Parameters for all known standard weight equations.
A data frame with observations on the following 13 variables:
Species name. Use wsVal() to see the list of available species.
Units of measurements. Metric uses lengths in mm and weight in grams. English uses lengths in inches and weight in pounds.
Type of equation (linear or quadratic).
Reference quartile (75, 50, or 25).
The type of length measurement used -- total length (TL) or fork length (FL).
The type of method used to derive the equation (Regression Line Percentile (RLP; see Murphy et al. (1990) and Murphy et al. (1991)), Empirical Percentile (EmP; see Gerow et al. (2005)), or Other).
Minimum total length (mm or in, depending on units) for which the equation should be applied.
Maximum total length (mm or in, depending on units) for which the equation should be applied.
The intercept for the model.
The slope for the linear equation or the linear coefficient for the quadratic equation.
The quadratic coefficient in the quadratic equation.
Source of the equation. These match the sources given in Neumann et al. (2012).
Comments about use of equation.
Relative weight
Standard weight
Condition
8-Condition.
The minimum TL for the English units were derived by rounding the converted minimum TL for the metric units to what seemed like common units (inches, half inches, or quarter inches).
Ogle, D.H. 2016. Introductory Fisheries Analyses with R. Chapman & Hall/CRC, Boca Raton, FL.
Gerow, K.G., R.C. Anderson-Sprecher, and W.A. Hubert. 2005. A new method to compute standard weight equations that reduces length-related bias. North American Journal of Fisheries Management 25:1288–1300.
Murphy, B.R., M.L. Brown, and T.A. Springer. 1990. Evaluation of the relative weight (Wr) index, with new applications to walleye. North American Journal of Fisheries Management 10:85–97.
Murphy, B. R., D. W. Willis, and T. A. Springer. 1991. The relative weight index in fisheries management: Status and needs. Fisheries (Bethesda) 16(2):30–38.
Neumann, R.M., C.S. Guy, and D.W. Willis. 2012. Length, Weight, and Associated Indices. Chapter 14 in Zale, A.V., D.L. Parrish, and T.M. Sutton, editors. Fisheries Techniques. American Fisheries Society, Bethesda, MD.
See wsVal and wrAdd for related functionality.