Proposed Standard Weight Equation and Standard Length Categories for Lake Chubsucker

Standard weight equations have been proposed for a variety of fishes, including many nongame species. Here, we developed standard weight (W-s) equations for Lake Chubsucker Erimyzon succetta using the traditional regression-line-percentile technique and the newer empirical-percentile method. Length and weight data for 19,727 Lake Chubsuckers from 8 to 42 cm TL and 129 populations were used in the final analysis. These fish were collected from 1977 to 2020 by various agency and university personnel from most known populations across the species' range in North America. This species is considered vulnerable, imperiled, or extirpated in several Midwestern and northern states, but it appears to be secure in the Southeast. The resulting W-s equations were log(10)W = -5.0962 + 3.1125 x log(10)L and log(10)W = -5.9735 + 3.8828 x log(10)L -0.1701 x (log(10)L)(2) for the RLP and quadratic empirical-percentile method techniques, respectively, where W is weight (g) and L is total length (TL, mm). The regression-line-percentile equation exhibited a greater length-related bias especially at the ends of the length spectrum, so we recommend the quadratic empirical-percentile equation for this species. We also developed standard length categories for assessing fish population size structure. We propose minimum lengths for five standard length categories of 11, 18, 24, 28, and 35 cm TL for stock, quality, preferred, memorable, and trophy sizes, respectively. Development of a W-s equation and standard length categories will aid biologists in assessing condition and size structure of wild Lake Chubsucker populations and those being propagated for supplemental stocking into trophy bass ponds for native forage or in areas with depressed native populations. Additionally, by evaluating this nongame species that occupies the same environments as higher profile game fish species, a more holistic approach of evaluating the overall health of systems can be examined.