DWEFage: Estimate ages of sea lamprey larvae from lengths

In JVAdams/GLFC: Great Lakes Fishery Commission

Estimate ages of sea lamprey larvae from lengths

Description

Generate Estimates of larval sea lamprey ages from the measured lengths of yearling and older larvae.

Usage

DWEFage(JustLens, LenFreq = rep(1, length(JustLens)), AgeLenKey = NULL)

Arguments

JustLens	A numeric vector with measured lengths of sea lamprey larvae for which age estimates are desired. It is assumed that no young of the year (YOY), age-0 larvae are included in the sample.
LenFreq	A numeric vector with the number of larvae corresponding to each measured length in JustLens. The default value will result in each length in JustLens being counted as a single observation.
AgeLenKey	A data frame with numeric variables Length and Age giving measured lengths and ages of sea lamprey larvae. The default value (NULL) will result in the use of a built in data base from 504 larvae collected during 1993-2001.

Value

A list of length two is returned. The first element is a numeric matrix with the number of larvae in each age (row) by length (column) category. There are 7 age categories from 1 to 7 and 31 length categories: <=20, >20 to <=25, ..., >160 to <=165, > 165. The second element is a numeric vector with the number of larvae in each age category.

References

Haeseker, SL, ML Jones, and JR Bence. 2003. Estimating uncertainty in the stock-recruitment relationship for St. Marys River sea lampreys. Journal of Great Lakes Research 29(Suppl. 1):728-741. [link]

Hoenig, JM and DM Heisey. 1987. Use of a log-linear model with the EM algorithm to correct estimates of stock composition and to convert length to age. Transactions of the American Fisheries Society 116(2):232-243.

Examples

DWEFage(c(120, 76, 39))

JVAdams/GLFC documentation built on Jan. 5, 2023, 12:59 a.m.