Jet washing of Salmonid spawning beds

River Frome

I guess we have been jet washing various salmonid spawning areas for the last fifteen years, if not longer.

Changes in land management and climatic variation, has over the years has contributed to an increased silt load for the Frome catchment, this in turn results in the spawning gravels becoming clogged and compacted, the Salmon, Sea Trout and Brown Trout work extra hard to cut their Redds, laying their eggs in the gravel and because the well oxygenated water that the eggs require to grow, cannot flow through the eggs, the result is always a large mortality.

Historically these fish have always favored certain areas in which to spawn, particular “Riffles” the rising gravels found below pools or long glides with plenty of cover.

We use high pressure water pumps to loosen the gravel, removing the compacted sediment, giving these valuable fish stocks a helping hand in their long term survival, and our Frome Salmon need all the help they can get!

I am pleased to say that for as long as we have been gravel washing we have always found Redds cut in the areas we have carefully selected for cleaning, and must thank the Environment Agency and the Frome Piddle and West Dorset Fisheries Association for their funding and support over the years for all these Salmon related projects.

We have now finished this autumn’s gravel washing program, finishing at the end of October, then as we hopefully receive large amounts of rain we can all wait with crossed fingers willing for a large run of Salmon and Sea Trout.

Conditions were on our side again this autumn, and with a complete lack in any weed growth our team were able to wash an incredible 4268 square meters of spawning habitat over our fifteen day contract.

Please click on link to view the locations and size of all the sites washed along with ten figure grid references.  Gravel washing sites 2010

The run of fish will hopefully happen over the next couple of months, spawning through the latter part of December, then we will be out in early January doing our annual Redd count, (as a follow up to all the gravel washing) marking by GPS as many large Redds as we can find in the Frome catchment.