The Gaspé Twist - as taught by Claude Bernard (an extension to the Turle Knot)
The Gaspé Twist is an extension of the proper Turle Knot (traditionally used to tie a tippet to an up-eye or down-eye fishing fly). The Gaspé Twist is shown here as taught here by Claude Bernard, on the Bonaventure River, Gaspé, Quebec, Canada, and is the knot they use for most of their salmon flies. Monsieur Claude Bernard is the President of the Board of Directors of the Canadian Fly Fishing Museum (http://www.mpmc-cffm.com/reception.htm), as well as a resident, expert, and fly fishing guide on the Bonaventure River for many years.
I am not sure if the Gaspé Twist adds any further protection from slippage to the standard Turle Knot. Interestingly, it is quite difficult to remove the tied knot from the fly, once the knot has been placed under stress. At least two cuts are required to free the Gaspé Twist from the eye of a salmon hook.