Water level, temperature and fly sizeIn my last post I wrote about the effect of this year's very cold water on the Findhorn on salmon behaviour. This article takes the discussion another step forward by comparing 2012 against the experience of the 10 previous years, before going on to examine some of the issues of fly size in differing water conditions.
The red marks plot the full dressed length of the fly (i.e. from the eye to the end of the feathers and tinsel) against the water level when each fish was caught, at normal water temperatures. The data encompasses 30 salmon from 2002-11, and shows clear correlation between the height and hence speed of water flow and the size of fly. Of course, this does not actually prove anything, because I did not test the hypothesis by trying to catch salmon in fast brown water with small flies, or in low water with big tubes. I was just following Falkus' advice.
|1 inch Cascade Conehead|
|Cascade Size 6|
|Size 16 Blue Charm|
3 x magnified
The sample is so small that there is no evidence that pattern X is better than Y, or that one colour is uniquely superior to any other. On the other hand, those fish were the product of many hours' application and thousands of casts, so we can reliably infer that all the other pattern/size combinations I tried were inferior, because they didn't catch anything. If undecided, revert to the Falkus hat selection method, but do match the size to the water speed.
But fly size and pattern are only two parts of the equation for catching salmon; depth and presentation follow, and are the subject of my next post.