Return Of The King Salmon’s Reappearance in the River Don
Don Catchment Rivers Trust Few species evoke images of pristine rivers more than the salmon. The ‘king of fish’, as it’s sometimes called, is a staple of the nature documentary, usually scaling waterfalls and narrowly avoiding the jaws of a grizzly in the wilds of North America. It therefore often surprises people in South Yorkshire when they learn that the River Don once sustained a huge salmon population. It is precisely this iconic status of the species and its connotations of healthy rivers that has been one of the motivating factors behind efforts in recent decades to help salmon recolonise the Don. If salmon returned, so the reasoning goes, then people would take note, recognising that the Don is valuable habitat for wildlife and no longer the foully polluted and smelly river it once was. Perhaps, after years of neglect, people would begin to treat the river better, questioning whether to throw in that empty drinks bottle or reconsidering what they pour down the drain. If people felt more positive about the river then it would be given a greater voice in decision making, such as investing more resources in improving it. The species of salmon native to Britain is known as Atlantic Salmon (Salmo salar). It is actually more closely related to the Brown Trout (Salmo trutta), another native fish, than the world’s six other salmon species, which all inhabit rivers draining into the Pacific. Young salmon live in freshwater, before
migrating out to sea and travelling to their feeding grounds in the North Atlantic. After one or more years at sea they return to their river of their birth to spawn and reproduce in swift flowing and relatively shallow river habitat (see page 21 for Life Cycle & Salmon Terms). Records show that salmon were once plentiful in the Don. Hecks (a type of salmon trap) were used to catch migrating fish in 17th century Doncaster, and next to nothing prices from market records show traders might have considered salmon to be inexhaustible. Two factors led to its loss from the Don. The first was the construction of large numbers of ever bigger weirs, built largely to draw water from the river to power water mills, or maintain water levels so boats could navigate the river and canal. These dam-like structures form barriers for the migrating salmon, and made it increasingly difficult for them to reach spawning habitat in the upper parts of the catchment. The second factor was the gross pollution of the Don caused by the growth of industry and mining and a burgeoning population. So extreme was this pollution that by the 20th century, much of the Don stank, it regularly turned yellow and was dead to plants and wildlife. In recent decades a remarkable recovery of the River Don has got underway, largely due to improvements in water quality
resulting from the decline of heavy industry, better regulations, and improved treatment of sewage. While many water quality issues still remain, the fact that salmon’s relatives, trout and grayling, are now doing well in the Don shows that the water is clean enough for salmon too. So how do you get salmon back to the Don? Well salmon have been attempting to migrate up the Don for a number of years, and have been observed jumping in vain to ascend barriers on the lower half of the river. You may be wondering why salmon are swimming up the Don when their homing instinct should lead them back to where they were born. The explanation is that their “internal satnavs” can make mistakes, and some individuals end up straying into different rivers. For example, one salmon found dead in 1976 downstream of Thorne had been tagged two years earlier on the River Ure in North Yorkshire. This unfortunate individual had taken a wrong turn into the heavily polluted Don on its way up the River Ouse. While the best thing we can do to help salmon return is to remove barriers, many on the Don can’t be as they still have important functions or heritage value. Therefore, over the last two decades various organisations including ourselves, Environment Agency (EA), Yorkshire Water (YW), Canal and River Trust (CRT), and
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