Willi,

In another post in this thread, I referred to a radio tracking study of
brown trout on a local stream which showed that trout lose considerable
weight over the winter, (at least in the experiment). I do not have a
report, only recollection of a preliminary verbal presentation of findings.
Among the discoveries was that trout do move around, some moving
considerable distances, 8-10 kms, others not as much.

Radio tracking is glamorous and consequently is somewhat of a fad among
field biologists working on almost every species imaginable these days. Some
aspects of it on some species bothers me. For instance, I was disturbed by
tracking experiments on endangered sea turtles; even to my untrained eye the
particular transmitter used had to have affected the hydrodynamics of the
creature. Most researchers never recover their specimens but I recall
reading of one team that did and found their specimen wasted and about to
die, presumably because of an inability to swim normally and feed. The lead
scientist chose to end his program at that point because of that. In the
case of trout in my home river, there was a very high mortality of the
specimens for reasons that apparently could not be identified. My suspicion
is that the fish might have been very highly stressed not by the transmitter
itself but by the procedure to install it. The fish are out of the water
for 5-10 minutes during which time they are only doused with water laced
with a disinfectant. This is inconsistent with the preachings of other
biologists who advise anglers to release their catch as quickly as
possible - I am surprised that any survived at all. However, in the case of
fairly abundant species such as trout, I suppose sacrificing a few to find
information to save many is a worthwhile trade off.

Yuji Sakuma

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