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## Context
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Individual parr need to undergo a smoltification process to be able to leave the river. It is well documented that this physiological, behavioural and morpholog- ical process is a function of individual growth (Thorpe, 1977) and that it is initiated much earlier than actually visible (see reviews of McCormick and Saunders, 1987; McCormick et al., 1998).
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## Modeling
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It was therefore opted for a initiation time at the beginning of winter with an actual seaward migration at the beginning of summer (as in Thorpe et al., 1998). We used the probabilistic reaction norm depending on body length and adjusted by Buoro et al. (2010) on the Scorff to simulate this process.
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An individual parr j would become a future smolt in autumn following the relation:
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$$ logit(P(Smj = 1)) = aSm × (Lj − LmidSm) $$
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where aSm and LmidSm (Table 2) were population parameters and Smj was the binary indicator state variable. The inter-individual variation for an identical L was considered in the probabilistic aspect of this implementation. |
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