ABSTRACT Analysis of 60 northern pike ( Esox lucius ) populations, assembled from published studies spanning the species' range and restricted to non‐flowing (lentic) systems, and analyzed using the von Bertalanffy growth function (VBGF), revealed substantial heterogeneity in growth parameters. Growth coefficients ( k ) ranged from 0.01 to 0.72 year −1 , asymptotic lengths () from 53 to 976 cm, and maximum observed lengths () from 35.1 to 113.2 cm. Biologically defensible thresholds were identified at k ≥ 0.25 year −1 and ≤ 113.2 cm, lose biological interpretability under realistic demographic constraints. Within this framework, the VBGF served two complementary roles: as a predictive model of linear growth trajectories and as a diagnostic representation of growth‐trajectory shape. The ratio emerged as an informative descriptor, capturing ontogenetic growth patterns along a continuum from near‐linear ( ≈0.07) to fully asymptotic ( ≈1.00) growth. This metric links empirical size‐at‐age observations with the degree to which asymptotic growth is expressed within finite lifespans. Integrating VBGF parameters ( k , ) with empirical descriptors (, lifespan) and cumulative thermal exposure (growing degree‐days) revealed two coherent growth regimes in northern pike along latitudinal thermal gradients: fast‐growing populations reaching moderate asymptotic sizes rapidly, and slow‐growing populations characterized by low growth coefficients and very large theoretical despite similar observed maximum lengths. Taken together, the ratio, combined with biologically grounded thresholds for k and , provides a parsimonious screening tool for identifying non‐asymptotic growth trajectories and a temperature‐ and time‐explicit framework for evaluating the expression of asymptotic growth across climatic gradients.
Lobyrev et al. (Fri,) studied this question.