Standard weight equation and standard-length categories for Flier

Objective To date, no standard weight equation has been developed to assess the condition of Flier Centrarchus macropterus across its range. Additionally, the current standard-length categories needed to be revised based on the more comprehensive data set that was obtained for this study. Thus, the primary objectives of this study were to (1) gather weight and length data sets for Flier throughout their native and introduced ranges and use them to develop a standard weight equation and (2) propose updated standard-length categories. Methods We developed a standard weight equation for the Flier using the regression-line-percentile (RLP) technique and the empirical-percentile-linear and the empirical-percentile-quadratic methods. Individual length and weight data for 8,192 fish from 58 populations and ranging in size from 80 to 305 mm total length (TL) were used in the analysis. The fish were collected from 1949 to 2024 from known populations across the species’ native and introduced ranges in North America. Results The results were nearly identical among the three methods; thus, we recommend the RLP-derived equation for describing this species for individuals from 80 to 240 mm TL. The resulting equation is log10W = 3.141 * log10L − 5.013 (RLP), where W is weight (g) and L is TL (mm). Although fish that were as large as 305 mm TL were included in our data set, bias was found at the upper end of the length spectrum due to low sample sizes. As a result, we caution using any of the equations for Flier ≥25 cm TL. We also developed standard-length categories for Flier with minimum lengths for five standard-length categories of 8, 13, 15, 18, and 23 cm TL for stock, quality, preferred, memorable, and trophy sizes, respectively. Conclusions The development of a standard weight equation and standard-length categories will aid biologists in assessing the condition and size structure of wild Flier populations and those being potentially propagated for supplemental stocking into areas with depressed populations across its native range. This information will be valuable for the future management and conservation of this valuable sunfish species.