Oakley Corners Pond Fishkill Investigation (2009)
Survey Number: 709005
Survey Dates: March 25, 2009
Neighbors called to report dead fish right after ice out. All fish appeared to have died several weeks or more prior to this investigation. The likely cause of the die-off was "winter-kill." Winterkill events are a result of low oxygen condition in a pond. After a pond freezes water can no longer re-oxygenate at the surface. Through the winter aerobic decay of organic matter, along with respiration of plants and animals in the pond, reduces the limited oxygen supply under the ice. Complete exhaustion of oxygen can occur depending on inflow/outflow, pond depth, organic matter buildup, duration of ice cover, and the depth of snow cover. A heavy snow cover will exacerbate the situation by blocking light penetration and shutting down any photosynthesis which would otherwise add oxygen to the water. This condition can render some ponds incapable of supporting any fish through the winter, in some years. Some fish, like bullheads, are more tolerant of low oxygen levels than other fish.
Approximately 40% of the pond shoreline was examined and 87 dead fish were observed (approximately 45% largemouth bass and 55% bluegill sunfish). One fish that was out on some of the remaining ice appeared to be a pickerel but definitive identification was not possible.
This fishkill event appeared to be far less severe than a previous event that occurred in the early 1990's. At that time the shoreline was littered with 100's - 1000's of dead fish. No dead tiger musky were observed during this year's assessment, and this could reflect upon poor recruitment that likely has occurred since largemouth bass numbers have increased. Anecdotal reports from anglers indicate that bass fishing has been very good for the past decade. This partial winter-kill event may allow for better survival of stocked tiger musky over the next few years but will likely impact the quality of fishing for bass. All but one of the dead bass observed was greater than 12 inches long. Three dead bass were in the 18-20 inch size range while the majority were between 14 and 16 inches long.