Length-Frequency Analysis Wizard
Length-Frequency Analysis Wizard (Hypostomus plecostomus)
(Designed by Rainer Froese in 2004)

Step 1: Introduction
Internet Explorer is tested to work for the L-F Wizard.

In the following you will be guided through an analysis of length-frequency data, resulting in an estimation of the degree of exploitation, and an indication of how much more could be caught with a different fishing strategy. For advanced users we also provide an approach to estimate Linf, Z/K, Z, annual reproductive rate (alpha), intrinsic rate of population increase (rmax), population doubling time (td), and fishing mortality associated with maximum sustainable yield (Fmsy).
We assume that you have a set of length frequency data for this species and that you have a good idea about the maximum length (largest fish caught during the last 5 - 10 years) of your population. Note that this analysis is based on the assumption that the size distribution in your sample is similar to that of the population as a whole (see Note). In every step you can click on the 'Background' button for definitions of parameters and equations.
In the next step you will be asked to enter your Length Frequency data (go to 'Length frequencies', 'L-F Data' if you want to use data from FishBase).


Note: It is assumed here (1) that the L-F sample covers a wide range of lengths, (2) that gear selection is accounted for and (3) that the sizes of monthly samples are more or less equal if the total sample is accumulated over more than one month. Accumulated samples should include altogether at least 500 specimens. If L-F data stem from a single sample it should include at least 1000 specimens. A good sample would be accumulated over 6 or more months and include over 1500 specimens.

cfm script by eagbayani, 03.03.02,  php script by kbanasihan 10.18.10,  last modified by kbanasihan 20.04.12