Subject: Rainbow Trout in UK

From: "A.J.Cann" <[email-masked]>
Date: 4 Oct 1995 12:58:24 GMT

I understand that rainbow trout (sorry, don't know the latin name) don't 
usually spawn naturally in the UK. It's easy to understand why since 
most are stocked in reservoirs, but there are also plenty in rivers 
which are suitable brown trout habitats. I have been told that there are 
recorded instances of rainbow trout spawning in 2 UK rivers. Does anyone 
know:
1) If all this is true?
2) If it is, what are the reasons (if known)?

Dr Alan J. Cann  PhD,   Department of Microbiology & Immunology,
University of Leicester,  P.O. Box 138,  Medical Sciences Building,
University Road, Leicester LE1 9HN,  UK.
Email: [email-masked]     http://www-micro.msb.le.ac.uk/AJC/nna.html

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From: [email-masked] (Grant Hughes)
Date: 5 Oct 1995 11:15:54 GMT

>Email: [email-masked]     http://www-micro.msb.le.ac.uk/AJC/nna.html

Rainbow trout (Oncorhynchus mykiss) have been released in many North
Atlantic drainages with little or no subsequent natural 
recruitment.

I recently asked a prominent Norwegian fresh water biologist about the
rainbow trout's lack of success but I didn't get a clear answer.  I don't
think it is generaly known why they do not thrive.  Perhaps they are
more sensitive to acidification (?).  Perhaps they are outcompeted
by established native Salmo species.  There are of course coexisting
populations of brown and rainbow trout in the USA.

I have read that rainbow trout have are relatively eurythermic, that is
they can live in a broader temperature range than other salmonids.

As for instances of spawning, I have heard of only a few isolated
cases in Norway (this goes for brrok trout (Salvelinus fontinalis) too).

Perhaps someone else has some details.

GCH

[email-masked]