Greetings,
Several weeks ago I posted a question about any current work on
using herring scale patterns as a means for stock seperation.
I did not recieve a lot of responses, but what I did get was much
appreciated which has lead to some follow up discussions.
For those who expressed interest in seeing a summary I've included the
original responses below.
If anyone who contacted me on this failed to get a personal reply,
please resend your message. My email server crashed soon after the
message was posted, and I am not sure what was lost. My appologies
if that was the case. Thanks again.
Here is my question first:
Peter Hagen wrote:
>
> Greetings Fish-Sci folks.
> We are considering a proposal for using herring scale pattern >analysis as a stock separation tool in Alaska. Several projects were >tried here about 10 years ago and from my reading the results were >mixed; with some success and some failures. The measurements >collected in those studies were distances between the scale annuli >along a single axis.
> My questions are
> 1) Is anyone currently using scale patterns on a routine basis to
>identify herring in mixed stock fisheries.
> 2) If so, what measurements are being used, how are those >measurements collected, and have other patterns in the scales been >evaluated.
>
> Herring scales are a new subject for me, so any other advice or
> suggestions would be appreciated.
> (I've done some literature review and the most recent paper on my
> list was Barros and Holst 1995)
>
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We use this method mainly connected to growth and recruitment studies.
As you know from Barros and mine article, we discrimeinate between what
we call components in one large stock, not between stocks. The
definition of stocks in herring is, however, not clear at all, and a
series of definitions exist. I send you a copy of my doctoral thesis
which will show you more of how the method was applied.
Sincerely Jens Christian
Dr. Jens Christian Holst
Scientist, Pelagic Section
Institute of Marine Research
Postboks 1870
5024 Bergen
Norway
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My name is Pat Rivers and I indirectly received the email you sent
regarding herring scales. My masters work involved scale analysis of
two cyprinids from Russia (not quite herring).
Two possible ideas for stock discrimination that I have are
1. Develop growth histories for all samples collected. This is done
using a linear growth model (see Weisberg CJFAS Vol 50(6) pages
1229-1237). If the stocks experience significantly different
environmental effects, cluster analysis may be a way to differentiate
them
2. If you still have the actual scales, use laser ablation for
elemental analysis of scale composition. This has been done
successfully for steelhead (I think,anyway).
See Wang, S. R. et al. in Appl. Spectrosc. 48:1321-1325.
I hope this is/was helpful. Good luck.
Pat Rivers" <[log in to unmask]>
*************
I don't know anyone who are working with scales, but there is a
scientist (Henrik Mosegaard) on the Danish Fisheries Research Institute
in Charlottenlund who has had some succes using otoliths as a tool in
stock delineation studies on herring. I belive that the same processes
(variation in juvenile growth among areas) are responsable for observed
differences among as well scales as otoliths between different stocks.
If you feel that a different approach to your scalereadings could give
you some inspiration, you could try search for some of Henrik
Mosegaards publications. His email adress is [log in to unmask]
Kind Regards
Espen Rasmussen
*************
Again thanks much.
--
Peter Hagen ~ email: [log in to unmask] ~
Alaska Dept. Fish & Game, P.0. Box 25526, Juneau AK USA,
99801-5526 ~ phone: 907-465-3499 ~ Fax 907-465-2765
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