on if individuals compete for resources at sea or not and on sea productivity. In summary, these findings demonstrate the importance of accounting for size- and food-dependent processes at sea, such as survival, growth, and size-dependent predatorprey interactions to increase our understanding of anadromous fish populations and how they will be affected by external drivers such as environmental change and fisheries.

Authors/Creators:Jacobson, Philip
Title:Size-dependent predator-prey interactions, distribution and mortality in salmon: effects on individuals and populations
Series Name/Journal:Acta Universitatis Agriculturae Sueciae
Year of publishing :2020
Number of Pages:42
Publisher:Department of Aquatic Resources, Swedish University of Agricultural Sciences
ISBN for printed version:978-91-7760-582-9
ISBN for electronic version:978-91-7760-583-6
Publication Type:Doctoral thesis
Article category:Other scientific
Version:Published version
Full Text Status:Public
Subjects:(A) Swedish standard research categories 2011 > 1 Natural sciences > 106 Biological Sciences (Medical to be 3 and Agricultural to be 4) > Ecology
Keywords:anadromy, habitat shifts, population dynamics, prey availability, salmon, size-dependent predator-prey interactions, size-structure, spatial distribution
Permanent URL:
ID Code:16962
Faculty:NJ - Fakulteten för naturresurser och jordbruksvetenskap
Department:(NL, NJ) > Department of Aquatic Resources
Deposited By: SLUpub Connector
Deposited On:08 May 2020 07:49
Metadata Last Modified:15 Jan 2021 19:22

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