Comparative Annulus Formation on Anatomical Structures of the White Sucker, Catostomus commersoni (Lacépède)

Abstract

Of 32 structures examined in the white sucker, annulus formation is potentially suited for age determination only on the dermethoid, frontal, lacrimal and rib bones, pectoral fin rays and body scales. Ages assigned by annulus counts on each of the above-noted structures, except scales, were in total agreement. Scale annulus counts were accurate determinants of age in slow-growing riverine stocks, but not in faster-growing lake fish using the same river for reproduction. A linear correlation (r=+0.978) between pectoral fin ray radii and standard length regardless of growth rate, and confirmed by tag-recovery data, permits the accurate back-calculation of white sucker growth using annuli formed on this structure.