If you’ve ever walked the banks of Barton Court on a warm summer evening, you may have noticed a flick of movement beneath the water or spotted empty claws and shells left behind near the edge by the otter. These signs usually point to one thing! Crayfish! Quietly industrious and surprisingly influential, crayfish have become one of the most talked-about inhabitants of the Kennet.
Native vs. Invader
Historically, the Kennet was home to the native white-clawed crayfish. Shy and slow-growing, this species thrived in clean, well-oxygenated water. Sadly, today it is rarely seen. The main reason for its decline is the arrival of the American signal crayfish, an invasive species introduced to Britain in the 20th century.
Signal crayfish are larger, more aggressive, and far more adaptable. They outcompete native species for food and shelter and carry crayfish plague, a disease deadly to white-clawed crayfish but harmless to themselves. As a result, the white-clawed crayfish has been eradicated from the River Kennet.
Engineers of the Riverbed
Crayfish are not just residents of the river; they are active engineers. By burrowing into banks, signal crayfish can accelerate erosion, causing sections of the riverbank to collapse. Their constant feeding on plants, insects, and fish eggs can also alter the balance of life in the water, sometimes reducing habitat for young fish and invertebrates.
At the same time, they are a valuable food source for predators like otters and herons. This creates a complicated picture: crayfish are both a problem and a key part of the modern Kennet ecosystem. On some lakes, the introduction of crayfish has led to perch growing to British record sizes.
Walking the Kennet with New Eyes
Once you know what to look for, crayfish signs are everywhere. Hollowed banks, snapped claws, and even the occasional live specimen hiding under a stone all tell a story of a river adapting to change. For anglers, conservationists, and casual walkers alike, crayfish are a reminder that rivers are living systems, constantly shaped by both natural forces and human decisions.
Looking Ahead
Efforts are ongoing to protect remaining pockets of native white-clawed crayfish in nearby catchments and to manage the impact of signal crayfish where possible. While removing them entirely from the Kennet is unrealistic, increased awareness can help protect the river’s broader health.
The next time you stroll along the River Kennet, pause for a moment and peer into the shallows. Beneath the surface, crayfish are busy shaping the river’s future one claw, burrow, and ripple at a time.