Fish passes

Many of the Yorkshire rivers have endured an industrial past that reduced their biological diversity. There are stories that during the industrial revolution the Aire was so heavily polluted on its course through Leeds that it's surface could be set on fire. Thankfully recent years has seen a more enlightened attitude and our rivers have see steady improvements, with some unhelpful dips after pollution events. There are still historic headaches that river managers have to tackle. All the Yorkshire rivers are dotted with weirs built to service the old mills. Whilst these have become a part of the aesthetic nature of riverscapes they pose problems for migratory species including lamprey, eels, salmon and trout that have to navigate their way upstream against barrier after barrier that impedes their rout. In low flows the fish can become trapped behind the smaller weirs. In some locations on the Wharfe, such as at Otley, the weirs effectively stop upstream migration of fish and have drastically altered the food webs of the upstream river system.



The Yorkshire Dales Rivers Trust have recently worked in partnership with the Environment Agency to develop a fish pass with photographic recording equipment at Boston Spa, on the river Wharfe. The pass is now up and running and it is hoped it will enable safe upstream migration for salmon, trout, eels and lamprey. The camera equipment will record each fish that navigates the pass to supply important data on fish movement. Ideally we would aim to provide all the significant unnatural barriers with similar passes but the cost is prohibitive so development of fish passes has to be very selective. In the meantime each fish pass is one more battle won to help improve the river ecosystem.