Process-based modelling of decadal trends in growth, survival, and smolting of wild salmon (Salmo salar) parr in a Scottish upland stream

William S.C. Gurney, Philip J. Bacon, Graham Tyldesley, Alan F. Youngson

Research output: Contribution to journalArticle

27 Citations (Scopus)

Abstract

This paper reports a new model of the freshwater stages of an anadromous fish, at the core of which is a stochastic description of the size-at-age dynamics of a growing cohort. Emigration is assumed to require the individual to exceed a threshold size at a critical time of year, thus making the distributions of survival to, and age at, smolting emergent properties of the model. The model is applied to a long-term data set on juvenile Atlantic salmon (Salmo salar) in the Girnock Burn, Scotland, to understand the role played by decadal temperature trends in generating changes in smolt production and age distribution. We conclude that changes in age at smolting are compatible with causation by shifts in the temperature regime. However, the large attenuation between a dramatic fall in spawner numbers and a relatively minor diminution in total smolt production does not result from the physiological effects of temperature but is rather a result of strongly density-dependent mortality between the deposition of ova and the appearance of catchable fry the following summer.
LanguageEnglish
Pages2606-2622
Number of pages16
JournalCanadian Journal of Fisheries and Aquatic Sciences
Volume65
Issue number12
DOIs
Publication statusPublished - 28 Nov 2008

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smoltification
parr
Salmo salar
salmon
highlands
smolt
smolts
modeling
temperature
emigration
anadromous fish
age structure
ova
fish fry
Scotland
mortality
summer
fish
trend

Keywords

  • modelling
  • decadal trends
  • salmon
  • smolt production
  • age distribution

Cite this

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Process-based modelling of decadal trends in growth, survival, and smolting of wild salmon (Salmo salar) parr in a Scottish upland stream. / Gurney, William S.C.; Bacon, Philip J.; Tyldesley, Graham; Youngson, Alan F.

In: Canadian Journal of Fisheries and Aquatic Sciences, Vol. 65, No. 12, 28.11.2008, p. 2606-2622.

Research output: Contribution to journalArticle

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