Lanzoni M., Aschonitis V., Milardi M., Castaldelli G., Fano E.A. 2018. A method to identify bimodal weight–length relations: Possible ontogenetic diet and/or metabolism shift effects in Anguilla anguilla (Actinopterygii: Anguilliformes: Anguillidae). Acta Ichthyol. Piscat. 48 (2): 163–171.

摘要

Background. The power function W = a  · Lb is commonly used to describe the weight–length (W–L) relation (WLR) of fish. Smaller/younger specimens may present different WLR from larger/older ones, introducing errors in the derivation of WLR of the total population. This difference appears through a breakpoint in the log–log plot of W–L data and can be justified due to biological factors or due to errors in the sampling procedure. The aim of the study is to propose a bilinear model (LinBiExp) that identifies the specific coordinates of the breakpoint in the log-transformed W–L measurements.