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.
Last edited by BillB; 06/02/09 02:34 PM.
