Wildlife officials are investigating after an estimated 2,000 dead fish have turned up in one Grand Island lake.
An angler ice fishing on Suchs Lake reported the fish kill to the Nebraska Game and Parks Commission last week.
"We had an angler who went over there to the lake to ice fish last week, and when he started drilling holes through the ice to fish, he noticed some dead fish floating up through them," fish and wildlife biologist Brad Eifert, of the Nebraska Game and Parks Commission, said.
A preliminary investigation revealed that low oxygen levels in the water led to the die-off, Eifert said.
"We had oxygen levels below one part per million, which is lethal to most fish species," he said.
One cause for those low oxygen levels, he said, could be the recent snow fall, covering the lake's surface, making it impossible for fish to breathe.
"The heavy snow cover inhibits sunlight penetration into the water," Eifert said, "which doesn't allow the plants to photosynthesize and produce oxygen, so when that happens, the plants actually use oxygen and then the oxygen levels drop fairly rapidly."
Officials say these kinds of fish kills aren't uncommon, but they usually occur later in the winter season.
"Normally they happen later in the year," Eifert said. "We haven't had ice for very long -- about three weeks now or about a month -- and the snow cover really wasn't as thick as we sometimes get, so it was a little unusual that way."
"It's a natural occurrence, it happens throughout the Midwest and it seems to happen to a lot of the smaller lakes and ponds," Todd McCoy, director of the Grand Island Parks and Recreation Department, said.
Also adding to the problem, city officials say, is the large number of geese that inhabit the lake.
"Sometimes the waterfowl with their deposits in the lake sometimes can make the lake not as clear, and that reduces the visibility, reduces the light that gets into the lake," McCoy said. "And in the winter time when you get the ice on top of the lake, you get snow on top of the lake, and then if you have murky conditions then some of the plants don't grow, and that reduces the oxygen levels."
So how will the die-off affect fishing at the popular lake?
"There'll be less fish in there for anglers to catch this spring, and probably a lot smaller fish for people to catch," Eiefert said.
But experts say it's likely that some of the fish will survive.
"The ones that do survive will actually grow larger, and they'll actually thrive a little bit more now that they'll have a little more space, a little more oxygen for them," McCoy said.
Officials plan to go in to the lake in the spring when it thaws and remove all the dead fish, which they say could cause a strong odor for a while.
"There'll be a lot of dead, floating carcasses, but they typically decompose rather quickly," McCoy said. "The smell will be around for a week or two, and then be gone."
Eifert says replacing the possible thousands of fish lost will be costly. At about $1.50 per fish, restocking the lake could add up to about $3,000.