Northwest Fisheries Science Center

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Document Type: Journal Article
Center: NWFSC
Document ID: 7880
Title: An improved trap for the capture and safe retention of salmon smolts
Author: Donovan R. Craddock
Publication Year: 1961
Journal: The Progressive Fish-Culturist
Volume: 23
Issue: 4
Pages: 190-192

One of the fundamental problems in many fishery programs is the development of equipment and techniques to obtain the fish samples necessary for the study.  Research to determine natural survival and production of salmon depends on assessing the size and composition of downstream migrations.  The mechanics of capturing the required smolt samples can be a difficult problem where the river is fairly large and funds and manpower are limited.

Weirs are costly to install and may be difficult and expensive to maintain. Fyke nets., on the other hand., have proved to be effective in capturing migrating fish in flowing waters.  They are not expensive to obtain, but require considerable manpower to operate because almost constant attention is necessary if the captured fish are to be retained alive.  This latter fact precludes use of the nets where large numbers of migrants are required for a mark­and-recovery program with a small staff.

The trap described here can be used to advantage in many projects where it is important to capture large numbers of downstream migrants and maintain them alive over extended periods of time.  It is especially adaptable to projects involving moderately large rivers and limited man­power. It is also inexpensive; a complete trap costs approximately $200.

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