Thanks Thanks:  0
Likes Likes:  56
Page 1 of 10 123 ... LastLast
Results 1 to 10 of 92
  1. #1

    Default How Accurate are Annual Rod Catch Returns and How True is the Historical Data ?

    I have been following all the various threads on the SFF recently and many of the threads are related - to do with the debate - Are Salmon stocks in Scotland on the decline or not?

    Some people say there is a decline, and other people say there is no decline.

    The consensus in government and many conservation bodies is that there is a decline in salmon numbers and many experienced anglers are noticing that is getting harder to catch fish in comparison to past years. Some anglers are now voting with their feet which means their actions are speaking for themselves - there must be a problem.

    What I haven't read much about is how accurate and true the annual rod catch data actually is, considering that the rod catches themselves could have been massaged significantly over the years by anglers/clubs/associations/beat owners/landowners/agents to meet their own specific needs - which I would imagine would mostly be for financial reasons.

    No doubt, some annual returns to FRS/MSS will be spot on and true, and some will be massaged for various reasons, and some will be kept the same each year to maintain a status quo - again for other reasons. In other cases no doubt, the annual catches are nothing more than an estimated guess.

    However if for example, there has been under-reporting of fish caught and killed over many years, this might explain why there is less salmon stocks in our rivers to fish for, and also less spawners. This could lead to the carrying capacity of rivers not being met, and the consequent number of smolts going to sea being reduced, and then a vicious cycle begins.

    Under-reporting over many years, perhaps in an attempt by anglers to keep the cost of permits down, or to keep good places secret, or annual club/syndicate membership fees down, or to keep the assessors rates down for beat/landowners, or to keep VAT payments down, could be possible reasons that the figures have been massaged. Also, it may be the case that an apparent abundance of fish to catch, meant that no one anticipated there was to be a problem with future stocks, and therefore did not see any reason to report accurate numbers of fish actually killed. Conservation is a relatively recent thing, as is C&R regimes.

    I think the government must be aware of the data issues, and that is why they are making all the changes they are making.

    If you take a local District Salmon Fishery Board as an example. The proprietors of the beats sit on the board committee. They each have a vested interest in how many salmon are caught, killed and released, and do the reporting on an individual basis direct to FRS/MSS as proprietors. To say they do not consider the financial implications of their own catch returns would be ridiculous, surely!

    Does anyone wish to make a stab at how accurate the rod catch data is and whether it should be used at all ???? !!!!
    Last edited by Gamekeeper; 17-02-2015 at 01:35 PM.

  2. #2
    Join Date
    Feb 2008
    Location
    Scotland
    Posts
    8,143

    Default

    Throw in catch and re-catch and it muddies the water further.

    Wonder how many of those fish on the Junction beat of the Tweed have been caught twice or even more as been known before.

  3. #3

    Default

    I don't think for one minute the recorded DATA is 100% accurate and I think it should only be used as a rough guide as to a general trend in fish stocks. I am aware that some fish are caught and not declared to owners and know of several instances of fish that were returned and subsequently caught again and that's on a small highland river where only 12 rods fish ,so whats happening elsewhere goodness knows.In most cases I think its a little unfair to blame riparian owners for getting figures wrong as the returns submitted to government are the sum total of those returned by the anglers themselves or at least that's the case here.

  4. #4

    Default

    Probably not that accurate but within 25 %

    I put this on another thread.

    Apart from the tweed in 2010 there are less fish.no doubt about it whatever a stats man will tell you.

    I have listed some variables but there are many more

    1 fish caught but not reported
    2 fish not caught but reported
    3 incorrect identification of fresh/kelt etc
    4 extension of fishing period
    5 removal of fishing(dams/drainage etc
    6 Significant increase in rod effort
    7 better equipment
    8 reduction in prawn worm etc
    9 increased/decreased poaching
    10 netting variations
    11 multiple catches


    Any others?

  5. #5

    Default

    What other methods do we have at our disposal which can give an indiction of the health of our salmon stocks?

    Catch returns may not be perfect but generally they are as good as its going to get.

  6. #6
    Join Date
    Oct 2009
    Location
    Ireland/Scotland
    Posts
    600

    Default

    Fish counters.

  7. #7

    Default

    Quote Originally Posted by Gamekeeper View Post
    I have been following all the various threads on the SFF recently and many of the threads are related - to do with the debate - Are Salmon stocks in Scotland on the decline or not?

    Some people say there is a decline, and other people say there is no decline.

    The consensus in government and many conservation bodies is that there is a decline in salmon numbers and many experienced anglers are noticing that is getting harder to catch fish in comparison to past years. Some anglers are now voting with their feet which means their actions are speaking for themselves - there must be a problem.

    What I haven't read much about is how accurate and true the annual rod catch data actually is, considering that the rod catches themselves could have been massaged significantly over the years by anglers/clubs/associations/beat owners/landowners/agents to meet their own specific needs - which I would imagine would mostly be for financial reasons.

    No doubt, some annual returns to FRS/MSS will be spot on and true, and some will be massaged for various reasons, and some will be kept the same each year to maintain a status quo - again for other reasons. In other cases no doubt, the annual catches are nothing more than an estimated guess.

    However if for example, there has been under-reporting of fish caught and killed over many years, this might explain why there is less salmon stocks in our rivers to fish for, and also less spawners. This could lead to the carrying capacity of rivers not being met, and the consequent number of smolts going to sea being reduced, and then a vicious cycle begins.

    Under-reporting over many years, perhaps in an attempt by anglers to keep the cost of permits down, or to keep good places secret, or annual club/syndicate membership fees down, or to keep the assessors rates down for beat/landowners, or to keep VAT payments down, could be possible reasons that the figures have been massaged. Also, it may be the case that an apparent abundance of fish to catch, meant that no one anticipated there was to be a problem with future stocks, and therefore did not see any reason to report accurate numbers of fish actually killed. Conservation is a relatively recent thing, as is C&R regimes.

    I think the government must be aware of the data issues, and that is why they are making all the changes they are making.

    If you take a local District Salmon Fishery Board as an example. The proprietors of the beats sit on the board committee. They each have a vested interest in how many salmon are caught, killed and released, and do the reporting on an individual basis direct to FRS/MSS as proprietors. To say they do not consider the financial implications of their own catch returns would be ridiculous, surely!

    Does anyone wish to make a stab at how accurate the rod catch data is and whether it should be used at all ???? !!!!

    The consensus in government, in Scotland at least, is that stocks are rising. see MSS status of Salmon and Sea trout stocks 2013.

    Rod catch data is always inaccurate, but usually consistently so. Take the 5 year averages over a long time frame and they give a fair indication of whether stocks are improving or declining. Add in counter data where available and netting and fixed engine returns and you get a picture that while in no way wholly accurate is a good indicator of stocks. That is exactly what MSS do and why they have draw the conclusion that they have i.e. that stocks are improving.

    2014 is looking like being about half the 5 year average for GB rivers. This is certainly not unprecedented but it is still pretty bad, especially coming off the back of 2013. However both years had very poor weather for angling and in both years netting catches were much higher than average. If 2015 turns out to be reasonably wet then I would expect catches to be back to around the 5 year average. The weather is probably the biggest single influencing factor in rod catches and therefore it is a mistake to see them in isolation.

    There is almost certainly some under reporting by tenants and over reporting by owners. I think changing preferences as to method make a huge difference. Greater access and more rod effort will also have a big effect. There are numerous other factors that have changed over time and no one really knows the answer.

    The point is that government has to make decisions. These decisions should be made on the best scientific evidence available. As far as Scotland is concerned MSS provide that data. There are many posters on here who feel they know better than MSS and who believe they have better data. That may well be so but lets have it and your workings rather than an assertion that there were more fish about in the old days.

    Rod catch data, warts and all, is going to be the mainstay of calculating stocks until we have far more and better counters. I'm quite sure that many in the accidental coalition of let them all goers, their friends in the Scottish government and their friends in salmon farming would be quite put out at good evidence being available.

  8. #8
    Join Date
    Aug 2008
    Location
    Yorkshire (were there a god it'd be god's own country) & Afrique
    Posts
    3,812

    Default

    Of course there are issues with them, overall we have to assume the level of underreporting / "stretching the truth" etc. is relatively constant in these days.

    EA and MSS use them as indicators. EA use them to base their CLs on, but that's another matter...

    There is an MSS paper that compared counter data with rod catches, and found relatively good correlation.

    This can be demonstrated to be relatively good for a number of counters, e.g. N Esk: Rod catches increased in line with counter increases (and conversely during the low flows of 2013 [and probably 2014 - data not yet available] also crashed in line with the counter decrease!) More on that later in another thread to demonstrate the point.

    ICES use them to estimate stocks, or not in the case of C&R'd rod caught fish (they are not counted!)

    Of course it's easy to sow doubt about such methods, and good accurate returns that show effort are best of all - CPUE appears a much better indicator of stock performance than just rod catch. After all we anglers like working out the rough CPUE before committing to fishing; (e.g. "look at the huge numbers caught at Park!" - "Yes but it fishes 12 rods" - This was obviously a few years ago when the beat was rodded up and had fuish in).

    That's one of the advantages of e.g. Naver/Helmsdale where rod numbers are the same as they've been for decades but the rod catches are still doing well (apologies Ron )

    Is they Tay's poor performance over the years just down to the reduction of bums on seats? With EA data we can tell - the Severn rod catch has gone down, but CPUE has gone up - less fishers catching more fish with less effort.

    However with MSS data, which does not record effort, anyone can claim anything.

    Rod catch, CPUE, with QA/QC by counters where possible (which ideally would be at the mouth of the river, differentiate fish, work in turbid conditions when TSS is high, and not be bypassable with a few feet on) would be ideal, but it's not an ideal world.

    Nowt better, mind.
    "...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

  9. #9

    Default

    Quote Originally Posted by Loxie View Post
    The consensus in government, in Scotland at least, is that stocks are rising. see MSS status of Salmon and Sea trout stocks 2013.

    Rod catch data is always inaccurate, but usually consistently so. Take the 5 year averages over a long time frame and they give a fair indication of whether stocks are improving or declining. Add in counter data where available and netting and fixed engine returns and you get a picture that while in no way wholly accurate is a good indicator of stocks. That is exactly what MSS do and why they have draw the conclusion that they have i.e. that stocks are improving.

    2014 is looking like being about half the 5 year average for GB rivers. This is certainly not unprecedented but it is still pretty bad, especially coming off the back of 2013. However both years had very poor weather for angling and in both years netting catches were much higher than average. If 2015 turns out to be reasonably wet then I would expect catches to be back to around the 5 year average. The weather is probably the biggest single influencing factor in rod catches and therefore it is a mistake to see them in isolation.

    There is almost certainly some under reporting by tenants and over reporting by owners. I think changing preferences as to method make a huge difference. Greater access and more rod effort will also have a big effect. There are numerous other factors that have changed over time and no one really knows the answer.

    The point is that government has to make decisions. These decisions should be made on the best scientific evidence available. As far as Scotland is concerned MSS provide that data. There are many posters on here who feel they know better than MSS and who believe they have better data. That may well be so but lets have it and your workings rather than an assertion that there were more fish about in the old days.

    Rod catch data, warts and all, is going to be the mainstay of calculating stocks until we have far more and better counters. I'm quite sure that many in the accidental coalition of let them all goers, their friends in the Scottish government and their friends in salmon farming would be quite put out at good evidence being available.
    I just finished some e-mail correspondence with the New Brunswick Department of Fisheries people on this same subject. They don't use rod catch for the Miramichi because they are harder to get accurately due to public access and diffuse ownership of the fishing. They use mark and recapture and some of its inaccuracies were discussed. There are plenty of issues with this method too. As Springer points out this the best available data and all that we really have to go by.

    It is amazing how fast things change. After the great year of 2011 everyone thought these fisheries were on an upswing. The last three years have all been down. We have hit record low numbers in more or less each of these years. Our parr counts have remained consistent. The problems are largely at sea. The Scottish government is going to have to be more on the ball than to think numbers overall are increasing... Maybe this is just a couple of bad years and all will be rosy again soon, but when the official estimates of many of the runs is the lowest ever recorded you have to be really concerned.
    There's a fine line between fishing and just standing on the shore like an idiot. Steven Wright

  10. #10
    Join Date
    Aug 2008
    Location
    Yorkshire (were there a god it'd be god's own country) & Afrique
    Posts
    3,812

    Default

    Actually, as a further thought, the point is that folk raising doubt about the accuracy of rod returns or e.g. netting CPUE, are often the very ones saying salmon stocks have crashed. On what that basis do they say stocks have crashed?

    Two years very poor fishing, which gave relatively low rod catches 2013 and 2014... or the global decline in netted salmon numbers. But 2013 was not a collapse compared to 2003 - it was much better, on the basis of the reported numbers.

    Now netting is a fine example. Salmon are said to have crashed because netted salmon numbers declined. But the crash occurred post 1980s fish farming when aquaculture fought a war (and won) to put netters out of business. There's a nigh-1:1 correlation between netted effort and net catch of salmon in available Scots data. There are two alternatives:

    • either that salmon are not there to catch (not borne out by record rod catches in the period 2004-2012, nor by record counter numbers on a few rivers) , or


    • that salmon are there (supported by the counter numbers and 2004-2012 record rod catches) but are not being caught because netting effort is so low and expansion of netting is not contemplated


    Of course we have our biases.

    Then it becomes a personal thing. And of course, it is highly political, and the lobbyists of the SCS and SSPO appear aligned against us anglers...
    "...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

Page 1 of 10 123 ... LastLast

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •