Friday 1 February 2013

Good Morning Ladies

In my last post I discussed the daft behaviour of over-sexed September cock salmon in the early morning.  This week it’s the turn of the more leisurely hens.

The graph shows that hen fish activity is more evenly spread over the day. There is an obvious bulge in the mid to late morning period, with lesser peaks in the afternoon and early evening. Actually, it’s not quite as simple as it appears.

 The expert statisticians would say that the shape of the graph and its peaks have more to do with my pattern of behaviour than the salmon's. I fish frantically from first light until last call for breakfast at 9; eat the hearty full English, shave and re-emerge onto the water at 10; and then fish through to beat changeover and a late lunch. I get back onto the water between 2.30 and 3, and then carry on until the call of bath and gin overcomes my fanaticism. You can see their logic: it could be correct, although it doesn’t explain the voids between 12 and 3 pm, and 4 and 6 pm. However, what blows the sceptics’ argument away is the evidence of the Tomatin House fishing records for this week. The catches of normal people show an even more pronounced mid-morning bulge.

The next thing we have to do is go through the data to discard the abnormalities. We have to be slightly cautious here because arguably all of these catches reflect abnormal salmon behaviour (“it’s all a fluke” – Falkus). However, this sample does contain some very flukey outliers towards the end of the day. For example, the 2 fish I took in near darkness in 2005 in low water, both small and stale (but very welcome as they broke my duck after 2 blank years). The big resident hen fish taken at 6 pm in freezing cold water in 2012 described in my ‘Brass Monkeys’ post was another bit of outrageous luck against the odds. Finally we have to look for exceptional circumstances, which in this sample is the 2011 season (sadly I missed the extraordinary week in the 2004). In 2011 the fishing conditions were good for 5 of the 6 days. There were lots of fish in the river that were running strongly but resting frequently in the face of the heavy water. As a result, and exceptionally, I fished for all but one day of the week with sink tips and tubes, catching 9 fish. (Whereas the great majority of the other fish in the 10 year sample were caught on floating lines, plain leaders and un-weighted flies). I suggest that the exceptional factors of 2011 tended to spread my catch more evenly across the day – for example the 2 lunchtime fish were unique to 2011. However, in 2011 the other rods’ catches still showed a strong mid-morning bias, possibly because most of them continued to fish normal floating tackle. Having taken my odd behaviour, the abnormal data and exceptional circumstances out of the equation, we are left with 2 marked peaks of hen fish activity. The larger one is centred at 11 am and the second, about half the size, at 3.15 pm. Is there any explanation? The regularity of the Tomatin September morning bulge rules out transient phenomena such as river level, barometric pressure, water and air temperature, oxygen levels, cloud cover and wind direction as the acute variable, because none of them vary regularly with the time of day. Obviously the conditions had to be right to catch fish (whatever the unknowns may be that ‘right’ entails – possibly all of the above). But all other factors being favourable and equal, there’s something that is time of day related that causes the 11 o’clock peak, and the only thing that regular is the sun.

If the sun is the factor, how might its light trigger the behaviour? The graph shows that the light intensity is about the same at 11 am and 3 pm in this week. However, I’m not proposing a theory that an intensity of X lumens stimulates a take. Instead I suggest that given otherwise favourable water and weather conditions and a fish that is inclined to take, this light level gives it the most stimulating view of a fly fished on a floating line and leader. Exactly what ‘stimulating’ comprises, I don’t know, but I’ll explore it in my next post.

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