Presently i am working on aging aspects of deep-sea fishes using length frequency data, and tried MIXDIST package for R system. but the interpretation of this model seems to be difficult. its help full to get any information about packages for creating age structure model for fishes using size data and its interpretation. i prefer R system for statistical models.
Thanks you
You can use FiSAT. It is vert simple. For a exemple, read the attached file.
von Bertalanffy's formula. Even you can use FiSAT software. It is simple enough.
FiSat is free from ICLARM
LFDA can also be used from MRAG-UK
Both are very simple and user friendly
You can use FiSAT. It is vert simple. For a exemple, read the attached file.
Sileesh.....it is free download and refer manual in the software itself. It will be easy for you.
Hi Sileesh,
If your question is really about estimating the absolute AGE of the fish, I'm afraid that analyzing the length frequency distribution will not really help.
By analyzing length frequency distributions, you may get the number of "cohorts" (although I doubt it will work efficiently for slow growing species!) but not the AGE of the individuals in each "cohort".
For obtaining the relationship between cohorts and age, you need some relationships between size and age (for individuals of the same population / stock) or to be able to obtain the size distribution for individuals from age 1+ onward (but I doubt it is possible for deep sea fishes).
Regards
Dom
Without "ground-truthing" i do not think it is possible - as Dominique already pointed out. You should take the otoliths together with weight and length data. There is not enough data about deep sea fishes.
Length-frequency analyses can provide you with a semi-discreet set of cohorts (depending on growth rate). However, unless you are sure that you have individuals from all ages (especially the youngest) in your sample, then you will need some way of knowing what the actual ages are. And having both age and length measurements for some individuals will help direct the length-frequency analysis by providing a mean length and standard deviation for each cohort. We are developing a method for assigning ages to individual un-aged fish based on length-frequency analysis and some individuals with known ages using mixdist. We are using it on Chinook Salmon and there are only three cohorts (ages 3, 4, and 5), making the interpretation pretty easy.
Ageing of otoliths will be the best thing, otherwise; input LF data into FiSAT and plot the VBGF curve; it gives reliable estimates if the data was collected in a way that is indicative of what exists in the wild.
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