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Cause Of Floating Dead Fish In Maryland Waters Remains A Mystery

BALTIMORE (WJZ)—As quickly as it started, a fish kill in Baltimore's Inner Harbor appears to be easing.

Alex DeMetrick reports what triggered the sudden die-off is still guesswork.

The city moved fast to remove the die-off, with skim boats collecting hauls more commonly seen on commercial fishing boats and as menhaden and shad died from the Inner Harbor out to the Key Bridge.

"And some of them were struggling at the surface, looking like they were trying to catch their breath. It was sad to see; it was just so widespread," said John Tapscott, Chesapeake Bay Foundation.

Tapscott captains the Chesapeake Bay Foundation's educational boat in the harbor. Tuesday's trip spotted far fewer dead fish but none of the usual triggers of die-offs, which normally happen later in the year in far warmer weather.

"We didn't really see any classic sign and even the oxygen yesterday, there was enough oxygen in the water for the fish to breathe," Tapscott said.

"I think it's pretty certain some kind of combination of nutrients, runoff and organic matter," said Dr. Donald Boesch, University of Maryland Center for Environmental Science.

Which takes rain to move off the hard surfaces of urban areas into the harbor and bay.

"People fertilizing lawns and gardens, animal waste," Boesch said.

Causing algae blooms that turn water brown during hot weather, choking off oxygen other life needs. But that's not happening--at least on the surface.

But wind could churn up dead water from below.

"So if you get a wind condition, it will take that material that consumes a lot of oxygen up to the surface," Boesch said.

But it's not clear if that happened this time.

"I think scientists are puzzled as to why. Everyone wants to know. I'd love to know why," Tapscott said.

Maryland's Department of the Environment says there are no signs of a toxic spill or a classic algae bloom. Answers from water tests will take at least a week.

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