An Evaluation of Calcified Structures and the Use of Digital Photographs in Brook Trout Age Estimation

Fish aging provides crucial data for fisheries managers to make informed decisions on catch limits and population status; however, there is a continuing discussion within the field on the accuracy and effectiveness of aging in fishes, including brook trout (Salvelinus fontinalis). This study was conducted to examine the precision and accuracy of age determination of brook trout using scales, fin rays, and otoliths.  Fish were collected from across the species range and age determination from a variety of calcified structures was analyzed to evaluate which structures yielded the most accurate and precise age results. Additionally, photographs of the calcified structures were taken to determine the validity of aging brook trout via digital images.

Surveys were administered to 36 brook trout fisheries managers across North America to determine current aging practices and assess the effectiveness of digital photography in aging. 143 Brook trout were then collected from Georgia, Virginia, Pennsylvania, New York, and Idaho by each state’s respective fisheries management agency. Fish were processed, and aging structures removed, prepared and photographed; the structures were presented to readers from Michigan, Georgia, Virginia, Pennsylvania and Idaho for age assessment. Inter/intra-reader and inter/intra-structure comparisons were completed and the use of digital photography in the aging process was assessed.