The North Carolina Department of Environmental Quality’s Division of Marine Fisheries and the U.S. Fish and Wildlife Service’s Edenton…
The North Carolina Department of Environmental Quality’s Division of Marine Fisheries and the U.S. Fish and Wildlife Service’s Edenton National Fish Hatchery have joined together to enhance the Striped Bass population in the lower Cape Fear River in hopes of boosting natural reproduction in the waterway.
With financial support provided by the North Carolina Marine & Estuary Foundation, 50,000 5-inch to 8-inch striped bass were grown out at the Edenton National Fish Hatchery over the summer and released into the Cape Fear River below Lock and Dam #1 in Bladen County. As part of the stocking strategy, more than 170,000 1-inch to 2-inch striped bass were also stocked into the river earlier this spring.
Although various numbers and sizes of striped bass have been stocked into the Cape Fear River for decades, this year’s stocking is different. For the first time in the Cape Fear system, the source broodfish (spawning adults) used for hatchery production originated from the Cooper River in South Carolina.
Why is this unusual? Since 2010, broodfish used to produce striped bass for stocking into the Cape Fear River have been taken from within the river to maintain genetic consistency. However, for many years prior, the broodfish used for hatchery production were taken from the Roanoke River. The introduction of Roanoke River fish (and their genetics) likely led to the replacement of the original wild strain of Cape Fear River striped bass. Environmental conditions in these two North Carolina rivers are quite different. Additionally, striped bass populations south of Cape Hatteras typically remain in their home rivers and do not migrate to the ocean, whereas older striped bass from the Roanoke River system have been documented migrating as far north as the Gulf of Maine.
While past stockings of hatchery fish survived and grew in the Cape Fear River, biologists observed little evidence that adult fish present during spring spawning seasons were able to reproduce successfully. In an effort to reverse this trend, newly hatched striped bass fry with Cooper River genetics were transferred in April from the South Carolina Department of Natural Resources to the Edenton National Fish Hatchery, where they were grown to an advanced size and stocked into the Cape Fear River this October and November.
The Cooper system in South Carolina is home to the nearest population of river-resident striped bass. The switch to South Carolina broodstock is intended to help improve genetic diversity and promote natural reproduction by re-introducing striped bass that share a similar riverine life history and experience similar river flows and environmental conditions.
“The goal of using South Carolina genetics in the Cape Fear River striped bass population is to see if the hatchery fish will first survive to spawning age, and then to see if they can reproduce naturally,” explained Chris Stewart, biologist supervisor for the North Carolina Division of Marine Fisheries. “The test here is to determine if the differences in egg characteristics will overcome the challenges to spawning in the system.”
A moratorium on all harvest of striped bass from the Cape Fear River has been in place for more than 15 years due to the low numbers of spawning adults and limited natural reproduction. The most likely causes of the lack of naturally produced fish are inadequate fish passage at the locks and dams, which block access to historic spawning grounds and reduce flows; poor water quality and pollution from various urban and agricultural sources, as well as storm events; and predation by non-native species, such as blue catfish and flathead catfish.
“The switch to a different strain of striped bass is an interesting management approach that will hopefully result in better angling opportunities on the Cape Fear River,” remarked Chad Thomas, Executive Director of the North Carolina Marine & Estuary Foundation. “We are proud to financially support this year’s stocking efforts and look forward to learning the results from the genetic evaluation that will follow.”
