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Dear list members

Over the past few years we have been counting Atlantic salmon smolts on
a small chalk stream in southern England using a combination of
resistivity counters, video surveillance and automatic PIT tag readers.
This has allowed a completely hands off approach and thus doesn't
interfere with the downstream migration. Over the years we have tried
several counting channels in a number of locations  including a glass
sided flume (1.4m wide; 1m high and 10m long),  which can carry the
entire discharge of the stream in which the smolts are to be counted.

My questions are:

1: Are there any technologies other than resistivity counters i.e.
hydro-acoustic, laser counters that could be used to count smolts (10 -
20cm) and deployed in such a situation (i.e. a small flume)?

2: Would these alternative methods allow an estimate of individual
sizes of migrating smolts?

Any ideas would be appreciated.

Many thanks

Adrian

===========================
Adrian C. Pinder
Centre for Ecology and Hydrology
Winfrith Technology Centre
Winfrith Newburgh
Dorchester
Dorset
DT2 8ZD
tel (direct): 01305 213579
email: [log in to unmask]
www.ceh.ac.uk
===========================

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