Now is the perfect time to witness one of our true wildlife miracles. For the past six months great silver torpedoes have been slowly nudging their way against the current of our major rivers to rest a few miles downstream of the tributaries where they hatched.
These are Atlantic salmon and they are waiting for autumnal rains to swell the rivers and streams sufficiently to allow their great bodies to be shiver through the shallows to reach the gravel beds where they will spawn as did their ancestors over countless generations. As the rivers rise with seasonal rain, they will surge upstream, driven by instincts so strong that they will leave the safety of the water to launch themselves into the air to pass waterfalls and weirs.
This is spectacular and surprisingly common (ask your local Wildlife Trust for the best spots). The best sightings are at waterfalls, but the larger fish are impressive in their own right in the shallows of the main river – or even as they move up to their bedding grounds, some of the best of which are in remarkably small streams.
The journey so far will have been perilous. Many receive terrible injuries as they are dashed on rocks, while in the past millions were caught in nets or harpooned with gaffs (giant fishing hooks, lashed to sticks). Despite this, the drive to reach the upland streams is instinctive and irresistible.
Theirs is one of the most impressive lifecycles of our native fauna. Each fish begins life as an egg laid in a scrape in a gravel bed. They emerge the following spring as a ‘parr’ and spend the next year feeding on aquatic insects in the nearby waters.
After a year the are called ‘smolts’ and are around the size of small trout. Driven by instinct, they migrate to the sea to feed on krill in the rich fishing grounds off Greenland while dodging the attentions of seals and killer whales. At some point between three and six years old they return to freshwater – and invariably this is to the same river where they hatched.
The first – and biggest – enter fresh water in early spring and it is these fish which are most prized by fly fishermen. Later in the summer smaller ‘grilse’ return. These have spent only one or two winters at sea in shallower coastal waters and are considerably smaller and less reproductive than their older brethren.
Once almost every British river boasted huge stocks of salmon, but by the middle years of the 20th century pollution meant most of the biggest rivers were devoid of fish. The only ones still to hold good stocks of this, the ‘king of fish’ were in the West Country, Wales and Scotland.
Fortunately, a by-product of water privatisation has been a dramatic increase in water quality. Just as importantly, the National Rivers Authority and its successor Natural England, have made great strides with habitat improvements, such as clearing debris in breeding brooks and maintaining gravel beds.
Once the water and habitat was right, the upper tributaries were restocked with fry (because the fish always return to their natal spawning beds, natural recolonisation was impossible). Salmon are now breeding naturally in the Thames and Mersey, for example, but it is the Tyne which has seen the most remarkable recovery. Until recently this was effectively a ‘dead’ river, but tighter regulation of sewage and industrial waste has seen a dramatic improvement in water quality to the extent that the Tyne is now officially the best salmon river south of the Scottish Border.