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Dear Sir:
I don't think so.
For younger fish, generally lower than one year, maybe otolith is
useful for age-determination. But for old fish, generally larger than one,
scale may be more useful for age-determination. Don't you think so?
The problem is how to make sure where the annual ring is, especially for
pelagic fish! They always migrate to where they like. Where they can find
food easily. Where the environmental conditions are most arrpeciable. And
then, what is the mechanisms of forming the annuli? Is it due to spawnning?
If the spwanning phenomenon can be found around year, then how to make sure
which one is the alnnuli? Is it due to another factors? What is it? Even
by tag eqperiments, how many rings are formed during the released time? Do
they have clear correlation? For different released size, do they have the
same tendence?
Theoretically, ring's forming should be deeply relative to the growth,
i.e., to the food available. How about the probability of food available
in nature? How about the time delay between the food available and the ring
forming? Is it relative to the quantity and quality of the available food?
I think before no clear answer for these questions, we are still shall
puzzled by age-determination. Do you think so?
With my best regards.
Yours sincerely. C. H. Wang
Division of Biology and Fishery, Institute of Oceanography,
National Taiwan University, Taipei, Taiwan, ROC
E-mail: [log in to unmask]
Tel: 886-2-23620377, or 886-2-23636040 ext. 415
Fax: 886-2-2362-0377
----- Original Message -----
寄件者: Jimmy H Waddell <[log in to unmask]>
收件者: <[log in to unmask]>
傳送日期: 2000年8月16日 AM 08:21
主旨: Re: comparison of scale ageing techniques
> Don't waste your time with scales. Go right to
> learning how to age otoliths. Scearch the literature
> you'll find plenty of reasons why.
>
> --- "Erik R. Zlokovitz" <[log in to unmask]>
> wrote:
> > Hello all,
> >
> > I am interested in comparing the accuracy and
> > precision of two scale-ageing
> > techniques for adult striped bass: preparation of
> > scale impressions using a
> > Carver heat press versus a standard roller press. Is
> > anyone familiar with a
> > study of this type on any species of fish?
> >
> > Thanks,
> > Erik Zlokovitz
> > Maryland DNR-Fisheries Service
> >
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