Salmon make a fast re­turn in restora­tion

Macclesfield Express - - THE LAUGHING BADGER - SEAN WOOD

AS promised, here’s an­other good news story from the nat­u­ral world; a river restora­tion project at Haweswa­ter in the Lakes, which was aimed at help­ing breed­ing salmon, has spawned suc­cess only a few months after it was fin­ished.

Dur­ing the sum­mer a one-kilo­me­tre stretch of Swin­dale Beck, which had been ar­ti­fi­cially straight­ened around two cen­turies years ago, was filled in and re­placed with a more nat­u­ral curv­ing course through a part­ner­ship project be­tween the RSPB, the En­vi­ron­ment Agency, United Util­i­ties and Nat­u­ral Eng­land. This slowed the flow of the river, cre­at­ing habi­tat more suit­able for spawn­ing salmon and trout, and in De­cem­ber 16 salmon were spot­ted in the new stretch of river.

Eggs are laid by fe­male fish in gravel de­pres­sions called ‘redds’. As the eggs are re­leased by the fe­male, they are im­me­di­ately fer­tilised by an ac­com­pa­ny­ing adult male, and of­ten by ma­ture ju­ve­nile males (of­ten re­ferred to as ‘pre­co­cious’ parr).

The fer­tilised eggs are then cov­ered with gravel by the fe­male. Spawn­ing oc­curs be­tween Novem­ber-De­cem­ber but in some lo­cal­i­ties, par­tic­u­larly in larger rivers, this may ex­tend from Oc­to­ber to late Fe­bru­ary. After spawn­ing has taken place about 90-95 per cent of all At­lantic salmon die. Some do, how­ever, sur­vive and some may spawn twice or more.

Gen­er­ally speak­ing, eggs usu­ally hatch dur­ing early spring. These young fish, which still have a yolk sac at­tached, are called ‘alevins’.

These fish re­main in the redd for a few weeks and emerge from the gravel in April or May, when they have ab­sorbed the yolk sac and are about three cen­time­tres in length.

The fish es­tab­lish ter­ri­to­ries and com­pete with each other to feed on a range of items within the stream.

As these ‘fry’ get larger, they de­velop prom­i­nent mark­ings on their sides and are then known as ‘parr’. De­pend­ing on the water tem­per­a­ture and the avail­abil­ity of food, they will live in the river for two to three years. Once they reach a size of up to 12cm, the parr un­dergo a phys­i­o­log­i­cal trans­for­ma­tion which al­lows them to sur­vive in marine en­vi­ron­ments.

The young fish, now called ‘smolts’, change in phys­i­cal ap­pear­ance, be­com­ing sil­ver, and start to leave the rivers dur­ing the late spring. Most of these fish will be gone by June.

At­lantic salmon al­ready spawn in other ar­eas of Swin­dale Beck, mi­grat­ing from the sea via the Sol­way Firth and the River Eden.

How­ever, the old straight­ened part of the river was too fast flow­ing for salmon to spawn, so the project has cre­ated new habi­tat by put­ting the curves back in this stretch of Swin­dale Beck.

The salmon eggs will hatch in spring, even­tu­ally emerg­ing from the gravel after an­other four to six weeks. They will re­main in the river for the next two to four years be­fore mi­grat­ing to the sea in spring time.

In ad­di­tion to cre­at­ing im­proved wildlife habi­tat, the restora­tion of Swin­dale Beck will have many other ben­e­fits, in­clud­ing help­ing to im­prove water qual­ity as well as con­tribut­ing to re­duc­ing the risk of down­stream flood­ing.

Lee Schofield, RSPB Site Man­ager at Haweswa­ter, said: “Habi­tat restora­tion is of­ten a slow process and we nor­mally don’t see the ben­e­fits of our work for years and some­times even decades.

“It’s re­ally up­lift­ing and in­spir­ing to work on a project where we get the chance to ex­pe­ri­ence suc­cess so soon after we’ve fin­ished.”

Oliver South­gate, River Restora­tion Project Man­ager at the En­vi­ron­ment Agency, said: “This project demon­strates the true essence of part­ner­ship work­ing. Ev­ery­one con­trib­uted through­out the project to en­sure we de­liv­ered the max­i­mum of ben­e­fits. It re­ally does show that na­ture will find a way if you al­low it to.

“It’s a bril­liant project and an­other one for the UK River prize-win­ning Cum­brian river restora­tion pro­gramme.”

Leap­ing salmon

The Laugh­ing Bad­ger Gallery, 99 Platt Street, Pad­field, Glos­sop

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