Friday, 11 April 2008

Fish pass - (10/04)

The fish pass - yet to be assembled

One of the many aspects the New Mills Torrs Hydro project has taken into consideration includes the preservation and possible improvement of the route of fishes' natural migration.

Our local rivers contain many species including barbel, chub, salmon, brown trout and grayling to name but a few - hence the number of Herons you will also see lurking.

To aid this migration upstream to spawning grounds an aluminium fish ladder or fish pass will be installed on the site. These are structures on or around artificial barriers (such as dams and weirs) to facilitate fishes' natural migration.

Most fish passes enable fish to pass upstream around the barriers by swimming and leaping up a series of relatively low steps (hence the term ladder) into the waters on the other side. The velocity of water falling over the steps has to be great enough to attract the fish to the ladder, but it cannot be so great that it washes fish back downstream or exhausts them to the point of inability to continue their journey upriver.

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