Pond Boss Forums INTRO Questions & Observations Another Selective Blue Gill Fishkill

This is similar to a post-last week, but I wanted to start a new post because this fish kill has all the earmarks of a dissolved oxygen crash, but it only killed blue gill.

My parents have a two acre pond in the middle of a cow pasture in North East Texas. The pond has not been managed at all since they moved to the property 30 years ago. It has LMB, BG, catfish and probably some GSF. The pond is spring fed from springs coming out of the side of the hill and as most water in this area is acidic and has iron in it. Over the years a lot of fish, some good size LMB included, have been caught, but like I said, not effort to manage the pond. A year ago Trent at Pond Medics came out and surveyed the pond. He said the water was ideal and that BG needed to be harvested.

This week-end, beginning on Saturday,May 30, large quantities( 100s) of blue gill were at the surface near the points where the spring entered the lake. No bass or blue-gill were observed. The water was reported to me to have been very green a few days before.

The blue gill were all size from 2 to 3 inches up to hand size. All the turtles were at the surface as well. We hand netted about 100 BG to move to my pond down the road. (Management plan called for additional BG this year)

By Sunday morning, 30 to 40 blue gill were dead. They were all sizes but included some large ones. Fish were continuing to congregate at the surface near the springs. The water was a dirty brown. These fish again were mostly blue gill, although one catfish and two or three bass were observed near the shore.

Additional fish died on Monday, but the lake appears to be returning to its regular green color. Less fish were swimming at the surface and few if any additional dead fish were observed.

A few more facts. This spring, the fields were fertilized with chicken manure from the local chicken houses. We have had a lot of rain in May--total 11.60 inches.

Weather leading up to fishkill was:

Sat 5/23 Temp 64-85 Rain .03"
Sun 5/24 64-74 Rain .97" cloudy
Mon 5/25 62-79
Tue 5/26 66-82
Wed 5/27 66-81 Rain 2.09"
Thu 5/28 57-83 partly cloudy
Fri 5/29 59-84 Sunny
Sat 5/30 57-88 Sunny fish first observed at surface
Sun 5/31 55-87 Sunny dead BG first observed; windy
Mon 6/1 62-88

So my guess is that the big rain event on Wednesday May 27 washed excess nutrients into the pond causing a phytoplankton bloom, that then died and caused an oxygen crash. Does this sound right? What causes the phytoplankton to die? Are there toxins in chicken house manure that would cause this reaction? The fields have been fertilized before with other types of fertilizer and nothing like this has ever happened. And more importantly, why just BG? All the dead fish I looked at were BG although some may have been GSF.

Chicken manure is very high in nitrogen so your ideas are probably correct. Hopefully one of the experts can comment on the toxins

How about ammonia which is very toxic at low levels? Whenever I've been around chicken manure it reeked of ammonia.

According to an article entitled "Good Poop, Bad Poop" chicken manure has more than triple the nitrogen of dairy cow manure, three times that of steer manure and double sheep manure.The analysis is generally N: 1.1, P:.80 and K: .50. Dairy cows by contrast are N: .25, P: .15 and K. .25. (Only rabbit manure is higher in N content with 2.4). The article also noted that "Poultry manure (chicken in particular) is the richest animal manure in N-P-K. Chicken manure is considered "hot" and must be composted before adding it to the garden. Otherwise, it will burn any plants it comes in contact with." http://www.plantea.com/manure.htm
The field was green so I am assuming the manure was at least partially composted.

Ammonia. I am not a chemist, only a lawyer, but according to a scholarly article on chicken manure from Clemson University:
"A portion of the nitrogen in poultry manure is in the ammonium (NH4+) form. Ammonium(NH4+) and ammonia (NH3-) can interchange rapidly depending on the pH. Ammonium will convert to ammonia at a pH that is greater than 6.5. Increasing the pH (more alkaline or less acid) increases the amount of ammonia and decreases the amount of ammonium. Most manure has a pH close to 7.0. Therefore, ammonium and a small fraction of ammonia are present. The Clemson University Agricultural Services Laboratory reports a single value for the ammonium nitrogen content of manure. This value includes both ammonical forms of nitrogen (NH4+ and
NH3-).http://www.clemson.edu/camm/Camm_p/Ch3/pch3b_00.pdf

The soils around the pond would tend to be on the acid side. So what I think this article says is than manure applied to acid soils is likely to have less ammonia that the normal manure which only has a "fraction" of ammonia present. But I will defer to the scientists. In any event, would ammonia just kill BG and not LMB? If so, have we have discovered a way to fix an BG overpopulated BG/LMB pond?

Bill,

Not a chemist here either although there are times I wish I was! And not doubting the nitrogen is high as you stated. Just made a personal observation about ammonia with chicken manure and I do know it takes very little unionized ammonia to be toxic to fish. It varies from species to species on what is the toxic level, but let's just say it's in parts per million in the water.

As far as just the bluegills, from my experience they tend to be more sensitive to stress than bass -- especially the larger bluegills. I've raised bass in cages, and I'm presently growing out bluegills and yellow perch in cages until they are large enough to sex. The bluegills seem to be the easiest to stress by far.

Could it be the bluegills are shallower or spawning, hence they got hit first by runoff? Perhaps the bass are deeper and done spawning and by the time the effluent made it to them it's been diluted?

I'm just conjecturing here so don't take it as gospel.

You may be right about ammonia. I understand a lot of chicken manure was put on the field. Plus cattle graze on it and have access to the pond. But the cattle have been a constant for 30 years.

The chicken manure came from local chicken houses. No telling what those chickens are fed and what is in the manure.

You may also be right about the BG being in the shallow water for spawning and thus be susceptible.

One other fact was my parents said the water seemed warmer than usual. I understand that warmer water holds less DO. The weather has been warm but nothing like it gets in the summer. Do you think the die-off of phytoplankton could also raise the water temperature?

There were hundreds of BG swarming around the springs. Maybe all the LMB are all gone and all we have left is a bunch of BG. No LMB or BG have been stocked since the original stocking done years ago.

Thanks for the input.

See this link and http://srac.tamu.edu/index.cfm?catid=25 then SRAC 0463 Ammonia in Fish Ponds

Dangerous short-term levels of

toxic un-ionized ammonia which

are capable of killing fish over a

few days start at about 0.6 mg/L

(ppm). Chronic exposure to toxic

un-ionized ammonia levels as low

as 0.06 mg/L (ppm) can cause gill

and kidney damage, reduction in

growth, possible brain malfunc-

tioning, and reduction in the oxygen-

carrying capacity of the fish.

Interesting article. It states that plankton algae is important in controlling ammonia levels in ponds. So the loss of the algae would not only impact DO levels, but also ammonia in the pond. Ammonia also enters the pond from the decaying of dying algae which would seem to compound the problem.