Patrick Walsh, who lives along the Neuse River on North Rivershore Drive, was startled to see lines of dead fish at the water’s edge Tuesday evening: “Thirty-pound skates, trout, a lot of large fish,” he said. “It’s not just the menhaden that are really oxygen sensitive.”
It’s the largest fish kill he’s seen, Walsh said, in the 18 years he’s lived here.
Travis Graves, the Lower Neuse Riverkeeper, took a boat to Fisher’s Landing, ground zero for the kill, and he agreed that it was large fish kill.
“Taking a swing in the ball park,” he said, “I’d say 200,000. If this goes down to the salt wedge in Havelock, it would be over a million.”
And it’s the second large fish kill of the year on a river where such kills don’t usually occur until August or September, Graves said, when the water has had time to get really warm.
The first kill took place on June 7 when menhaden, flounder and crabs floated to the surface. On Tuesday evening, they were floating again.
Approaching Fisher’s Landing by water on Wednesday, dead fish were floating in lines along the surface: At first the little menhaden, but soon flounder were floating upside down as were occasional bass, stiff and curled on their sides. Every so often a crab bobbed in the water.
Some bodies floated in larger circles, and receded in spots.
“What triggered this fish kill is, from the data we’ve collected so far, high water temperatures,” Graves said, “and a lot of fresh water from the recent rains causing stratification in the river. That’s where the salt water gets trapped along the bottom by the fresh water flowing over the top, and the trapped salt water becomes hypoxic. It uses up the oxygen.”
But, while heat and rain is the “spark that sets it off,” the kills find their fuel from high nutrients in the water, Graves said. Those nutrients have a number of sources, all human.
“The nutrient solution is caused by wastewater treatment plants,” he said. “They discharge nutrients in the water. Chemical fertilizers are (also) a big issue, and a lot of the CAFOs (Concentrated Animal Feeding Operation). The large poultry and swine operations land-apply their waste, then the stormwater takes all that and transports it straight into the creeks and streams that feed the river.”
As a result, large algae blooms form in the winter and spring. As the water warms the algae dies off, and the act of their decomposition removes more of the oxygen from the water, Graves said.
The menhaden, he said, float for about 24 hours before sinking to the bottom where their decomposition will only add to the oxygen-depleting problem.
During the June incident, Graves had noted that fish kills could increase as the state moves to dismantle laws protecting riparian buffers, a strip of brush and trees that current law requires be left on shorelines to absorb nutrients that otherwise would reach the water.
“Our legislators are working as we speak to dismantle the environmental laws that are in place to protect against these kind of things,” he said then. “If we don’t see some change in the oxygen levels, we might be in for a long summer.”
That summer may have arrived.
Contact Bill Hand at email@example.com , 252-635-5677, and follow him @BillHandNBSJ.