Candidate models explaining variation in senescence.

We used the Weibull model [28] to estimate senescence rates. The Weibull model has two parameters that define the hazard function: α, which represents the shape of the hazard function, and λ, which represents the magnitude of the hazard given the shape of the function. We also included a day of entry parameter, b, because previous work has shown that early breeding salmon senesce slower than late breeding salmon [16]. Listed is the general model structure, the negative log-likelihood (NLL), the number of parameters (No. parameters), Akaike's Information Criterion (AIC), and the ΔAIC (relative to the best model, model VII). See Table S1 of the Electronic Supporting Information for explicit formulae for each of the above models.