Proposed standard weight equation and length standards for Florida Bass

Abstract Objective To improve the conservation and management of Florida Bass Micropterus salmoides, we sought to develop a species-specific standard weight equation and establish length standards. Methods Length and weight data for 131,691 Florida Bass that were collected from 73 populations within the species’ natural geographic range and a large portion of the introduced range in North America were used to develop the equations with both the regression-line percentile and empirical-percentile methods. Given the potential for genetic introgression between Florida Bass and Largemouth Bass M. nigricans in some systems, genetic testing results were used to confirm that only Florida Bass (individual Q-value ≥ 95%) were included in this study. A validation data set consisting of 37 populations and 51,389 individuals was used to evaluate each of the equations for length-related bias. Length standards were also developed based on all available information, including the longest fish on record and current state-level regulations and angler catch designations. Results The resulting standard weight (Ws) equation for fish with a total length (TL) ≥10 cm and <70 cm was based on the quadratic empirical-percentile method: log10W = 1.551 × log10L + 0.357 × (log10L)2 − 3.485 (metric) and log10W = 2.553 × log10L + 0.357 × (log10L)2 − 3.259 (English), where W is weight in grams (metric) or pounds (English) and L is TL in millimeters (metric) or inches (English). This equation is preferred, as it outperformed the two linear options, particularly at the smaller (10–14 cm) size-groups. To evaluate fish population size structure, we also propose minimum lengths for five length standards of 18, 30, 40, 51, and 61 cm TL (7, 12, 16, 20, and 24 inches TL) for stock, quality, preferred, memorable, and trophy fish, respectively. Conclusions Florida Bass have been stocked extensively due to their economic importance and trophy value across North America. In addition to the threats that this poses to the conservation of Black Bass species, it presents challenges to fisheries managers because some of these species and their hybrids cannot be distinguished visually. The development of a Ws equation and length standards will aid biologists in evaluating and monitoring the Florida Bass across populations as part of continued conservation and management efforts for this species. Additional efforts to revisit, define, and compare the Ws and length standards of other genetically verified Black Bass species, particularly the Largemouth Bass, are still needed.