Friday 30 November 2012

Where are they?

The answer to the question rests on some basic understandings.  The behaviour of salmon in rivers is directly linked to the fact that they are genetically hard-wired to complete their life-mission to reproduce.  From the time the salmon enters fresh water, everything it does is focused on the successful completion of that objective, which above all requires it to survive.  The greatest risk is exhaustion leading to death.  Consequently the salmon’s survival rests on the preservation of the extraordinary but finite stock of energy stored in its cells (primarily the flank walls), which is being heavily depleted by the internal creation of eggs or milt. About 80% of the mass of a mature salmon is muscle: by the end of the spawning cycle 25-30% of its body weight will have gone, which equates to 40% of its muscle mass.  Energy conservation is especially pronounced in hen fish, but less so in cocks, owing to the effects of testosterone on their behaviour (I’ll write about this in a future post).  This is why a higher proportion of hens than cocks survive spawning.

Obstacle - Canadian scale

In British rivers comparatively little of that muscle loss is attributable to the effort of swimming upstream.  First, because the salmon’s basic design is so efficient, its power so great and its reserves of stored convertible muscle energy so huge.  On the eastern seaboard of Canada it ascends rivers 3-5 times longer than any in Britain, and surmounts correspondingly bigger obstacles.  The longest salmon run on the West coast is over 1,000 Km.

Given the right water level and temperature, salmon can tackle most rivers in Britain with ease.  In the absence of major obstacles they can cruise at 3 mph for long periods.  Second, salmon are highly efficient swimmers, always following the line of least resistance whilst running upstream in order to conserve energy.  In a strong current this will be close to the bottom where the effect of flow friction is greatest and the water is moving much more slowly than in the upper layers.  I have unpleasant boyhood memories of standing waist deep without the benefit of waders in the freezing River Brathay in Cumbria on an A level geography field trip measuring current profiles.  At last the knowledge gained has proved useful to enhance standing waist deep in a freezing cold Scottish river.
Salmon will stop and rest for a host of different reasons, and for varying periods.  In thinking about resting it is essential to bear in mind that they do not come into the estuary, then at the first sniff of fresh water engage third gear and drive upstream at 3 mph all the way to the spawning redd.  Studies of GPS and RF tagged salmon have shown some remarkably erratic behaviour and movement both up and down rivers.  For example, by the early autumn there are fish spread along the entire 100 mile length of the Tweed system from Berwick to Moffat.  Some of them have progressed little more than 10 miles in the 6 months since they entered the river, whilst others have run 75 miles in 3 days.    One GPS-tagged fish went up and down the Tyne 3 times before running the full length of the North Tyne to spawn (no Geordie jokes please).  In common with so much else to do with salmon behaviour, no one knows why.  But it is during their rests, however long or short, that salmon and fly are most likely to coincide.
For this blog generalisation will suffice.  I think there are 3 broad types of rest.
·         Long term residential – I shall stay here until the urge moves me upstream, which may not be for months.  I will park in a comfortable spot, switch off and go into suspended animation to conserve my energy and grow my eggs in peace.  We’ve all seen fish like this – often large hens – and no matter hard we try, we rarely if ever catch one.  Certainly I never have.
·         Mid term waiting – I want to move on, but there’s not enough water.  These fish seem to switch off, but wake up periodically, become active and sometimes get caught.  Their active periods seem to be in common with other fish in the same pool, often at similar times of day.  We don’t know what causes these periodic flurries of activity.
·         Short halt – I want to gather my breath; or check out what lies ahead; or prepare myself to tackle an obstacle.  The places where these fish halt are easily identifiable in the head, middle and tail of a pool.   The running fish are alert, active and thus eminently catchable, because I have caught far more of this category than all the others combined.  In part this may be helped by the tendency of salmon to accumulate in these short halt lies in substantial numbers.  On the Findhorn I once saw a dozen running fish in a lie no more than a metre square taking a short halt before going up some shallow fast water.

11 pounder taken from short halt lie
River Findhorn September 2011
    The picture shows an 11 pounder taken with a Cascade conehead tube and fast sink tip in the Garden Pool of the Tomatin House water of the Findhorn.  It was taken from the short halt lie identifiable from the 'standing wave' in the mid stream just to the left of my head.  The water there is about 5-6' deep.  The obstacle of shallow water is about 50 metres upstream out of shot to the right.  Such 'standing waves' form when the river is up where collections of boulders drive the flow up to the surface.

In all cases what the salmon wants is a lie that is safe; provides a good supply of oxygen (which requires a steady flow of water through the gills); and conserves their energy by allowing them to hold their position with the minimum of effort.  The dominant factor is surviving to breed, which overrides everything else.
The salmon’s notions of safe are conditioned by the accumulated survival experience of the whole species, not the individual.  After several hundred thousand generations there is a lot of survival-based evolution hard-wired into salmon DNA.  They don’t like shallow water, because as parr they were vulnerable to herons and other avian predators.  Comfort starts at depths of around 75 cm/30 in, so don’t bother with fishing anything much shallower than that.  They don’t like too much free space below or behind them, because that is direction from which otters and mink attack, so reckon on them being at or near the bottom.  Pike and cannibal trout lurk in shady spots in slow water, so don’t bother to fish there.  Putting all those bits together gives us a pretty good idea where a salmon may lie, and as importantly, where it won’t.  There’s no point wasting your precious week casting to water a salmon considers dangerous.  It also tells us, for any given lie, how deep we have to fish the fly to get it close enough to an energy-conserving salmon to have a chance of stimulating it to take.  I’ve never caught a fish with a floating tip in water over 1.8 m/ 6 ft deep, but have been successful over the same lies with sink tips and/or weighted tubes.  Of course that statement excludes fluked running fish snatching at flies on or near the surface (see Brass Monkeys post); and over-sexed cock fish (a future post).
And that leads us on to the questions of why does the salmon take a fly; and how can we increase the chance of that happening?


Tuesday 27 November 2012

Hot and Cold Running Water

Water level, temperature and fly size

In 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
Actual size
The red marks do make a few points.  Most obviously they show that however hard you try, catching salmon in low water is difficult, mainly because the fish are switched off.  In contrast, the cluster along the 0.4 metre line shows how much easier life becomes when the water is up and the fish are awake, running and active.  There are nearly 4 times as many fish in those 2 clusters than in the low water string.  It also indicates that at that level, the combinations of 1 inch tubes and coneheads in brown water and 8/10 Shrimp and Cascade doubles in clearing water are highly effective.

Cascade Size 6
Actual size
In contrast the blue ellipse covers the 3 fish I took in the exceptionally cold conditions of 2012.  The flies were about 2 sizes larger (e.g. size 6-8 double) than those successfuly employed at normal temperatures (typically 10-12 double) given the same water level.  Whilst it does not prove Hugh Falkus' contention of colder water - bigger fly, it suggests that it is probably correct.

Size 16 Blue Charm
3 x magnified
When you get down to the tail end of the graph you are into the realm of almost random events with very small flies.  The extreme case was a 11 lbs hen fish caught on a brilliant sunny morning on a tiny size 16 Blue Charm delivered by a Vision 12' #7 grilse rod on a long fine leader.  The others were taken on a mixture of small Stoats, Shrimps and Blue Charms in the 12-14 range. 

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.

Sunday 25 November 2012

Reflections on 2012 - Brass Monkeys and Tubes

Over the past 10 years of our regular September week on the Upper Findhorn we have seen all sorts of conditions.  Often there has been too little water (2002, 2003, 2005, 2009), which in most cases coincided with high temperatures.  Occasionally there has been too much (2010) water, and in three years (2004, 2007, 2011) it was just right and we caught plenty of fish.  This year was unusual: there were almost perfect water levels and plenty of fish in the river, but we caught precious few of them. 

The most likely explanation for our failure was that both water and air were freezing cold.  The rain was falling out of the back of a succession of cold fronts in a northerly airstream.  Once we had sleet, but up in the catchment area several hundred metres higher it must have been close to zero every day.  As a result the river's temperature remained in the range 5-7 C (42-45 F).  By sheer coincidence I had, for the first time ever, packed my grandfather's 1920s Hardy water thermometer, magnificent in its nickel-silver tube, which allowed me to measure accurately in the first and only year that is was necessary.  The accepted wisdom is that in the spring salmon do not start running into fresh water until river temperatures get above 5 C (see Atlantic Salmon Trust ) and that once in the river they tend to be torpid and dour when it's very cold. 

The experts suggest that the answer is bigger flies, fished deep and slow.  In the event we only caught 14 fish, and they succumbed to such a variety of things that we couldn't tell whether the advice really worked.  As ever fluke remained the dominant factor: the first fish of the week was caught on the surface with a size 8 shrimp double on a plain leader in less than a metre of water; another took a fly as it hit the surface (the fact that it was a copper tube attached to a sink tip was wholly irrelevant); and two grilse displayed marked non-conformist tendencies in knee-deep rapids.  The only valid generalisation was that generalisations tend to be wrong in the short term.

Dalnahoyn Pool, Upper Findhorn
September 2012
As in previous years, we found that unique and undetectable factors created brief periods when one or more rods caught fish, irrespective of the techniques used.  For example, I caught all 3 of my fish in a period of 2 hours on the Thursday afternoon.  It was cold (air 6, water 7 C) and windy with occasional bright spells.  The water was perfect: lightly coloured and steady at about +10"/25 cm, which would allow fish to run freely if they wished.  The first (16 lbs) took a 1" copper Cascade tube on a 10 ft 4 ips sink tip in a classic 'pause' lie below the head of a pool (it's one of my favourites and very reliable). 

Head of Dalnahoyn Pool
Surface take
September 2012

The next (8 lbs), 20 minutes later was the 'dry fly' take described above, clearly a running fish in the fast water at the head, andthereby a complete fluke (the chances of such coincidence of moving fly and moving fish are microscopic, but at least a running fish is alert and active, which helps). 

Colonel's Pool
Deep and slow
September 2012
And the last (18 lbs) was a complete one-off fluke that obeyed the rules.  Walking back to the house I stopped to fish a very deep elbow pool that holds resident fish that show but never take.  Getting down 10'/3 m before starting the swing called for Skagit head, T14 tungsten tip and a 1 1/2" brass tube.  Knocking a fish unconscious was a distinct possibility.  This is not pretty fishing ( see video ), but it's a useful technique because you cannot overhead or single Spey cast that amount of weight safely.  Twenty five metres out; sink like a stone; and then slowly back, feeling the bumps on the rocks, until half way in there was one more animated bump that led to 15 minutes of deep, dour battle. 

What did I learn from all this? 

  • Buy a small, light and cheap thermometer, then hope that you won't need it.
  • It's hard work when it's cold because most of the fish are switched off.
  • Moving fish will offer the best chances, so focus your efforts on the heads (leavers) and tails (arrivers) of the pools.
  • Be careful and look after yourself - see below.

Health Warning - Hypothermia

Wading in water at 5C is potentially dangerous.  Even if you have all the Simms ninja gear (which is great) be very careful as hypothermia creeps upon you faster than you might expect, especially if you are over 50, or if younger, less than fully fit.  It will get you even faster if you drank a little too much the night before; and faster still if you then fish before breakfast.  Driven by enthusiasm I made all 3 mistakes on the first morning; forgot the military training of my youth; and lost half a day's precious fishing to recovery.

These are the danger signs of hypothermia onset:

  • General dulling of the senses: if you stop hearing the water clearly, beware.
  • Light headedness: small errors in casting and wading are telling you something.
  • Loss of colour, contrast and greying of vision: look out, it's now getting serious.
  • When you start seeing blue shading in the grey, get out of the water immediately, because the next stage is unconsciousness!