Fish Kill on the Tolka

Bromium

Photo's taken this morning.









I gathered the fish from a short section of the Tolka this morning. There was no sign of any dead fish as I walked past this section towards another section which I know contains better sized fish. As I turned the corner I noticed that the council were removing trees that had fallen into the river with recent winds using quite heavy machinery.

As I got closer I noticed a 1lb fish dead in the water and noticed a lot of debris floating down the river. The river was extremely cloudy with silt and I walked back from the direction I came I noticed the dead fish in the pictures above.

I am wondering if the extreme levels of silt stirred up cold have caused this fish kill as all the fish I gathered up to take a look at had their gills full of silt.

uch

Jesus thats an awful shame, did you contact IFI to let them know ?

Bromium

I sent them an email containing the photos as I could not ring as I was into work straight after.

AlanG

nasty - what section was it at?

Bromium

Violet Hill

thefisherbuy

Wow,


Jeasus If that was on my wild river.....
But Please god they will stock in some fish,

Sorry to hear this.

Bizzum

Bromium wrote: »

I sent them an email containing the photos as I could not ring as I was into work straight after.

You'll be glad to know the Co Co workers reported the fish kill.
There is an emergency number manned 24 hours a day 7 days a week that every angler should have on speed dial an not be playing around with emails.

wgsten

Such a shame, real sorry to read this bad news.

Bromium

Bizzum wrote: »

You'll be glad to know the Co Co workers reported the fish kill.
There is an emergency number manned 24 hours a day 7 days a week that every angler should have on speed dial an not be playing around with emails.

I took the time to document the fish kill and contacted the authorities in the best way possible at the time due to the fact I had to work. So I did what I could even if was "playing around with emails".

Bizzum

Bromium wrote: »

I took the time to document the fish kill and contacted the authorities in the best way possible at the time due to the fact I had to work. So I did what I could even if was "playing around with emails".

I don't for a second want to be critical of your efforts. I'm just pointing out that in my mind this was an emergency. The correct thing to do was report it directly to the authorities as swiftly as possible, before taking photos or gathering up dead fish ( which for future reference is illegal). There is an emergency phone line for precisely this type of incident.

Again I'm not having a pop at you OP. I'm just pointing it out for anyone else that comes across an emergency situation.

Bromium

Bizzum wrote: »

I don't for a second want to be critical of your efforts. I'm just pointing out that in my mind this was an emergency. The correct thing to do was report it directly to the authorities as swiftly as possible, before taking photos or gathering up dead fish ( which for future reference is illegal). There is an emergency phone line for precisely this type of incident.

Again I'm not having a pop at you OP. I'm just pointing it out for anyone else that comes across an emergency situation.

Have the number firmly stored in the phone now which incidentally I didn't have with me only the digital camera. But hopefully I won't need to report something like this again although by all accounts this is the second fish kill in a few months on that stretch. Did you happen to hear how many fish were killed?

Bizzum

Bromium wrote: »

Did you happen to hear how many fish were killed?

I didn't ask to be honest with ya, but you're right, it is the 2nd such incident on this river. Worryingly enough.

tin79

It could well have been the silt. I know from personal experience via my work that trout are sensitive to high levels of particulate turbidity (cloudiness) in the water.

It causes gill damage by fusing the lamellae of the gills and that reduces potential for oxygen extraction. There is usually a critical point that they tip over, go a few turbidity units over and the effect kicks in rapidly.

Small juvenile trout of that size tend to be the most sensitive life stage too. Turbidity from earthworking on that scale will settle quickly as the particles are generally quite large (your picture seems to confirm that) so the effect should not be too widespread (assuming it is the silt that causes it).

Better that than a slurry spill or similar at least.

whelzer

Tin, could you expand on this. I wouldn't have thought silt caused this - I've no expert knowledge in this area whatsoever so I could be talking total crap. However over the years I've seen rivers so flooded and coloured that it it amazing anything could survive, Rivers normally knee high bursting their banks and like treakle? A few days later they tend to fish ok if not great. It seems to me this is just normal nature and trout, insects etc have evolved over 000s of years to cope with such conditions.

A quick google shows this is the 4th recorded kill on the Tolka in 14 years - shocking stuff imho.
Make that 5 kills - just found another from 2002...

Fair play to the people that help this river - uphill battle or what?

Bizzum

whelzer wrote: »

over the years I've seen rivers so flooded and coloured that it it amazing anything could survive, Rivers normally knee high bursting their banks and like treakle? A few days later they tend to fish ok if not great.

I don't know anything about the Tolka, but I can make a general comment:
In flood conditions you have a huge dilution factor, and fish are pushed into hold ups out of the max flow.
An issue like on the Tolka, we are dealing with near drought conditions, very low water levels, relatively high water temps, big demand on oxygen, no dilution factor. It would take very little to cause a problem.

tin79

Bizzum wrote: »

I don't know anything about the Tolka, but I can make a general comment:
In flood conditions you have a huge dilution factor, and fish are pushed into hold ups out of the max flow.
An issue like on the Tolka, we are dealing with near drought conditions, very low water levels, relatively high water temps, big demand on oxygen, no dilution factor. It would take very little to cause a problem.

That's pretty much it. Its down to concentration of silt per litre of water, ambient oxygen levels and the size of the particles.

What tends to happen with turbidity in the water is that you reach a critical concentration above which the gill function is rapidly reduced. The silt particles bind to the gills and block the sites for absorbtion of oxygen from the water.

When you have already low oxygen levels in the water (low water levels lately, unseasonal heat) you get effects that you wouldn't see even with the same levels of turbidity in winter.

In winter the water might look cloudy during a flood but the overall concentration of silt would (could) be lower than in this case because of the greater overall water volume. The effects are also less severe because the water temperature is lower (fishes oxygen demand will be lower too) and the dissolved oxygen in the water will be higher.

Trout haven't evolved a tolerance to high silt levels. They are one of the most sensitive species to it. Coarse fish are much more tolerant of it.

whelzer

Good stuff chaps thanks..

ardinn

Bizzum wrote: »

You'll be glad to know the Co Co workers reported the fish kill.
There is an emergency number manned 24 hours a day 7 days a week that every angler should have on speed dial an not be playing around with emails.

Whats the number?

tin79

ardinn wrote: »

Whats the number?

Unless its changed recently its

1890 34 74 24 or for easier recall 1890 FISH 24

http://www.midlandangling.com/features/poachers-polluters-beware-%E2%80%93-inland-fisheries-ireland-launch-24-hour-phone-service

Bizzum

ardinn wrote: »

Whats the number?

Sorry, I was away for a while. Tin gave ya the number above.
I'd add to this that you should have in your phone the mobile number of the Fisheries staff in your area, ultimately the 24hr number will go back to the staff in the area but it can be quicker to go direct if ya know the lads involved.

Bizzum

http://www.fisheriesireland.ie/Press-releases/construction-company-convicted-following-major-river-dodder-fish-kill.html

Press release today. Some positive news.Restocking funded and penalty.

Edited to add: I see this has been posted on another thread, I didn't cop it at the time. No harm leaving it here anyway.

Bromium

Bizzum wrote: »

http://www.fisheriesireland.ie/Press-releases/construction-company-convicted-following-major-river-dodder-fish-kill.html

Press release today. Some positive news.Restocking funded and penalty.

Edited to add: I see this has been posted on another thread, I didn't cop it at the time. No harm leaving it here anyway.

If we could get something like the same for the Tolka it would be great. Does anyone know who restocks the river is it the Tolka Trout Anglers or someone else.

harry Bailey esq

i saw two very healthy looking trout in the valley in finglas yesterday morn,salmon are appearing again apparently too likewise otters.that would indicate a clean river.probably some toxic waste from up in damastown.bad form.

tin79

harry Bailey esq wrote: »

i saw two very healthy looking trout in the valley in finglas yesterday morn,salmon are appearing again apparently too likewise otters.that would indicate a clean river.probably some toxic waste from up in damastown.bad form.

What are you basing that assertion on? The toxic waste bit I mean.

Flysfisher

A miserable 2000 that's pathetic.

ytpe2r5bxkn0c1

Flysfisher wrote: »

A miserable 2000 that's pathetic.

2000 PLUS full restocking.

fiacha

Bromium wrote: »

If we could get something like the same for the Tolka it would be great. Does anyone know who restocks the river is it the Tolka Trout Anglers or someone else.

The Tolka Trout Anglers stock the river before each competition during the season. That is all they do for the river.

harry Bailey esq

tin79 wrote: »

What are you basing that assertion on? The toxic waste bit I mean.

its heavily industrialized at damastown,an educated guess really.the stretch of the river between blanch village and drumcondra has an abundance of trout,both wild and stocked.salmon are spawning again,a resident heron at glasnevin,plenty of kingfishers,eels and water voles,also otters.the river is in pretty good shape of late.

tin79

harry Bailey esq wrote: »

its heavily industrialized at damastown,an educated guess really.the stretch of the river between blanch village and drumcondra has an abundance of trout,both wild and stocked.salmon are spawning again,a resident heron at glasnevin,plenty of kingfishers,eels and water voles,also otters.the river is in pretty good shape of late.

So complete hearsay and supposition then you mean? I can pretty much assure you there are no toxic waste emissions. The water would be very heavily monitored and the factories there have very specialised waste water systems.

harry Bailey esq

tin79 wrote: »

So complete hearsay and supposition then you mean? I can pretty much assure you there are no toxic waste emissions. The water would be very heavily monitored and the factories there have very specialised waste water systems.

on the wildlife side its no hearsay,I witness it regularly.toxic waste?as i said.it was a guess on my part.how can you 'pretty much' assure me about emissions? or is that just a guess on your part?

danbrosnan

There will be a third pollution event in the tolka wait till you see...

You know why????

BECAUSE THE TOLKA ISNT IN KERRY OR MAYO!!!