Friday, March 30, 2012

Wild Fish Go Where They Please

Wild fish go where they please. This can make catching them somewhat difficult, but there are ways to direct fish in the direction you want them to go. Juvenile salmon naturally migrate downstream and we use this instinct to our advantage when trying to collect information about their size and numbers.

Screw trap (at bottom) with panels
When setting up a sampling device such as a screw trap or fyke net, fish need to be guided into the trap. The trap is usually set up in the middle of a stream or in higher flow areas and, in some cases, panels need to be set up to act as a wall. This wall of panels is set up so that it points downstream like an arrow, directing fish into the trap. Once the fish are caught, they are measured, weighed, and marked. They are then released, unharmed, to continue their migration downstream.

Scientists have used weir panels to control the movement of fish for decades. Knowing the amount of fish that use a river is vital in sustaining a healthy population. The information collected from these sampling activities tells scientists if a fish population is in danger and if action needs to be taken to protect it.  In this way, we can protect fish populations for future generations to enjoy and appreciate

If you see panels like these (or ones like them) in a river or stream, please do not touch them. Climbing on or wiggling them could endanger the information they are helping to collect. Please feel free to LOOK, but DON’T TOUCH. Scientists are trying to help the fish and we need your help to do it!  


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