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  1. #21

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    Quote Originally Posted by Loxie View Post
    Why?
    Oh simple.
    Just relative proportionality. Example

    Use economy base line October 2007 (at worst time of crash) then variation to 2017 makes economy look great. nice +ive line like a bit like / (equivalent, look at my fish numbers go up, cool)

    Economy base line 2005 then that shows economy very different . Line goes - then 2007 very fast \ then very little gradient up to 2017... ( or oh no fish stock collapse and very slow recovery)

    But both graph shows same real number of fishes. I don't know what 1996 was. but is easy to do graphs in much better way and make a very better case, which ever way it goes.

  2. #22

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    Quote Originally Posted by Koka kola View Post
    Oh simple.
    Just relative proportionality. Example

    Use economy base line October 2007 (at worst time of crash) then variation to 2017 makes economy look great. nice +ive line like a bit like / (equivalent, look at my fish numbers go up, cool)

    Economy base line 2005 then that shows economy very different . Line goes - then 2007 very fast \ then very little gradient up to 2017... ( or oh no fish stock collapse and very slow recovery)

    But both graph shows same real number of fishes. I don't know what 1996 was. but is easy to do graphs in much better way and make a very better case, which ever way it goes.
    The OP also contains a graph showing all the recorded catches, so anyone who has read it can see exactly how 1996 fits the bigger picture nationally. Locally there will be some variation, naturally, but I don’t think it was the intention of the OP to give us a graph for the entire GB since 1952 on a river by river basis but more an indication about how different regions have fared in the last 20 years. How would you have made a graph to show that better?

  3. #23

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    Quote Originally Posted by Loxie View Post
    The OP also contains a graph showing all the recorded catches, so anyone who has read it can see exactly how 1996 fits the bigger picture nationally. Locally there will be some variation, naturally, but I don’t think it was the intention of the OP to give us a graph for the entire GB since 1952 on a river by river basis but more an indication about how different regions have fared in the last 20 years. How would you have made a graph to show that better?
    I can't see that graph you mention apart from a 96 baseline one? Maybe I'm missing it, but all are on 1996 = 100 model so, only compared to that.

    The problem is to know what 100 means comparatively to any other year. I don't know but this can be very important I think. To make it better? just be clear what 96 was compared to other years, even better, give a standard deviation of the mean. My school maths stops me about here now.
    Last edited by Koka kola; 18-11-2017 at 05:39 PM.

  4. #24

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    Quote Originally Posted by Koka kola View Post
    I can't see that graph you mention apart from a 96 baseline one? Maybe I'm missing it, but all are on 1996 = 100 model so, only compared to that.

    The problem is to know what 100 means comparatively to any other year. I don't know but this can be very important I think. To make it better? just be clear what 96 was compared to other years, even better, give a standard deviation of the mean. My school maths stops me about here now.
    My mistake it was an addendum to the OP by the OP, as it were. This one:
    80DDD3C5-83A9-4A00-A8DC-E67B6165526C.png

  5. #25
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    Default coca colonisation...

    Some interesting feedback, thanks.

    Picking up on some of the most important bits…

    Quote Originally Posted by Klink Eastwood View Post
    Am i reading this correctly . I know that some like to be left field in their thinking on here, and look at challenging white when in reality its black, but surely more rods fishing on a beat covering all the pools and all the little pockets of water in between, give a far greater chance of covering and connecting with fish. I get the reduced CPUE rates in the examples given, but whenever ive fished... lets say association water over the years, yes...its not great when you arrive and see a good few anglers queuing to go through the pools, or interspersed down the bank step by stepping downstream, but the overriding opinion of the brethren where i come from is, at least we will all know if the fish are there if one or two are getting in on the action. I honestly cant remember thinking, there`s 10 anglers out today and only 2 caught. I wish there was only 3 of us out as i bet 6 fish would have been banked by now. How much fish are missed when beats are not fully rodded and only certain pools are being covered ?, ive read that very same argument right here on this very forum by prominent posters as to reasoning to poor catches in favourable conditions. So which one is it?. Its not just the best pools that hold fish. And if that`s on poor mans waters, id only assume better beats hold more fish throughout its length.
    I think you have a fair point there Certainly my impression of association and some private water…




    Quote Originally Posted by Westcountry View Post
    Since 1996 allowing for the ups and downs of fishing small spate rivers in the Westcountry that are dependent on weather:
    I'm not seeing as many fish.
    I'm not catching as many fish.
    I'm not seeing as many fish on the redds.


    I'm sure I'm not alone in this and I'm sure others saying the same from other regions aren't all wrong either. So in the face of that what do graphs and long well constructed forum posts prove?


    Andy
    First off, perhaps don’t look for “proof”. This is not about proof, but thinking. In your case, not seeing as many fish or catching as many fish may mean that there are not as many fish about as there were in 1996. It could be as simple as that. Yes.

    Then again, there could be other explanations. I don’t know you or your circumstances, but I can speak for myself. I do not catch as many fish as I used to in 1996. There are a number of reasons for this. I don’t always fish the same beats; where I do, I tend to concentrate more on lies that have produced for me and not seek new water (of course rivers change, so do lies, beats and overall river catches); I’m not as good at covering the water as I was 20 years ago, and hence tend to not fish as eagerly as I did, or in the “necky” places I used to. I don’t have anywhere near enough free time and just don’t fish as often as I used to because of changed personal circumstances. I rarely use bait anymore. That’s just me. If you can say hand on heart you should catch the same as you did and your effort is exactly as it was, then you are right. There are fewer fish about now.


    Having said that, again the SW has suffered more than other regions. There’s no doubt that catch per unit effort is down over the 20 years for the SW region (check the CPUE data on the maps CLICK HERE) - not many greens down there, and that suggests there are fewer fish about. No problem with that, the rivers are towards the edge of the Atlantic salmon’s range, and increasingly anthropogenically affected, and climate change perhaps compounds things too.

    For the record here is the catch per unit effort data (=catch / rod days fished) to compare with the catches and effort graphs in the OP – I will edit the graph into the OP as well:

    Eng&Wal CPUE Regional Performance.jpg.

    You can see the SW has consistently fare poorly, being below most other regions during the “surge” in salmon catches between 2004 and 2012, so perhaps your gut impression is spot on.

    Pretty graphs and long well-constructed forum posts or not, none of it means (and I’ve never said) all is rosy, everywhere, all the time. The variance between rivers is the one thing that sounds alarm bells.




    Quote Originally Posted by uskgrub View Post
    the one thing those graphs show me is how the runs of fish for the whole of the uk are generally very much connected to each other, when scotland has a rise in catches so do england and wales and likewise when the catches fall, the graph shows almost identical peaks and troughs.
    This for me only strengthens my strong belief that its what happens at sea is by far the biggest factor on the numbers of fish we get returning over any given time period as this is the one main thing all our salmon have in common from the north of scotland to the south of england is they have spent the same time period or winters out at sea and been met by either good survival conditions or bad.
    Its all well and good spending millions on habitat improvement etc but at the end of the day if our smolts cant survive due to poor conditions when they reach the salt whether that be high predation levels, lack of food or a number of things combined then unfortunately no matter how good our rivers are for the lucky few fish who make it back i dont believe it will make much of a difference

    That’s an important point, so thanks for making it.

    Some of the confusion arises because the graph as presented make it look that way. In reality the correlation between individual years catches of Scotland vs. England & Wales is low. Let’s have another look at the graph with some added tie lines to compare the two exactly:

    E&W and Scots RCS Performance Full Timescale Lines.png


    You can clearly see they are not identical peaks and troughs. There are some glaring differences which cause serious problems for your theory, IMO.
    But even if they were that would not be a smoking gun for an “all at sea” cause. Despite what some of the folk “liking” your post would wish.

    It is clear that the overall “general abundance” spikes are generally pretty close, but there are glaring examples. There are a number of reasons that may be. Clearly you have a strong belief that this is down to issues at sea. I understand this. But please allow me to present a different alternative:

    The ocean influences the weather as well as the climate (decadal weather variation). Both weather and climate affect salmon.

    Both affect the rivers.

    Both may affect salmon run timings.

    Both affect fishing conditions and hence catches.

    Smolt output and survival can vary greatly year to year. They are influenced affected by floods. So is fishing effort and success. So perhaps what you see as “ocean influence” is correct – through rainfall, river levels etc..
    Send more smolts out on a big flood, and more come back (see Andy Moore’s presentation on the AST smolt conference materials).

    Have good fishing conditions with good spates, and more come in and get caught.

    The drought year of 1976 clearly bucked trends! Note the low catches.

    So, perhaps with respect, all this indicates is that England, Wales and Scotland share similar climates and weather, overall and on average. The weather and it’s cycles are broadly similar, but not exact, hence the catches have broadly similar, not exact, trends.

    However, I think the other main implication in that graph is more obvious: Note that from the 1970s onwards the general trends of the 10-year averages diverge. General peaks and troughs are mirrored, but the Scotland trend remains stable and increases over time. By contrast England and Wales become suppressed and there is a relative decline compared to Scotland.

    To me, that underlines the possibility that this just reflects anthropogenic impacts on catchments – Scotland, with ± 5m people is doing better on average whereas England & Wales with ± 55 million people are doing worse. When you dig down into the data of individual river catchments (like HERE) you see that this is quite true from river to river.

    Still, there’s obviously a lot of potential for shades of grey between the black of rivers and the white of the ocean.
    "...hooking mortality is higher than you'd expect: further evidence that as a numbers game, catch-and-release fishing isn't always as straightforward as it seems"
    John Gierach


    Fed up of debating C&R - see Hidden Content

    Unless otherwise stated, data used in any graph/figure/table are Crown copyright, used with the permission of MSS and/or EA and/or ICES. MSS / EA / ICES are not responsible for interpretation of these data by third parties

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