Standardised removal and sectioning locations for shovelnose sturgeon fin rays

Abstract

Abstract  Fin rays are a common structure used in age and growth analyses, but many inconsistencies exist regarding removal and processing methodology. The purpose of this study was to evaluate precision of age estimates obtained from shovelnose sturgeon, Scaphirhynchus platorynchus (Rafinesque) fin rays sectioned at different locations. Fin rays were examined from 203 shovelnose sturgeon sampled from Pools 9, 13 and 14 of the Mississippi River. Three readers provided age estimates for sections acquired from five locations along fin rays to determine the optimum location for removing and sectioning fin rays. Precision and readability were generally greater for fin ray sections close to the articulating process on the fin ray (i.e. proximal) and decreased as sections approached the tip (i.e. distal). Based on these results, it is recommended that scientists remove shovelnose sturgeon fin rays at the articulating process and section immediately distal to the conspicuous curve in the fin ray close to the articulating process of the ray.