Proposed Standard Weight (Ws) Equations and Standard Length Categories for Redbreast Sunfish and Spotted Sunfish

Abstract

AbstractWe developed standard weight (Ws ) equations for Redbreast Sunfish Lepomis auritus and Spotted Sunfish L. punctatus using the traditional regression‐line‐percentile (RLP) technique and the empirical‐percentile‐linear (EmP‐L), and the empirical‐percentile quadratic (EmP‐Q) method. Individual length and weight data for 175,541 Redbreast Sunfish from 8 to 31 cm TL across 315 populations and 66,851 Spotted Sunfish from 7 to 21 cm TL across 130 populations were used in the final analysis. These fish were collected from 1975 to 2021 by various agency and university personnel from most known populations across the species' native and introduced ranges in North America. We present the EmP‐L‐derived Ws equations for the Redbreast Sunfish as log10W = 3.1218 × log10L − 5.0018 and the Spotted Sunfish as log10W = 3.3343 × log10L − 5.3739, where W is weight (g) and L is total length (TL, mm). Equations from all methods exhibited length‐related bias, but the EmP‐L equations had a median bias of 0–0.6 for the length range that comprised 99.7% (for 8–24 cm TL) of Redbreast Sunfish and 99.0% (for 7–18 cm TL) of Spotted Sunfish in our data set. Regardless of the equation, the most bias was found at the upper end of the length spectrum, so we do not recommend these equations for Redbreast Sunfish ≥30 cm TL or Spotted Sunfish ≥20 cm TL. We also developed standard length categories for Redbreast Sunfish with minimum lengths for five standard length categories of 8, 13, 18, 20, and 25 cm TL for stock, quality, preferred, memorable, and trophy sizes and for Spotted sunfish 5, 10, 13, 15, and 18 cm TL, respectively. Development of a Ws equation and standard length categories will aid biologists in assessing condition and size structure of wild Redbreast Sunfish and Spotted Sunfish populations and those being propagated for supplemental stocking into areas with depressed native populations.