North Dakota is expected to see an end to the fish kills that have plagued the Midwest this summer.
Scott Gangl of the State Game and Fish department said North Dakota had nearly a dozen fish kills this year, with the largest being on the James River near LaMoure.
“It was really shallow and it warmed up to the point where it was killing northern pike, just by the heat alone,” he said. “They’re a cool-water fish and the temperatures got too extreme for them.”
Fish kills are generally the result of excessive heat and a lack of oxygen in the water, causing the fish to suffocate. Gangl said this summer lake temperatures rose so fast and stayed high for so long that in many cases the heat killed them before oxygen became sparse.
The kill in the James River was the first the department investigated in June. Since late July the reports of dead fish have been dying off. Gangl said neighboring states, Minnesota and South Dakota have had much worse conditions than North Dakota, where heat and drought conditions were not as severe.
“What we’ve observed so far wasn’t too extreme, but there were a few surprises. Some of them were in places that are typically along the border line anyways, and have occasional fish kills. There’s some others that were shallow, slough-type lakes that when they get warm and dry they start to dry back.”
Gangl said the department was very concerned about fish kills earlier this summer, but as the nights have grown longer and the high temperatures have subsided, North Dakota is over the hump as far as kills are concerned.
“We may still see some this summer but the future is looking a lot brighter than a month ago,” said Gangl.
Gangl said there might be silver lining to the James River fish kill, in that an invasive species, silver carp, had been found in the river last year when water was higher and may have been eradicated this year.
“We’re not sure yet if it’s going to effect it,” he said. “We’re hoping is what much less hospitable for them because they’re adapted to large rivers.”