Grass Carp Used to Control Hydrilla

The bald eagle that died and was recovered in 2015 had decomposed too much to determine its cause of death, according to federal officials, but the disease related to Hydrilla could be a possible cause. The NC Wildlife Resources Com­mission continues to combat Hydrilla by stocking infested areas with triploid grass carp.

Grass Carp was used in the Weaver Creek sub-impoundment of Jordan Lake for aquatic weed control successfully so far.  Weaver Creek is a public fishing area with bank fishing, non-motor boat launch off NC 1008 near Ebenezer boat ramp, New Hill..

Here’s an update from NCWRC on what happened.

In 2013, approximately 30 acres of brittle naiad and Hydrilla were found in the Weaver Creek sub-impoundment of Jordan Lake. Both brittle naiad and Hydrilla are invasive exotic species.  Army Corp of Engineers, State Parks, NCSU, NC Division of Water Resources—Aquatic Weed Program and the Wildlife Resources Commission surveyed the rest of Jordan Lake in the fall of 2013 and did not find any additional hydrilla.

In the spring 2014, NCDWR-AWP stocked approximately 200 triploid Grass Carp in the Weaver Creek sub-impoundment to control Hydrilla within the sub-impoundment and help ensure Hydrilla did not get out into the main reservoir.

The 2014 Fall Hydrilla survey said no hydrilla was found in Weaver Creek nor in the rest of the reservoir. The Grass Carp appeared to have controlled hydrilla.

The 2015 Fall Hydrilla survey reported no hydrilla was found in Weaver Creek. No hydrilla was found in the main part of the reservoir. Hydrilla was identified in Folkners Branch Sub-impoundment.

• A full survey of Folkners Branch Sub-impoundment was not preformed.

• USACE identified less than 2 acres of hydrilla in the back of the sub-impoundment in a very shallow area

• NCDWR was going to treat this area with herbicide in 2016 and replace the grate on top of the culvert with one where Grass Carp could not escape into the main reservoir.

Jordan has very little to no submerged aquatic vegetation. Water willow, an emergent plant has been spreading throughout Jordan. It provides habitat for juvenile and adult sportfish. If any Grass Carp leave the Weaver Creek sub-impoundment, they should have minimal impacts to existing submerged aquatic vegetation in the main reservoir, especially at the level they were stocked. Water Willow is not on Grass Carp’s preferred edible list and should have no impact on the existing water willow.

The 2016 Fall Hydrilla survey found no hydrilla in Weav­er Creek or Folkners Branch Sub-impoundment. No hydrilla was found in the main part of the reservoir. No additional control efforts have been taken except for monitoring.

Fall vegetation surveys are planned for the fall of 2017.

It is important to remember that Hydrilla tubers can remain dormant for at least 6-7 years before sprouting.