Some further thoughts on the use of salt

[carpepecheur]

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.

Edited January 9, 2020 by carpepecheur

[oscsha]

What would you class as an average 'carp' lake ?

 

[greekskii]

2 hours ago, carpepecheur said:

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.

I’d say a vast majority of lakes are freshwater. Definition being 0ppt. Freshwater Fish have a naturally high salt concentration in their body. The salt wants to transfer over to the weaker solution, that being freshwater as it has no salt in it. Freshwater fish tend to lose salt and absorb water. This is why they have efficient kidneys which can excrete water very quickly. Sources of salt for freshwater fish are mainly reabsorbing it from their urea before it’s excreted, clay & food items. I would assume that it is not necessarily sodium chloride that is required, more so just sodium in general to maintain the sodium:potassium balance required for osmosis. 

[carpepecheur]

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.

[greekskii]

22 minutes ago, carpepecheur said:

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? 

I dont think even the scientists know about salt turnover and replenishment. I think you'd be looking at small amounts at any one time. I did look it up with my research but what's out there is very minimal to be perfectly honest! My guess is that the more active a carp is, means the more salt it needs? 

32 minutes ago, carpepecheur said:

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?

Research out there suggest that things like caddisfly, mayfly, etc larvaes are not tolerant of salinity at all whereas shrimps, snails, etc. actually can tolerate it. This study actually found that at low salinity levels and at over 8ppt all freshwater inverts sampled had higher mortalities however at levels between 1.5 - 2.2ppt there was no more moralities than at freshwater. Again the tests are done with salt water, not salt laid bare on the ground. I am with you and think that a large deposit of salt crystals laid direct on the lake bed will basically burn it and create a dead zone.

[salokcinnodrog]

13 hours ago, chillfactor said:

Nick,  put some photos up years back of a pile of pellet that was dumped in the margin . Killed the lake bed as it rotted down , left in bare . Point being lots of items lobbed in lakes in high quantities have the ability to cause the effects you mention , if they weren't eaten or disturbed .  Not a salt user myself so not trying to defend anything. 

Really good read so far 😎

Good memory Mate. Those pellets were there for months, and fish avoided even swimming over them.

I was digging around when this 'salt craze' started with my concerns. 

Now most baits do contain salt, sweetcorn ( tinned is often in a mix of salt and sugar), your boilies will contain salt as standard, often as a preservative as well as in the ingredients themselves.

 

There has been various research relating to adding sodium chloride to the carp's diet as carp are often used as a food source in poorer countries, so best growth is required. I recall finding one from University of Chicago that at 5% of the diet, growth and conversion to protein stopped totally.

The University of Basrah did a big study which the optimum amount is 1.5%.

It is a pdf file if anyone is interested

 

I'm still not a salt user myself; I don't add it into my particles or groundbait or my boilies.

I could come up with various questions like 'at what point is too much?', but that has all been said before.

 

I'm certain that even with undertow not all dips and troughs get flow through them, there is a 'barrier' between the main water and the water in the dip. 

[carpepecheur]

12 hours ago, oscsha said:

What would you class as an average 'carp' lake ?

 

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".

[carpepecheur]

1 hour ago, greekskii said:

I dont think even the scientists know about salt turnover and replenishment. I think you'd be looking at small amounts at any one time. I did look it up with my research but what's out there is very minimal to be perfectly honest! My guess is that the more active a carp is, means the more salt it needs? 

 

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.

Edited January 10, 2020 by carpepecheur

[greekskii]

11 minutes ago, carpepecheur said:

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.

1g of salt per Litre is what it is. One teaspoon of salt weighs around 5.5g. Let’s get very rough here, it’s the same as putting just less than half a teaspoon of salt in a 2L bottle of water. 

[yonny]

45 minutes ago, carpepecheur said:

Apparently Mark Holmes, who people often quote as an authority, suggests that carp need more salt in spring

It worries me that he's quoted as an authority. He's without doubt a decent angler and I do enjoy listening to him but I find he can be prone to contradicting himself now and again.

[carpepecheur]

I repeated the earlier experiment with some water disturbance as Yonny suggested. This time I pricked a tiny hole in the bag to help it dissolve quicker.  I first tried to simulate a carp thrashing around then I introduced some undertow. I have a clock at the side so you can see where I have speeded the footage up. There is a very faint colouring in the upper layers but most of it stays near the bottom althought not as concentrated as the earlier test.

 

 

 

Edited January 10, 2020 by carpepecheur

[yonny]

I don't think it's possible to effectively simulate undertow with this set up. I certainly don't think a couple of blasts through a blow pipe can replicate the effects of undertow.

I'm also not convinced that the little paddle jobby gives an accurate representation of the water displacement caused by a carp. They are pretty big and very powerful.

[carpepecheur]

Yes, I agree Yonny. It was only an indication and best I could do at the time. What was interesting was that with just a tiny prick of a hole in the bag, it collapsed almost immediately. Did you notice the wave of salt solution wash around the bottom of the tank? The undissolved (presumably due to contact with salt) remains of the bag floated to the top.

 

The only scientific method I can think of is to use salinity metres in a real lake and actually measure this in a real situation. Unfortunately, now that I have retired, I no longer have access to such equipment.

 

My experience is that when you are able to make precise measurements the results do not always agree with theory. Despite everyone telling me it was impossible, I once proved that Brighton goes up and down with the tide.