Supplied photo courtesy of Hope Sutton
Thousands of Atlantic menhaden died and washed up onto Masonboro Island after clustering in a narrow area of Loosins Creek on the backside of Masonboro Island.
A one-mile stretch of coastline from the Masonboro Inlet jetty south to Loosins Creek on the backside of Masonboro Island was littered with dead menhaden last week.
Members of the public alerted both the North Carolina Marine Patrol and North Carolina’s division of Coastal Management, which manages the Coastal Reserve and the National Estuarine Research Reserve Program, of the phenomenon on Jan. 9.
The fish are Atlantic menhaden. North Carolina Department of Environment and Natural Resources -officials said it appeared the fish clustered by the thousands in a narrow area of Loosins Creek. This behavior had been previously observed in winter months, and is thought to be a defensive response to the presence of predators.
“Menhaden are used to the open ocean environment,” said Hope Sutton, southern sites manager for the North Carolina Coastal Reserve. “They’re not used to running into dead ends. That’s not what they’re programmed to deal with.”
Unfortunately for the menhaden, the high concentration of fish in the narrow area where they clustered almost entirely depleted the available oxygen in the water in less than an hour.
The North Carolina Division of Water Quality keeps records of fish kills, and reports 17 in 2012. Seven of those were in freshwater, and nine in estuaries. Sutton said it’s unclear exactly how many fish were killed, but others are estimating more than a 100,000. Only two of the 17 reported fish kills in 2012 boasted such numbers.
Sutton said the majority of fish kills occur due to contaminants in the water. Situations like the one on Jan. 9 — in which a school of fish perished — are rare, but a similar situation occurred several years ago near Mason’s Inlet.
A nationwide water monitoring station located in the area where the fish kill occurred picked up the abrupt drop in oxygen levels. Maintained by the North Carolina Division of Coastal Management, the program known as the System-Wide Monitoring Program, or SWMP, has two Masonboro area stations that provide water quality readings.
“A lot of water monitoring done is in response to something, like heavy rains,” Sutton said. “Our stations are there, gathering information, all the time.”
In a press release from NCDENR, surface water protection supervisor for North Carolina Division of Water Quality Jim Gregson pointed out the benefit of these stations.
“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. The data recorded by coastal management’s monitoring station was a big help in determining the cause of this event,” Gregson said.
On Jan. 15, Sutton said there were still a large number of dead menhaden floating around the waters surrounding Masonboro Island, and thousands of gulls and hundreds of pelicans could be seen feeding on them.
“It’s sort of a circle of life kind of thing,” Sutton said. “Menhanden, as far as where they fit into the ecosystem, are fish that are there to feed other critters. In this case, it just means that there’s going to be a lot of gulls and pelicans with nutrients stored up so they can make more babies this year.”
State officials have yet to release any public health advisories related to the dead menhaden, but Sutton warned that visitors to Masonboro Island may encounter an unpleasant odor.
“It’s pretty ripe over there right now,” Sutton said. “With the temperatures we’ve had recently. … It is so stinky.”