River Height vs Salmon Catches

How many anglers check the river height to assess their chances of catching a salmon before leaving home and does river height play a part in determining salmon catches?
My good friend Jim McLaughlin has been collecting fish catch figures from Wyesham, on the bottom part of the river Wye for the last three years and he has compared the figures with influencing factors such river height, moon phase and rising/falling water. Below is the data for river height vs catch numbers.

Catches by heightThe catches vs river height appears to follow a normal distribution curve with a mean of 0.7 metres and a standard deviation of 0.2 metres. This is just so striking and for this reason is a very important consideration ! This curve would probably be closer to the normal distribution pattern if it was taken over a longer period and if the 2014 catch figures had not been so low.
Hutton in his book “Rod fishing for Salmon on the Wye says “I cannot emphasise too much this question of height of the water; we find it the main factor in catching salmon.”  His figures for fish caught vs height of water 1908-1917 follow a normal distribution pattern although there are two sets of data; for bait and for fly. The optimum (mean) height for The Carrots was 1ft 9 ins (0.53 metres). For bait it was 2ft – 2ft 3ins (0.61 – 0.69 metres). The following distribution diagram is for the total of both methods.

Catches-by-height-1908-to-1917This unquestionably follows the normal distribution pattern – more fish caught and over a longer time period. Therefore I think we can conclude that the height of the river is significant and so it is important to check the height of your local gauge if you want to assess your chances of catching a salmon. Don’t be put off if the height is not close to the mean because you still have a chance but with considerably reduced odds!
In my next post I will give you the surprising results of moon phase and rising/falling levels versus catch rates.

About John Symonds

I mainly fish the rivers Wye,Usk and Ithon for salmon, trout and grayling. Also fish in Ireland on the rivers Moy, Suir and Blackwater. Specialist skills photography and graphic design relating to fishing, casting and fly-tying. Qualifications include Advanced Professional Game Angling Instructor (APGAI) single and two-handed fly rods, International Federation of Fly Fishers (FFF) two handed casting instructor and Level 2 Angling Trust Coach.
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