At the beginning of the month I was lucky enough to have the opportunity to work with Suttles on construction sites along the River Aire as part of our DNAire project in partnership with Environment Agency. These construction sites are allowing fish migration to take place along the Aire, with fish passes being built to allow migratory fish, like salmon, to get back up the river to their spawning grounds of Skipton.
Fish passes are needed on the Aire due to the multiple weirs existing from the industrial revolution. These weirs act as barriers to fish due to a combination of the weirs being too steep and the river being too shallow to allow coarse fish to get the momentum to leap over the weirs. Installing the fish passes is a huge engineering project and I am grateful I got to be part of the experience. We hope that salmon being able to migrate and spawn once more will add to the improving condition of the Aire.
Working on the construction sites has allowed me to see the engineering, hard construction and planning that goes into creating the fish pass structures and how hard it is to be working in and near water. During the building process the river must be dammed and re-directed to allow for a dry workspace before the old weir face can be destroyed and building of the structure for the new fish pass can be started. It is crazy to think that the weir at Kirkstall has been around since the 12th century and that no one will have stood on it and seen the beautiful stone work as I had the opportunity to since then. It also surprised me how large the fish pass structures actually are and the precise engineering needed to make sure the baffles in the fish pass would serve their purpose to churn up the water so that the fish can use the currents to swim against the water up and over the weirs.
The image above shows construction work at Kirkstall Abbey and just how large the fish passes are. Here you can see the steelwork at the top of the fish pass which needs to be put in to make sure the structure will hold against the large pressure of the flowing river. After the steelwork the fish pass is concreted as you can see in the lower part of the fish pass and the baffles installed. To the left of the fish pass there is also going to be an eel pass installed to also help smaller fish and eels get over the weirs.
Im going to be returning to Uni in Leeds soon but Ill be back. I can’t wait to hopefully see salmon in the Aire very soon!