The Conservation Officer, Cole Letourneau did conduct a field visit on 8/25/21 to confirm the presence of deceased fish in the cove in Atkinson, off of Stickney Street. He did confirm that there were a number of dead fish, approximately a 100 or more that had collected into the cove or in close proximity along the shore. He collected a dead fish and noticed that they were pale in cover but did not have any fungus or advanced decomposition and were relatively stiff from morbidity. All the fish that he reported were yellow perch; however, he had heard reports from shorefront owners of a few dead largemouth bass. He estimated that the fish had probably only been dead for maybe 3-5 days. He also had noticed that there were “live” yellow perch (smaller) in close proximity to the dead fish. Prior to this report, I also reached out to the Department of Agricultures, Pesticide Bureau (Matt Boziak) to report the fish kill since many lakefront residents were questioning the potential impacts that may have been associated with the recent herbicide treatment that was conducted on August 9, 2021 for treating the exotic species of Spiny Naiad. He explained that he was dispatching their enforcement personnel to collect fish and to bring the dead fish to the State laboratory for testing. The lab was going to test the fish for any potential presence of Diquat, the herbicide used for the treatment. The lab results are still pending and the report will be sent to the NHFGD at some time. Any questions about the herbicide product of Diquat should be referred to the Department of Agriculture since they are the permitting agency for all herbicide treatments within the State.
In addition, the environmental factors that have occurred recently and that may have played a significant role for this fish kill is the recent hurricane weather that transpired over the weekend. The extreme wind and weather conditions may have possibly increased the turbidity within the shallow coves that the fish had been located in, as well as, the exposure of extreme temperatures that we have had this entire week. These conditions could have easily resulted in an extreme decrease in dissolved oxygen within the areas of the schooling yellow perch and/or contributed to an increase in water temperature that may have exceeded the maximum temperature tolerance for yellow perch causing them to be stressed and ultimately dying. Also, it was noted that the dead fish had flared gills and most of the yellow perch looked to be the same size (4-6 “), which is often associated with a dissolved oxygen problem causing stress in fish. Larger fish succumb to dissolved oxygen deficiencies faster than smaller fish. So in conclusion, I think that recent extreme weather conditions in addition to possible decaying plant/organic matter churned from the lake bottom created a “perfect storm” to diminish water quality conditions that became stressful for fish that were located in the lake’s shallow depths and isolated coves. Hopefully, since the Conservation officer noticed that there were live yellow perch within the same cove of the dead fish, that the water quality degradation was an isolated incident and hopefully will not continue. I believe that this weeks “heat wave” is supposed to diminish over the weekend, which should restore normal water quality conditions within the waterbody. Also, any questions about other water quality issues (cyanobacteria) should be referred to the Department of Environmental Services. I hope you find this information helpful.
NH Fish and Game Department
Environmental Review Coordinator,