Published 1:47 pm Saturday, August 2, 2008
fish kill in a creek
Lack of oxygen
is likely reason,
By MIKE VOSS
Extremely low levels of dissolved oxygen are the likely cause of a fish kill that occurred in Blounts Creek, according to a spokeswoman with the Pamlico River Rapid Response Team.
The kill occurred near Cotton Patch Landing sometime late Thursday or early Friday, said Jill Paxson, the team’s supervisor, on Friday afternoon. About 900 juvenile Atlantic menhaden were killed, she said.
Paxson said water samples taken at the fish-kill site indicated dissolved-oxygen levels as low as 0.49 milligrams per liter.
Paxson said the team observed no lesions on the dead fish, but it sent some of the dead fish to a state laboratory in Raleigh to be analyzed. Some previous fish kills, which included fish with lesions, in the Pamlico and Neuse rivers, were caused by pfiesteria piscicida, a small organism, according to JoAnn Burkholder and other researchers at N.C. State University. They said pfiesteria piscicida could cause lesions on fish.
Other factors such as parasites, bacteria and viruses can cause lesions or sores on fish, according to scientists.
Pamlico-Tar Riverkeeper Heather Jacobs said she was notified of the fish kill about 8 a.m. Friday. In turn, Jacobs said, she notified the team. Jacobs said she likely will not visit the fish-kill site.
Summer weather conditions in North Carolina, and most other Southern states, create water-quality conditions that can be severely stressful, if not fatal, to estuarine fish species, particularly the Atlantic menhaden that inhabits coastal areas, according to a DWQ fact sheet.
So far this year, the team as received five reports of fish kills on Blounts Creek, four of them since May, Paxson said. Overall, the team has received 13 calls reporting fish kills throughout the Pamlico River estuary this year, she said.
Last year, sometime around Aug. 11, a fish kill involving multiple species near the Cotton Patch Landing area of Blounts Creek likely was caused, at least in part, by low levels of dissolved oxygen in the water, according to Jacobs, who went to that fish-kill site. Jacobs estimated she saw 50,000 to 100,000 dead menhaden, ranging in size from 2 inches long to 6 inches long. Aside from menhaden, most of the other dead species — and the largest of the dead fish — were found farther up Blounts Creek near Herring Run, Jacobs reported.
The fish kill covered an estimated 2-mile section of the creek, Jacobs reported.
The rapid-response team, first formed in June 1998, is based in Washington. It is responsible for monitoring water quality conditions in the lower Pamlico River watershed. The team’s primary mission is rapid evaluation of acute water quality-related events like fish kills and algal blooms. During routine operations, the team performs regular monitoring duties along the river, collecting twice-monthly ambient water quality monitoring at long term sites and works collaboratively with other research agencies in monitoring field parameters (dissolved oxygen, pH, temperature, salinity) to track conditions.
Confirmed fish kills of 25 or more fish are recorded by the state’s rapid-response teams or other investigators.
In 2007, there were five reported fish kills in the Pamlico-Tar River Basin and 27 reported fish kills in 12 of the state’s 17 river basins. Nine of those 27 fish kills occurred in estuarine waters. Eighteen were freshwater kills, according to the N.C. Division of Water Quality.
Although most fish kills in 2007 occurred at freshwater locations, the majority of that year’s fish mortality occurred in estuarine waters, according to DWQ’s Web site. Mortality counts for fish kills in 2007 ranged from 31 to 100,000.
From 1996 through 2007, there were 86 reported fish kills in the Pamlico-Tar River Basin and 543 reported fish kills across the state. From 1996 through 2007, the number of reported fish kills has ranged from one in 2005 to 23 in 2001. During that period, the Roanoke River Basin experienced 10 fish kills.
From 1996 through 2007, the Pamlico-Tar River Basin was third-highest in fish kills with 86. During that period, the Neuse River Basin experienced 177 fish kills, with the Cape Fear River Basin experiencing 111 fish kills.
The Pamlico River Rapid Response Team is on call 24 hours a day, seven days a week. The team has a hotline anyone may call to report fish kills or algal blooms. The hotline number 1-877-337-2383. The team also may be reached at (252) 948-3999.