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#75525 - 09/14/06 11:17 AM Trout Mortality in muddy water???
Michael Ebaugh Offline
Lunker

Registered: 01/10/06
Posts: 62
Loc: Michigan
Stats
1/3 acre pond (50 yrs. old)
Size = 60 x 225 ft. long
excavateded in Aug. 2005
Depths range from 3ft - 12ft
Avg. depth = 7 ft
Two wells -
1)2" steel -artesian w/ 8 gpm
2)2" steel - 1/2 hp pumped well - 25 gpm
Dual diffuser 1/4hp aeration linked to thermostatically controlled switch - On at 60 or LOWER and off at 62
Pond temp currently - low 60's
200, 10-11" Rainbow trout stocked in April 2006
Have grown to 16" inchers!
2 weeks ago- lost 7 trout- 3 floaters, 4 sinkers
in a 4 day period following 1.33 inches rain on one day and .7" the next (according to web weather, as I live 130 miles away!)
Water was much murkier when I arrive and found the dead trout than is typically. Since excavation- we are getting some sand / soil erosion during heavy rains like this

QUESTION:
How sensitive are rainbow trout to muddy water / suspended soils in the water? I have zero knowledge base on this issue. Anyone out there who knows about this??

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#75526 - 09/14/06 12:13 PM Re: Trout Mortality in muddy water???
Cecil Baird1 Offline
Hall of Fame

Lunker

Registered: 08/08/02
Posts: 20043
Loc: Northeastern Indiana
Mike,

First of all I apologize profusely for not sending you the D.O./temp meter. Everytime I thought about it I was in the middle of something and couldn't put it in the box. Part of the problem was I needed to change the membrane too, and needed to get some distilled water to do so. Kept forgetting to get some! I assume there is no need for it now, now that the hot weather is over? I'm really sorry!

As far as turbid water it does irritate their gills a little but if it's not constant they can handle it. Your well flow should flush the turbidity over time. Afterall it does happen in the wild. The larger the fish the better they are able to handle the turbidity, as the larger fish have thicker gill filaments. Fry, and fingerlings can develop gill infection if the water has particles in it. It's known as environmental gill disease.

Also something that I have noticed which concurs with what a fish farmer said is, there are times when you will get some mortality after a heavy rain for some unclear reason. Not sure why but, it's possible the rain washes in some aeromonas bacteria from the soil. However the mortality is usually isolated and doesn't last.

If possible you should try and do something to keep run off out of your pond. Or least prevent erosion that washes in soil. I had my ponds designed with a birm around the edges. Burlap over grass seeding has worked great for me, just after the pond is first excavated until the grass takes hold.

Now that the hot weather is over how many survivors do you think you have? Be aware that some of your dead trout will decompose on the bottom and never float up.
_________________________
If pigs could fly bacon would be harder to come by and there would be a lot of damaged trees.







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#75527 - 09/14/06 05:36 PM Re: Trout Mortality in muddy water???
Michael Ebaugh Offline
Lunker

Registered: 01/10/06
Posts: 62
Loc: Michigan
Thanks for the thoughful reply! Wondered about the D.O. meter, but assumed you just got busy. Not sure I need it now that we survived a pretty nasty hot summer with perhaps 10+ days of 90's and even a few high 90's days.

In sorting this out, the 8 trout deaths, after your input I can now conclude the following:

1) I need to put some burlap or maybe that black weed barrier stuff temporarily on the open dirt banks(I'll seed next spring as well)

2) the wash out factor got screwed up because my brother attached a 5" pvs s- curve to the output pipe to attempt to start rasining the water levels another 6" - so zero outflow (I have since yanked it off- so there is continous outflow (maybe 15 gpm or so)

3)I am reasonably confident that the death rate was limited to less than 10, since my brother saw zero mortalities on 8/28, the web weather history reports the two heavy rain days were 8/29 and 8/30 and I arrive on 8/30 dound 7 dead and three days later he was up there agin and found 1 additional dead. So- there wasn't much un-monitored time and little rotting time with 60-65 degree water etc.

4) Good news is that we estimate over 100-120 survivors, given the very active feeding.

5) the other mistake we made was to up the feeding schedule during the hottest time (late July / early August) to 3+ lbs. The we dropped it to 2.75lbs(1.7% tbw / daily per chart) When I found the dead trout, I dropped it 20% to about 2.25 lbs. /day and given yoru previous post on this- it is likely to increase health. I am guessing the diabetes dynamic kicked in. I am planning on dropping it another 25% next week when I go up again to perhaps 1.7lbs or less / day as water temps are likely to have dropped to about 58-60.

I think these changes, burlap near edges, cut back feeding and KEEP output flowing will re-stabilize the pond. Thanks for helping me to put all the pieces together. I appreciate your knowledge, helpful info and support!!!

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#75528 - 09/14/06 09:45 PM Re: Trout Mortality in muddy water???
Cecil Baird1 Offline
Hall of Fame

Lunker

Registered: 08/08/02
Posts: 20043
Loc: Northeastern Indiana
Only one thing more... I wouldn't necessarily drop feeding as the water cools. It's actually going into their peak metabolism in that range so they will be hungrier and could grow 2 to 3 inches before winter if you feed them enough. Additionally cooler water eliminates your D.O. potential problems as it holds more D.O. and as temps drop unionized ammonia does too although total nitrogen levels can go up.
_________________________
If pigs could fly bacon would be harder to come by and there would be a lot of damaged trees.







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#75529 - 09/15/06 12:36 PM Re: Trout Mortality in muddy water???
Michael Ebaugh Offline
Lunker

Registered: 01/10/06
Posts: 62
Loc: Michigan
Great advice - I think my "learning curve" mistake was feeding them at max. rate per chart (1.4% tbw) (I'm using the North Carolina Cooperative Extension Commercial Trout Aquacutlure chart http://www.ces.ncsu.edu/copubs/ag/aqua/trout/015/
As I jsut looked at the chart, I realize I was feeding them based on a smaller size. Now they are 16", I've been feeding at 1.5%, versus what it tells me should be 1.1% tbw / day- ouch!! I am sure that negatively contributed to the large algae bloom I ahd in late July!

Trout Feed Chart I picked up a few years back that seems scientifically grounded) as a general rule. The mistake was maintaining that highest level of feed rate during the peak heat -where the pond temps eeked up to 73 surface temp and 70-72 in some depths *precariously near mortality temp!) AT that time I should have dropped feed rate way back as I beleive this extra feed is literally a waste and goes right through them.

So- now that pond temps are between 58-62 range (I'll measure this weekend) you are reminding me they are at their peak metabolic growth range. Fabulous reminder! And I should keep the feed rate to the chart rate of .9 %tbw / day. Ther eis always alot to learn here!
THANKS for your wonderful expertise and guidance! You're the best!!!

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#75530 - 09/15/06 01:37 PM Re: Trout Mortality in muddy water???
Cecil Baird1 Offline
Hall of Fame

Lunker

Registered: 08/08/02
Posts: 20043
Loc: Northeastern Indiana
Mike,

Thanks for the kind words but I'm still learning too just a little farther along then you are.

In one of my aquaculture books it's said that sometimes at peak metabolic rate the trout want more to eat then is advised and you can give it too them for extra growth. I'll have to find it. I know you can overfeed fish but there are times in my trout pond where they just can't seem to get enough to eat.
_________________________
If pigs could fly bacon would be harder to come by and there would be a lot of damaged trees.







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