North Carolina Wildlife Resources Commission fisheries biologists have been assessing fish populations in coastal rivers this week to determine the impacts of low dissolved oxygen following Hurricane Irene.

They have found that with the exception of the Cape Fear River basin, which suffered little impact to its fish populations, many coastal North Carolina rivers are experiencing oxygen levels too low to sustain fish populations.

As oxygen levels remain depressed, biologists expect fish kills will continue.

"These fish kills, while unfortunate, are naturally occurring events that typically follow a major hurricane," said Chad Thomas, NCWRC's coastal region fisheries supervisor. "Given time, the fish populations in the impacted rivers will recover, as they did after Hurricane Isabel in 2003."

As of last Thursday (Sept. 1), the rivers experiencing low dissolved-oxygen levels and reported fish kills were:

• Roanoke River, from Williamston downstream to the mouth of the river at Albemarle Sound and adjacent creeks including the Cashie River, with widespread fish kills throughout.
• Chowan River from the North Carolina/Virginia state line to just north of Holiday Island near Edenton and adjacent creeks except the Meherrin River.
• Tar River from Old Sparta to Washington and adjacent creeks with a major fish kill reported in the Greenville area.
• Neuse River from just below Kinston to New Bern and adjacent creeks with widespread fish kills in the New Bern area.
• The Trent, New, White Oak, Newport and Scuppernong rivers.

Biologists report storm-water runoff, in conjunction with swamp waters high in organic materials, causes a significant decrease in dissolved oxygen.

"It is important to note that low dissolved oxygen is the main culprit in these fish kills, rather than contaminants, pollution or other factors," Thomas said.

After dissolved oxygen levels begin to recover, Commission staff will evaluate the extent of impacts to fish communities. In October, biologists will use electrofishing equipment to determine the numbers and types of fish that remain within these areas.

"Our assessments will ramp up during spring 2012 to document levels of spawning fish that have returned to impacted areas," Thomas said. "We will also evaluate the success of native fish reproduction next year by sampling for juvenile fishes in the fall of 2012."

From these findings, Commission biologists will implement recovery strategies for impacted populations.

"We saw these types of fish kills when Isabel blew through the state back in 2003, and we've learned a lot from our experience dealing with storm's aftermath," Thomas said. "Past experiences have shown that our coastal river systems are very resilient to tropical events."

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