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Dear colleagues,

    I was recently confronted with the problem of determining what is a "juvenile" fish and whether "immature" would have the same meaning. As it is probably a tricky question, I would like to hear your comments.

    I did a quick research on definitions, and juvenile is often defined as being an immature fish or YOY.
    However, it seems to me that "juvenile" refers to a development stage in the life-cycle of the individual, while "immature" refers specifically to a stage of gonadal development. A juvenile fish would necessarily be an immature one, however there are situations in which an "adult" fish can be immature (i.e., it has the length of an adult fish, but its gonads are still immature). I would say that these terms refer to different contexts: the gonadal development stages (e.g., immature-maturing-mature-spent) and the individual ontogenetic development phases (egg, larvae, post-larvae, juvenile, and so on - I´m not particularly familiar with these).
    I realized that a biological, technical definition of "adult" is not easy find too. 

    Is there a precise definition for "juvenile"?  Or is it just a term with a losely defined meaning? 


    Any comments are welcome.
    Thanks

Fernando.

Fernando Gertum Becker
Ichthylogy Lab
Museu de Ciências Naturais
Fundação Zoobotânica do RS
av. Salvador França, 1427, Jardim Botânico
Porto Alegre, RS  90690-000
Brazil
tel. 51 - 3320-2053
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