On Nov 9, 8:03 am, Willi wrote:
Tim

Came across this researching something else. Thought you might be
interested:

https://research.idfg.idaho.gov/Fish...Reports/Volume...

Some different results using a different (maybe better?) methodology.
Like all fish studies, the methodology has some drawbacks but it seems
much better than the confining that the other studies used to measure
mortality in streams and rivers.

Willi

Hi WIlli,

This was a really good read, thanks for passing it along. I agree that
there are some big question marks in the technique. The results depend
on snorkelers finding the corpses of fish that die. The control being
frozen fish anchored. Seems a little questionable to me, for several
reasons, but the results being fairly consistent with the aggregate of
other studies makes me think it's a good enough methodology. Several
things are clear. 1) Mortality is cumulative, increasing fairly
dramatically as the resource is exploited 2) It was not clear in the
study if mortality during high-stress periods such as warm water
temperatures is increased, potentially exponentially 3) Mortality from
Catch and Release fishing is, and can never be, 0. Overall, this study
suggests 3% mortality from C&R through flyfishing, in Yellowstone
park. An assumption is that differing regulations, perhaps mandatory
catch/kill/quit regulations would reduce both the overall pressure,
could target desirable classes for optimal growth, yield and health of
the fishery.

Tim