carpepecheur

You seem to confirm what I have been discovering which is that not enough is known about the exchange of salt. I suspect the actual amount a carp needs is incredibly small compared to the amount anglers might throw at the problem (even assuming it is a problem) Apparently Mark Holmes, who people often quote as an authority, suggests that carp need more salt in spring. Am I correct in thinking that salt is lost in two ways – by excretion and by osmosis (the denser body fluids moving towards the less dense water)? If this is the case, maximum secretion and hence salt loss takes place in summer when carp are consuming more and the water is warmer therefore less dense. When you talk about ppt, I have been trying to visualise what that number looks like. If my (dodgy) calculations are correct 1 ppt is like putting an average egg (30 ml) into 2,400 full size (50M X 25M) Olympic swimming pools 1 metre deep.

Sorry oscha, i missed this post earlier. I did not mean to ignore or avoid your question. I simply meant any lake containing carp. I was wondering if there was a very low level of natural salinity present but the answer to that question is "no".

Thanks again for the info and education Greekski. Out of curiosity do you know how many milligrams of salt (or should that be sodium ions?) a carp of say 10 lb weight needs to replace in a year? Is there any particular time a carp needs more salt and if so why? Most posts I have seen defend the use of salt by quoting how much the carp can tolerate as evidenced by experts like koi keepers. Do you know which aquatic life is most affected by salt and what level in ppt that might be? Sorry to be a pain but I find the subject very interesting.

Huge respect to you for your chosen career Greekski. So are you saying there is zero ppt salt in an average carp lake or are you referring to pure water? If there is no salt in the water where do the carp get their salt from for their natural osmoregulation? Your point that anglers are hypocritical professing care for the fish then hooking it out of its environment on a metal hook is very well made. Because of my over thinking nature, I have struggled with this dilemma a lot. I still go fishing. A lot of anglers care a great deal about their environment but far too many do not.

"Why pick on the poor old salt granule" Because, unlike bait or weed removal, the evidence I have seen suggests salt has an accumulative effect. Bait disintegrates, weed grows back but salt just goes on building up. People thought a few bits of plastic would have no effect on the vast oceans - well we are better educated now ---- aren't we? However I proudly accept your criticism that I over think things. Yes I do.

I am learning a lot from this discussion. Greekski, you said carp can osmote (I think I just invented a new verb) better in a salinity of 2PPT. Do you know what the typical salinity of a carp lake normally is? I have no idea myself as I am not a biologist but I am curious. The point I was (badly) trying to make is that the danger is not to the carp directly but to the aquatic flora and fauna on and in the lake bed. I repeat I am not a biologist but I suspect some at least some of it has a lower tolerance to salt. Surely we are [censored]ing up the aquatic ecosystem by adding salt even by just a small amount just to give an edge to our fishing. My comment about not understanding the water table was to say I do not understand how salt can be purged from a lake by diffusion or filtration through the water table, especially as the consensus seems to be that the salt is distributed throughout the water column and not as I hypothesise forming a layer on the lake bed. I am fairly convinced by the evidence I have seen that salt accumulates. The idea seems to be that the amount of salt polluting our lakes by anglers is so small we should not worry about it. Well when we started dumping plastics in the oceans it was thought they were so vast in expanse and depth it that surely it couldn’t do any harm. Now generations later we are somewhat wiser (although still not doing enough about it).

Yes totally agree. I have just the spot in mind. It is an enclosed and gated lake with hardly any fishing activity. It holds a huge head of carp at around the 10 lb mark. There is a shallow area dropping off into deep water. I have already tested the use of raw maize there and the carp hoovered it all up. Watch this space.

Mark Holmes apparently watched carp dig a hole around some sticks of rock salt and came to the conclusion that carp were attracted to salt. It is a reasonable conclusion to come to. However my interpretation of that observation is that the salt kills all the small organisms within a small area and the carp move in to eat them. I believe Mark Holmes suggestion is they do not eat the salt but rub against it to absorb salt into their bodies to replace that lost over winter. If that is the case why dig a hole? If, on the other hand, the salt had penetrated a small distance into the silt, the carp would dig to find even more dead organisms to eat ths supporting my suggestion. I can't find any scientific evidence that carp actively seek out high salt concentrations of salt for their osmoregulatory process. The process takes place naturally from salts already in the system. If, has been suggested, that they are attracted to an area baited with salt, how much do they need and how often? I would guess that one block of salt would serve the entire fish population for many months. It seems self evident that the actual amount of salt they actually need is incredibly small compared to the amounts being spodded in by anglers. Yonny, I see you have a theory that salt does not sit on the bottom and kill everything. Other than wishful thinking how do you know? Sure there is disturbance by water currents and fish activity but my simple experiment suggests a fair amount of salt at toxic levels will rest on the bottom causing damage to aquatic life. I have access to an unvisited lake and next spring I am going to make some PVA salt water bombs and see what happens in a real environment. Meanwhile I think the best approach is - if in doubt leave it out.

That's a good point. When I cleaned the tank the lead weight I used was covered with a gloopy mess. I wonder what would happen to a bag of sweetcorn? Lots of stuff to investigate and so little time.

No I didn't. The reason was I was surprised by how slow the PVA took to melt and did not want to disturb it. We know that adding salt to a mix allows you to put a wet mix in a pva bag without it melting but I expected it to dissolve from the outside very quickly. What seems to happen is a skin forms inside which doesn't fully dissolve. The sequence after the bag was in the tank took about 15 minutes. I speeded it up because it was boring to watch. I will try as you suggest and see if it disperses quicker through the water or if it settles back down again. I am also interested to see how it disperses in the water over time.

Thanks for comments. Just what I was looking for. In reply :- “you were very surprised but the result of this experiment but I think the result was exactly what you and I expected” I was expecting some separation between the denser salt and the water but I was astonished that the salt remained so concentrated in such a very thin layer on the bottom of the tank. “To replicate those volumes in a water body of any significance would take many thousands of tonnes of salt at a guess.” I used about 10 ml of rock salt and it covered about 0.1 square metres. That equates to 100 ml per sqr metre. A 5 acre lake is roughly 4000 square metres so it would need 400 litres of salt to entirely cover it under the same conditions. That is not a huge amount. Roughly 1000 kilo. Ok this is under laboratory conditions and there are many variables in real life. I suspect the salt solution would roll down hill and fill up hollows and low spots. I have no idea how long it would take to diffuse through the water column. I feel another experiment coming on. “If we imagined that the salt did stay in a concentrated area when introduced to a large body of water it could certainly go some way to explaining why "salting a spot" can be so effective, particularly on rich, weedy waters. It'd clear the spot nicely ready for perfect presentation.” Yes, that is precisely my point. You create a mini desert in that area. I believe that, when salt is initially introduced, it kills off the microorganisms and the carp move in for a free lunch. However it leaves behind an inert bed. Is that what we really want to do? “I think the statement that still waters have no natural mechanism by which salt can be removed is misleading. Salt is water soluble and the water in lakes is constantly recycled through natural water cycles (rain vs. dispersal through groundwater). In the concentrations used for carp fishing this has a negligible effect (imo) on a water body.” This is a relevant point and I have no understanding of how salt may disperse through groundwater. I would suggest that even if it does, it has already done its damage to the lake bed. “ anglers rarely use a saturated solutions (did I see undissolved salt in the glass before it was added to the pva bag?) “ Yes I just put in a tablespoon of salt into a glass. But surely if people are putting a salt lick into a swim the initial solution in direct contact with the salt is saturated so the demo is not that representative “for me, it's a moot point however, as I for one don't use salt in my carping,” I think that is the attitude everyone should adopt. “It's more a case of them needing it than liking it. It's a mineral that is very difficult for them to obtain in a freshwater environment and carp need it to function.” I am not sure I agree. Is there any evidence for this? Carp seem to have evolved for thousands of years without the need of extra salt added artificially. I have never come across a case of carp suffering from a lack of salt. But I could be completely wrong. “I agree with you that anglers should be aware of possible dangers but imo that "oh well" decision couldn't possibly result in the hundreds of tonnes of salt it would take to even match the salinity levels preferred of their tanks by koi keepers.” I have been trying to demonstrate that it is NOT the levels of salt that the Koi experts find acceptable that is the danger. It is the much smaller amounts that endanger microorganism growth.

This is France where the main occupation is making rules and the major passion is swerving round them. I totally support the rules relating to transport or return of live crayfish. I am guessing the other rules restricting their catching were designed years ago when it was legal to catch the native species and was an attempt at preventing overfishing them. Despite fishing little used and remote locations I did once get caught by a garde de peche (bailiff) in possession of 150 crayfish. He simply gave me a warning, explained the rules and then showed me the correct way to kill a crayfish. These days I always take my dog with me when I am fishing and he gives me plenty of warning if someone is coming so that I can ensure I am not breaking any rules.

In a recent thread about bait, I expressed my concern about the safety of using salt when carp fishing. It has been niggling me that I did not make my concern known very clearly. I set up an experiment to try and demonstrate my thoughts more clearly. I would be interested if anyone else shares my concerns.

I find crayfish a deadly bait for carp. Unfortunately, their use, here in France, is covered by complicated rules. First you have to catch them. Considering how prolific they are, it is less easy to catch them legally. As I understand it, the use of traps is forbidden as is also catching them by hand. You can only use rod and line (maximum of 4) or a drop net – called a “balance” (maximum of 6). A fishing licence is also obligatory. Once you have caught them, you must kill them (unless they are the very rare native species in which case you have already broken the law). They may not be returned alive to the water or transported live away from the water. From memory the fine is an eye watering 22,500 euros (the same fine as transporting live carp), However, having obtained a bucket of dead crayfish, simply mash them up as small as possible and mix it in with your ground bait. I have found this very effective. I am sure you could also extract some “juice” to put in your boilie mix. I believe crayfish make an excellent hook bait but the rules state that the use of a crayfish for such use is illegal. It does not specify live or dead. I would not be caught using one Alternatively, you can take them home and make crayfish bisque which is a dish to die for. I have a recipe if anyone is interested.

Planning to spend some time fishing a new lake next year on an abandoned estate. I need to install some stepping stones across the boundary stream so I don’t get wet every time, make the hole in the fence bigger but not so big it attracts attention and undesirables, hack a short cut through some very dense brambles and clear a swim to make it fishable.

I love that expression. Whether cooked maize is more attractive than raw maize is a different question. I have left piles of both side by side overnight. In the morning it has all gone. Whether they took the cokked before the raw, I couldn't say. However I am fishing waters with hardly any pressure from other anglers.

I totally agree with what you said Yonny but you seem to infer that it is therefore safe to send out a few spodfulls of pink Himalayan rock salt. I think you are wrong and will explain why I think that. There are three very simple experiments you can do to help understand my concerns. 1) Put a blob of that bright green goo stuff, that I have seen on UK web sites, onto the bed of a lake where you can observe it. You will notice that, because it is heavier than water, it spreads out along the bottom of the lake. (Actually there are youtube videos showing this to save you doing it yourself.) 2) Drop a couple of sugar cubes into the bottom of a cup of tea, without stirring, then drink it slowly straight away. You should notice that as you get to the end of the cup it gets sweeter and sweeter. (not rocket science is it?) 3) Get some live daphnia from a pet shop where it is sold as fish food and watch them swim around in a glass of water. Drop some rock salt to the bottom of the glass. You will see that the daphnia move towards the top of the glass to get away from the brine and then eventually die. What I think happens when you spod out a dose of rock salt is that it takes a finite time to dissolve. As it dissolves the water around the rock salt becomes extremely salty. This strong brine is heavier than water and sinks to the bottom where it spreads out much like the goo. The salt continues to dissolve adding more strong brine to that already on the lake bed. Eventually the salt completely dissolves and the brine solution continues to disperse in the lake until it is virtually undetectable. BUT by then the damage has been done. The strong brine first brings all the small organisms up from the silt and then kills them (a bit like catching razor fish that I mentioned earlier) . This is may be why rock salt appears to attract fish. The carp move in and eat all the small dead organisms and, if there happens to be a bait in the area, they take that as well. So each time a spod of rock salt is cast out, an inert mini desert is created where all food has been destroyed. It may only be a metre diameter but you can see how it won’t take many anglers to do quite a bit of damage without even knowing they are doing it. Unless you can prove me wrong I suggest we stick to our principles established earlier and avoid the use of salt.

That was an interesting article but it did not quite give the whole picture. Salt water at 0.3% concentration is only used to treat fish when there is a specific problem in a Koi pond. Even if the fish can survive, it has other effects. If salinity levels reach 0.10% or above - anacharis, water hyacinths and lotus will not be able to live in the water. If salinity levels reach 0.20% or above - lavender musk and water lilies will not be able to live in the water. If salinity levels reach 0.30% or above – the majority of other aquatic plants will suffer. This includes forget-me-nots, zebra rush, cattails and floating hearts. (Source of info :- https://www.allpondsolutions.co.uk) I remember reading an article where a famous name placed a salt lick in a lake and observed what happened. Eventually carp were attracted to the area and, over time, completely cleared the area of weed and even left a shallow depression where they had been feeding. His conclusion was that salt is a great attractor. My conclusion from his observation was quite different. If you have ever been out and caught razor fish on a beach at low tide you will understand. The technique is to pour a little bit of salt into their hole. After several seconds the razor fish comes up and sticks out above the surface to get rid of the irritant. (They are delicious to eat and make a superb bait for Bass). I guess something similar is happening at the salt lick in the carp lake. I suggest that as the salt lick dissolves it creates a very strong salt solution locally before being dispersed in the rest of the lake. This concentrated salt solution, being denser than freshwater, spreads along the bottom disturbing and eventually killing all the microorganisms that carp like to feed on. This provides a ready feast for carp who move in and make a killing while it lasts. This then leaves an inert cleared space which the name reported seeing. This is pure speculation on my part but just as likely as the explanation that the carp are therefore attracted to the salt lick. So using our established logic we should avoid salt. Coming back to your 24 tons of salt in a one-acre lake, I believe this to be rather misleading. Apart from the damage it would do to other pond life, if you are spodding out lumps of salt it will be in a relatively small area. This will cause very high concentrations locally and do damage before it is dispersed generally into the lake. In addition, salt water is denser than fresh water so will form underwater pockets of higher concentration doing further damage. Because the article appeared in a (presumably) respected carp magazine it is accepted without question. Using our established logic, we should avoid such practise.

Sorry Yonny there was no criticism intended of this friendly, experienced and often well informed forum. Perhaps I should have used the term “general consensus in carp fishing” instead. The logic being applied in the raw maize discussion seems to be:- although there is no direct evidence, one can imagine a situation in which expanding maize can harm a fish therefor it is better to err on the side of caution and not use it. To which I say, if that logic holds up, then that logic should be applied consistently. You asked for an example so I suggest the use of salt. Carp cannot exist without salt, so the argument goes that extra salt in bait or in the environment helps to replace that needed by the carp and is therefore attractive to them and beneficial to their health. I can find no evidence of carp in a normal lake suffering from lack of salt. Of course it has to be the right kind of salt and Himalyan rock salt seems to be de rigueur for carp fishing. However, there is plenty of evidence of too much salt being toxic to most forms of life. It is easy to imagine that too much salt can cause harm to a fish but how much is too much? Therefore, using the logic we have already established, we should avoid the use of salt completely.

There seems to be a clear implication on this forum that the use of raw maize should be avoided because, despite any clear evidence to the contrary, it can be imagined that the maize can expand in the gut and harm the fish. I do understand that argument but why isn’t the same logic applied to other aspects of carp bait?

I am sure Hinders are "reputable", whatever that means. I notice they sell raw maize described as effective and affordable for £1.35 per kilo (if you buy their largest economy pack) plus £13 shipping. I can drive to my local shop and buy it for 25p per kilo. I could drive to a local farm at harvest time and fill a trailer full of the stuff for a fraction of even that price but I can only store so much. If I wanted to proves that using raw maize was actually harmful to fish, personally I would not cite Hinders as a source of scientific knowledge. If I could not find experimental evidence that an expansion of 10% in the gut of a feeding and excreting carp transended the elastic limit of that gut, then I would expect to find at least some Bayesian inference to support that hypothesis. I have been unable to find either. I am simply asking for help in finding such evidence to justify changing my approach. Isn't that what forums like this are all about?

Yes I have investigated tiger nuts. They are a different animal to maize. I drive to Valencia where a lot of it is grown and buy sacks of the biggest and freshest "nuts" I can find. Here is a suggestion, Instead of soaking them in water, soak them in Tiparros fish sauce, available in bulk from chinese supermarkets. I found it vey succesful and yes tiger nuts do swell up a lot compared to maize.

That is exactly right, it is all about risk and, as you pointed out, you and I fish completely different types of water. I have assed the risk. I have actually measured the worst case scenario when using maize. I have scoured the imternet without success for any properly scrutinised, scientific evidence of raw maize causing damage to fish. If anyone has any links I am definately open to changing my mind. Since the day dot, people have been worshipping various gods. That does not make me religious. "Put and take" lakes are not my cup of tea but if someone has spent vast amounts of time and money establishing a fishery I guess they are entitled to make up any rules they want which they think will protect their investment.That does not make them right. That is a different argument. If you want to feed your fish then I guess HNV baits are the way to go but they cost money and , as an impovorished pensioner, I am happier with 25p per kilo maize. The fact that it does not quickly meet the nutritional requirements of a carp is a plus point as far as I am concerned. It means the fish need to eat a lot more bait to get what they need from it. Getting fish to feed and keeping them going is, in my opinion, a sensible tactic. I groundbait regularly and in quite large amounts but have never seen bait go rotten or witnessed distressed fish afterwards. I realise Yonny, that I am paddling a lone canoe. I am not trying to change anyone's tactics. I am simply amd constantly looking for information to test my personal conclusions.

I believe Hinders is a supplier of bait for carp. Would you not think that they have a vested interest in making baits seem more complicated than they need to be? You said “Unfortunately fish have died because of problems with swelling”. I have found no direct positive evidence of this (plenty of speculation). Do you have a reference? Just for the record, the owner of the lake where Benson died found some uncooked tiger nuts nearby and suggested Benson was poisoned. The taxidermist who prepared Benson for mounting found no trace of particles and suggested the cause was gravidity as he saw evidence of spawning. I am not aware of any formal autopsy being performed. I have no desire to encourage harm to any animal but I do like to make informed decisions.

Sorry Goldie, the stomach comment was an easy cheap shot and not germane to the discussion. I should explain that I used to be a surveyor and have a hang-up about measurement. I did a small simple experiment. I filled a glass with water then poured in some maize until it was level with the rim. I waited 17 hours and observed how much it expanded. I scraped off the corn which had expanded above the rim and weighed it at 56 grams. I then weighed the total amount of maize and it weighed 548 grams. I conclude that the volume has expanded by 10%. I also observed that most of the expansion occurred in the first 6 hours. Now if we assume that the carp did not grind down the maize with its pharyngeal teeth before swallowing and it ate the maize straight away before it had time to start absorbing water, and that it continues to expand during the feeding period as digestion takes place, the absolute worst expansion it can experience is 10%. I am no biologist but I feel fairly sure that any expansion of maize after a carp has swallowed it is not going to kill it or cause any serious problems.