Annulus formation and validation in pectoral spines of channel catfish

Buckmeier, D. L., Texas Parks and Wildlife Department, Heart of the Hills Research Station, HC 07, Box 62, Ingram, TX 78025;
830/866-3356; FAX 830/866-3549; daveb@ktc.com

Irwin, E. R., USGS – Alabama Cooperative Fish and Wildlife Research Unit, Auburn University, 311 Funchess Hall, Auburn, AL
36849; 334/844-9190; FAX 334/844-9208; eirwin@acesag.auburn.edu

Pectoral spine sections through the basal recess are typically used to age channel catfish Ictalurus punctatus. However, validation of ages based on articulating process sections of pectoral spines of flathead catfish Pylodictis olivaris indicates that annuli can be lost because of expansion of the central lumen as fish age. Previous research has indicated 58-82% accuracy for spines sectioned through the basal recess for channel catfish (ages 2-4). Otoliths and pectoral spines were collected from
known-age channel catfish (ages 1-3) to compare the accuracy of age assignments derived from each structure and determine time of annulus formation. Two methods were used to process pectoral spines for aging. First, spines were sectioned through the articulating process (through the dorsal and anterior processes) and viewed using transmitted light. Second, the cut portion of the spine was viewed using a fiber optic filament to illuminate annuli. Both methods accurately aged channel catfish (mean=90%) and minimized error due to loss of annuli from expansion of the central lumen. In addition, the fiber optic method reduced processing time. Both methods were less accurate as fish age increased. Marginal increment analyses indicated annulus formation occurred in late April and May. Annuli on otolith sections were present; however, they were
generally faint and difficult to discern.

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Texas Chapter of the American Fisheries Society
Last modified: 03/03/04 04:15:38 PM