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Fellow list-members,
thanks for this discussion which is very interesting.


At 20.41 01/03/2005, Chris McDonough wrote:

>In terms of strict definitions, a juvenile or immature fish is one that has
>not reached sexual maturity, regardless of size or age.  One usually thinks
>of a Y-O-Y when you hear the term "juvenile" and immature certainly falls
>within this stage as well.  But many fish species (billfish for example)
>don't reach sexual maturity until they reach a fairly large size.  While you
>are correct that taking the terms by themselves "juvenile"  (usually used to
>refer to a life stage) and "immature" (used to refer to reproductive state)
>may mean something slightly different, in terms of the life history of a
>fish, any fish that has not reached sexual maturity is both a juvenile and
>immature.  (....)

hmmm...  so in your opinion a still immature large-sized fish (like
billfish in your example) is still to be considered a juvenile? Even though
it is several years old?

I (which am not a fish biologist by any means) tend to agree with Bill
Snyder and with his definitions of juvenile (generally a y-o-y) and of
sub-adult (although this sounds like a non-perfectly orthodox term).

A further different case is that of fishes (like the Mediterranean red
mullet, Mullus barbatus) which spawn generally at the end of the first
year. In this case we would have maturing (or even fully mature) y-o-y-
specimens.

Further comments are highly welcome.

Carlo

*****************************************
Carlo Pipitone
CNR-IAMC
Laboratorio di Ecologia Marina
via Giovanni da Verrazzano 17
91014 Castellammare del Golfo (TP)
Italy
---------
Tel: +39 0924 35013
Fax:+39 0924 35084
E-mail: [log in to unmask]
Web site: http://www.irma.pa.cnr.it
*****************************************

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