Spate Rivers & Woody Debris!
Spate rivers, such as the River Teign, are distinctly characterised by their highly variable flow conditions, often experiencing rapid increases in water levels due to heavy rainfall or the melting of snow. These sudden surges can have profound and sometimes dramatic effects on the riverine landscape. High water events can uproot trees along the riverbanks, allowing these trees, as well as other woody debris, to be swept downstream in a powerful current. This influx of organic material plays a crucial dual role within the ecosystem: while it can create temporary blockages that significantly alter flow patterns and habitat structures, it also provides vital resources for aquatic life and contributes meaningfully to the natural cycle of decay and renewal. Understanding and managing these complex dynamics is essential for the conservation of our river habitats and the diverse species that depend on them for survival.
Rushford Bridge (Upper Teign) during a high spate looking downstream
Looking upstream to the same bridge in more normal flows
Andy Hurst from the Lune Rivers Trust recently presented to South West Rivers Association members and the findings from his work revealed a concerning and alarming trend, where multiple generations of young salmon and sea trout are facing severe and unprecedented threats from increasingly fierce winter storms and high spates. These ‘next generation’ of smolts and young fish were pretty much wiped out during our more common-place wetter, heavier winter storms.
The natural fluctuations in river flow, which were previously a regular occurrence and part of the river's rhythm, have significantly escalated due to the impacts of climate change, leading to dramatic and often catastrophic increases in water levels that wash away crucial spawning habitats and young fish alike! This relentless cycle of destruction hampers the recovery of these migratory species, whose populations are already under considerable pressure from pollution, habitat loss, and other human factors. As these vital fish struggle to survive in the face of such adverse and challenging conditions, the intricate ecological balance of the river is severely jeopardised, thereby highlighting the urgent need for comprehensive and effective conservation efforts to safeguard their future and preserve the integrity of this precious ecosystem.
Perhaps these more severe events and consequent river spates are simply washing away young salmon and trout, diminishing their chances of survival as they navigate through altered river systems.
This is where Woody Debris, caused by these intense storms can help - Not everything is bad news!
Woody debris plays a vital role in creating intricate habitats for young salmonoids, offering refuge from predators and strong currents while promoting healthy growth and development. The presence of fallen trees and branches in the river provides shelters that not only protect these juvenile fish but also encourage the formation of diverse microhabitats, which are crucial for their survival.
Sometimes, a lucky and ‘divinely placed’ natural barrier (leaky dam) serves as an organic hydro brake that holds waters back to peak lop river flow, creating more favourable conditions where young salmonoids can thrive.
An example of ‘divinely placed’ woody debris during a storm. Notice how diverse the flow characteristic of this small stretch of river is following nature’s placing of the objects!
Slower sections of the river reduce the velocity of the water, allowing sediments and gravels to settle fostering a rich environment where aquatic life can flourish. Conversely, where flow and velocities are increased, we tend to see better scouring of the riverbed and removal of silts. Either way, both are good news stories. Together, these elements contribute significantly to the ecological balance of our waterways, ensuring the future vitality of migratory fish species.
As with everything in riverine ecosystems, it’s all about balance. Not just in nature, but with those who use the river for recreation - The fly fisher!
An excess of woody debris can impede angling activities, especially in fly fishing, where precision and open access to pools and likely fish-holding areas are seen to be more favoured within the angler’s agenda. Striking a balance between maintaining sufficient woody debris for ecological health whilst ensuring that anglers can enjoy their pursuits is vital. I must confess that I really enjoy the ‘guerrilla type of fishing’ - scrambling over logs and trees and testing myself to pitch a dry fly over the nose of an almost impossible fish. Although, horses for courses, put thirty years on me and maybe my priorities and wishes will change!?
To this end, thoughtful management strategies are necessary to sustain both the river's biodiversity and the recreational opportunities it offers, ensuring a harmonious coexistence of nature and pastime for all involved.
A good example of prime habitat - Not everyone’s cup of tea, but great for both fish and angler alike.
Luckily, having two of the longest-standing Fly Fishing associations, the Upper & Lower Teign Fisheries on the River has, over the years, offered up and honed the right approach.
The rules are simple…
Where woody debris and perceived blockers do not impede the angling experience or migration of salmon, trout and sea trout both upstream and downstream, then the debris is left in the river for nature to take its course.
Should this not be the case, then both fishing associations promote active work parties that volunteer to restore the correct balance and remove or reduce these stubborn blockers.
Volunteering for bank clearing and blocker removal in the Upper and Lower Fishing Associations is an invaluable way to contribute to the conservation of the River Teign and its vital ecosystems. By dedicating some of your time to this essential work, you will not only help restore and improve fish habitats but also enhance access for the angling community. Engaging in these practical tasks fosters a deeper connection with the river and brings the opportunity to collaborate with like-minded individuals committed to preserving our natural heritage and improving the habitat for those above and below the water line.
For those of you who already have, you’ll know that our subscribers are notified of upcoming volunteer opportunities via email, ensuring they remain informed and engaged with any upcoming conservation events. Each notification includes detailed information on dates, and locations allowing individuals to select activities that align with their interests or expertise.
It goes without saying that we value the commitment of our volunteers and strive to cultivate a community that is both passionate and actively participates in the preservation of the River Teign, the long-standing fishing associations and the wildlife the river supports. By fostering this connection, we empower our supporters to contribute meaningfully to our shared mission.
Who knows, after getting involved you may look back on your efforts and think, perhaps the next logical step is to learn how to fly fish!?
