Mixed-Effects Modelling of Scale Growth Profiles Predicts the Occurrence of Early and Late Fish Migrants

摘要: Fish growth is commonly used as a proxy for fitness but this only valid if individual variation can be interpreted in relation to conspecifics' performance. Unfortunately, assessing rates problematic under natural conditions because subjects typically need marked, repeated measurements of body size are difficult obtain the field, and recaptures may limited few time events which will generally vary among individuals. The analysis consecutive rings (circuli) found on scales other hard structures offers an alternative mark recapture examining fish aquatic vertebrates where visualized, accounting autocorrelations seasonal stanzas has proved challenging. Here we show how mixed-effects modelling scale increments (inter-circuli spacing) reconstruct trajectories sea trout (Salmo trutta) correctly classify 89% individuals into early or late seaward migrants (smolts). Early grew faster than during their first year life freshwater two populations, suggesting that migration was triggered by ontogenetic (intrinsic) drivers, rather competition with conspecifics. Our study highlights profound effects have age at paradigmatic migrant illustrates inter-circuli spacing detailed when these cannot marked caught once.