Evaluation of a new preparation technique for flathead catfish pectoral spines

We evaluated the precision and processing times of two methods used to prepare flathead catfish Pylodictus olivaris pectoral spines.  The first method utilized a bench-mounted sander to remove the portion of the articulating process traditionally cut using jeweler’s or low-speed saws.  Structures prepared with this method were compared to conventional sections of the basal recess of the pectoral spine.  The two methods produced structures with equally precise age estimates; however, exact agreement between structures prepared using the two methods was only 41%.  When age estimates of the two methods did not agree, basal recess sections were generally assigned older ages than articulating processes.  Preparation time was similar, although readers noted that more effort was needed to age and manipulate articulating process samples under the microscope.  In addition, both readers agreed that basal sections were generally more readable than articulating processes.  If sanding of articulating processes is used as a spine preparation method, caution should be used to avoid sanding too far into the central portion of the process which contains annuli from early years of life.