State environmental officials reported on January 11, 2013, hundreds of thousands of dead Atlantic Menhaden fish at Masonboro Island in Wilmington NC.
The dead fish are along the Masonboro Island beaches and in the water, stretching over a one-mile area from the Mason Inlet jetty to Loosins Creek, officials with the NC Department of Environment and Natural Resources reported.
NC’s Division of Coastal Management, which manages Masonboro Island through its Coastal Reserve and National Estuarine Research Reserve Program, was first notified of the fish kill by a member of the public. The NC Marine Patrol also responded to a report from the public.
The Atlantic Menhaden appear to have clustered by the thousands in a narrow area at Loosins Creek, causing dissolved oxygen levels in the water to plummet to nearly zero in less than one hour, killing the fish. This situation has been previously observed in winter months, and occurs when the menhaden begin to tighten their school, possibly due to the presence of predators.
Coastal Management maintains a System-wide Monitoring Program, or SWMP, monitoring station in the area where the fish kill occurred. The station continuously monitors the water for dissolved oxygen levels, temperature and pH levels, among other data. The monitoring station recorded a significant drop in dissolved oxygen levels in the early morning hours of January 8th. The Masonboro Island station is part of a national network of monitoring stations in coastal estuaries.
“This may be the first time we have had continuous monitoring of water quality in an area at the exact time of a fish kill,” said Jim Gregson, Surface Water Protection supervisor for the state Division of Water Quality. “The data recorded by Coastal Management’s monitoring station was a big help in determining the cause of this event.”
Source: Michele Walker, ncdenr.gov