As Zach said, freshness is indeed the key to reliable SCA. 
 
If you can't get the fish straight onto/into ice, an alternative is to inject a preservative into the stomach/body cavity. People have used formalin in the past, but you might have fun getting it past the Health and Safety people. 
 
If you really want to know whats in the gloop, you could take a DNA based approach. Alternatively, use isotopes on the fish? 
 
Good luck 
Chris 
 
________________________________ 
From: Zachary Whitener 
Sent: Tue, Nov 22, 2011 8:36 AM 
To: [log in to unmask] 
CC: 
Subject: Re: Herring stomach analysis 
 
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Good morning, 
 
How are you getting these herring?  How long after capture do they get to 
you?  I have worked with both Atlantic herring and Alewives and have 
learned that freshness is paramount since digestion continues even after 
the fish is dead.  The best scenarios are to cut them from the fish and get 
them either on ice or in ethanol (the better option) as soon as possible to 
halt further digestion.  The prey items are so small that any further 
digestion renders identification almost impossible.  I hope this helps. 
 
Zach Whitener 
 
On Tue, Nov 22, 2011 at 7:15 AM, Mareike Volkenandt <[log in to unmask]>wrote: 
 
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> Hello everyone! 
> 
> I just started with my PhD-thesis. Between other things, I would like to 
> look at the stomach content of Herring from different size classes. It's 
> the 
> first time, that I'm doing such an analysis. We weight the stomachs and 
> visually estimate level of fullness. We also want to identify prey species. 
> In a test run, I had difficulties recognizing any prey species or groups in 
> the stomach. It was only a big, brownish, digested mix of something... 
> 
> Do you have any advise on a best method or way of handling? 
> Could you recommend me any identification keys or literature references 
> that 
> were helpful for your work? 
> 
> Thank you in advance. 
> 
> Mareike 
> 
> 
> ------------------------------------------------------------------------------------------- 
> Mareike Volkenandt 
> MARES Phd student 
> 
> Marine Biodiversity Research Group 
> Marine & Freshwater Research Center 
> Galway - Mayo Institute of Technology 
> Dublin Rd 
> Galway, Ireland 
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> Phone: +353(0)9174 2502 
> [log in to unmask] 
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> About MARES: http://www.mares-eu.org/ 
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