2.4.3 | Cormack–Jolly–Seber model
We estimated the predictors for apparent survival using the Cormack–Jolley–Seber (CJS) model using the R package “marked ” version 1.2.6 (Laake et al., 2013). The CJS model enables us to estimate both capture probability (cp ) and apparent survival (φ ) by including both emigration and actual survival rates from capture histories (Lebreton et al., 1992). We constructed models separately to estimate the factors predicting apparent survival and capture probability. For the model predicting apparent survival (φ ), we included FL, body condition, parasite numbers, and their interactions (i.e. body condition × parasite numbers and FL × parasite numbers) in June 2020 as predictors, and we constructed models that included all possible additive and multiplicative interactions among predictors. Since fish size was the strongest predictor for estimating the capture probability of salmonids (Saunders et al ., 2011; Hedger et al., 2018), we only included FL as an explanatory variable to estimate the capture probability (cp ). The best model with the lowest Akaike’s information criterion value (AIC: Akaike, 1983) was selected.