Blog Archives

Computing SE for PSD indices

December 9, 2016
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A user of my Introductory Fisheries Analyses with R book recently asked me how to compute standard errors (SE) for the various PSD indices by using the usual equation for the SE of a proportion (square root of p times (1-p) divided by n). B...

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Pauly et al. (1992) Seasonal Cessation in Growth Model

October 10, 2016
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I recently published a technical note in Fisheries Research that described an algorithm for implementing the “seasonal cessation in growth model” of @Paulyetal1992. Describing an algorithm for a growth model does not seem like a useful...

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Exploring the Half-Life Property of K

June 11, 2016
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A colleague recently questioned whether the loge(2)/K, where K is the Brody growth coefficient in the typical parameterization of the von Bertalanffy growth function, represents the “amount of time it takes for a fish to grow from any length to a length halfway between the initial length and the asymptotic mean length (Linf)”. This phenomenon is briefly illustrated...

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FSA v0.8.7 Released

May 7, 2016
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A new minor version (0.8.7) of the FSA (Fisheries Stock Assessment) package was recently released and is now on CRAN. A full description of changes is here. Three major changes are described below. Removed the dynamicPlot=TRUE option fr...

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Histograms by Just Defining Bin Width

March 10, 2016
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Histograms by Just Defining Bin Width

The Problem – Binning for Length Frequency Histograms Fisheries scientists often make histograms of fish lengths. For example, the code below uses hist() (actually hist.formula()) from the FSA package to construct a histogram of total lengths for Chinook Salmon from Argentinian waters. library(FSA) data(ChinookArg) hist(~tl,data=ChinookArg,xlab="Total Length (cm)") The default bins for these histograms are rarely what the...

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FSA v0.8.5 Released

February 17, 2016
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A new minor version (0.8.5) of the FSA (Fisheries Stock Assessment) package was recently released and is now on CRAN. A full description of changes is here. Major changes are: agePrecision(): Fixed bug related to computations of percent agreement when NA values were present. There was an inconsistency between when what="precision" and what="difference" was used in...

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IFAR Preview in Google Books

December 22, 2015
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A preview of the Introductory Fisheries Analyses with R book is available here on Google Books. The preview is only of the Table of Contents and Chapter 1. However, you can search within the book, though pages returned by the search are not...

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Published — Introductory Fisheries Analyses with R

December 6, 2015
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Published — Introductory Fisheries Analyses with R

I am pleased to announce that my Introductory Fisheries Analyses with R (IFAR) book has been published, almost two weeks ahead of schedule. Details about the book (and companion website) are here and it can be purchased from CRC Press (at a ...

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R Workshop at SFS Meeting

November 23, 2015
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I just noticed that there will be an Introduction to R workshop at the Society for Freshwater Science Annual Meeting in Sacramento on 20-May-20-16. Here is a link to the announcement.

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Bioenergetics in R Workshop

November 15, 2015
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It was just brought to my attention that there will be a workshop at the upcoming Midwest Fish and Wildlife Conference (Grand Rapids, MI) on the Bioenergetics 4.0 shiny app. The announcement from here (where there is a registration link) is ...

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