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Clean gravel patches

Karl Heptonstall

Karl Heptonstall

Senior Member
On my wanders down the riverbank I've noticed some patches of clean gravel, usually above some rapids. Is this caused by barbel feeding? I started seeing them around this time last year.
 
Hello Karl

I have also noticed gravel patches or bars this time of year on the Teme ,I m not sure but have thought the current caused it as gravel had built up in some areas , around sharp bends ect , ive seen videos of Barbel hovering around the gravel sucking away at it cleaning it up , Lee Fletcher done a great thread on this a few years back on the old BFW , perhaps you may find it.

Good post :)
 
Thanks for that paul I'll have a look. These patches I've seen are more localised, certainly looks like something's been feeding over them.
 
Was having a paddle in the river yesterday with a fly rod when I spotted a group of lamprey spawning, sucking onto the pebbles and shifting them about. This was on one of the clean gravel patches so either this is the cause or it was just a coincidence. Great to watch
 
How big are these patches Karl? One of the rivers I fish is almost entirely rocks and gravel and clean patches are a reliable pointer to locating fish. Large patches indicate a group of feeding fish grazing over an area. Small patches could be a solitary specimen feeding or perhaps spawning fish. In most cases I believe the gravel is clean due to fish activity on it rather than the fish being attracted to it because it's clean, my reason being I've observed other similar runs in terms of depth/substrate where the gravel appears dark due to algea/detritus which if current/flow was the determining factor these too should be clean. For years I misinterpreted the advice 'find clean gravel and you've found the fish' to mean fish are attracted to such areas - I now believe they create such areas - either way the advice holds true!
 
Some are around a couple of foot in diameter and others around six foot, they look just like fish have been feeding and there are often a couple close together. The surrounding areas are covered in algae so it's easy to see how the fish would clean it up by feeding heavily. It was interesting to watch the lamprey, there were around a dozen and they were sucking onto the stones so you could see how they would soon create a patch. I'd still put my money on barbel creating these patches though!
 
Interesting this . The clean patches of gravel you describe appear relatively small in size . If they are '' cleaned '' by fish I wonder what it is that attracts them to such a small area and apparently feed voraciously ?
 
I agree Mike, a very interesting subject. I have not noticed it in my relatively short time barbel fishing, but that may be because the river I mainly fish is usually not clear enough to notice such things.

However, I did notice it in lakes during my carp fishing years, and a newly cleaned spot was always good for a few fish...until they wised up and moved on. They were definitely feeding spots, as that proved, plus you could induce the fish to create one by constantly feeding small item such as hemp onto one spot.

Sadly, I never did discover why the original spots occurred, what the attraction was. It can't have been blood worm or similar, as they inhabit silty areas...in fact there is very little natural insect life that does exist on gravel in sufficient quantities to induce such feeding activity. Intriguing.

Of course the 'natural' spots may be something quite simple...they may actually be areas where someone else has deposited bait...as in pre-baiting :D

Cheers, Dave.
 
Karl Heptonstall said:
Was having a paddle in the river yesterday with a fly rod when I spotted a group of lamprey spawning, sucking onto the pebbles and shifting them about. This was on one of the clean gravel patches so either this is the cause or it was just a coincidence. Great to watch
Click to expand...

In this instance my money's on the lampreys. I used to see exactly the same thing on the Dorset Stour when the lampreys were spawning.

Regarding clean patches caused by feeding activity, this can often be caused by minnows feeding over beds of small particles such as hemp or micro pellets...it's not always caused by the larger fish species.
 
Shouldn't be caused by fish feeding on bait Tim as I don't think any has gone in, unless someone else's pre baiting!
Could it be a mixture of the lamprey spawning and then fish feeding on the spawn? I have no idea on lamprey numbers in the wharfe but it's possible this could be happening all along the stretch. I'm back out for another paddle tomorrow so will try investigate a few more patches.
 
Clean areas of gravel can be spawning redds, where the female cleans the gravel to allow extra oxygen supply to the eggs. If this is the case then extra caution should be applied if you intend to wade in the area.
 
Interestingly I came across two different groups of lamprey today (seven in the first and a dozen in the next) in patches of gravel similar to those described above. As I posted on the Nidd thread, I easily picked a couple of them up and they weren't one bit bothered by my presence, in particular, the proximity of my boots in the water.

Here's a little more information from a quick google search:

Mature river lamprey, having spent one to two years mainly in estuaries, stop feeding in the autumn and move upstream into medium to large rivers, usually migrating into fresh water from October to December. These mature adults require a migration route free of obstacles – natural, such as waterfalls, or man-made (for example, dams, weirs or pollution barriers) – in order to reach their spawning grounds with minimum effort and delay. During winter and early spring they continue to migrate upstream at night when conditions are suitable, hiding under stones and vegetation during the day.

Spawning in British rivers starts when the water temperature reaches 10–11ºC, usually in March and April (Morris & Maitland 1987).The spawning grounds are areas of small stones and gravel in flowing water. The nest, which may be constructed by up to a dozen or more adults, is an oval depression, 30–70 cm across and 2–10 cm deep. Spawning of each female may take place over several days. The whitish eggs (Hardisty 1964) immediately adhere to sand particles when they are laid, and mostly become embedded in the nest substrate (Hagelin and Steffner 1958; Hagelin 1959).There is a high mortality at this time from various piscivorous birds and mammals, and all lampreys die after spawning
(Larsen 1980).

Here's a link to the article: http://mulkearlife.com/wp-content/uploads/2014/01/lamprey-ecolgy.pdf

What I found interesting was that todays were all river lamprey (as opposed to brook lamprey), were about 30cm long and had negotiated a man-made weir further downstream to get to where they were.
 
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Karl Heptonstall said:
What do you mean by redds Neil? I wouldn't wade over or bellow these patches, just incase it is spawning fish.
Click to expand...

Hi Karl,

Spawning redds I mean where a patch of gravel is cleaned by female fish to deposit her eggs. Although it might not be of course, just a thought, however it might be chub or barbel, or even game fish if you have in that river.

Certainly though these clear patches often are seen to hold spawning Barbel, on the Teme, & Bristol Avon I have observed this, (when these rivers had a good number of Barbel.)
 
Thanks for that Neil, there are trout and grayling in the area and a few chub too. I've also started to spot an odd barbel on the shallows so could be any of them!
Interesting reading Anthony, sounds like you spotted the same as me and they also had to cross a weir.
 
Karl Heptonstall said:
Thanks for that Neil, there are trout and grayling in the area and a few chub too. I've also started to spot an odd barbel on the shallows so could be any of them!
Interesting reading Anthony, sounds like you spotted the same as me and they also had to cross a weir.
Click to expand...

It's interesting stuff Karl, I believe fish 'share' Redds too so could be a combination of a number of fish that spawn there.

Here on the Lower Severn in the Spring Sea Lamprey can be seen below the huge weir in Tewkesbury pairing up for spawning, these Lamprey are as big as a metre long and have a very distinct mottled skin. I have seen these always on clean gravel, close to the bank, along with Chub and the odd Barbel.
 
Could be a combination of lamprey spawning and chub and barbel feeding on the eggs?
 
Looks like your right Clive, I looked at several different spots last week, all had lamprey on them. Today I've been watching barbel, chub and some other fish feeding well over the areas.
 
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