Accurate age estimates are critical for understanding life histories of fishes and developing management strategies for fish populations. However, validation of age estimates requires known-age fish, which are often lacking. We used known-age (ages 1–25) muskellunge (Esox masquinongy) to determine the precision and accuracy of age estimates from fin rays. We also determined whether fin location (anal or pelvic), fin ray number, and preparation methods affected accuracy and precision. Lastly, we determined whether von Bertalanffy growth parameters estimated from fin ray ages were similar to parameters estimated from known ages. Precision and accuracy of age estimates from anal and pelvic rays were similar and estimates were relatively precise (coefficient of variation = 8.5%) and accurate (mean absolute difference from known age = 0.85 years) for ages 4–15, but ages were overestimated for younger fish and underestimated for older fish. Growth models based on estimated age were similar to models based on known age. Anal and pelvic rays offer a nonlethal alternative for age estimation of muskellunge ages 4–15 and for producing reliable estimates of growth.

With the exception of Northern Pike Esox lucius, there is a paucity of information on the precision of age estimates based on calcified structures for esocid species, especially Chain Pickerel E. niger. We estimated ages for 42 Chain Pickerel from Stevens Creek Reservoir on the Savannah River, South Carolina-Georgia. Ages were estimated using sectioned pelvic, pectoral, dorsal, and anal fin rays, scales, cleithra (sectioned and whole), and otoliths to assess precision between repeated readings (four readers). Precision was evaluated by calculating agreement among readers, CV, and mean absolute difference (MAD) in estimates between reader pairs. We tested for differences in precision of estimates among structures using linear mixed models with CV or MAD as the response. Finally, we used age bias plots to evaluate whether there were structure or reader-related systematic biases in estimates. Coefficient of variation and MAD were significantly related to structure type (CV: P = 0.006, MAD: P = 0.001) and mean estimated age (CV: P < 0.001, MAD: P = 0.025). Precision was poor for all structures and poorest for age-0 fish; however, all analyses indicated that otoliths provided the most precise estimates. We observed agreement in estimates among all readers for 40% of the otoliths examined and consensus agreement for 74% of the estimates. Coefficient of variation for otoliths declined from 67% for fish with a mean estimated age of 0 years to 5% for age-4 fish. Conversely, MAD for otoliths increased from 0.34 years for fish with a mean estimated age of 0 to 0.46 years for age-4 fish. Estimates from all structures, except pectoral rays, were negatively biased compared with estimates from otoliths. We recommend the use of otoliths for age estimation of Chain Pickerel, but managers and researchers should be cognizant of and evaluate the potential effects of variability in age estimates among readers on their analyses.