The paradigm of body condition: a critical reappraisal of current methods based on mass and length

Summary 1. Body condition is a major concept in ecology addressed in countless studies, and a variety of non‐destructive methods are used to estimate the condition of individuals based on the relationship between body mass M and measures of length L . There is currently no consensus about the most appropriate condition index (CI) method, and various traditions have been established within subdisciplines in which ecologists tend to apply that method used previously by their peers. 2. Here, we present a reappraisal of six conventional CI methods: Fulton’s index ( K = M / L 3 ), Quételet’s index (BMI = M / L 2 ), Relative condition ( K n , computed as the observed individual mass divided by the predicted mass M i…