cave trout : how are they disseminated ?

Andyj23UK

New member
hi - on sunday - I made the acquaintance of 2 cave trout [ bona fide brown trout of aprox 5 and 8 inches length ] in dr bannisters hand basin [ the upper most section of upper long churns ]

which got me thinking - how did they get there - and what is their survival chances ?

there is a theory that fish eggs can adhere to the fir / feet / feathers of birds or aquatic animals [ otter ? ] and be transported to unreachable sites

but this is a disputed theory [ to put it politely ]

and of coutse I cannot rule out the notion of some cavers carrying a bucket up there with fish they have " acquired " just to stock the cave

I discussed it yesterday with a caving companion who opined " could a fish egg survive regurgitation from a gull ? " a plausible idea I had not considered

any other ideas or theories on this

I have double checked the maps - and topo - and personally cannot see any realistic migration path for fish to get to a point that they could swim to or be flushed into dr bannisters

TIA
 

Pitlamp

Well-known member
If you're seriously interested in this one then you need to make contact with BCRA's Biological Recorder, who is probably the best person in the UK caving community to answer that particular question.
 

JeremyG

New member
Some years ago a friend dug a (big) pond for Trout but after only a couple of years Carp appeared. This was not in such a remote location but the transfer by birds theory does stack up.

There are lots of caves with fish and I have often wondered if there is enough food in the streamway for them to survive.
 

pwhole

Well-known member
I believe there are many ways eggs can be transported about by other animals. New ponds on surface will 'acquire' fish after a few years, even if only sticklebacks and minnows to begin with. Think of them as the 'silver birch' of fish, colonising new areas. Additionally, eels can travel overground breathing air, as long as they're wet, and may well take eggs along with them adhering to skin or whatever. Mind you, eels aren't normally found in chalk streams or cave systems, but I suspect there are a myriad of ways for trout to survive in unusual habitats.
 

Blakethwaite

New member
There are what I take to be eels in the Milwr Tunnel which takes a good deal of its water from cave systems. I have no idea whether they hold exclusive rights over other fish however...  :doubt:

Back on the subject of trout, the caves & mines in the Dales I can think of with trout (or trouty looking fish anyway...) in them seem to always have them which if nothing else suggests that feeding & breeding in such conditions is not something that is problematic, perhaps suggesting long-term residency?

Hungry now!
 

gus horsley

New member
Andyj23UK said:
I discussed it yesterday with a caving companion who opined " could a fish egg survive regurgitation from a gull ? " a plausible idea I had not considered

TIA

It's not likely. Gulls in particular have probably some of the most corrosive digestive juices in the animal kingdom.

However, there is the possibility that they could represent the remains of a pre-glacial colony which entered the system before Alum Pot formed by swimming up the stream which formerly ran down the dry valley leading down to the road.  This isn't as far-fetched as it sounds as other isolated brown trout colonies (such as in Ireland) have been proved to be pre-glacial relicts by DNA comparisons.
 

Peter Burgess

New member
Gus that would make these fish a valuable scientific feature. Can the same be said for some of the cavers you meet in caves? Pre-glacial community?
 

bograt

Active member
I certainly feel pre-glacial most of the time but you are unlikely to meet me in a cave these days, nasty, dark, muddy places. :unsure:

Re; the trout, were they coloured, white, or transparent?, blind, or not?, how big?.
 

cavermark

New member
bograt said:
I certainly feel pre-glacial most of the time but you are unlikely to meet me in a cave these days, nasty, dark, muddy places. :unsure:

Re; the trout, were they coloured, white, or transparent?, blind, or not?, how big?.

..how did they taste?  :eek:
 

martinm

New member
JeremyG said:
There are lots of caves with fish and I have often wondered if there is enough food in the streamway for them to survive.

In the Manifold Valley we have numerous swallets with fish and other wildlife in them to provide a plentiful food source. For example:-

In Ladyside Pot the first downstream sump is full of Bullheads and if you look in the pools upstream in the cave after the river has just gone down there are worms, leeches and shrimps.

In Redhurst Swallet we have personally seen Eels and the odd trout which presumably been washed in and there are lots of similar foodstuffs for them too. The Eels bury themselves in the silt until the cave floods again. The Fourth sump is also called Bullyhead Sump for a reason!

In Darfar Pot I have seen sizable Trout in the river entrance before we let it silt over and the terminal sump had numerous fish in it when I dived it in the 80's. Again, the silt banks contain worms etc.

None of the fish are white or blind as far as I know and so have probably been washed in during floods...

Regards, Mel.
 

Aubrey

Member
Sometimes fish are dropped by freak weather storms. Is it possible the ancestors of todays residents were dropped upstream of the caves?
 

bograt

Active member
I'm inclined to think along the lines of egg transfer by animals, maybe even a pet dog, they only have to drink in the river in the valley, pick up a few eggs on their muzzle fur, then drink in the stream.
 

caving_fox

Active member
Mind you, eels aren't normally found in chalk streams or cave systems, but I suspect there are a myriad of ways for trout to survive in unusual habitats

There are eels (about 1ft long when I saw one recently) in Doolin river cave (Ireland). White coloured so adapted there for some significant time. I'm not sure about blind. The white fish also found there have eyes, but don't seem to respond to much.
 

bograt

Active member
Fisherstreet Pot often fills to the top in flood so it would not be difficult for eels to swim in from the sea, there is also the obvious underwater connection to the bay.

I have also seen white and transparent blind trout in Little Neath, they do have eyes, but they don't seem to have functional pupils (like severe cataracts). 
 

Subpopulus Hibernia

Active member
caving_fox said:
There are eels (about 1ft long when I saw one recently) in Doolin river cave (Ireland). White coloured so adapted there for some significant time. I'm not sure about blind. The white fish also found there have eyes, but don't seem to respond to much.

There was an article in Irish Speleology in 1965 on a trout specimen taken from the Doolin River Cave. The specimen was small and white. On being returned to daylight it turned darkened considerably within 24 hours. It's eyes were said to be normal, though the cornea was somewhat clouded. It was underdeveloped and generally in poor condition. The conclusion was that the trout had'nt been in the cave all that long.

The Doolin river Cave trout are probably washed in as fry from the Aille River, a surface stream that flows over the cave at points and looses water to the system. Whatever trout get washed in probably don't have the most fruitful of lives, and I doubt that there's enough food down there to sustain a permanent colony. As for being adapted for a significant time, I'd doubt it given given that the trout turned brown once it was brought back to the surface.
 

pwhole

Well-known member
There are white shrimp-like creatures happily swimming around Speedwell's Far Canal, especially around the Bung and Pit Props areas where there's more static water. So if they OK there, then I guess further downstream nearer surface, there'd be plenty for trout to feed on, if they can find 'em.
 

adam

Member
A couple of years ago I went down Diccan Pot and while waiting at the top of the last pitch, I thought I spied a wee fishy in the water. I turned my ageing nova up to its feeble max, and sure enough, there was a pale and rather malnourished looking trout.

For anyone not familiar with Diccan, this section of stream is no more than 10 m long with some large vertical pitches above it and a very large vertical pitch below. The trout was inhabiting a shallow pool with a bedrock floor; not ideal trout habitat. I did feel sorry for it.

Anyway it got me thinking about how on earth Timmy the Trout could have got there. The answer is obviously that there is a self-sustaining population of trout in the stream above Long Churn and that fish are sometimes washed or swim into the caves below, as seen in Dr Bannister's. Once in the caves, the only way is down, so these fish will eventually end up, dead or alive, in the Alum Pot sump. The stream above, called Whit-a-Green Spring, is somewhat less than a kilometre long and on open moorland/grassland. That a population of trout could persist here is surprising enough, but considering its isolation by the cave of supposedly several hundred thousand years, even more so.

I don't buy the 'transported by birds or animals' theory. Having seen and handled trout eggs, I find it completely implausible. I think the most likely explanation, as suggested by Aubrey, is that they have been introduced by people at some point in the past. How long ago is anyone's guess. I also like gus horsley's idea that the fish are relic populations from before the cave was formed. Is it also possible that the fish introduced themselves during a more recent glacial period when there was some sort of hydrological connection to the main river? I don't know enough about glaciers or geology to know how likely or not that is.

I think it would be really interesting to survey Whit-a-Green Spring along with Long Churn Spring and Alum Pot Beck to see which have fish, and in what numbers. It would be even better if a genetic study could be done to shed some light on the origins of these fish.
 

Tripod

Member
I have been interested to see the references to Eels, worms, mud and wonder if some of the Eels and worms could be Brook Lampreys? These creatures spend most of their life blind and living in silt, only developing eyes when they mature, leave the silt, spawn and die. The long-tem problem for Lampreys, as for Trout would be finding suitable spawning sites underground as both have a preferred gravel size in which to make their Redds/nests.
On shrimps, I have seen these in Lathkill Head Cave and swimming on the footpath in Lathkill Dale, below Holmes Groove at times of flood. Apparently these Shrimps live in cracks below the ground/stream bed surface in dry times, emerging when the water returns. What is intriguing to me is that there must be an upstream migration in order to keep the streams populated from the headwaters down and an underground migration at that. For small fish and other creatures a downstream migration to a resurgence and beyond is possible, in places where upstream migration (of fish) would not be. In the Manifold they would have to go deep though!
Any reference to Eels is worth having as they are becoming rarer. I do know that Eels live in some underground places and I have known fish and invertebrate populations in the strangest places, even surviving extreme conditions.
 

adam

Member
We saw a couple of lampreys (not sure which species) in Doolin River Cave this summer.

I remember talking to a diver after he's visited one of the sumps in Matienzo which he said was full of large eels. I think it could have been in Torca la Vaca.

In terms of breeding underground, I think that's quite unlikely, as you say due to lack of suitable habitat. Graham Proudlove  is quite clear that in the UK there are no specialised cave fish, just normal fish which migrate into caves. This is a good video on the subject of cave trout:
https://www.youtube.com/watch?v=Zd71fDdkqL0

From what he says about the Ingleborough Cave trout, that suggests there are trout in Fell Beck. Has anyone seen fish in there?
 

ah147

New member
There's eels in OFD (as well as an otter occasionally).

Shrimp are quite common in sumps...I see them in nearly every one that I dive and I believe they are called "nicaphragrus" or something equally unmemorable.
 
Top