Parameters for all known standard weight equations.

Format

A data frame with observations on the following 13 variables:

species

Species name.

units

Units of measurements. Metric uses lengths in mm and weight in grams. English uses lengths in inches and weight in pounds.

type

Type of equation (linear or quadratic).

ref

Reference quartile (75, 50, or 25).

measure

The type of length measurement used -- total length (TL) or fork length (FL).

method

The type of method used to derive the equation (RLP,EmP, or Other).

min.len

Minimum total length (mm or in, depending on units) for which the equation should be applied.

max.len

Maximum total length (mm or in, depending on units) for which the equation should be applied.

int

The intercept for the model.

slope

The slope for the linear models or the linear coefficient for the quadratic equation.

quad

The quadratic coefficient in the quadratic equations.

source

Source of the equation. These match the sources given in Neumann et al. 2012.

comment

Comments about use of equation.

Source

Most of these equations can be found in 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.

Some species were not in Neumann et al (2012) and are noted as such in the comments variable.

Details

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).

Topic(s)

  • Relative weight

  • Standard weight

  • Condition

IFAR Chapter

8-Condition.

References

Ogle, D.H. 2016. Introductory Fisheries Analyses with R. Chapman & Hall/CRC, Boca Raton, FL.

See also

See wsVal and wrAdd for related functionality.

Examples

str(WSlit)
#> 'data.frame': 179 obs. of 13 variables: #> $ species: Factor w/ 93 levels "Aegean Chub",..: 1 2 2 3 3 3 4 4 4 5 ... #> $ units : Factor w/ 2 levels "English","metric": 2 1 2 2 2 2 2 2 2 1 ... #> $ type : Factor w/ 2 levels "linear","quadratic": 2 1 1 2 2 2 2 2 2 1 ... #> $ ref : int 75 75 75 25 50 75 25 50 75 75 ... #> $ measure: Factor w/ 4 levels "BL","CL","FL",..: 4 4 4 4 4 4 4 4 4 4 ... #> $ method : Factor w/ 3 levels "EmP","Other",..: 1 3 3 1 1 1 1 1 1 3 ... #> $ min.len: num 70 6 150 70 70 70 40 40 40 5 ... #> $ max.len: num 220 NA NA 390 390 390 390 390 390 NA ... #> $ int : num -3.8 -3.35 -5.07 -6 -5.4 ... #> $ slope : num 1.78 3.12 3.12 3.63 3.15 ... #> $ quad : num 0.329 NA NA -0.111 -0.011 0.188 -0.128 -0.043 0.075 NA ... #> $ source : Factor w/ 49 levels "Anderson and Gutreuter (1983)",..: 18 5 5 11 11 11 11 11 11 5 ... #> $ comment: Factor w/ 13 levels "body length",..: 7 6 6 7 11 7 7 11 11 6 ...
head(WSlit)
#> species units type ref measure method min.len max.len #> 1 Aegean Chub metric quadratic 75 TL EmP 70 220 #> 2 Bigmouth Buffalo English linear 75 TL RLP 6 NA #> 3 Bigmouth Buffalo metric linear 75 TL RLP 150 NA #> 4 Bigmouth Sleepers (all) metric quadratic 25 TL EmP 70 390 #> 5 Bigmouth Sleepers (all) metric quadratic 50 TL EmP 70 390 #> 6 Bigmouth Sleepers (all) metric quadratic 75 TL EmP 70 390 #> int slope quad source #> 1 -3.801 1.783 0.329 Giannetto et al. (2012) #> 2 -3.346 3.118 NA Bister et al. (2000) #> 3 -5.069 3.118 NA Bister et al. (2000) #> 4 -6.000 3.631 -0.111 Cooney and Kwak (2010) #> 5 -5.400 3.153 -0.011 Cooney and Kwak (2010) #> 6 -4.323 2.237 0.188 Cooney and Kwak (2010) #> comment #> 1 not in Neumann et al. (2012) #> 2 none #> 3 none #> 4 not in Neumann et al. (2012) #> 5 Quadratic term not significant; not in Neumann et al. (2012) #> 6 not in Neumann et al. (2012)